KVM x86 fixes for 6.18:
- Expand the KVM_PRE_FAULT_MEMORY selftest to add a regression test for the
bug fixed by commit 3ccbf6f470 ("KVM: x86/mmu: Return -EAGAIN if userspace
deletes/moves memslot during prefault")
- Don't try to get PMU capabbilities from perf when running a CPU with hybrid
CPUs/PMUs, as perf will rightly WARN.
- Rework KVM_CAP_GUEST_MEMFD_MMAP (newly introduced in 6.18) into a more
generic KVM_CAP_GUEST_MEMFD_FLAGS
- Add a guest_memfd INIT_SHARED flag and require userspace to explicitly set
said flag to initialize memory as SHARED, irrespective of MMAP. The
behavior merged in 6.18 is that enabling mmap() implicitly initializes
memory as SHARED, which would result in an ABI collision for x86 CoCo VMs
as their memory is currently always initialized PRIVATE.
- Allow mmap() on guest_memfd for x86 CoCo VMs, i.e. on VMs with private
memory, to enable testing such setups, i.e. to hopefully flush out any
other lurking ABI issues before 6.18 is officially released.
- Add testcases to the guest_memfd selftest to cover guest_memfd without MMAP,
and host userspace accesses to mmap()'d private memory.
GICv5 hosts optionally include FEAT_GCIE_LEGACY, which allows them to
execute GICv3-based VMs on GICv5 hardware. Update the GICv3
documentation to reflect this now that GICv3 guests are supports on
compatible GICv5 hosts.
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
KVM rejects calls to KVM_{GET,SET}_VCPU_EVENTS for an uninitialized vCPU
as of commit cc96679f3c03 ("KVM: arm64: Prevent access to vCPU events
before init"). Update the corresponding API documentation.
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Add a guest_memfd flag to allow userspace to state that the underlying
memory should be configured to be initialized as shared, and reject user
page faults if the guest_memfd instance's memory isn't shared. Because
KVM doesn't yet support in-place private<=>shared conversions, all
guest_memfd memory effectively follows the initial state.
Alternatively, KVM could deduce the initial state based on MMAP, which for
all intents and purposes is what KVM currently does. However, implicitly
deriving the default state based on MMAP will result in a messy ABI when
support for in-place conversions is added.
For x86 CoCo VMs, which don't yet support MMAP, memory is currently private
by default (otherwise the memory would be unusable). If MMAP implies
memory is shared by default, then the default state for CoCo VMs will vary
based on MMAP, and from userspace's perspective, will change when in-place
conversion support is added. I.e. to maintain guest<=>host ABI, userspace
would need to immediately convert all memory from shared=>private, which
is both ugly and inefficient. The inefficiency could be avoided by adding
a flag to state that memory is _private_ by default, irrespective of MMAP,
but that would lead to an equally messy and hard to document ABI.
Bite the bullet and immediately add a flag to control the default state so
that the effective behavior is explicit and straightforward.
Fixes: 3d3a04fad2 ("KVM: Allow and advertise support for host mmap() on guest_memfd files")
Cc: David Hildenbrand <david@redhat.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Tested-by: Ackerley Tng <ackerleytng@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20251003232606.4070510-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Rework the not-yet-released KVM_CAP_GUEST_MEMFD_MMAP into a more generic
KVM_CAP_GUEST_MEMFD_FLAGS capability so that adding new flags doesn't
require a new capability, and so that developers aren't tempted to bundle
multiple flags into a single capability.
Note, kvm_vm_ioctl_check_extension_generic() can only return a 32-bit
value, but that limitation can be easily circumvented by adding e.g.
KVM_CAP_GUEST_MEMFD_FLAGS2 in the unlikely event guest_memfd supports more
than 32 flags.
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Tested-by: Ackerley Tng <ackerleytng@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20251003232606.4070510-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Pull x86 kvm updates from Paolo Bonzini:
"Generic:
- Rework almost all of KVM's exports to expose symbols only to KVM's
x86 vendor modules (kvm-{amd,intel}.ko and PPC's kvm-{pr,hv}.ko
x86:
- Rework almost all of KVM x86's exports to expose symbols only to
KVM's vendor modules, i.e. to kvm-{amd,intel}.ko
- Add support for virtualizing Control-flow Enforcement Technology
(CET) on Intel (Shadow Stacks and Indirect Branch Tracking) and AMD
(Shadow Stacks).
It is worth noting that while SHSTK and IBT can be enabled
separately in CPUID, it is not really possible to virtualize them
separately. Therefore, Intel processors will really allow both
SHSTK and IBT under the hood if either is made visible in the
guest's CPUID. The alternative would be to intercept
XSAVES/XRSTORS, which is not feasible for performance reasons
- Fix a variety of fuzzing WARNs all caused by checking L1 intercepts
when completing userspace I/O. KVM has already committed to
allowing L2 to to perform I/O at that point
- Emulate PERF_CNTR_GLOBAL_STATUS_SET for PerfMonV2 guests, as the
MSR is supposed to exist for v2 PMUs
- Allow Centaur CPU leaves (base 0xC000_0000) for Zhaoxin CPUs
- Add support for the immediate forms of RDMSR and WRMSRNS, sans full
emulator support (KVM should never need to emulate the MSRs outside
of forced emulation and other contrived testing scenarios)
- Clean up the MSR APIs in preparation for CET and FRED
virtualization, as well as mediated vPMU support
- Clean up a pile of PMU code in anticipation of adding support for
mediated vPMUs
- Reject in-kernel IOAPIC/PIT for TDX VMs, as KVM can't obtain EOI
vmexits needed to faithfully emulate an I/O APIC for such guests
- Many cleanups and minor fixes
- Recover possible NX huge pages within the TDP MMU under read lock
to reduce guest jitter when restoring NX huge pages
- Return -EAGAIN during prefault if userspace concurrently
deletes/moves the relevant memslot, to fix an issue where
prefaulting could deadlock with the memslot update
x86 (AMD):
- Enable AVIC by default for Zen4+ if x2AVIC (and other prereqs) is
supported
- Require a minimum GHCB version of 2 when starting SEV-SNP guests
via KVM_SEV_INIT2 so that invalid GHCB versions result in immediate
errors instead of latent guest failures
- Add support for SEV-SNP's CipherText Hiding, an opt-in feature that
prevents unauthorized CPU accesses from reading the ciphertext of
SNP guest private memory, e.g. to attempt an offline attack. This
feature splits the shared SEV-ES/SEV-SNP ASID space into separate
ranges for SEV-ES and SEV-SNP guests, therefore a new module
parameter is needed to control the number of ASIDs that can be used
for VMs with CipherText Hiding vs. how many can be used to run
SEV-ES guests
- Add support for Secure TSC for SEV-SNP guests, which prevents the
untrusted host from tampering with the guest's TSC frequency, while
still allowing the the VMM to configure the guest's TSC frequency
prior to launch
- Validate the XCR0 provided by the guest (via the GHCB) to avoid
bugs resulting from bogus XCR0 values
- Save an SEV guest's policy if and only if LAUNCH_START fully
succeeds to avoid leaving behind stale state (thankfully not
consumed in KVM)
- Explicitly reject non-positive effective lengths during SNP's
LAUNCH_UPDATE instead of subtly relying on guest_memfd to deal with
them
- Reload the pre-VMRUN TSC_AUX on #VMEXIT for SEV-ES guests, not the
host's desired TSC_AUX, to fix a bug where KVM was keeping a
different vCPU's TSC_AUX in the host MSR until return to userspace
KVM (Intel):
- Preparation for FRED support
- Don't retry in TDX's anti-zero-step mitigation if the target
memslot is invalid, i.e. is being deleted or moved, to fix a
deadlock scenario similar to the aforementioned prefaulting case
- Misc bugfixes and minor cleanups"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (142 commits)
KVM: x86: Export KVM-internal symbols for sub-modules only
KVM: x86: Drop pointless exports of kvm_arch_xxx() hooks
KVM: x86: Move kvm_intr_is_single_vcpu() to lapic.c
KVM: Export KVM-internal symbols for sub-modules only
KVM: s390/vfio-ap: Use kvm_is_gpa_in_memslot() instead of open coded equivalent
KVM: VMX: Make CR4.CET a guest owned bit
KVM: selftests: Verify MSRs are (not) in save/restore list when (un)supported
KVM: selftests: Add coverage for KVM-defined registers in MSRs test
KVM: selftests: Add KVM_{G,S}ET_ONE_REG coverage to MSRs test
KVM: selftests: Extend MSRs test to validate vCPUs without supported features
KVM: selftests: Add support for MSR_IA32_{S,U}_CET to MSRs test
KVM: selftests: Add an MSR test to exercise guest/host and read/write
KVM: x86: Define AMD's #HV, #VC, and #SX exception vectors
KVM: x86: Define Control Protection Exception (#CP) vector
KVM: x86: Add human friendly formatting for #XM, and #VE
KVM: SVM: Enable shadow stack virtualization for SVM
KVM: SEV: Synchronize MSR_IA32_XSS from the GHCB when it's valid
KVM: SVM: Pass through shadow stack MSRs as appropriate
KVM: SVM: Update dump_vmcb with shadow stack save area additions
KVM: nSVM: Save/load CET Shadow Stack state to/from vmcb12/vmcb02
...
Pull kvm updates from Paolo Bonzini:
"This excludes the bulk of the x86 changes, which I will send
separately. They have two not complex but relatively unusual conflicts
so I will wait for other dust to settle.
guest_memfd:
- Add support for host userspace mapping of guest_memfd-backed memory
for VM types that do NOT use support KVM_MEMORY_ATTRIBUTE_PRIVATE
(which isn't precisely the same thing as CoCo VMs, since x86's
SEV-MEM and SEV-ES have no way to detect private vs. shared).
This lays the groundwork for removal of guest memory from the
kernel direct map, as well as for limited mmap() for
guest_memfd-backed memory.
For more information see:
- commit a6ad54137a ("Merge branch 'guest-memfd-mmap' into HEAD")
- guest_memfd in Firecracker:
https://github.com/firecracker-microvm/firecracker/tree/feature/secret-hiding
- direct map removal:
https://lore.kernel.org/all/20250221160728.1584559-1-roypat@amazon.co.uk/
- mmap support:
https://lore.kernel.org/all/20250328153133.3504118-1-tabba@google.com/
ARM:
- Add support for FF-A 1.2 as the secure memory conduit for pKVM,
allowing more registers to be used as part of the message payload.
- Change the way pKVM allocates its VM handles, making sure that the
privileged hypervisor is never tricked into using uninitialised
data.
- Speed up MMIO range registration by avoiding unnecessary RCU
synchronisation, which results in VMs starting much quicker.
- Add the dump of the instruction stream when panic-ing in the EL2
payload, just like the rest of the kernel has always done. This
will hopefully help debugging non-VHE setups.
- Add 52bit PA support to the stage-1 page-table walker, and make use
of it to populate the fault level reported to the guest on failing
to translate a stage-1 walk.
- Add NV support to the GICv3-on-GICv5 emulation code, ensuring
feature parity for guests, irrespective of the host platform.
- Fix some really ugly architecture problems when dealing with debug
in a nested VM. This has some bad performance impacts, but is at
least correct.
- Add enough infrastructure to be able to disable EL2 features and
give effective values to the EL2 control registers. This then
allows a bunch of features to be turned off, which helps cross-host
migration.
- Large rework of the selftest infrastructure to allow most tests to
transparently run at EL2. This is the first step towards enabling
NV testing.
- Various fixes and improvements all over the map, including one BE
fix, just in time for the removal of the feature.
LoongArch:
- Detect page table walk feature on new hardware
- Add sign extension with kernel MMIO/IOCSR emulation
- Improve in-kernel IPI emulation
- Improve in-kernel PCH-PIC emulation
- Move kvm_iocsr tracepoint out of generic code
RISC-V:
- Added SBI FWFT extension for Guest/VM with misaligned delegation
and pointer masking PMLEN features
- Added ONE_REG interface for SBI FWFT extension
- Added Zicbop and bfloat16 extensions for Guest/VM
- Enabled more common KVM selftests for RISC-V
- Added SBI v3.0 PMU enhancements in KVM and perf driver
s390:
- Improve interrupt cpu for wakeup, in particular the heuristic to
decide which vCPU to deliver a floating interrupt to.
- Clear the PTE when discarding a swapped page because of CMMA; this
bug was introduced in 6.16 when refactoring gmap code.
x86 selftests:
- Add #DE coverage in the fastops test (the only exception that's
guest- triggerable in fastop-emulated instructions).
- Fix PMU selftests errors encountered on Granite Rapids (GNR),
Sierra Forest (SRF) and Clearwater Forest (CWF).
- Minor cleanups and improvements
x86 (guest side):
- For the legacy PCI hole (memory between TOLUD and 4GiB) to UC when
overriding guest MTRR for TDX/SNP to fix an issue where ACPI
auto-mapping could map devices as WB and prevent the device drivers
from mapping their devices with UC/UC-.
- Make kvm_async_pf_task_wake() a local static helper and remove its
export.
- Use native qspinlocks when running in a VM with dedicated
vCPU=>pCPU bindings even when PV_UNHALT is unsupported.
Generic:
- Remove a redundant __GFP_NOWARN from kvm_setup_async_pf() as
__GFP_NOWARN is now included in GFP_NOWAIT.
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (178 commits)
KVM: s390: Fix to clear PTE when discarding a swapped page
KVM: arm64: selftests: Cover ID_AA64ISAR3_EL1 in set_id_regs
KVM: arm64: selftests: Remove a duplicate register listing in set_id_regs
KVM: arm64: selftests: Cope with arch silliness in EL2 selftest
KVM: arm64: selftests: Add basic test for running in VHE EL2
KVM: arm64: selftests: Enable EL2 by default
KVM: arm64: selftests: Initialize HCR_EL2
KVM: arm64: selftests: Use the vCPU attr for setting nr of PMU counters
KVM: arm64: selftests: Use hyp timer IRQs when test runs at EL2
KVM: arm64: selftests: Select SMCCC conduit based on current EL
KVM: arm64: selftests: Provide helper for getting default vCPU target
KVM: arm64: selftests: Alias EL1 registers to EL2 counterparts
KVM: arm64: selftests: Create a VGICv3 for 'default' VMs
KVM: arm64: selftests: Add unsanitised helpers for VGICv3 creation
KVM: arm64: selftests: Add helper to check for VGICv3 support
KVM: arm64: selftests: Initialize VGICv3 only once
KVM: arm64: selftests: Provide kvm_arch_vm_post_create() in library code
KVM: selftests: Add ex_str() to print human friendly name of exception vectors
selftests/kvm: remove stale TODO in xapic_state_test
KVM: selftests: Handle Intel Atom errata that leads to PMU event overcount
...
KVM x86 CET virtualization support for 6.18
Add support for virtualizing Control-flow Enforcement Technology (CET) on
Intel (Shadow Stacks and Indirect Branch Tracking) and AMD (Shadow Stacks).
CET is comprised of two distinct features, Shadow Stacks (SHSTK) and Indirect
Branch Tracking (IBT), that can be utilized by software to help provide
Control-flow integrity (CFI). SHSTK defends against backward-edge attacks
(a.k.a. Return-oriented programming (ROP)), while IBT defends against
forward-edge attacks (a.k.a. similarly CALL/JMP-oriented programming (COP/JOP)).
Attackers commonly use ROP and COP/JOP methodologies to redirect the control-
flow to unauthorized targets in order to execute small snippets of code,
a.k.a. gadgets, of the attackers choice. By chaining together several gadgets,
an attacker can perform arbitrary operations and circumvent the system's
defenses.
SHSTK defends against backward-edge attacks, which execute gadgets by modifying
the stack to branch to the attacker's target via RET, by providing a second
stack that is used exclusively to track control transfer operations. The
shadow stack is separate from the data/normal stack, and can be enabled
independently in user and kernel mode.
When SHSTK is is enabled, CALL instructions push the return address on both the
data and shadow stack. RET then pops the return address from both stacks and
compares the addresses. If the return addresses from the two stacks do not
match, the CPU generates a Control Protection (#CP) exception.
IBT defends against backward-edge attacks, which branch to gadgets by executing
indirect CALL and JMP instructions with attacker controlled register or memory
state, by requiring the target of indirect branches to start with a special
marker instruction, ENDBRANCH. If an indirect branch is executed and the next
instruction is not an ENDBRANCH, the CPU generates a #CP. Note, ENDBRANCH
behaves as a NOP if IBT is disabled or unsupported.
From a virtualization perspective, CET presents several problems. While SHSTK
and IBT have two layers of enabling, a global control in the form of a CR4 bit,
and a per-feature control in user and kernel (supervisor) MSRs (U_CET and S_CET
respectively), the {S,U}_CET MSRs can be context switched via XSAVES/XRSTORS.
Practically speaking, intercepting and emulating XSAVES/XRSTORS is not a viable
option due to complexity, and outright disallowing use of XSTATE to context
switch SHSTK/IBT state would render the features unusable to most guests.
To limit the overall complexity without sacrificing performance or usability,
simply ignore the potential virtualization hole, but ensure that all paths in
KVM treat SHSTK/IBT as usable by the guest if the feature is supported in
hardware, and the guest has access to at least one of SHSTK or IBT. I.e. allow
userspace to advertise one of SHSTK or IBT if both are supported in hardware,
even though doing so would allow a misbehaving guest to use the unadvertised
feature.
Fully emulating SHSTK and IBT would also require significant complexity, e.g.
to track and update branch state for IBT, and shadow stack state for SHSTK.
Given that emulating large swaths of the guest code stream isn't necessary on
modern CPUs, punt on emulating instructions that meaningful impact or consume
SHSTK or IBT. However, instead of doing nothing, explicitly reject emulation
of such instructions so that KVM's emulator can't be abused to circumvent CET.
Disable support for SHSTK and IBT if KVM is configured such that emulation of
arbitrary guest instructions may be required, specifically if Unrestricted
Guest (Intel only) is disabled, or if KVM will emulate a guest.MAXPHYADDR that
is smaller than host.MAXPHYADDR.
Lastly disable SHSTK support if shadow paging is enabled, as the protections
for the shadow stack are novel (shadow stacks require Writable=0,Dirty=1, so
that they can't be directly modified by software), i.e. would require
non-trivial support in the Shadow MMU.
Note, AMD CPUs currently only support SHSTK. Explicitly disable IBT support
so that KVM doesn't over-advertise if AMD CPUs add IBT, and virtualizing IBT
in SVM requires KVM modifications.
KVM x86 changes for 6.18
- Don't (re)check L1 intercepts when completing userspace I/O to fix a flaw
where a misbehaving usersepace (a.k.a. syzkaller) could swizzle L1's
intercepts and trigger a variety of WARNs in KVM.
- Emulate PERF_CNTR_GLOBAL_STATUS_SET for PerfMonV2 guests, as the MSR is
supposed to exist for v2 PMUs.
- Allow Centaur CPU leaves (base 0xC000_0000) for Zhaoxin CPUs.
- Clean up KVM's vector hashing code for delivering lowest priority IRQs.
- Clean up the fastpath handler code to only handle IPIs and WRMSRs that are
actually "fast", as opposed to handling those that KVM _hopes_ are fast, and
in the process of doing so add fastpath support for TSC_DEADLINE writes on
AMD CPUs.
- Clean up a pile of PMU code in anticipation of adding support for mediated
vPMUs.
- Add support for the immediate forms of RDMSR and WRMSRNS, sans full
emulator support (KVM should never need to emulate the MSRs outside of
forced emulation and other contrived testing scenarios).
- Clean up the MSR APIs in preparation for CET and FRED virtualization, as
well as mediated vPMU support.
- Rejecting a fully in-kernel IRQCHIP if EOIs are protected, i.e. for TDX VMs,
as KVM can't faithfully emulate an I/O APIC for such guests.
- KVM_REQ_MSR_FILTER_CHANGED into a generic RECALC_INTERCEPTS in preparation
for mediated vPMU support, as KVM will need to recalculate MSR intercepts in
response to PMU refreshes for guests with mediated vPMUs.
- Misc cleanups and minor fixes.
Add a KVM-defined ONE_REG register, KVM_REG_GUEST_SSP, to let userspace
save and restore the guest's Shadow Stack Pointer (SSP). On both Intel
and AMD, SSP is a hardware register that can only be accessed by software
via dedicated ISA (e.g. RDSSP) or via VMCS/VMCB fields (used by hardware
to context switch SSP at entry/exit). As a result, SSP doesn't fit in
any of KVM's existing interfaces for saving/restoring state.
Internally, treat SSP as a fake/synthetic MSR, as the semantics of writes
to SSP follow that of several other Shadow Stack MSRs, e.g. the PLx_SSP
MSRs. Use a translation layer to hide the KVM-internal MSR index so that
the arbitrary index doesn't become ABI, e.g. so that KVM can rework its
implementation as needed, so long as the ONE_REG ABI is maintained.
Explicitly reject accesses to SSP if the vCPU doesn't have Shadow Stack
support to avoid running afoul of ignore_msrs, which unfortunately applies
to host-initiated accesses (which is a discussion for another day). I.e.
ensure consistent behavior for KVM-defined registers irrespective of
ignore_msrs.
Link: https://lore.kernel.org/all/aca9d389-f11e-4811-90cf-d98e345a5cc2@intel.com
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-14-seanjc@google.com
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Enable KVM_{G,S}ET_ONE_REG uAPIs so that userspace can access MSRs and
other non-MSR registers through them, along with support for
KVM_GET_REG_LIST to enumerate support for KVM-defined registers.
This is in preparation for allowing userspace to read/write the guest SSP
register, which is needed for the upcoming CET virtualization support.
Currently, two types of registers are supported: KVM_X86_REG_TYPE_MSR and
KVM_X86_REG_TYPE_KVM. All MSRs are in the former type; the latter type is
added for registers that lack existing KVM uAPIs to access them. The "KVM"
in the name is intended to be vague to give KVM flexibility to include
other potential registers. More precise names like "SYNTHETIC" and
"SYNTHETIC_MSR" were considered, but were deemed too confusing (e.g. can
be conflated with synthetic guest-visible MSRs) and may put KVM into a
corner (e.g. if KVM wants to change how a KVM-defined register is modeled
internally).
Enumerate only KVM-defined registers in KVM_GET_REG_LIST to avoid
duplicating KVM_GET_MSR_INDEX_LIST, and so that KVM can return _only_
registers that are fully supported (KVM_GET_REG_LIST is vCPU-scoped, i.e.
can be precise, whereas KVM_GET_MSR_INDEX_LIST is system-scoped).
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Link: https://lore.kernel.org/all/20240219074733.122080-18-weijiang.yang@intel.com [1]
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Explicitly document that the behavior of KVM_SET_PIT2 strictly conforms
to the Intel 8254 PIT hardware specification, specifically that a write of
'0' adheres to the spec's definition that a programmed count of '0' is
converted to the maximum possible value (2^16). E.g. an unaware userspace
might attempt to validate that KVM_GET_PIT2 returns the exact state set
via KVM_SET_PIT2, and be surprised when the returned count is 65536, not 0.
Add a references to the Intel 8254 PIT datasheet that will hopefully stay
fresh for some time (the internet isn't exactly brimming with copies of
the 8254 datasheet).
Link: https://lore.kernel.org/all/CANypQFbEySjKOFLqtFFf2vrEe=NBr7XJfbkjQhqXuZGg7Rpoxw@mail.gmail.com
Signed-off-by: Jiaming Zhang <r772577952@gmail.com>
Link: https://lore.kernel.org/r/20250905174736.260694-1-r772577952@gmail.com
[sean: add context Link, drop local APIC change, massage changelog accordingly]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Now that all the x86 and arm64 plumbing for mmap() on guest_memfd is in
place, allow userspace to set GUEST_MEMFD_FLAG_MMAP and advertise support
via a new capability, KVM_CAP_GUEST_MEMFD_MMAP.
The availability of this capability is determined per architecture, and
its enablement for a specific guest_memfd instance is controlled by the
GUEST_MEMFD_FLAG_MMAP flag at creation time.
Update the KVM API documentation to detail the KVM_CAP_GUEST_MEMFD_MMAP
capability, the associated GUEST_MEMFD_FLAG_MMAP, and provide essential
information regarding support for mmap in guest_memfd.
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shivank Garg <shivankg@amd.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20250729225455.670324-22-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM/arm64 changes for 6.17, round #1
- Host driver for GICv5, the next generation interrupt controller for
arm64, including support for interrupt routing, MSIs, interrupt
translation and wired interrupts.
- Use FEAT_GCIE_LEGACY on GICv5 systems to virtualize GICv3 VMs on
GICv5 hardware, leveraging the legacy VGIC interface.
- Userspace control of the 'nASSGIcap' GICv3 feature, allowing
userspace to disable support for SGIs w/o an active state on hardware
that previously advertised it unconditionally.
- Map supporting endpoints with cacheable memory attributes on systems
with FEAT_S2FWB and DIC where KVM no longer needs to perform cache
maintenance on the address range.
- Nested support for FEAT_RAS and FEAT_DoubleFault2, allowing the guest
hypervisor to inject external aborts into an L2 VM and take traps of
masked external aborts to the hypervisor.
- Convert more system register sanitization to the config-driven
implementation.
- Fixes to the visibility of EL2 registers, namely making VGICv3 system
registers accessible through the VGIC device instead of the ONE_REG
vCPU ioctls.
- Various cleanups and minor fixes.
KVM x86 misc changes for 6.17
- Prevert the host's DEBUGCTL.FREEZE_IN_SMM (Intel only) when running the
guest. Failure to honor FREEZE_IN_SMM can bleed host state into the guest.
- Explicitly check vmcs12.GUEST_DEBUGCTL on nested VM-Enter (Intel only) to
prevent L1 from running L2 with features that KVM doesn't support, e.g. BTF.
- Intercept SPEC_CTRL on AMD if the MSR shouldn't exist according to the
vCPU's CPUID model.
- Rework the MSR interception code so that the SVM and VMX APIs are more or
less identical.
- Recalculate all MSR intercepts from the "source" on MSR filter changes, and
drop the dedicated "shadow" bitmaps (and their awful "max" size defines).
- WARN and reject loading kvm-amd.ko instead of panicking the kernel if the
nested SVM MSRPM offsets tracker can't handle an MSR.
- Advertise support for LKGS (Load Kernel GS base), a new instruction that's
loosely related to FRED, but is supported and enumerated independently.
- Fix a user-triggerable WARN that syzkaller found by stuffing INIT_RECEIVED,
a.k.a. WFS, and then putting the vCPU into VMX Root Mode (post-VMXON). Use
the same approach KVM uses for dealing with "impossible" emulation when
running a !URG guest, and simply wait until KVM_RUN to detect that the vCPU
has architecturally impossible state.
- Add KVM_X86_DISABLE_EXITS_APERFMPERF to allow disabling interception of
APERF/MPERF reads, so that a "properly" configured VM can "virtualize"
APERF/MPERF (with many caveats).
- Reject KVM_SET_TSC_KHZ if vCPUs have been created, as changing the "default"
frequency is unsupported for VMs with a "secure" TSC, and there's no known
use case for changing the default frequency for other VM types.
Enable ring-based dirty memory tracking on riscv:
- Enable CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL as riscv is weakly
ordered.
- Set KVM_DIRTY_LOG_PAGE_OFFSET for the ring buffer's physical page
offset.
- Add a check to kvm_vcpu_kvm_riscv_check_vcpu_requests for checking
whether the dirty ring is soft full.
To handle vCPU requests that cause exits to userspace, modified the
`kvm_riscv_check_vcpu_requests` to return a value (currently only
returns 0 or 1).
Signed-off-by: Quan Zhou <zhouquan@iscas.ac.cn>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20e116efb1f7aff211dd8e3cf8990c5521ed5f34.1749810735.git.zhouquan@iscas.ac.cn
Signed-off-by: Anup Patel <anup@brainfault.org>
* kvm-arm64/vgic-v4-ctl:
: Userspace control of nASSGIcap, courtesy of Raghavendra Rao Ananta
:
: Allow userspace to decide if support for SGIs without an active state is
: advertised to the guest, allowing VMs from GICv3-only hardware to be
: migrated to to GICv4.1 capable machines.
Documentation: KVM: arm64: Describe VGICv3 registers writable pre-init
KVM: arm64: selftests: Add test for nASSGIcap attribute
KVM: arm64: vgic-v3: Allow userspace to write GICD_TYPER2.nASSGIcap
KVM: arm64: vgic-v3: Allow access to GICD_IIDR prior to initialization
KVM: arm64: vgic-v3: Consolidate MAINT_IRQ handling
KVM: arm64: Disambiguate support for vSGIs v. vLPIs
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
* kvm-arm64/el2-reg-visibility:
: Fixes to EL2 register visibility, courtesy of Marc Zyngier
:
: - Expose EL2 VGICv3 registers via the VGIC attributes accessor, not the
: KVM_{GET,SET}_ONE_REG ioctls
:
: - Condition visibility of FGT registers on the presence of FEAT_FGT in
: the VM
KVM: arm64: selftest: vgic-v3: Add basic GICv3 sysreg userspace access test
KVM: arm64: Enforce the sorting of the GICv3 system register table
KVM: arm64: Clarify the check for reset callback in check_sysreg_table()
KVM: arm64: vgic-v3: Fix ordering of ICH_HCR_EL2
KVM: arm64: Document registers exposed via KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS
KVM: arm64: selftests: get-reg-list: Add base EL2 registers
KVM: arm64: selftests: get-reg-list: Simplify feature dependency
KVM: arm64: Advertise FGT2 registers to userspace
KVM: arm64: Condition FGT registers on feature availability
KVM: arm64: Expose GICv3 EL2 registers via KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS
KVM: arm64: Let GICv3 save/restore honor visibility attribute
KVM: arm64: Define helper for ICH_VTR_EL2
KVM: arm64: Define constant value for ICC_SRE_EL2
KVM: arm64: Don't advertise ICH_*_EL2 registers through GET_ONE_REG
KVM: arm64: Make RVBAR_EL2 accesses UNDEF
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
KVM TDX fixes for 6.16
- Fix a formatting goof in the TDX documentation.
- Reject KVM_SET_TSC_KHZ for guests with a protected TSC (currently only TDX).
- Ensure struct kvm_tdx_capabilities fields that are not explicitly set by KVM
are zeroed.
We never documented which GICv3 registers are available for save/restore
via the KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS interface.
Let's take the opportunity of adding the EL2 registers to document the whole
thing in one go.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250714122634.3334816-12-maz@kernel.org
[ oliver: fix trailing whitespace ]
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Proper testing greatly simplifies both patch development and review,
but it can be unclear what kind of userspace or guest support
should accompany new features. Clarify maintainer expectations
in terms of testing expectations; additionally, list the cases in
which open-source userspace support is pretty much a necessity and
its absence can only be mitigated by selftests.
While these ideas have long been followed implicitly by KVM contributors
and maintainers, formalize them in writing to provide consistent (though
not universal) guidelines.
Suggested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
While the file could stand a larger update, these are the bare minimum changes
needed to make it more widely applicable.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reject KVM_SET_TSC_KHZ vCPU ioctl if guest's TSC is protected and not
changeable by KVM, and update the documentation to reflect it.
For such TSC protected guests, e.g. TDX guests, typically the TSC is
configured once at VM level before any vCPU are created and remains
unchanged during VM's lifetime. KVM provides the KVM_SET_TSC_KHZ VM
scope ioctl to allow the userspace VMM to configure the TSC of such VM.
After that the userspace VMM is not supposed to call the KVM_SET_TSC_KHZ
vCPU scope ioctl anymore when creating the vCPU.
The de facto userspace VMM Qemu does this for TDX guests. The upcoming
SEV-SNP guests with Secure TSC should follow.
Note, TDX support hasn't been fully released as of the "buggy" commit,
i.e. there is no established ABI to break.
Fixes: adafea1106 ("KVM: x86: Add infrastructure for secure TSC")
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>
Link: https://lore.kernel.org/r/71bbdf87fdd423e3ba3a45b57642c119ee2dd98c.1752444335.git.kai.huang@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reject the KVM_SET_TSC_KHZ VM ioctl when vCPUs have been created and
update the documentation to reflect it.
The VM scope KVM_SET_TSC_KHZ ioctl is used to set up the default TSC
frequency that all subsequently created vCPUs can use. It is only
intended to be called before any vCPU is created. Allowing it to be
called after that only results in confusion but nothing good.
Note this is an ABI change. But currently in Qemu (the de facto
userspace VMM) only TDX uses this VM ioctl, and it is only called once
before creating any vCPU, therefore the risk of breaking userspace is
pretty low.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>
Link: https://lore.kernel.org/r/135a35223ce8d01cea06b6cef30bfe494ec85827.1752444335.git.kai.huang@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Allow a guest to read the physical IA32_APERF and IA32_MPERF MSRs
without interception.
The IA32_APERF and IA32_MPERF MSRs are not virtualized. Writes are not
handled at all. The MSR values are not zeroed on vCPU creation, saved
on suspend, or restored on resume. No accommodation is made for
processor migration or for sharing a logical processor with other
tasks. No adjustments are made for non-unit TSC multipliers. The MSRs
do not account for time the same way as the comparable PMU events,
whether the PMU is virtualized by the traditional emulation method or
the new mediated pass-through approach.
Nonetheless, in a properly constrained environment, this capability
can be combined with a guest CPUID table that advertises support for
CPUID.6:ECX.APERFMPERF[bit 0] to induce a Linux guest to report the
effective physical CPU frequency in /proc/cpuinfo. Moreover, there is
no performance cost for this capability.
Signed-off-by: Jim Mattson <jmattson@google.com>
Link: https://lore.kernel.org/r/20250530185239.2335185-3-jmattson@google.com
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250626001225.744268-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Introduce a new KVM capability to expose to the userspace whether
cacheable mapping of PFNMAP is supported.
The ability to safely do the cacheable mapping of PFNMAP is contingent
on S2FWB and ARM64_HAS_CACHE_DIC. S2FWB allows KVM to avoid flushing
the D cache, ARM64_HAS_CACHE_DIC allows KVM to avoid flushing the icache
and turns icache_inval_pou() into a NOP. The cap would be false if
those requirements are missing and is checked by making use of
kvm_arch_supports_cacheable_pfnmap.
This capability would allow userspace to discover the support.
It could for instance be used by userspace to prevent live-migration
across FWB and non-FWB hosts.
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Jason Gunthorpe <jgg@nvidia.com>
CC: Oliver Upton <oliver.upton@linux.dev>
CC: David Hildenbrand <david@redhat.com>
Suggested-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Donald Dutile <ddutile@redhat.com>
Signed-off-by: Ankit Agrawal <ankita@nvidia.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20250705071717.5062-7-ankita@nvidia.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Allow userspace to advertise TDG.VP.VMCALL subfunctions that the
kernel also supports. For each output register of GetTdVmCallInfo's
leaf 1, add two fields to KVM_TDX_CAPABILITIES: one for kernel-supported
TDVMCALLs (userspace can set those blindly) and one for user-supported
TDVMCALLs (userspace can set those if it knows how to handle them).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Exit to userspace for TDG.VP.VMCALL<GetTdVmCallInfo> via KVM_EXIT_TDX,
to allow userspace to provide information about the support of
TDVMCALLs when r12 is 1 for the TDVMCALLs beyond the GHCI base API.
GHCI spec defines the GHCI base TDVMCALLs: <GetTdVmCallInfo>, <MapGPA>,
<ReportFatalError>, <Instruction.CPUID>, <#VE.RequestMMIO>,
<Instruction.HLT>, <Instruction.IO>, <Instruction.RDMSR> and
<Instruction.WRMSR>. They must be supported by VMM to support TDX guests.
For GetTdVmCallInfo
- When leaf (r12) to enumerate TDVMCALL functionality is set to 0,
successful execution indicates all GHCI base TDVMCALLs listed above are
supported.
Update the KVM TDX document with the set of the GHCI base APIs.
- When leaf (r12) to enumerate TDVMCALL functionality is set to 1, it
indicates the TDX guest is querying the supported TDVMCALLs beyond
the GHCI base TDVMCALLs.
Exit to userspace to let userspace set the TDVMCALL sub-function bit(s)
accordingly to the leaf outputs. KVM could set the TDVMCALL bit(s)
supported by itself when the TDVMCALLs don't need support from userspace
after returning from userspace and before entering guest. Currently, no
such TDVMCALLs implemented, KVM just sets the values returned from
userspace.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
[Adjust userspace API. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Handle TDVMCALL for GetQuote to generate a TD-Quote.
GetQuote is a doorbell-like interface used by TDX guests to request VMM
to generate a TD-Quote signed by a service hosting TD-Quoting Enclave
operating on the host. A TDX guest passes a TD Report (TDREPORT_STRUCT) in
a shared-memory area as parameter. Host VMM can access it and queue the
operation for a service hosting TD-Quoting enclave. When completed, the
Quote is returned via the same shared-memory area.
KVM only checks the GPA from the TDX guest has the shared-bit set and drops
the shared-bit before exiting to userspace to avoid bleeding the shared-bit
into KVM's exit ABI. KVM forwards the request to userspace VMM (e.g. QEMU)
and userspace VMM queues the operation asynchronously. KVM sets the return
code according to the 'ret' field set by userspace to notify the TDX guest
whether the request has been queued successfully or not. When the request
has been queued successfully, the TDX guest can poll the status field in
the shared-memory area to check whether the Quote generation is completed
or not. When completed, the generated Quote is returned via the same
buffer.
Add KVM_EXIT_TDX as a new exit reason to userspace. Userspace is
required to handle the KVM exit reason as the initial support for TDX,
by reentering KVM to ensure that the TDVMCALL is complete. While at it,
add a note that KVM_EXIT_HYPERCALL also requires reentry with KVM_RUN.
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Mikko Ylinen <mikko.ylinen@linux.intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
[Adjust userspace API. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull UML updates from Johannes Berg:
"The only really new thing is the long-standing seccomp work
(originally from 2021!). Wven if it still isn't enabled by default due
to security concerns it can still be used e.g. for tests.
- remove obsolete network transports
- remove PCI IO port support
- start adding seccomp-based process handling instead of ptrace"
* tag 'uml-for-linux-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (29 commits)
um: remove "extern" from implementation of sigchld_handler
um: fix unused variable warning
um: fix SECCOMP 32bit xstate register restore
um: pass FD for memory operations when needed
um: Add SECCOMP support detection and initialization
um: Implement kernel side of SECCOMP based process handling
um: Track userspace children dying in SECCOMP mode
um: Add helper functions to get/set state for SECCOMP
um: Add stub side of SECCOMP/futex based process handling
um: Move faultinfo extraction into userspace routine
um: vector: Use mac_pton() for MAC address parsing
um: vector: Clean up and modernize log messages
um: chan_kern: use raw spinlock for irqs_to_free_lock
MAINTAINERS: remove obsolete file entry in TUN/TAP DRIVER
um: Fix tgkill compile error on old host OSes
um: stop using PCI port I/O
um: Remove legacy network transport infrastructure
um: vector: Eliminate the dependency on uml_net
um: Remove obsolete legacy network transports
um/asm: Replace "REP; NOP" with PAUSE mnemonic
...
Pull hyperv updates from Wei Liu:
- Support for Virtual Trust Level (VTL) on arm64 (Roman Kisel)
- Fixes for Hyper-V UIO driver (Long Li)
- Fixes for Hyper-V PCI driver (Michael Kelley)
- Select CONFIG_SYSFB for Hyper-V guests (Michael Kelley)
- Documentation updates for Hyper-V VMBus (Michael Kelley)
- Enhance logging for hv_kvp_daemon (Shradha Gupta)
* tag 'hyperv-next-signed-20250602' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (23 commits)
Drivers: hv: Always select CONFIG_SYSFB for Hyper-V guests
Drivers: hv: vmbus: Add comments about races with "channels" sysfs dir
Documentation: hyperv: Update VMBus doc with new features and info
PCI: hv: Remove unnecessary flex array in struct pci_packet
Drivers: hv: Remove hv_alloc/free_* helpers
Drivers: hv: Use kzalloc for panic page allocation
uio_hv_generic: Align ring size to system page
uio_hv_generic: Use correct size for interrupt and monitor pages
Drivers: hv: Allocate interrupt and monitor pages aligned to system page boundary
arch/x86: Provide the CPU number in the wakeup AP callback
x86/hyperv: Fix APIC ID and VP index confusion in hv_snp_boot_ap()
PCI: hv: Get vPCI MSI IRQ domain from DeviceTree
ACPI: irq: Introduce acpi_get_gsi_dispatcher()
Drivers: hv: vmbus: Introduce hv_get_vmbus_root_device()
Drivers: hv: vmbus: Get the IRQ number from DeviceTree
dt-bindings: microsoft,vmbus: Add interrupt and DMA coherence properties
arm64, x86: hyperv: Report the VTL the system boots in
arm64: hyperv: Initialize the Virtual Trust Level field
Drivers: hv: Provide arch-neutral implementation of get_vtl()
Drivers: hv: Enable VTL mode for arm64
...
KVM SVM changes for 6.16:
- Wait for target vCPU to acknowledge KVM_REQ_UPDATE_PROTECTED_GUEST_STATE to
fix a race between AP destroy and VMRUN.
- Decrypt and dump the VMSA in dump_vmcb() if debugging enabled for the VM.
- Add support for ALLOWED_SEV_FEATURES.
- Add #VMGEXIT to the set of handlers special cased for CONFIG_RETPOLINE=y.
- Treat DEBUGCTL[5:2] as reserved to pave the way for virtualizing features
that utilize those bits.
- Don't account temporary allocations in sev_send_update_data().
- Add support for KVM_CAP_X86_BUS_LOCK_EXIT on SVM, via Bus Lock Threshold.
KVM/riscv changes for 6.16
- Add vector registers to get-reg-list selftest
- VCPU reset related improvements
- Remove scounteren initialization from VCPU reset
- Support VCPU reset from userspace using set_mpstate() ioctl
KVM/arm64 updates for 6.16
* New features:
- Add large stage-2 mapping support for non-protected pKVM guests,
clawing back some performance.
- Add UBSAN support to the standalone EL2 object used in nVHE/hVHE and
protected modes.
- Enable nested virtualisation support on systems that support it
(yes, it has been a long time coming), though it is disabled by
default.
* Improvements, fixes and cleanups:
- Large rework of the way KVM tracks architecture features and links
them with the effects of control bits. This ensures correctness of
emulation (the data is automatically extracted from the published
JSON files), and helps dealing with the evolution of the
architecture.
- Significant changes to the way pKVM tracks ownership of pages,
avoiding page table walks by storing the state in the hypervisor's
vmemmap. This in turn enables the THP support described above.
- New selftest checking the pKVM ownership transition rules
- Fixes for FEAT_MTE_ASYNC being accidentally advertised to guests
even if the host didn't have it.
- Fixes for the address translation emulation, which happened to be
rather buggy in some specific contexts.
- Fixes for the PMU emulation in NV contexts, decoupling PMCR_EL0.N
from the number of counters exposed to a guest and addressing a
number of issues in the process.
- Add a new selftest for the SVE host state being corrupted by a
guest.
- Keep HCR_EL2.xMO set at all times for systems running with the
kernel at EL2, ensuring that the window for interrupts is slightly
bigger, and avoiding a pretty bad erratum on the AmpereOne HW.
- Add workaround for AmpereOne's erratum AC04_CPU_23, which suffers
from a pretty bad case of TLB corruption unless accesses to HCR_EL2
are heavily synchronised.
- Add a per-VM, per-ITS debugfs entry to dump the state of the ITS
tables in a human-friendly fashion.
- and the usual random cleanups.
Starting in the 6.15 kernel, VMBus interrupts are automatically
assigned away from a CPU that is being taken offline. Add documentation
describing this case.
Also add details of Hyper-V behavior when the primary channel of
a VMBus device is closed as the result of unbinding the device's
driver. This behavior has not changed, but it was not previously
documented.
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/20250520044435.7734-1-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250520044435.7734-1-mhklinux@outlook.com>
* kvm-arm64/nv-nv:
: .
: Flick the switch on the NV support by adding the missing piece
: in the form of the VNCR page management. From the cover letter:
:
: "This is probably the most interesting bit of the whole NV adventure.
: So far, everything else has been a walk in the park, but this one is
: where the real fun takes place.
:
: With FEAT_NV2, most of the NV support revolves around tricking a guest
: into accessing memory while it tries to access system registers. The
: hypervisor's job is to handle the context switch of the actual
: registers with the state in memory as needed."
: .
KVM: arm64: nv: Release faulted-in VNCR page from mmu_lock critical section
KVM: arm64: nv: Handle TLBI S1E2 for VNCR invalidation with mmu_lock held
KVM: arm64: nv: Hold mmu_lock when invalidating VNCR SW-TLB before translating
KVM: arm64: Document NV caps and vcpu flags
KVM: arm64: Allow userspace to request KVM_ARM_VCPU_EL2*
KVM: arm64: nv: Remove dead code from ERET handling
KVM: arm64: nv: Plumb TLBI S1E2 into system instruction dispatch
KVM: arm64: nv: Add S1 TLB invalidation primitive for VNCR_EL2
KVM: arm64: nv: Program host's VNCR_EL2 to the fixmap address
KVM: arm64: nv: Handle VNCR_EL2 invalidation from MMU notifiers
KVM: arm64: nv: Handle mapping of VNCR_EL2 at EL2
KVM: arm64: nv: Handle VNCR_EL2-triggered faults
KVM: arm64: nv: Add userspace and guest handling of VNCR_EL2
KVM: arm64: nv: Add pseudo-TLB backing VNCR_EL2
KVM: arm64: nv: Don't adjust PSTATE.M when L2 is nesting
KVM: arm64: nv: Move TLBI range decoding to a helper
KVM: arm64: nv: Snapshot S1 ASID tagging information during walk
KVM: arm64: nv: Extract translation helper from the AT code
KVM: arm64: nv: Allocate VNCR page when required
arm64: sysreg: Add layout for VNCR_EL2
Signed-off-by: Marc Zyngier <maz@kernel.org>
Add a toggleable VM capability to reset the VCPU from userspace by
setting MP_STATE_INIT_RECEIVED through IOCTL.
Reset through a mp_state to avoid adding a new IOCTL.
Do not reset on a transition from STOPPED to RUNNABLE, because it's
better to avoid side effects that would complicate userspace adoption.
The MP_STATE_INIT_RECEIVED is not a permanent mp_state -- IOCTL resets
the VCPU while preserving the original mp_state -- because we wouldn't
gain much from having a new state it in the rest of KVM, but it's a very
non-standard use of the IOCTL.
Signed-off-by: Radim Krčmář <rkrcmar@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250515143723.2450630-5-rkrcmar@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Add support for KVM_CAP_X86_BUS_LOCK_EXIT on SVM CPUs with Bus Lock
Threshold, which is close enough to VMX's Bus Lock Detection VM-Exit to
allow reusing KVM_CAP_X86_BUS_LOCK_EXIT.
The biggest difference between the two features is that Threshold is
fault-like, whereas Detection is trap-like. To allow the guest to make
forward progress, Threshold provides a per-VMCB counter which is
decremented every time a bus lock occurs, and a VM-Exit is triggered if
and only if the counter is '0'.
To provide Detection-like semantics, initialize the counter to '0', i.e.
exit on every bus lock, and when re-executing the guilty instruction, set
the counter to '1' to effectively step past the instruction.
Note, in the unlikely scenario that re-executing the instruction doesn't
trigger a bus lock, e.g. because the guest has changed memory types or
patched the guilty instruction, the bus lock counter will be left at '1',
i.e. the guest will be able to do a bus lock on a different instruction.
In a perfect world, KVM would ensure the counter is '0' if the guest has
made forward progress, e.g. if RIP has changed. But trying to close that
hole would incur non-trivial complexity, for marginal benefit; the intent
of KVM_CAP_X86_BUS_LOCK_EXIT is to allow userspace rate-limit bus locks,
not to allow for precise detection of problematic guest code. And, it's
simply not feasible to fully close the hole, e.g. if an interrupt arrives
before the original instruction can re-execute, the guest could step past
a different bus lock.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Manali Shukla <manali.shukla@amd.com>
Link: https://lore.kernel.org/r/20250502050346.14274-5-manali.shukla@amd.com
[sean: fix typo in comment]
Signed-off-by: Sean Christopherson <seanjc@google.com>
