michael/linux
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

x86/cpufeatures: Add X86_FEATURE_X2AVIC_EXT

Browse Source 
Add CPUID feature bit for x2AVIC extension that enables AMD SVM to
support up to 4096 vCPUs in x2AVIC mode. The primary change is in the
size of the AVIC Physical ID table, which can now go up to 8 contiguous
4k pages. The number of pages allocated is controlled by the maximum
APIC ID for a guest, and that controls the number of pages to allocate
for the AVIC Physical ID table. AVIC hardware is enhanced to look up
Physical ID table entries for vCPUs > 512 for locating the target APIC
backing page and the host APIC ID of the physical core on which the
guest vCPU is running.

Signed-off-by: Naveen N Rao (AMD) <naveen@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/e5c9c471ab99a130bf9b728b77050ab308cf8624.1757009416.git.naveen@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Naveen N Rao
2025-09-05 00:03:06 +05:30
committed by Sean Christopherson
parent 54ffe74cc4
commit 5d0316e25d
2 changed files with 2 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/cpufeatures.h
View File

@@ -500,6 +500,7 @@
#define X86_FEATURE_IBPB_EXIT_TO_USER (21*32+14) /* Use IBPB on exit-to-userspace, see VMSCAPE bug */
#define X86_FEATURE_ABMC (21*32+15) /* Assignable Bandwidth Monitoring Counters */
#define X86_FEATURE_MSR_IMM (21*32+16) /* MSR immediate form instructions */
#define X86_FEATURE_X2AVIC_EXT (21*32+17) /* AMD SVM x2AVIC support for 4k vCPUs */
/*
* BUG word(s)

1
arch/x86/kernel/cpu/scattered.c
View File

@@ -49,6 +49,7 @@ static const struct cpuid_bit cpuid_bits[] = {
{ X86_FEATURE_PROC_FEEDBACK, CPUID_EDX, 11, 0x80000007, 0 },
{ X86_FEATURE_AMD_FAST_CPPC, CPUID_EDX, 15, 0x80000007, 0 },
{ X86_FEATURE_MBA, CPUID_EBX, 6, 0x80000008, 0 },
{ X86_FEATURE_X2AVIC_EXT, CPUID_ECX, 6, 0x8000000a, 0 },
{ X86_FEATURE_COHERENCY_SFW_NO, CPUID_EBX, 31, 0x8000001f, 0 },
{ X86_FEATURE_SMBA, CPUID_EBX, 2, 0x80000020, 0 },
{ X86_FEATURE_BMEC, CPUID_EBX, 3, 0x80000020, 0 },