Commit 2ff8fb1e authored by Zhao Liu's avatar Zhao Liu Committed by Sean Christopherson
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KVM: x86: Advertise AVX10.2 CPUID to userspace 



Bump up the maximum supported AVX10 version and enumerate AVX10.2 to
userspace when it's supported by the host.

Intel AVX10 Version 2 (Intel AVX10.2) includes a suite of new
instructions delivering new AI features and performance, accelerated
media processing, expanded Web Assembly, and Cryptography support, along
with enhancements to existing legacy instructions for completeness and
efficiency, and it is enumerated as version 2 in CPUID 0x24.0x0.EBX[bits
0-7] [1].

AVX10.2 has no current kernel usage and requires no additional host
kernel enabling work (based on AVX10.1 support) and provides no new
VMX controls [2]. Moreover, since AVX10.2 is the superset of AVX10.1,
there's no need to worry about AVX10.1 and AVX10.2 compatibility issues
in KVM.

Therefore, it's safe to advertise AVX10.2 version to userspace directly
if host supports AVX10.2.

[1]: Intel Advanced Vector Extensions 10.2 Architecture Specification
     (rev 5.0).
[2]: Note: Since AVX10.2 spec (rev 4.0), it has been declared "AVX10/512
     will be used in all Intel products, supporting vector lengths of
     128, 256, and 512 in all product lines", and the VMX support (in
     earlier revisions) for AVX10/256 guest on AVX10/512 host has been
     dropped.

Tested-by: default avatarXudong Hao <xudong.hao@intel.com>
Signed-off-by: default avatarZhao Liu <zhao1.liu@intel.com>
Reviewed-by: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Link: https://patch.msgid.link/20251120050720.931449-4-zhao1.liu@intel.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 58cbaf64

arch/x86/kvm/cpuid.c

+1 −1
Original line number Diff line number Diff line
@@ -1666,7 +1666,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) 
		 * is guaranteed to be >=1 if AVX10 is supported.  Note #2, the

		 * version needs to be captured before overriding EBX features!

		 */

		avx10_version = min_t(u8, entry->ebx & 0xff, 1);

		avx10_version = min_t(u8, entry->ebx & 0xff, 2);

		cpuid_entry_override(entry, CPUID_24_0_EBX);

		entry->ebx |= avx10_version;