KVM: x86: Advertise AMX-COMPLEX CPUID to userspace

Latest Intel platform GraniteRapids-D introduces AMX-COMPLEX, which adds
two instructions to perform matrix multiplication of two tiles containing
complex elements and accumulate the results into a packed single precision
tile.

AMX-COMPLEX is enumerated via CPUID.(EAX=7,ECX=1):EDX[bit 8]

Advertise AMX_COMPLEX if it's supported in hardware.  There are no VMX
controls for the feature, i.e. the instructions can't be interecepted, and
KVM advertises base AMX in CPUID if AMX is supported in hardware, even if
KVM doesn't advertise AMX as being supported in XCR0, e.g. because the
process didn't opt-in to allocating tile data.

Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20230802022954.193843-1-tao1.su@linux.intel.com
[sean: tweak last paragraph of changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index ad6566636c22def78cc91ca6616c0feac0b51590..5a88affb2e1a4958c74a6e8a809e3498f9e07388 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -647,7 +647,8 @@ void kvm_set_cpu_caps(void)
        );
 
        kvm_cpu_cap_init_kvm_defined(CPUID_7_1_EDX,
-               F(AVX_VNNI_INT8) | F(AVX_NE_CONVERT) | F(PREFETCHITI)
+               F(AVX_VNNI_INT8) | F(AVX_NE_CONVERT) | F(PREFETCHITI) |
+               F(AMX_COMPLEX)
        );
 
        kvm_cpu_cap_mask(CPUID_D_1_EAX,

diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index 56cbdb24400ae13a99356dcbf1dd81ed54dda95e..b816506783755a1ce87d511014c9903fe3e25798 100644 (file)
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -43,6 +43,7 @@ enum kvm_only_cpuid_leafs {
 /* Intel-defined sub-features, CPUID level 0x00000007:1 (EDX) */
 #define X86_FEATURE_AVX_VNNI_INT8       KVM_X86_FEATURE(CPUID_7_1_EDX, 4)
 #define X86_FEATURE_AVX_NE_CONVERT      KVM_X86_FEATURE(CPUID_7_1_EDX, 5)
+#define X86_FEATURE_AMX_COMPLEX         KVM_X86_FEATURE(CPUID_7_1_EDX, 8)
 #define X86_FEATURE_PREFETCHITI         KVM_X86_FEATURE(CPUID_7_1_EDX, 14)
 
 /* CPUID level 0x80000007 (EDX). */