Two XCR0 bits are defined for AMX to support XSAVE mechanism. Bit 17 is for tilecfg and bit 18 is for tiledata.
The value of XCR0[17:18] is always either 00b or 11b. Also, SDM recommends that only 64-bit operating systems enable Intel AMX by setting XCR0[18:17]. If a 32-bit guest tries to set dynamic bits, it fails to pass vcpu->arch.guest_supported_xcr0 check and gets a #GP.
Signed-off-by: Yang Zhong yang.zhong@intel.com Signed-off-by: Jing Liu jing2.liu@intel.com --- arch/x86/kvm/x86.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a48a89f73027..c558c098979a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -210,7 +210,7 @@ static struct kvm_user_return_msrs __percpu *user_return_msrs; #define KVM_SUPPORTED_XCR0 (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \ | XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \ | XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \ - | XFEATURE_MASK_PKRU) + | XFEATURE_MASK_PKRU | XFEATURE_MASK_XTILE)
u64 __read_mostly host_efer; EXPORT_SYMBOL_GPL(host_efer); @@ -990,6 +990,12 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) if ((xcr0 & XFEATURE_MASK_AVX512) != XFEATURE_MASK_AVX512) return 1; } + +#ifdef CONFIG_X86_64 + if ((xcr0 & XFEATURE_MASK_XTILE) && + ((xcr0 & XFEATURE_MASK_XTILE) != XFEATURE_MASK_XTILE)) + return 1; +#endif vcpu->arch.xcr0 = xcr0;
if ((xcr0 ^ old_xcr0) & XFEATURE_MASK_EXTEND)