From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> commit 5c89be1dd5cfb697614bc13626ba3bd0781aa160 upstream. Full equality check of CPUID data on update (kvm_cpuid_check_equal()) may fail for SGX enabled CPUs as CPUID.(EAX=0x12,ECX=1) is currently being mangled in kvm_vcpu_after_set_cpuid(). Move it to __kvm_update_cpuid_runtime() and split off cpuid_get_supported_xcr0() helper as 'vcpu->arch.guest_supported_xcr0' update needs (logically) to stay in kvm_vcpu_after_set_cpuid(). Cc: stable@xxxxxxxxxxxxxxx Fixes: feb627e8d6f6 ("KVM: x86: Forbid KVM_SET_CPUID{,2} after KVM_RUN") Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Message-Id: <20220124103606.2630588-2-vkuznets@xxxxxxxxxx> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kvm/cpuid.c | 54 +++++++++++++++++++++++++++++++-------------------- 1 file changed, 33 insertions(+), 21 deletions(-) --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -176,10 +176,26 @@ void kvm_update_pv_runtime(struct kvm_vc vcpu->arch.pv_cpuid.features = best->eax; } +/* + * Calculate guest's supported XCR0 taking into account guest CPUID data and + * supported_xcr0 (comprised of host configuration and KVM_SUPPORTED_XCR0). + */ +static u64 cpuid_get_supported_xcr0(struct kvm_cpuid_entry2 *entries, int nent) +{ + struct kvm_cpuid_entry2 *best; + + best = cpuid_entry2_find(entries, nent, 0xd, 0); + if (!best) + return 0; + + return (best->eax | ((u64)best->edx << 32)) & supported_xcr0; +} + static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *entries, int nent) { struct kvm_cpuid_entry2 *best; + u64 guest_supported_xcr0 = cpuid_get_supported_xcr0(entries, nent); best = cpuid_entry2_find(entries, nent, 1, 0); if (best) { @@ -218,6 +234,21 @@ static void __kvm_update_cpuid_runtime(s vcpu->arch.ia32_misc_enable_msr & MSR_IA32_MISC_ENABLE_MWAIT); } + + /* + * Bits 127:0 of the allowed SECS.ATTRIBUTES (CPUID.0x12.0x1) enumerate + * the supported XSAVE Feature Request Mask (XFRM), i.e. the enclave's + * requested XCR0 value. The enclave's XFRM must be a subset of XCRO + * at the time of EENTER, thus adjust the allowed XFRM by the guest's + * supported XCR0. Similar to XCR0 handling, FP and SSE are forced to + * '1' even on CPUs that don't support XSAVE. + */ + best = cpuid_entry2_find(entries, nent, 0x12, 0x1); + if (best) { + best->ecx &= guest_supported_xcr0 & 0xffffffff; + best->edx &= guest_supported_xcr0 >> 32; + best->ecx |= XFEATURE_MASK_FPSSE; + } } void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu) @@ -241,27 +272,8 @@ static void kvm_vcpu_after_set_cpuid(str kvm_apic_set_version(vcpu); } - best = kvm_find_cpuid_entry(vcpu, 0xD, 0); - if (!best) - vcpu->arch.guest_supported_xcr0 = 0; - else - vcpu->arch.guest_supported_xcr0 = - (best->eax | ((u64)best->edx << 32)) & supported_xcr0; - - /* - * Bits 127:0 of the allowed SECS.ATTRIBUTES (CPUID.0x12.0x1) enumerate - * the supported XSAVE Feature Request Mask (XFRM), i.e. the enclave's - * requested XCR0 value. The enclave's XFRM must be a subset of XCRO - * at the time of EENTER, thus adjust the allowed XFRM by the guest's - * supported XCR0. Similar to XCR0 handling, FP and SSE are forced to - * '1' even on CPUs that don't support XSAVE. - */ - best = kvm_find_cpuid_entry(vcpu, 0x12, 0x1); - if (best) { - best->ecx &= vcpu->arch.guest_supported_xcr0 & 0xffffffff; - best->edx &= vcpu->arch.guest_supported_xcr0 >> 32; - best->ecx |= XFEATURE_MASK_FPSSE; - } + vcpu->arch.guest_supported_xcr0 = + cpuid_get_supported_xcr0(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent); kvm_update_pv_runtime(vcpu);