From 275a87244ec8320e5d319132caa787329b04bb7e Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 3 May 2023 09:08:37 -0700 Subject: KVM: x86: Don't adjust guest's CPUID.0x12.1 (allowed SGX enclave XFRM) Drop KVM's manipulation of guest's CPUID.0x12.1 ECX and EDX, i.e. the allowed XFRM of SGX enclaves, now that KVM explicitly checks the guest's allowed XCR0 when emulating ECREATE. Note, this could theoretically break a setup where userspace advertises a "bad" XFRM and relies on KVM to provide a sane CPUID model, but QEMU is the only known user of KVM SGX, and QEMU explicitly sets the SGX CPUID XFRM subleaf based on the guest's XCR0. Reviewed-by: Kai Huang Tested-by: Kai Huang Signed-off-by: Sean Christopherson Message-Id: <20230503160838.3412617-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/cpuid.c | 16 ---------------- 1 file changed, 16 deletions(-) (limited to 'arch') diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 123bf8b97a4b..0c9660a07b23 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -253,7 +253,6 @@ static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_e int nent) { struct kvm_cpuid_entry2 *best; - u64 guest_supported_xcr0 = cpuid_get_supported_xcr0(entries, nent); best = cpuid_entry2_find(entries, nent, 1, KVM_CPUID_INDEX_NOT_SIGNIFICANT); if (best) { @@ -292,21 +291,6 @@ static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_e 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) -- cgit v1.2.3-58-ga151