Commit ad45413d authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: VMX: Don't rely _only_ on CPUID to enforce XCR0 restrictions for ECREATE 



Explicitly check the vCPU's supported XCR0 when determining whether or not
the XFRM for ECREATE is valid.  Checking CPUID works because KVM updates
guest CPUID.0x12.1 to restrict the leaf to a subset of the guest's allowed
XCR0, but that is rather subtle and KVM should not modify guest CPUID
except for modeling true runtime behavior (allowed XFRM is most definitely
not "runtime" behavior).

Reviewed-by: default avatarKai Huang <kai.huang@intel.com>
Tested-by: default avatarKai Huang <kai.huang@intel.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20230503160838.3412617-2-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent afb2acb2

arch/x86/kvm/vmx/sgx.c

+9 −2
Original line number Diff line number Diff line
@@ -170,12 +170,19 @@ static int __handle_encls_ecreate(struct kvm_vcpu *vcpu, 
		return 1;

	}



	/* Enforce CPUID restrictions on MISCSELECT, ATTRIBUTES and XFRM. */

	/*

	 * Enforce CPUID restrictions on MISCSELECT, ATTRIBUTES and XFRM.  Note

	 * that the allowed XFRM (XFeature Request Mask) isn't strictly bound

	 * by the supported XCR0.  FP+SSE *must* be set in XFRM, even if XSAVE

	 * is unsupported, i.e. even if XCR0 itself is completely unsupported.

	 */

	if ((u32)miscselect & ~sgx_12_0->ebx ||

	    (u32)attributes & ~sgx_12_1->eax ||

	    (u32)(attributes >> 32) & ~sgx_12_1->ebx ||

	    (u32)xfrm & ~sgx_12_1->ecx ||

	    (u32)(xfrm >> 32) & ~sgx_12_1->edx) {

	    (u32)(xfrm >> 32) & ~sgx_12_1->edx ||

	    xfrm & ~(vcpu->arch.guest_supported_xcr0 | XFEATURE_MASK_FPSSE) ||

	    (xfrm & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {

		kvm_inject_gp(vcpu, 0);

		return 1;

	}