KVM: x86: introduce kvm_supported_xcr0()
XSAVE support for KVM is already using host_xcr0 & KVM_SUPPORTED_XCR0 as
a "dynamic" version of KVM_SUPPORTED_XCR0.
However, this is not enough because the MPX bits should not be presented
to the guest unless kvm_x86_ops confirms the support. So, replace all
instances of host_xcr0 & KVM_SUPPORTED_XCR0 with a new function
kvm_supported_xcr0() that also has this check.
Note that here:
if (xstate_bv & ~KVM_SUPPORTED_XCR0)
return -EINVAL;
if (xstate_bv & ~host_cr0)
return -EINVAL;
the code is equivalent to
if ((xstate_bv & ~KVM_SUPPORTED_XCR0) ||
(xstate_bv & ~host_cr0)
return -EINVAL;
i.e. "xstate_bv & (~KVM_SUPPORTED_XCR0 | ~host_cr0)" which is in turn
equal to "xstate_bv & ~(KVM_SUPPORTED_XCR0 & host_cr0)". So we should
also use the new function there.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a37da6b..3f5fb45 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3084,9 +3084,7 @@
* CPUID leaf 0xD, index 0, EDX:EAX. This is for compatibility
* with old userspace.
*/
- if (xstate_bv & ~KVM_SUPPORTED_XCR0)
- return -EINVAL;
- if (xstate_bv & ~host_xcr0)
+ if (xstate_bv & ~kvm_supported_xcr0())
return -EINVAL;
memcpy(&vcpu->arch.guest_fpu.state->xsave,
guest_xsave->region, vcpu->arch.guest_xstate_size);