Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes:
> Signal VM-Fail for the single-context variant of INVEPT if the specified
> EPTP is invalid. Per the INEVPT pseudocode in Intel's SDM, it's subject
> to the standard EPT checks:
>
> If VM entry with the "enable EPT" VM execution control set to 1 would
> fail due to the EPTP value then VMfail(Invalid operand to INVEPT/INVVPID);
>
> Fixes: bfd0a56b90005 ("nEPT: Nested INVEPT")
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx/nested.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 8578513907d7..f3774cef4fd4 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -5156,8 +5156,12 @@ static int handle_invept(struct kvm_vcpu *vcpu)
> }
>
> switch (type) {
> - case VMX_EPT_EXTENT_GLOBAL:
> case VMX_EPT_EXTENT_CONTEXT:
> + if (!nested_vmx_check_eptp(vcpu, operand.eptp))
> + return nested_vmx_failValid(vcpu,
> + VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID);
I was going to ask "and we don't seem to check that current nested VMPTR
is valid, how can we know that nested_vmx_failValid() is the right
VMfail() to use" but then I checked our nested_vmx_failValid() and there
is a fallback there:
if (vmx->nested.current_vmptr == -1ull && !vmx->nested.hv_evmcs)
return nested_vmx_failInvalid(vcpu);
so this is a non-issue. My question, however, transforms into "would it
make sense to introduce nested_vmx_fail() implementing the logic from
SDM:
VMfail(ErrorNumber):
IF VMCS pointer is valid
THEN VMfailValid(ErrorNumber);
ELSE VMfailInvalid;
FI;
to assist an innocent reader of the code?"
> + fallthrough;
> + case VMX_EPT_EXTENT_GLOBAL:
> /*
> * TODO: Sync the necessary shadow EPT roots here, rather than
> * at the next emulated VM-entry.
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
--
Vitaly
