On Mon, Dec 19, 2016 at 12:48 PM, David Matlack <dmatlack@xxxxxxxxxx> wrote:
> kvm_skip_emulated_instruction() should not be called after emulating
> a VM-entry failure during or after loading guest state
> (nested_vmx_entry_failure()). Otherwise the L1 hypervisor is resumed
> some number of bytes past vmcs->host_rip.
Ah, I see. Sorry for that regression.
These paths are supposed to trigger TF-induced singlestep exceptions
though. Quoting from the Intel SDM (Vol 3, Chapter 26)
"EFLAGS.TF = 1 causes a VM-entry instruction to generate a single-step
debug exception only if failure of one of the checks in Section 26.1
and Section 26.2 causes control to pass to the following instruction.
A VM-entry does not generate a single-step debug exception in any of
the following cases: (1) the instruction generates a fault; (2)
failure of one of the checks in Section 26.3 or in loading MSRs causes
processor state to be loaded from the hoststate area of the VMCS; or
(3) the instruction passes all checks in Section 26.1, Section 26.2,
and Section 26.3 and there is no failure in loading MSRs"
- Kyle
> Fixes: eb2775621701e6ee3ea2a474437d04e93ccdcb2f
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index c41d7ff..0e7ad72 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -10474,12 +10474,12 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
> !nested_guest_cr4_valid(vcpu, vmcs12->guest_cr4)) {
> nested_vmx_entry_failure(vcpu, vmcs12,
> EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> - goto out;
> + return 1;
> }
> if (vmcs12->vmcs_link_pointer != -1ull) {
> nested_vmx_entry_failure(vcpu, vmcs12,
> EXIT_REASON_INVALID_STATE, ENTRY_FAIL_VMCS_LINK_PTR);
> - goto out;
> + return 1;
> }
>
> /*
> @@ -10499,7 +10499,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
> ia32e != !!(vmcs12->guest_ia32_efer & EFER_LME))) {
> nested_vmx_entry_failure(vcpu, vmcs12,
> EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> - goto out;
> + return 1;
> }
> }
>
> @@ -10517,7 +10517,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
> ia32e != !!(vmcs12->host_ia32_efer & EFER_LME)) {
> nested_vmx_entry_failure(vcpu, vmcs12,
> EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> - goto out;
> + return 1;
> }
> }
>
> --
> 2.8.0.rc3.226.g39d4020
>
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