2019-10-01 16:51:19

by Sean Christopherson

Subject: [PATCH] KVM: nVMX: Fix consistency check on injected exception error code

Current versions of Intel's SDM incorrectly state that "bits 31:15 of
the VM-Entry exception error-code field" must be zero. In reality, bits
31:16 must be zero, i.e. error codes are 16-bit values.

The bogus error code check manifests as an unexpected VM-Entry failure
due to an invalid code field (error number 7) in L1, e.g. when injecting
a #GP with error_code=0x9f00.

Nadav previously reported the bug[*], both to KVM and Intel, and fixed
the associated kvm-unit-test.

[*] https://patchwork.kernel.org/patch/11124749/

Reported-by: Nadav Amit <[email protected]>
Cc: [email protected]
Signed-off-by: Sean Christopherson <[email protected]>
---
arch/x86/kvm/vmx/nested.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 41abc62c9a8a..e76eb4f07f6c 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2610,7 +2610,7 @@ static int nested_check_vm_entry_controls(struct kvm_vcpu *vcpu,

/* VM-entry exception error code */
if (CC(has_error_code &&
- vmcs12->vm_entry_exception_error_code & GENMASK(31, 15)))
+ vmcs12->vm_entry_exception_error_code & GENMASK(31, 16)))
return -EINVAL;

/* VM-entry interruption-info field: reserved bits */
--
2.22.0

2019-10-01 16:51:52

by Jim Mattson

Subject: Re: [PATCH] KVM: nVMX: Fix consistency check on injected exception error code

On Tue, Oct 1, 2019 at 9:21 AM Sean Christopherson
<[email protected]> wrote:
>
> Current versions of Intel's SDM incorrectly state that "bits 31:15 of
> the VM-Entry exception error-code field" must be zero. In reality, bits
> 31:16 must be zero, i.e. error codes are 16-bit values.
>
> The bogus error code check manifests as an unexpected VM-Entry failure
> due to an invalid code field (error number 7) in L1, e.g. when injecting
> a #GP with error_code=0x9f00.
>
> Nadav previously reported the bug[*], both to KVM and Intel, and fixed
> the associated kvm-unit-test.
>
> [*] https://patchwork.kernel.org/patch/11124749/
>
> Reported-by: Nadav Amit <[email protected]>
> Cc: [email protected]
> Signed-off-by: Sean Christopherson <[email protected]>
Reviewed-by: Jim Mattson <[email protected]>

2019-10-03 10:36:44

by Paolo Bonzini

Subject: Re: [PATCH] KVM: nVMX: Fix consistency check on injected exception error code

On 01/10/19 18:28, Jim Mattson wrote:
> Reviewed-by: Jim Mattson <[email protected]>

Queued, thanks.

Paolo