From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: linmiaohe <linmiaohe@huawei.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, pbonzini@redhat.com, rkrcmar@redhat.com,
sean.j.christopherson@intel.com, wanpengli@tencent.com,
jmattson@google.com, joro@8bytes.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com
Subject: Re: [PATCH] KVM: nVMX: set rflags to specify success in handle_invvpid() default case
Date: Thu, 23 Jan 2020 09:55:44 +0100 [thread overview]
Message-ID: <8736c6sga7.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <1579749241-712-1-git-send-email-linmiaohe@huawei.com>
linmiaohe <linmiaohe@huawei.com> writes:
> From: Miaohe Lin <linmiaohe@huawei.com>
>
> In handle_invvpid() default case, we just skip emulated instruction and
> forget to set rflags to specify success. This would result in indefinite
> rflags value and thus indeterminate return value for guest.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> Chinese New Year is coming. Happy Spring Festival! ^_^
Happy Spring Festival!
> ---
> 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 7608924ee8c1..985d3307ec56 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -5165,7 +5165,7 @@ static int handle_invvpid(struct kvm_vcpu *vcpu)
> break;
> default:
> WARN_ON_ONCE(1);
> - return kvm_skip_emulated_instruction(vcpu);
> + break;
> }
>
> return nested_vmx_succeed(vcpu);
Your patch seems to do the right thing, however, I started wondering if
WARN_ON_ONCE() is the right thing to do. SDM says that "If an
unsupported INVVPID type is specified, the instruction fails." and this
is similar to INVEPT and I decided to check what handle_invept()
does. Well, it does BUG_ON().
Are we doing the right thing in any of these cases?
--
Vitaly
next prev parent reply other threads:[~2020-01-23 8:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 3:14 [PATCH] KVM: nVMX: set rflags to specify success in handle_invvpid() default case linmiaohe
2020-01-23 8:55 ` Vitaly Kuznetsov [this message]
2020-01-23 9:23 ` Paolo Bonzini
2020-01-23 9:45 ` Vitaly Kuznetsov
2020-01-23 9:54 ` Paolo Bonzini
2020-01-23 18:22 ` Jim Mattson
2020-01-23 23:01 ` Sean Christopherson
2020-01-24 10:53 ` Vitaly Kuznetsov
2020-01-23 9:36 linmiaohe
2020-02-03 3:29 linmiaohe
2020-02-03 9:48 ` Vitaly Kuznetsov
2020-02-04 1:06 linmiaohe
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