From: Tom Lendacky <thomas.lendacky@amd.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, Jim Mattson <jmattson@google.com>,
Joerg Roedel <joro@8bytes.org>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Brijesh Singh <brijesh.singh@amd.com>
Subject: Re: [PATCH] KVM: SVM: Make sure GHCB is mapped before updating
Date: Thu, 8 Apr 2021 11:18:43 -0500 [thread overview]
Message-ID: <8654d5eb-e6d0-af94-db46-7a4fce8caa0d@amd.com> (raw)
In-Reply-To: <2b282772-afaa-2fd4-0794-4449eda6fd02@redhat.com>
On 4/8/21 11:14 AM, Paolo Bonzini wrote:
> On 08/04/21 18:04, Tom Lendacky wrote:
>>>>> + if (!err || !sev_es_guest(vcpu->kvm) ||
>>>>> !WARN_ON_ONCE(svm->ghcb))
>>>> This should be WARN_ON_ONCE(!svm->ghcb), otherwise you'll get the right
>>>> result, but get a stack trace immediately.
>>> Doh, yep.
>> Actually, because of the "or's", this needs to be:
>>
>> if (!err || !sev_es_guest(vcpu->kvm) || (sev_es_guest(vcpu->kvm) &&
>> WARN_ON_ONCE(!svm->ghcb)))
>
> No, || cuts the right-hand side if the left-hand side is true. So:
>
> - if err == 0, the rest is not evaluated
>
> - if !sev_es_guest(vcpu->kvm), WARN_ON_ONCE(!svm->ghcb) is not evaluated
That's what I was doing in my head, but I guess I need more coffee... :)
Thanks,
Tom
>
> Paolo
>
prev parent reply other threads:[~2021-04-08 16:18 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 18:30 [PATCH] KVM: SVM: Make sure GHCB is mapped before updating Tom Lendacky
2021-04-07 20:08 ` Sean Christopherson
2021-04-07 20:36 ` Tom Lendacky
2021-04-07 21:07 ` Sean Christopherson
2021-04-08 16:04 ` Tom Lendacky
2021-04-08 16:14 ` Paolo Bonzini
2021-04-08 16:18 ` Tom Lendacky [this message]
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