From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Maxim Levitsky <mlevitsk@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Wanpeng Li <wanpengli@tencent.com>,
Borislav Petkov <bp@alien8.de>, Joerg Roedel <joro@8bytes.org>,
Jim Mattson <jmattson@google.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH 1/7] KVM: VMX: read idt_vectoring_info a bit earlier
Date: Wed, 17 Feb 2021 17:29:26 +0100 [thread overview]
Message-ID: <26f7ee7b-568f-c838-d0e0-db125cfbd4e5@redhat.com> (raw)
In-Reply-To: <YC1Cljte2ozGSKV/@google.com>
On 17/02/21 17:21, Sean Christopherson wrote:
> On Wed, Feb 17, 2021, Maxim Levitsky wrote:
>> On Wed, 2021-02-17 at 17:06 +0100, Paolo Bonzini wrote:
>>> On 17/02/21 15:57, Maxim Levitsky wrote:
>>>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>>>> index b3e36dc3f164..e428d69e21c0 100644
>>>> --- a/arch/x86/kvm/vmx/vmx.c
>>>> +++ b/arch/x86/kvm/vmx/vmx.c
>>>> @@ -6921,13 +6921,15 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
>>>> if (unlikely((u16)vmx->exit_reason.basic == EXIT_REASON_MCE_DURING_VMENTRY))
>>>> kvm_machine_check();
>>>>
>>>> + if (likely(!vmx->exit_reason.failed_vmentry))
>>>> + vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
>>>> +
>>>
>>> Any reason for the if?
>>
>> Sean Christopherson asked me to do this to avoid updating idt_vectoring_info on failed
>> VM entry, to keep things as they were logically before this patch.
>
> Ya, specifically because the field isn't valid if VM-Enter fails. I'm also ok
> with an unconditional VMREAD if we add a comment stating that it's unnecessary
> if VM-Enter failed, but faster in the common case.
It's okay, just good to know!
Thanks,
paolo
next prev parent reply other threads:[~2021-02-17 16:31 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 14:57 [PATCH 0/7] KVM: random nested fixes Maxim Levitsky
2021-02-17 14:57 ` [PATCH 1/7] KVM: VMX: read idt_vectoring_info a bit earlier Maxim Levitsky
2021-02-17 16:06 ` Paolo Bonzini
2021-02-17 16:18 ` Maxim Levitsky
2021-02-17 16:21 ` Sean Christopherson
2021-02-17 16:29 ` Paolo Bonzini [this message]
2021-02-17 14:57 ` [PATCH 2/7] KVM: nSVM: move nested vmrun tracepoint to enter_svm_guest_mode Maxim Levitsky
2021-02-17 14:57 ` [PATCH 3/7] KVM: x86: add .complete_mmu_init arch callback Maxim Levitsky
2021-02-17 14:57 ` [PATCH 4/7] KVM: nVMX: move inject_page_fault tweak to .complete_mmu_init Maxim Levitsky
2021-02-17 17:29 ` Sean Christopherson
2021-02-17 17:37 ` Paolo Bonzini
2021-02-17 17:57 ` Sean Christopherson
2021-02-17 18:00 ` Paolo Bonzini
2021-02-17 18:49 ` Maxim Levitsky
2021-02-17 18:43 ` Maxim Levitsky
2021-02-18 9:45 ` Paolo Bonzini
2021-02-17 14:57 ` [PATCH 5/7] KVM: nSVM: fix running nested guests when npt=0 Maxim Levitsky
2021-02-17 15:27 ` Maxim Levitsky
2021-02-17 14:57 ` [PATCH 6/7] KVM: nVMX: don't load PDPTRS right after nested state set Maxim Levitsky
2021-02-17 17:52 ` Sean Christopherson
2021-02-17 18:06 ` Paolo Bonzini
2021-02-17 14:57 ` [PATCH 7/7] KVM: nSVM: call nested_svm_load_cr3 on nested state load Maxim Levitsky
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