linux-kernel - Re: [PATCH v2 04/22] x86/kvm: Don't call kvm_spurious

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Message-ID: <1b891612-18e6-48ed-cfb5-05e8aca79dcb@redhat.com>
Date:   Thu, 18 Jul 2019 15:18:50 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...db.de>, Jann Horn <jannh@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH v2 04/22] x86/kvm: Don't call kvm_spurious_fault() from
 .fixup

On 18/07/19 15:16, Sean Christopherson wrote:
>> Acked-by: Paolo Bonzini <pbonzini@...hat.com>
>>
>> This has a side effect of adding a jump in a generally hot path, but
>> let's hope that the speculation gods for once help us.
> Any reason not to take the same approach as vmx_vmenter() and ud2 directly
> from fixup?  I've never found kvm_spurious_fault() to be all that helpful,
> IMO it's a win win. :-)

Honestly I've never seen a backtrace from here but I would rather not
regret this when a customer encounters it...

Paolo