lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <Y8nqWl+kOvc8WPdK@google.com>
Date:   Fri, 20 Jan 2023 01:11:54 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Like Xu <like.xu.linux@...il.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 8/8] KVM: x86/cpuid: Use fast return for cpuid "0xa"
 leaf when !enable_pmu

On Fri, Nov 11, 2022, Like Xu wrote:
> From: Like Xu <likexu@...cent.com>
> 
> Although when !enable_pmu, KVM will have zero-padded kvm_pmu_cap to do
> subsequent cpuid leaf assignments, one extra branch instruction saves
> a few subsequent zero-assignment instructions, speeding things up a bit.

I doubt my motivation was performance, I'm guessing I suggested adding the explicit
!enable_pmu check because relying on kvm_pmu_cap to be zeroed isn't obvious.

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ