From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Joe Perches <joe@perches.com>
Cc: Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Igor Mammedov <imammedo@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 2/2] KVM: x86: Use memcmp in kvm_cpuid_check_equal()
Date: Wed, 26 Jan 2022 11:03:54 +0100 [thread overview]
Message-ID: <878rv2izjp.fsf@redhat.com> (raw)
In-Reply-To: <864dfbfdc44e288e99cf7baa3aa8f7c8568db507.camel@perches.com>
Joe Perches <joe@perches.com> writes:
> On Mon, 2022-01-24 at 11:36 +0100, Vitaly Kuznetsov wrote:
>> kvm_cpuid_check_equal() should also check .flags equality but instead
>> of adding it to the existing check, just switch to using memcmp() for
>> the whole 'struct kvm_cpuid_entry2'.
>
> Is the struct padding guaranteed to be identical ?
>
Well, yes (or we're all doomeed):
- 'struct kvm_cpuid_entry2' is part of KVM userspace ABI, it is supposed
to be stable.
- Here we compare structs which come from the same userspace during one
session (vCPU fd stays open), I can't imagine how structure layout can
change on-the-fly.
--
Vitaly
next prev parent reply other threads:[~2022-01-26 10:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-24 10:36 [PATCH 0/2] KVM: x86: Partially allow KVM_SET_CPUID{,2} follow-up Vitaly Kuznetsov
2022-01-24 10:36 ` [PATCH 1/2] KVM: x86: Move CPUID.(EAX=0x12,ECX=1) mangling to __kvm_update_cpuid_runtime() Vitaly Kuznetsov
2022-01-24 10:36 ` [PATCH 2/2] KVM: x86: Use memcmp in kvm_cpuid_check_equal() Vitaly Kuznetsov
2022-01-24 14:02 ` Paolo Bonzini
2022-01-24 15:10 ` Vitaly Kuznetsov
2022-01-24 16:52 ` Sean Christopherson
2022-01-24 17:07 ` Paolo Bonzini
2022-01-24 19:08 ` Sean Christopherson
2022-01-24 21:03 ` Joe Perches
2022-01-26 10:03 ` Vitaly Kuznetsov [this message]
2022-01-26 16:02 ` Sean Christopherson
2022-01-26 16:25 ` Vitaly Kuznetsov
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