From: Paolo Bonzini <pbonzini@redhat.com>
To: Jim Mattson <jmattson@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
"kvm list" <kvm@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"KarimAllah Ahmed" <karahmed@amazon.de>,
"David Woodhouse" <dwmw@amazon.co.uk>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@kernel.org>,
stable@vger.kernel.org
Subject: Re: [PATCH 2/3] KVM: nVMX: fix wrong condition for SPEC_CTRL and PRED_CMD MSRs
Date: Thu, 22 Feb 2018 10:39:15 +0100 [thread overview]
Message-ID: <7ef4216d-6ebf-0ffe-c477-b820a2c942c3@redhat.com> (raw)
In-Reply-To: <CALMp9eSbH67rm2vDnuaCjSU0JRsZxT1cW2qoyWQREV_iSAVaTw@mail.gmail.com>
On 22/02/2018 01:07, Jim Mattson wrote:
> On Wed, Feb 21, 2018 at 1:41 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> We need to change the default all-1s bitmap if the MSRs are _not_
>> intercepted. However, the code was disabling the intercept when it was
>> _enabled_ in the VMCS01. This is not causing bigger trouble,
>> because vmx_vcpu_run checks the VMCS02's MSR bitmap and would do the
>> right thing even if fed garbage... but it's obviously a bug and it can
>> cause extra MSR reads and writes when running nested guests.
>>
>> Fixes: d28b387fb74da95d69d2615732f50cceb38e9a4d
>> Fixes: 15d45071523d89b3fb7372e2135fbd72f6af9506
>> Cc: x86@kernel.org
>> Cc: Radim Krčmář <rkrcmar@redhat.com>
>> Cc: KarimAllah Ahmed <karahmed@amazon.de>
>> Cc: David Woodhouse <dwmw@amazon.co.uk>
>> Cc: Jim Mattson <jmattson@google.com>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Ingo Molnar <mingo@kernel.org>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>
> Wasn't this already fixed by 206587a9fb76 ("X86/nVMX: Properly set
> spec_ctrl and pred_cmd before merging MSRs")?
Ouch, yes, and my patch would have no conflicts at all so it would
reintroduce the bug! Will resend v2 without it.
Paolo
next prev parent reply other threads:[~2018-02-22 9:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-21 21:41 [PATCH 0/3] x86/pti: KVM: fixes and optimizations for IBRS Paolo Bonzini
2018-02-21 21:41 ` [PATCH 1/3] KVM: x86: use native MSR ops for SPEC_CTRL Paolo Bonzini
2018-02-21 23:49 ` Jim Mattson
2018-02-22 17:07 ` Konrad Rzeszutek Wilk
2018-02-23 9:37 ` Paolo Bonzini
2018-02-23 17:22 ` Konrad Rzeszutek Wilk
2018-02-23 17:35 ` Paolo Bonzini
2018-02-23 17:55 ` Konrad Rzeszutek Wilk
2018-02-21 21:41 ` [PATCH 2/3] KVM: nVMX: fix wrong condition for SPEC_CTRL and PRED_CMD MSRs Paolo Bonzini
2018-02-22 0:07 ` Jim Mattson
2018-02-22 9:39 ` Paolo Bonzini [this message]
2018-02-21 21:41 ` [PATCH 3/3] KVM: VMX: mark RDMSR path as unlikely Paolo Bonzini
2018-02-22 0:25 ` Jim Mattson
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