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Date:   Wed, 29 Sep 2021 10:33:21 -0300
From:   Marcelo Tosatti <mtosatti@redhat.com>
To:     Oliver Upton <oupton@google.com>
Cc:     kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Marc Zyngier <maz@kernel.org>, Peter Shier <pshier@google.com>,
        Jim Mattson <jmattson@google.com>,
        David Matlack <dmatlack@google.com>,
        Ricardo Koller <ricarkol@google.com>,
        Jing Zhang <jingzhangos@google.com>,
        Raghavendra Rao Anata <rananta@google.com>,
        James Morse <james.morse@arm.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        linux-arm-kernel@lists.infradead.org,
        Andrew Jones <drjones@redhat.com>,
        Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH v8 3/7] KVM: x86: Fix potential race in KVM_GET_CLOCK
Message-ID: <20210929133320.GA10977@fuller.cnet>
References: <20210916181538.968978-1-oupton@google.com>
 <20210916181538.968978-4-oupton@google.com>
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On Thu, Sep 16, 2021 at 06:15:34PM +0000, Oliver Upton wrote:
> Sean noticed that KVM_GET_CLOCK was checking kvm_arch.use_master_clock
> outside of the pvclock sync lock. This is problematic, as the clock
> value written to the user may or may not actually correspond to a stable
> TSC.
> 
> Fix the race by populating the entire kvm_clock_data structure behind
> the pvclock_gtod_sync_lock.
> 
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Oliver Upton <oupton@google.com>

ACK patches 1-3, still reviewing the remaining ones...