KVM: x86: Fix potential race in KVM_GET_CLOCK

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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>
Message-Id: <20210916181538.968978-4-oupton@google.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Oliver Upton 2021-09-16 18:15:34 +00:00 • committed by Paolo Bonzini

parent 45e6c2fac0

commit 55c0cefbdb

1 changed files with 23 additions and 13 deletions

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arch/x86/kvm/x86.c

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