diff options
| author | Liran Alon <liran.alon@oracle.com> | 2017-11-05 16:11:30 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-05 11:24:33 +0100 |
| commit | f5477da6c3b0f8df578a55dfdeebe18458303e4d (patch) | |
| tree | 946366ed000a0b0307e00a14f63afb24d5822ca9 | |
| parent | e18a963b36a001b0067f9091b4ea23aa152af341 (diff) | |
KVM: x86: pvclock: Handle first-time write to pvclock-page contains random junk
commit 51c4b8bba674cfd2260d173602c4dac08e4c3a99 upstream.
When guest passes KVM it's pvclock-page GPA via WRMSR to
MSR_KVM_SYSTEM_TIME / MSR_KVM_SYSTEM_TIME_NEW, KVM don't initialize
pvclock-page to some start-values. It just requests a clock-update which
will happen before entering to guest.
The clock-update logic will call kvm_setup_pvclock_page() to update the
pvclock-page with info. However, kvm_setup_pvclock_page() *wrongly*
assumes that the version-field is initialized to an even number. This is
wrong because at first-time write, field could be any-value.
Fix simply makes sure that if first-time version-field is odd, increment
it once more to make it even and only then start standard logic.
This follows same logic as done in other pvclock shared-pages (See
kvm_write_wall_clock() and record_steal_time()).
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kvm/x86.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 595f8149c0d9..a4294fd1caa7 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1797,6 +1797,9 @@ static void kvm_setup_pvclock_page(struct kvm_vcpu *v) */ BUILD_BUG_ON(offsetof(struct pvclock_vcpu_time_info, version) != 0); + if (guest_hv_clock.version & 1) + ++guest_hv_clock.version; /* first time write, random junk */ + vcpu->hv_clock.version = guest_hv_clock.version + 1; kvm_write_guest_cached(v->kvm, &vcpu->pv_time, &vcpu->hv_clock, |