kvm: fix wrong address when writing Hyper-V tsc page

When kvm_write_guest writes the tsc_ref structure to the guest, or it will lead
the low HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT bits of the TSC page address
must be cleared, or the guest can see a non-zero sequence number.

Otherwise Windows guests would not be able to get a correct clocksource
(QueryPerformanceCounter will always return 0) which causes serious chaos.

Signed-off-by: Xiaoming Gao <newtongao@tencnet.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f32a02578c0d1985b424edaf992aede89b5cd7b4..f6449334ec4514741f7f79481e419d30442d1ac2 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1898,7 +1898,7 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
                if (!(data & HV_X64_MSR_TSC_REFERENCE_ENABLE))
                        break;
                gfn = data >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT;
-               if (kvm_write_guest(kvm, data,
+               if (kvm_write_guest(kvm, gfn << HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT,
                        &tsc_ref, sizeof(tsc_ref)))
                        return 1;
                mark_page_dirty(kvm, gfn);