Commit e1fa108d authored Jun 19, 2014 by Xiaoming Gao Committed by Paolo Bonzini Jun 19, 2014

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>

parent 682367c4

arch/x86/kvm/x86.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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);

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