KVM: x86: update masterclock values on TSC writes (7f187922) · Commits · 戴 / test

When the guest writes to the TSC, the masterclock TSC copy must be updated as well along with the TSC_OFFSET update, otherwise a negative tsc_timestamp is calculated at kvm_guest_time_update. Once "if (!vcpus_matched && ka->use_master_clock)" is simplified to "if (ka->use_master_clock)", the corresponding "if (!ka->use_master_clock)" becomes redundant, so remove the do_request boolean and collapse everything into a single condition. Signed-off-by:

Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

+10 −9

Original line number	Diff line number	Diff line
		@@ -1235,21 +1235,22 @@ void kvm_track_tsc_matching(struct kvm_vcpu *vcpu)
		{
		#ifdef CONFIG_X86_64
		bool vcpus_matched;
		bool do_request = false;
		struct kvm_arch *ka = &vcpu->kvm->arch;
		struct pvclock_gtod_data *gtod = &pvclock_gtod_data;

		vcpus_matched = (ka->nr_vcpus_matched_tsc + 1 ==
		atomic_read(&vcpu->kvm->online_vcpus));

		if (vcpus_matched && gtod->clock.vclock_mode == VCLOCK_TSC)
		if (!ka->use_master_clock)
		do_request = 1;

		if (!vcpus_matched && ka->use_master_clock)
		do_request = 1;

		if (do_request)
		/*
		* Once the masterclock is enabled, always perform request in
		* order to update it.
		*
		* In order to enable masterclock, the host clocksource must be TSC
		* and the vcpus need to have matched TSCs. When that happens,
		* perform request to enable masterclock.
		*/
		if (ka->use_master_clock \|\|
		(gtod->clock.vclock_mode == VCLOCK_TSC && vcpus_matched))
		kvm_make_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu);

		trace_kvm_track_tsc(vcpu->vcpu_id, ka->nr_vcpus_matched_tsc,

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