@@ -1209,21 +1209,22 @@ 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,
This is a note to let you know that I have just added a patch titled KVM: x86: update masterclock values on TSC writes to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt7. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From f474bf036e540daceea09cb04480932bef966fb5 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti <mtosatti@redhat.com> Date: Tue, 4 Nov 2014 21:30:44 -0200 Subject: KVM: x86: update masterclock values on TSC writes commit 7f187922ddf6b67f2999a76dcb71663097b75497 upstream. 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> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/x86/kvm/x86.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) -- 2.1.4