Eric Lee / smarc-ti-linux-kernel

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Commit d204feb2946a5b9f9a73c1d20c25a3930dc56fcd

Authored by Marcelo Tosatti
Committed by Greg Kroah-Hartman
1 parent f21d9d4448

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 10 additions and 9 deletions Side-by-side Diff

... ... @@ -1237,21 +1237,22 @@
1237 1237 {
1238 1238 #ifdef CONFIG_X86_64
1239 1239 bool vcpus_matched;
1240   - bool do_request = false;
1241 1240 struct kvm_arch *ka = &vcpu->kvm->arch;
1242 1241 struct pvclock_gtod_data *gtod = &pvclock_gtod_data;
1243 1242  
1244 1243 vcpus_matched = (ka->nr_vcpus_matched_tsc + 1 ==
1245 1244 atomic_read(&vcpu->kvm->online_vcpus));
1246 1245  
1247   - if (vcpus_matched && gtod->clock.vclock_mode == VCLOCK_TSC)
1248   - if (!ka->use_master_clock)
1249   - do_request = 1;
1250   -
1251   - if (!vcpus_matched && ka->use_master_clock)
1252   - do_request = 1;
1253   -
1254   - if (do_request)
  1246 + /*
  1247 + * Once the masterclock is enabled, always perform request in
  1248 + * order to update it.
  1249 + *
  1250 + * In order to enable masterclock, the host clocksource must be TSC
  1251 + * and the vcpus need to have matched TSCs. When that happens,
  1252 + * perform request to enable masterclock.
  1253 + */
  1254 + if (ka->use_master_clock ||
  1255 + (gtod->clock.vclock_mode == VCLOCK_TSC && vcpus_matched))
1255 1256 kvm_make_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu);
1256 1257  
1257 1258 trace_kvm_track_tsc(vcpu->vcpu_id, ka->nr_vcpus_matched_tsc,