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authorPavel Tatashin <pasha.tatashin@soleen.com>2019-01-26 12:49:56 -0500
committerPaolo Bonzini <pbonzini@redhat.com>2019-02-20 22:48:19 +0100
commitb5179ec4187251a751832193693d6e474d3445ac (patch)
treef70f0d51691ebf10f510037555af7d8d6c3901b1 /virt/kvm
parent4f44c4eec5b72020c6d99e9e4f3d0505874c98c9 (diff)
x86/kvmclock: set offset for kvm unstable clock
VMs may show incorrect uptime and dmesg printk offsets on hypervisors with unstable clock. The problem is produced when VM is rebooted without exiting from qemu. The fix is to calculate clock offset not only for stable clock but for unstable clock as well, and use kvm_sched_clock_read() which substracts the offset for both clocks. This is safe, because pvclock_clocksource_read() does the right thing and makes sure that clock always goes forward, so once offset is calculated with unstable clock, we won't get new reads that are smaller than offset, and thus won't get negative results. Thank you Jon DeVree for helping to reproduce this issue. Fixes: 857baa87b642 ("sched/clock: Enable sched clock early") Cc: stable@vger.kernel.org Reported-by: Dominique Martinet <asmadeus@codewreck.org> Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm')
0 files changed, 0 insertions, 0 deletions