diff options
| author |   Zachary Amsden <zamsden@redhat.com> | 2010-08-19 22:07:30 -1000 |
|---|---|---|
| committer |   Avi Kivity <avi@redhat.com> | 2010-10-24 10:51:24 +0200 |
| commit | 1d5f066e0b63271b67eac6d3752f8aa96adcbddb (patch) | |
| tree | b3ba7c2783edbc6d9e6658d91e991913ba264684 /arch/x86/include | |
| parent | x86: pvclock: Move scale_delta into common header (diff) | |
| download | linux-dev-1d5f066e0b63271b67eac6d3752f8aa96adcbddb.tar.xz linux-dev-1d5f066e0b63271b67eac6d3752f8aa96adcbddb.zip | |
KVM: x86: Fix a possible backwards warp of kvmclock
Kernel time, which advances in discrete steps may progress much slower
than TSC. As a result, when kvmclock is adjusted to a new base, the
apparent time to the guest, which runs at a much higher, nsec scaled
rate based on the current TSC, may have already been observed to have
a larger value (kernel_ns + scaled tsc) than the value to which we are
setting it (kernel_ns + 0).
We must instead compute the clock as potentially observed by the guest
for kernel_ns to make sure it does not go backwards.
Signed-off-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 5ab1c3fb34ef..789e9462668f 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -339,6 +339,8 @@ struct kvm_vcpu_arch { unsigned int time_offset; struct page *time_page; u64 last_host_tsc; + u64 last_guest_tsc; + u64 last_kernel_ns; bool nmi_pending; bool nmi_injected; |