diff options
| author | Joerg Roedel <joerg.roedel@amd.com> | 2011-03-25 09:44:48 +0100 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2011-05-11 07:57:04 -0400 |
| commit | 8f6055cbaf68cbd9ff2692a2cfa691b43629ccd4 (patch) | |
| tree | e178845f4d0f061f90e57337f28be6640da8bd6d /arch/x86/kvm/x86.c | |
| parent | 1e993611d0dc879fde25515dc9867d1cfd4c5137 (diff) | |
KVM: X86: Make tsc_delta calculation a function of guest tsc
The calculation of the tsc_delta value to ensure a
forward-going tsc for the guest is a function of the
host-tsc. This works as long as the guests tsc_khz is equal
to the hosts tsc_khz. With tsc-scaling hardware support this
is not longer true and the tsc_delta needs to be calculated
using guest_tsc values.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 78d729174d99..fcce29b7b6fa 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2113,8 +2113,13 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) kvm_x86_ops->vcpu_load(vcpu, cpu); if (unlikely(vcpu->cpu != cpu) || check_tsc_unstable()) { /* Make sure TSC doesn't go backwards */ - s64 tsc_delta = !vcpu->arch.last_host_tsc ? 0 : - native_read_tsc() - vcpu->arch.last_host_tsc; + s64 tsc_delta; + u64 tsc; + + kvm_get_msr(vcpu, MSR_IA32_TSC, &tsc); + tsc_delta = !vcpu->arch.last_guest_tsc ? 0 : + tsc - vcpu->arch.last_guest_tsc; + if (tsc_delta < 0) mark_tsc_unstable("KVM discovered backwards TSC"); if (check_tsc_unstable()) { |