Make the match of TSC find TSC writes that are close to each other instead of perfectly identical; this allows the compensator to also work in migration / suspend scenarios.
Signed-off-by: Zachary Amsden <[email protected]> --- arch/x86/kvm/x86.c | 17 +++++++++++++---- 1 files changed, 13 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bb7451b..1c737b2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -897,7 +897,11 @@ void guest_write_tsc(struct kvm_vcpu *vcpu, u64 data) { struct kvm *kvm = vcpu->kvm; u64 offset, ns, elapsed; +<<<<<<< HEAD struct timespec ts; +======= + s64 sdiff; +>>>>>>> db4c819... oops spin_lock(&kvm->arch.tsc_write_lock); offset = data - native_read_tsc(); @@ -905,16 +909,21 @@ void guest_write_tsc(struct kvm_vcpu *vcpu, u64 data) monotonic_to_bootbased(&ts); ns = timespec_to_ns(&ts); elapsed = ns - kvm->arch.last_tsc_nsec; + sdiff = data - kvm->arch.last_tsc_write; + if (sdiff < 0) + sdiff = -sdiff; /* - * Special case: identical write to TSC within 5 seconds of + * Special case: close write to TSC within 5 seconds of * another CPU is interpreted as an attempt to synchronize - * (the 5 seconds is to accomodate host load / swapping). + * The 5 seconds is to accomodate host load / swapping as + * well as any reset of TSC during the boot process. * * In that case, for a reliable TSC, we can match TSC offsets, - * or make a best guest using kernel_ns value. + * or make a best guest using elapsed value. */ - if (data == kvm->arch.last_tsc_write && elapsed < 5ULL * NSEC_PER_SEC) { + if (sdiff < nsec_to_cycles(5ULL * NSEC_PER_SEC) && + elapsed < 5ULL * NSEC_PER_SEC) { if (!check_tsc_unstable()) { offset = kvm->arch.last_tsc_offset; pr_debug("kvm: matched tsc offset for %llu\n", data); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
