|
 |
5d9a194 |
@@ -, +, @@
|
|
|
5d9a194 |
VMX: x86: handle host TSC calibration failure
|
|
|
5d9a194 |
|
|
|
5d9a194 |
If the host TSC calibration fails, tsc_khz is zero (see tsc_init.c).
|
|
|
5d9a194 |
Handle such case properly in KVM (instead of dividing by zero).
|
|
|
5d9a194 |
|
|
|
5d9a194 |
https://bugzilla.redhat.com/show_bug.cgi?id=859282
|
|
|
5d9a194 |
|
|
|
5d9a194 |
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
|
|
|
5d9a194 |
Signed-off-by: Gleb Natapov <gleb@redhat.com>
|
|
|
5d9a194 |
--- a/arch/x86/kvm/x86.c
|
|
|
5d9a194 |
+++ a/arch/x86/kvm/x86.c
|
|
|
5d9a194 |
@@ -1079,6 +1079,10 @@ static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
|
|
|
5d9a194 |
u32 thresh_lo, thresh_hi;
|
|
|
5d9a194 |
int use_scaling = 0;
|
|
|
5d9a194 |
|
|
|
5d9a194 |
+ /* tsc_khz can be zero if TSC calibration fails */
|
|
|
5d9a194 |
+ if (this_tsc_khz == 0)
|
|
|
5d9a194 |
+ return;
|
|
|
5d9a194 |
+
|
|
|
5d9a194 |
/* Compute a scale to convert nanoseconds in TSC cycles */
|
|
|
5d9a194 |
kvm_get_time_scale(this_tsc_khz, NSEC_PER_SEC / 1000,
|
|
|
5d9a194 |
&vcpu->arch.virtual_tsc_shift,
|
|
|
5d9a194 |
@@ -1156,20 +1160,23 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
|
|
|
5d9a194 |
ns = get_kernel_ns();
|
|
|
5d9a194 |
elapsed = ns - kvm->arch.last_tsc_nsec;
|
|
|
5d9a194 |
|
|
|
5d9a194 |
- /* n.b - signed multiplication and division required */
|
|
|
5d9a194 |
- usdiff = data - kvm->arch.last_tsc_write;
|
|
|
5d9a194 |
+ if (vcpu->arch.virtual_tsc_khz) {
|
|
|
5d9a194 |
+ /* n.b - signed multiplication and division required */
|
|
|
5d9a194 |
+ usdiff = data - kvm->arch.last_tsc_write;
|
|
|
5d9a194 |
#ifdef CONFIG_X86_64
|
|
|
5d9a194 |
- usdiff = (usdiff * 1000) / vcpu->arch.virtual_tsc_khz;
|
|
|
5d9a194 |
+ usdiff = (usdiff * 1000) / vcpu->arch.virtual_tsc_khz;
|
|
|
5d9a194 |
#else
|
|
|
5d9a194 |
- /* do_div() only does unsigned */
|
|
|
5d9a194 |
- asm("idivl %2; xor %%edx, %%edx"
|
|
|
5d9a194 |
- : "=A"(usdiff)
|
|
|
5d9a194 |
- : "A"(usdiff * 1000), "rm"(vcpu->arch.virtual_tsc_khz));
|
|
|
5d9a194 |
+ /* do_div() only does unsigned */
|
|
|
5d9a194 |
+ asm("idivl %2; xor %%edx, %%edx"
|
|
|
5d9a194 |
+ : "=A"(usdiff)
|
|
|
5d9a194 |
+ : "A"(usdiff * 1000), "rm"(vcpu->arch.virtual_tsc_khz));
|
|
|
5d9a194 |
#endif
|
|
|
5d9a194 |
- do_div(elapsed, 1000);
|
|
|
5d9a194 |
- usdiff -= elapsed;
|
|
|
5d9a194 |
- if (usdiff < 0)
|
|
|
5d9a194 |
- usdiff = -usdiff;
|
|
|
5d9a194 |
+ do_div(elapsed, 1000);
|
|
|
5d9a194 |
+ usdiff -= elapsed;
|
|
|
5d9a194 |
+ if (usdiff < 0)
|
|
|
5d9a194 |
+ usdiff = -usdiff;
|
|
|
5d9a194 |
+ } else
|
|
|
5d9a194 |
+ usdiff = USEC_PER_SEC; /* disable TSC match window below */
|
|
|
5d9a194 |
|
|
|
5d9a194 |
/*
|
|
|
5d9a194 |
* Special case: TSC write with a small delta (1 second) of virtual
|