On Sat, 11 Aug 2018 at 18:56, Thomas Gleixner <tglx@linutronix.de> wrote:
>
> On Sat, 11 Aug 2018, Thomas Gleixner wrote:
>
> > On Sat, 11 Aug 2018, Matthew Wilcox wrote:
> >
> > > On Sat, Aug 11, 2018 at 12:28:24PM +0500, Mikhail Gavrilov wrote:
> > > > Hi guys.
> > > > I am catched new bug. It occured when I start virtual machine.
> > > > Can anyone look?
> > >
> > > I'd suggest that st->lock should be taken with irqsave.  Like this;
> > > please test.
> >
> > That should fix it, but that's suboptimal because that's an extra
> > safe/restore in switch_to(). So we better disable interrupts at the other
> > call site. Patch below.
>
> Which is wrong as well. The placement of the speculation update call in the
> SVM code should be moved, so just SVM is affected by a slightly larger irq
> disabled region and no overhead at all for all others. Revised patch below.
>
> Thanks,
>
>         tglx
>
> 8<------------------
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index f059a73f0fd0..9c9b976d1afd 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -5580,8 +5580,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
>
>         clgi();
>
> -       local_irq_enable();
> -
>         /*
>          * If this vCPU has touched SPEC_CTRL, restore the guest's value if
>          * it's non-zero. Since vmentry is serialising on affected CPUs, there
> @@ -5590,6 +5588,8 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
>          */
>         x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl);
>
> +       local_irq_enable();
> +
>         asm volatile (
>                 "push %%" _ASM_BP "; \n\t"
>                 "mov %c[rbx](%[svm]), %%" _ASM_BX " \n\t"
>


I am tested this patch, but it not help solve issue.
New dmesg output is attached here.