Re: switching from KVM guest to the host .... TLBs not present?
Jes Sorensen <[email protected]>
| Newsgroups | org.kernel.vger.kvm-ia64 |
|---|---|
| Message-ID | <[email protected]> |
Zhang, Xiantao wrote: > Yeah, that is very strange! I will check it tomorrow, and have to sleep now :-) > Xiantao Hi Xiantao, I think I got it! We were calling local_irqs_disable() before calling down_read(), but down_read() can sleep and so may return with local interrupts re-enabled..... I have reordered things so now we should be safe. How does this patch look to you? Cheers, Jes
0001-kvm-ia64-vti-local-irq-disable.patch
(text/x-patch, 1.2 KB)
Reorder locking as down_read() may return with local interrupts enabled, which means we could go into vti_vcpu_run() with interrupts enabled. This caused random crashes on the Altix as the timer interrupt tried to read a memory mapped clock source, for which the TLB had not yet been reinstated in the exit, before ipsr was retored. Signed-off-by: Jes Sorensen <[email protected]> --- arch/ia64/kvm/kvm-ia64.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) Index: linux-2.6.git/arch/ia64/kvm/kvm-ia64.c =================================================================== --- linux-2.6.git.orig/arch/ia64/kvm/kvm-ia64.c +++ linux-2.6.git/arch/ia64/kvm/kvm-ia64.c @@ -610,20 +610,22 @@ int r; again: - preempt_disable(); - local_irq_disable(); - if (signal_pending(current)) { - local_irq_enable(); - preempt_enable(); r = -EINTR; kvm_run->exit_reason = KVM_EXIT_INTR; goto out; } + /* + * down_read() may sleep and return with interrupts enabled + */ + down_read(&vcpu->kvm->slots_lock); + + preempt_disable(); + local_irq_disable(); + vcpu->guest_mode = 1; kvm_guest_enter(); - down_read(&vcpu->kvm->slots_lock); r = vti_vcpu_run(vcpu, kvm_run); if (r < 0) { local_irq_enable();