Hi,
On Thu, Feb 01, 2018 at 12:55:12PM +1100, Stephen Rothwell wrote:
> Hi all,
>
> Today's linux-next merge of the kvm tree got a conflict in:
>
> virt/kvm/arm/arch_timer.c
>
> between commit:
>
> 36e5cfd410ad ("KVM: arm/arm64: Properly handle arch-timer IRQs after vtimer_save_state")
>
> from Linus' tree and commits:
>
> 70450a9fbe06 ("KVM: arm/arm64: Don't cache the timer IRQ level")
> 13e59ece5b30 ("KVM: arm/arm64: Fix incorrect timer_is_pending logic")
>
> from the kvm tree.
>
> I fixed it up (I think - see below) and can carry the fix as
> necessary. This is now fixed as far as linux-next is concerned, but any
> non trivial conflicts should be mentioned to your upstream maintainer
> when your tree is submitted for merging. You may also want to consider
> cooperating with the maintainer of the conflicting tree to minimise any
> particularly complex conflicts.
>
While the suggested fix is functional it does result in some code
duplication, and the better resolution is the following:
diff --cc virt/kvm/arm/arch_timer.c
index cc29a8148328,fb6bd9b9845e..000000000000
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@@ -92,27 -92,18 +92,22 @@@ static irqreturn_t kvm_arch_timer_handl
{
struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
struct arch_timer_context *vtimer;
- u32 cnt_ctl;
- if (!vcpu) {
- pr_warn_once("Spurious arch timer IRQ on non-VCPU thread\n");
- return IRQ_NONE;
- }
+ /*
+ * We may see a timer interrupt after vcpu_put() has been called which
+ * sets the CPU's vcpu pointer to NULL, because even though the timer
+ * has been disabled in vtimer_save_state(), the hardware interrupt
+ * signal may not have been retired from the interrupt controller yet.
+ */
+ if (!vcpu)
+ return IRQ_HANDLED;
vtimer = vcpu_vtimer(vcpu);
- if (!vtimer->irq.level) {
- cnt_ctl = read_sysreg_el0(cntv_ctl);
- cnt_ctl &= ARCH_TIMER_CTRL_ENABLE | ARCH_TIMER_CTRL_IT_STAT |
- ARCH_TIMER_CTRL_IT_MASK;
- if (cnt_ctl == (ARCH_TIMER_CTRL_ENABLE | ARCH_TIMER_CTRL_IT_STAT))
- kvm_timer_update_irq(vcpu, true, vtimer);
- }
+ if (kvm_timer_should_fire(vtimer))
+ kvm_timer_update_irq(vcpu, true, vtimer);
- if (unlikely(!irqchip_in_kernel(vcpu->kvm)))
+ if (static_branch_unlikely(&userspace_irqchip_in_use) &&
+ unlikely(!irqchip_in_kernel(vcpu->kvm)))
kvm_vtimer_update_mask_user(vcpu);
return IRQ_HANDLED;
Thanks,
-Christoffer
