KVM: arm/arm64: Fix lost IRQs from emulated physcial timer when blocked

BugLink: https://bugs.launchpad.net/bugs/1835972
commit 245715cbe83ca934af5d20e078fd85175c62995e upstream.

When the VCPU is blocked (for example from WFI) we don't inject the
physical timer interrupt if it should fire while the CPU is blocked, but
instead we just wake up the VCPU and expect kvm_timer_vcpu_load to take
care of injecting the interrupt.

Unfortunately, kvm_timer_vcpu_load() doesn't actually do that, it only
has support to schedule a soft timer if the emulated phys timer is
expected to fire in the future.

Follow the same pattern as kvm_timer_update_state() and update the irq
state after potentially scheduling a soft timer.

Reported-by: Andre Przywara <andre.przywara@arm.com>
Cc: Stable <stable@vger.kernel.org> # 4.15+
Fixes: bbdd52cfcba29 ("KVM: arm/arm64: Avoid phys timer emulation in vcpu entry/exit")
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index b06135e17c2e073dd86bf56702919a1bb64e672e..385ab82b81066066b355a7a83adf58830d0b9b8d 100644 (file)
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -474,6 +474,7 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
 {
        struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
        struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+       struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
 
        if (unlikely(!timer->enabled))
                return;
@@ -489,6 +490,10 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
 
        /* Set the background timer for the physical timer emulation. */
        phys_timer_emulate(vcpu);
+
+       /* If the timer fired while we weren't running, inject it now */
+       if (kvm_timer_should_fire(ptimer) != ptimer->irq.level)
+               kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer);
 }
 
 bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu)