arm/arm64: KVM: arch timer: Reset CNTV_CTL to 0

Provide a better quality of implementation and be architecture compliant
on ARMv7 for the architected timer by resetting the CNTV_CTL to 0 on
reset of the timer.

This change alone fixes the UEFI reset issue reported by Laszlo back in
February.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Drew Jones <drjones@redhat.com>
Cc: Wei Huang <wei@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 76e38d231e9959d085673b4eda7e4065f4a7fbb7..48c6e1ac6827f14be7eaede56bfd1ae3d185d217 100644 (file)
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -199,6 +199,14 @@ int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
         */
        timer->irq = irq;
 
+       /*
+        * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
+        * and to 0 for ARMv7.  We provide an implementation that always
+        * resets the timer to be disabled and unmasked and is compliant with
+        * the ARMv7 architecture.
+        */
+       timer->cntv_ctl = 0;
+
        /*
         * Tell the VGIC that the virtual interrupt is tied to a
         * physical interrupt. We do that once per VCPU.