From: Christoffer Dall <christoffer.dall@linaro.org>
Date: Fri, 15 Dec 2017 00:30:12 +0100
Subject: KVM: arm/arm64: Fix timer enable flow
Patch-mainline: v4.15-rc5
Git-commit: 0eb7c33cadf6b2f1a94e58ded8b0eb89b4eba382
References: bsc#1077761

When enabling the timer on the first run, we fail to ever restore the
state and mark it as loaded.  That means, that in the initial entry to
the VCPU ioctl, unless we exit to userspace for some reason such as a
pending signal, if the guest programs a timer and blocks, we will wait
forever, because we never read back the hardware state (the loaded flag
is not set), and so we think the timer is disabled, and we never
schedule a background soft timer.

The end result?  The VCPU blocks forever, and the only solution is to
kill the thread.

Fixes: 4a2c4da1250d ("arm/arm64: KVM: Load the timer state when enabling the timer")
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Alexander Graf <agraf@suse.de>
---
 virt/kvm/arm/arch_timer.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -846,10 +846,7 @@
 no_vgic:
 	preempt_disable();
 	timer->enabled = 1;
-	if (!irqchip_in_kernel(vcpu->kvm))
-		kvm_timer_vcpu_load_user(vcpu);
-	else
-		kvm_timer_vcpu_load_vgic(vcpu);
+	kvm_timer_vcpu_load(vcpu);
 	preempt_enable();
 
 	return 0;