arm64: KVM: Disable virtual timer even if the guest is not using it

When running a guest with the architected timer disabled (with QEMU and the kernel_irqchip=off option, for example), it is important to make sure the timer gets turned off. Otherwise, the guest may try to enable it anyway, leading to a screaming HW interrupt. The fix is to unconditionally turn off the virtual timer on guest exit. Cc: [email protected] Reviewed-by: Christoffer Dall <[email protected]> Signed-off-by: Marc Zyngier <[email protected]>
jix · Sep 17, 2015 · c4cbba9 · c4cbba9
1 parent c2f5851
commit c4cbba9
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
@@ -562,15 +562,16 @@
 	mrs	x3, cntv_ctl_el0
 	and	x3, x3, #3
 	str	w3, [x0, #VCPU_TIMER_CNTV_CTL]
-	bic	x3, x3, #1		// Clear Enable
-	msr	cntv_ctl_el0, x3
 
 	isb
 
 	mrs	x3, cntv_cval_el0
 	str	x3, [x0, #VCPU_TIMER_CNTV_CVAL]
 
 1:
+	// Disable the virtual timer
+	msr	cntv_ctl_el0, xzr
+
 	// Allow physical timer/counter access for the host
 	mrs	x2, cnthctl_el2
 	orr	x2, x2, #3