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

commit c4cbba9fa078f55d9f6d081dbb4aec7cf969e7c7 upstream.

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.

Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 4dad27ba7d3d2e1d441b7b1661e9b03287456461..64f9e60b31da1e45fe419a30829943ca5ba40454 100644 (file)
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -844,8 +844,6 @@
        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
 
@@ -853,6 +851,9 @@
        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