arm: 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: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm/kvm/interrupts_head.S b/arch/arm/kvm/interrupts_head.S
index 702740d..51a5950 100644 (file)
--- a/arch/arm/kvm/interrupts_head.S
+++ b/arch/arm/kvm/interrupts_head.S
@@ -515,8 +515,7 @@ ARM_BE8(rev r6, r6  )
 
        mrc     p15, 0, r2, c14, c3, 1  @ CNTV_CTL
        str     r2, [vcpu, #VCPU_TIMER_CNTV_CTL]
-       bic     r2, #1                  @ Clear ENABLE
-       mcr     p15, 0, r2, c14, c3, 1  @ CNTV_CTL
+
        isb
 
        mrrc    p15, 3, rr_lo_hi(r2, r3), c14   @ CNTV_CVAL
@@ -529,6 +528,9 @@ ARM_BE8(rev r6, r6  )
        mcrr    p15, 4, r2, r2, c14     @ CNTVOFF
 
 1:
+       mov     r2, #0                  @ Clear ENABLE
+       mcr     p15, 0, r2, c14, c3, 1  @ CNTV_CTL
+
        @ Allow physical timer/counter access for the host
        mrc     p15, 4, r2, c14, c1, 0  @ CNTHCTL
        orr     r2, r2, #(CNTHCTL_PL1PCEN | CNTHCTL_PL1PCTEN)