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Subject[PATCH 4.1 007/202] arm: KVM: Disable virtual timer even if the guest is not using it
Date
4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@arm.com>

commit 688bc577ac42ae3d07c889a1f0a72f0b23763d58 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.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/arm/kvm/interrupts_head.S | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/arch/arm/kvm/interrupts_head.S
+++ b/arch/arm/kvm/interrupts_head.S
@@ -518,8 +518,7 @@ 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
@@ -532,6 +531,9 @@ 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)



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