This is a note to let you know that I've just added the patch titled
arm: KVM: Disable virtual timer even if the guest is not using it
to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-kvm-disable-virtual-timer-even-if-the-guest-is-not-using-it.patch
and it can be found in the queue-4.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 688bc577ac42ae3d07c889a1f0a72f0b23763d58 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <[email protected]>
Date: Wed, 16 Sep 2015 16:18:59 +0100
Subject: arm: KVM: Disable virtual timer even if the guest is not using it
From: Marc Zyngier <[email protected]>
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 <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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
@@ -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)
Patches currently in stable-queue which might be from [email protected] are
queue-4.2/arm-kvm-fix-incorrect-device-to-ipa-mapping.patch
queue-4.2/arm-kvm-disable-virtual-timer-even-if-the-guest-is-not-using-it.patch
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