This is a note to let you know that I've just added the patch titled
arm64: 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:
arm64-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 <stable@xxxxxxxxxxxxxxx> know about it.
>From c4cbba9fa078f55d9f6d081dbb4aec7cf969e7c7 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier@xxxxxxx>
Date: Wed, 16 Sep 2015 16:18:59 +0100
Subject: arm64: KVM: Disable virtual timer even if the guest is not using it
From: Marc Zyngier <marc.zyngier@xxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kvm/hyp.S | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -840,8 +840,6 @@
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
@@ -849,6 +847,9 @@
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
Patches currently in stable-queue which might be from marc.zyngier@xxxxxxx are
queue-4.2/arm64-head.s-initialise-mdcr_el2-in-el2_setup.patch
queue-4.2/kvm-arm64-add-workaround-for-cortex-a57-erratum-852523.patch
queue-4.2/arm64-kvm-disable-virtual-timer-even-if-the-guest-is-not-using-it.patch
queue-4.2/arm-arm64-kvm-vgic-check-for-irqchip_in_kernel-when-mapping-resources.patch
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