[PATCH 2/3] arm64: KVM: Disable virtual timer even if the guest is not using it
marc.zyngier at arm.com
Thu Sep 17 05:11:24 PDT 2015
On 17/09/15 12:17, Christoffer Dall wrote:
> On Wed, Sep 16, 2015 at 04:58:06PM +0100, Marc Zyngier wrote:
>> 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
>> Cc: stable at vger.kernel.org
>> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
>> arch/arm64/kvm/hyp.S | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
>> index 6addf97..38f5434 100644
>> --- a/arch/arm64/kvm/hyp.S
>> +++ b/arch/arm64/kvm/hyp.S
>> @@ -570,8 +570,6 @@ alternative_endif
> The context confuses me; did you happen to base this on your VHE
No, that's on top of 4.3-rc1, which happens to have this:
and for some reason git doesn't use save_timer_state as the context anchor.
>> 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
>> @@ -579,6 +577,8 @@ alternative_endif
>> str x3, [x0, #VCPU_TIMER_CNTV_CVAL]
>> + msr cntv_ctl_el0, xzr
> We could have a comment here, but ok.
I'll add something.
>> // Allow physical timer/counter access for the host
>> mrs x2, cnthctl_el2
>> orr x2, x2, #3
> Reviewed-by: Christoffer Dall <christoffer.dall at linaro.org>
Jazz is not dead. It just smells funny...
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