| Message ID | 1442419087-24648-3-git-send-email-marc.zyngier@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 > exit. > > Cc: stable@vger.kernel.org > Signed-off-by: Marc Zyngier <marc.zyngier@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 patches? > 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 > > @@ -579,6 +577,8 @@ alternative_endif > str x3, [x0, #VCPU_TIMER_CNTV_CVAL] > > 1: > + msr cntv_ctl_el0, xzr > + We could have a comment here, but ok. > // Allow physical timer/counter access for the host > mrs x2, cnthctl_el2 > orr x2, x2, #3 > -- > 2.1.4 > Otherwise: Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
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 >> exit. >> >> Cc: stable@vger.kernel.org >> Signed-off-by: Marc Zyngier <marc.zyngier@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 > patches? No, that's on top of 4.3-rc1, which happens to have this: [...] alternative_if_not ARM64_HAS_SYSREG_GIC_CPUIF bl __restore_vgic_v2_state alternative_else bl __restore_vgic_v3_state alternative_endif .endm .macro save_timer_state [...] 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 >> >> isb >> >> @@ -579,6 +577,8 @@ alternative_endif >> str x3, [x0, #VCPU_TIMER_CNTV_CVAL] >> >> 1: >> + 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 >> -- >> 2.1.4 >> > > Otherwise: > > Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> > Thanks! M.
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 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 @@ -579,6 +577,8 @@ alternative_endif str x3, [x0, #VCPU_TIMER_CNTV_CVAL] 1: + msr cntv_ctl_el0, xzr + // Allow physical timer/counter access for the host mrs x2, cnthctl_el2 orr x2, x2, #3
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> --- arch/arm64/kvm/hyp.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)