Commit c4cbba9f authored Sep 16, 2015 by Marc Zyngier

arm64: KVM: Disable virtual timer even if the guest is not using it



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
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

parent c2f58514

arch/arm64/kvm/hyp.S

+3 −2

Original line number	Diff line number	Diff line
		@@ -562,8 +562,6 @@
		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

		@@ -571,6 +569,9 @@
		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