On Tue, Jan 08, 2013 at 06:43:27PM +0000, Christoffer Dall wrote: > From: Marc Zyngier <marc.zyngier@xxxxxxx> > > Do the necessary save/restore dance for the timers in the world > switch code. In the process, allow the guest to read the physical > counter, which is useful for its own clock_event_device. [...] > @@ -476,6 +513,7 @@ vcpu .req r0 @ vcpu pointer always in r0 > * for the host. > * > * Assumes vcpu pointer in vcpu reg > + * Clobbers r2-r4 > */ > .macro restore_timer_state > @ Disallow physical timer access for the guest > @@ -484,6 +522,30 @@ vcpu .req r0 @ vcpu pointer always in r0 > orr r2, r2, #CNTHCTL_PL1PCTEN > bic r2, r2, #CNTHCTL_PL1PCEN > mcr p15, 4, r2, c14, c1, 0 @ CNTHCTL > + > +#ifdef CONFIG_KVM_ARM_TIMER > + ldr r4, [vcpu, #VCPU_KVM] > + ldr r2, [r4, #KVM_TIMER_ENABLED] > + cmp r2, #0 > + beq 1f > + > + ldr r2, [r4, #KVM_TIMER_CNTVOFF] > + ldr r3, [r4, #(KVM_TIMER_CNTVOFF + 4)] > + mcrr p15, 4, r2, r3, c14 @ CNTVOFF > + isb > + > + ldr r4, =VCPU_TIMER_CNTV_CVAL > + add vcpu, vcpu, r4 > + ldrd r2, r3, [vcpu] > + sub vcpu, vcpu, r4 > + mcrr p15, 3, r2, r3, c14 @ CNTV_CVAL > + > + ldr r2, [vcpu, #VCPU_TIMER_CNTV_CTL] > + and r2, r2, #3 > + mcr p15, 0, r2, c14, c3, 1 @ CNTV_CTL > + isb How many of these isbs are actually needed, given that we're going to make an exception return to the guest? The last one certainly looks redundant and I can't see the need for ordering CNTVOFF vs CNTV_CVAL. I can see an argument to putting one *before* CNTV_CTL, but you don't have one there! Will -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
