On Wed, Nov 20, 2013 at 07:12:42PM +0000, Peter Maydell wrote: > On 20 November 2013 18:51, Christoffer Dall <christoffer.dall@xxxxxxxxxx> wrote: > > Therefore, set the pause flag on the vcpu at VCPU init time (which can > > reasonably be expected to be completed for all CPUs by user space before > > running any VCPUs) and clear both this flag and the feature (in case the > > feature can somehow get set again in the future) and ping the waitqueue > > on turning on a VCPU using PSCI. > > Tangential, but your phrasing prompted me to ask: how does > the "start in PSCI power-off" boot protocol work for system reset? > Since the kernel doesn't currently provide a "reset this v CPU" > ioctl userspace has to do reset manually[*]; how do we say "take > this vCPU which has started up and run once, and put it back > into PSCI power-off" ? > > [*] this is pretty tedious, since it involves reading every CPU > register on the vCPU before first run in order to feed the kernel > back a bunch of info it already knows about the reset state of > a vCPU. > So, from looking at the code and the API specification calling KVM_ARM_VCPU_INIT does exactly this and also resets all core and cp15 registers for you - you would here be able to set the power-off flag and pause those CPUs so PSCI can wake them up again. Am I missing something here? This makes me wonder if it's worth adding to Documentation/virtual/kvm/api.txt that KVM_ARM_VCPU_INIT should be called on all VCPUs before running any of the VCPUs... -Christoffer -- 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
