On 20 November 2013 19:21, Christoffer Dall <christoffer.dall@xxxxxxxxxx> wrote: > On Wed, Nov 20, 2013 at 07:12:42PM +0000, Peter Maydell wrote: >> 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? Well, we call KVM_ARM_VCPU_INIT as part of our CPU init, but I didn't think you were allowed to call it a second time later on to do a CPU reset (ie as part of system reset when the guest asks for a system reset as part of 'shutdown -r now'). Is that valid? If so, it would probably be good to specifically document it... -- PMM _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
