On 2011-12-02 22:27, Eric B Munson wrote: > On Fri, 02 Dec 2011, Jan Kiszka wrote: > >> On 2011-12-02 20:19, Eric B Munson wrote: >>> Often when a guest is stopped from the qemu console, it will report spurious >>> soft lockup warnings on resume. There are kernel patches being discussed that >>> will give the host the ability to tell the guest that it is being stopped and >>> should ignore the soft lockup warning that generates. >>> >>> Signed-off-by: Eric B Munson <emunson@xxxxxxxxx> >>> Cc: Avi Kivity <avi@xxxxxxxxxx> >>> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx> >>> Cc: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> >>> Cc: ryanh@xxxxxxxxxxxxxxxxxx >>> Cc: aliguori@xxxxxxxxxx >>> Cc: kvm@xxxxxxxxxxxxxxx >>> >>> --- >>> Changes from V2: >>> Move ioctl into hw/kvmclock.c so as other arches can use it as it is >>> implemented >>> >>> Changes from V1: >>> Remove unnecessary encapsulating function >>> >>> hw/kvmclock.c | 24 ++++++++++++++++++++++++ >>> 1 files changed, 24 insertions(+), 0 deletions(-) >>> >>> diff --git a/hw/kvmclock.c b/hw/kvmclock.c >>> index 5388bc4..756839f 100644 >>> --- a/hw/kvmclock.c >>> +++ b/hw/kvmclock.c >>> @@ -16,6 +16,7 @@ >>> #include "sysbus.h" >>> #include "kvm.h" >>> #include "kvmclock.h" >>> +#include "cpu-all.h" >>> >>> #include <linux/kvm.h> >>> #include <linux/kvm_para.h> >>> @@ -69,11 +70,34 @@ static void kvmclock_vm_state_change(void *opaque, int running, >>> } >>> } >>> >>> +static void kvmclock_vm_state_change_vcpu(void *opaque, int running, >>> + RunState state) >>> +{ >>> + int ret; >>> + CPUState *penv = first_cpu; >>> + >>> + if (running) { >>> + while (penv) { >> >> or: for (cpu = first_cpu; cpu != NULL; cpu = cpu->next_cpu) { >> > > Functionally equivalent and I see both in the code, is there a standard? Not really. I once tried to introduce an iterator macro, but it was refused. The above is just more compact. But this is only a minor nit. > >>> + ret = kvm_vcpu_ioctl(penv, KVM_GUEST_PAUSED, 0); >>> + if (ret) { >>> + if (ret != ENOSYS) { >>> + fprintf(stderr, >>> + "kvmclock_vm_state_change_vcpu: %s\n", >>> + strerror(-ret)); >>> + } >>> + return; >>> + } >>> + penv = (CPUState *)penv->next_cpu; >> >> Unneeded cast. >> > > Also following an example seen elsewhere. Generally, we try to avoid those pointless casts. > >>> + } >>> + } >>> +} >>> + >> >> Again: please use checkpatch.pl. >> > > Sorry, tough to get used to hitting space bar that many times... > >>> static int kvmclock_init(SysBusDevice *dev) >>> { >>> KVMClockState *s = FROM_SYSBUS(KVMClockState, dev); >>> >>> qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s); >>> + qemu_add_vm_change_state_handler(kvmclock_vm_state_change_vcpu, NULL); >>> return 0; >>> } >>> >> >> Why not extend the existing handler? > > Because the new handler doesn't touch the KVMClockState object. If this is > preferred, I have no objection. The separate registration looks strange to me. And the fact that you don't need to object doesn't justify a callback of its own. > >> >> I still wonder if the IOCTL interface is actually kvmclock specific. But >> Marcello asked for this, and we could still change it when some arch >> comes around that provides it independent of kvmclock. > > The flag itself is stored in the pvclock_vcpu_time_info structure, and anything > else that touches that structure uses ioctls. That's the host-guest interface. But I'm talking about the kvm-qemu interface here which has no relation to how the "was paused" information is transferred to the guest. Jan
Attachment:
signature.asc
Description: OpenPGP digital signature