Messages in this thread | | | From | "Graf (AWS), Alexander" <> | Subject | Re: [PATCH v2 04/15] kvm: x86: Add per-VM APICv state debugfs | Date | Wed, 28 Aug 2019 19:36:03 +0000 |
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> Am 28.08.2019 um 20:41 schrieb Suthikulpanit, Suravee <Suravee.Suthikulpanit@amd.com>: > > Alex, > >> On 8/27/19 3:20 AM, Alexander Graf wrote: >> >> >>> On 26.08.19 21:41, Suthikulpanit, Suravee wrote: >>> Alex, >>> >>>> On 8/19/2019 4:57 AM, Alexander Graf wrote: >>>> >>>> >>>>> On 15.08.19 18:25, Suthikulpanit, Suravee wrote: >>>>> Currently, there is no way to tell whether APICv is active >>>>> on a particular VM. This often cause confusion since APICv >>>>> can be deactivated at runtime. >>>>> >>>>> Introduce a debugfs entry to report APICv state of a VM. >>>>> This creates a read-only file: >>>>> >>>>> /sys/kernel/debug/kvm/70860-14/apicv-state >>>>> >>>>> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> >>>> >>>> Shouldn't this first and foremost be a VM ioctl so that user space >>>> can inquire its own state? >>>> >>>> >>>> Alex >>> >>> I introduce this mainly for debugging similar to how KVM is currently >>> provides >>> some per-VCPU information: >>> >>> /sys/kernel/debug/kvm/15957-14/vcpu0/ >>> lapic_timer_advance_ns >>> tsc-offset >>> tsc-scaling-ratio >>> tsc-scaling-ratio-frac-bits >>> >>> I'm not sure if this needs to be VM ioctl at this point. If this >>> information is >>> useful for user-space tool to inquire via ioctl, we can also provide it. >> >> I'm mostly thinking of something like "info apic" in QEMU which to me >> seems like the natural place for APIC information exposure to a user. > > I could not find QEMU "info apic". I assume you meant "info lapic", > which provides information specific to each local APIC (i.e. per-vcpu).
Or maybe even "info kvm" :). I think you get the point.
> >> The problem with debugfs is that it's not accessible to the user that >> created the VM, but only root, right? > > Hm, you are right. I'll also look into also adding ioctl interface then.
Thanks!
Alex
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