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@xxxxxxx> >>> >>> 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). > 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, Suravee
