On Wed, Feb 21, 2024 at 01:34:31AM -0500, Shaoqin Huang wrote: > diff --git a/docs/system/arm/cpu-features.rst b/docs/system/arm/cpu-features.rst > index a5fb929243..7c8f6a60ef 100644 > --- a/docs/system/arm/cpu-features.rst > +++ b/docs/system/arm/cpu-features.rst > @@ -204,6 +204,29 @@ the list of KVM VCPU features and their descriptions. > the guest scheduler behavior and/or be exposed to the guest > userspace. > > +``kvm-pmu-filter`` > + By default kvm-pmu-filter is disabled. This means that by default all pmu > + events will be exposed to guest. > + > + KVM implements PMU Event Filtering to prevent a guest from being able to > + sample certain events. It depends on the KVM_ARM_VCPU_PMU_V3_FILTER > + attribute supported in KVM. It has the following format: > + > + kvm-pmu-filter="{A,D}:start-end[;{A,D}:start-end...]" > + > + The A means "allow" and D means "deny", start is the first event of the > + range and the end is the last one. The first registered range defines > + the global policy(global ALLOW if the first @action is DENY, global DENY > + if the first @action is ALLOW). The start and end only support hexadecimal > + format. For example: > + > + kvm-pmu-filter="A:0x11-0x11;A:0x23-0x3a;D:0x30-0x30" > + > + Since the first action is allow, we have a global deny policy. It > + will allow event 0x11 (The cycle counter), events 0x23 to 0x3a are > + also allowed except the event 0x30 which is denied, and all the other > + events are denied. Can you document whether the policy evaluation stops at the first matching range, or checks all ranges ie, if you have kvm-pmu-filter="A:0x1-0x9;D=0x7-0x7" will an input of '0x7' be allowed (because it matches the first range and stops), or denied (because the second range overrides the result of the first) With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|