Re: [PATCH] KVM: x86: Add fixed counters to PMU filter

[Wei Wang]

On 07/19/2019 02:38 AM, Eric Hankland wrote:
> From: ehankland <ehankland@xxxxxxxxxx>
>
> Updates KVM_CAP_PMU_EVENT_FILTER so it can also whitelist or blacklist
> fixed counters.
>
> Signed-off-by: ehankland <ehankland@xxxxxxxxxx>
> ---
>   Documentation/virtual/kvm/api.txt | 13 ++++++++-----
>   arch/x86/include/uapi/asm/kvm.h   |  9 ++++++---
>   arch/x86/kvm/pmu.c                | 30 +++++++++++++++++++++++++-----
>   3 files changed, 39 insertions(+), 13 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 2cd6250b2896..96bcf1aa1931 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -4090,17 +4090,20 @@ Parameters: struct kvm_pmu_event_filter (in)
>   Returns: 0 on success, -1 on error
>   
>   struct kvm_pmu_event_filter {
> -       __u32 action;
> -       __u32 nevents;
> -       __u64 events[0];
> +	__u32 action;
> +	__u32 nevents;
> +	__u32 fixed_counter_bitmap;
> +	__u32 flags;
> +	__u32 pad[4];
> +	__u64 events[0];
>   };
>   
>   This ioctl restricts the set of PMU events that the guest can program.
>   The argument holds a list of events which will be allowed or denied.
>   The eventsel+umask of each event the guest attempts to program is compared
>   against the events field to determine whether the guest should have access.
> -This only affects general purpose counters; fixed purpose counters can
> -be disabled by changing the perfmon CPUID leaf.
> +The events field only controls general purpose counters; fixed purpose
> +counters are controlled by the fixed_counter_bitmap.
>   
>   Valid values for 'action':
>   #define KVM_PMU_EVENT_ALLOW 0
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index e901b0ab116f..503d3f42da16 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -435,9 +435,12 @@ struct kvm_nested_state {
>   
>   /* for KVM_CAP_PMU_EVENT_FILTER */
>   struct kvm_pmu_event_filter {
> -       __u32 action;
> -       __u32 nevents;
> -       __u64 events[0];
> +	__u32 action;
> +	__u32 nevents;
> +	__u32 fixed_counter_bitmap;
> +	__u32 flags;
> +	__u32 pad[4];
> +	__u64 events[0];
>   };
>   
>   #define KVM_PMU_EVENT_ALLOW 0
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index aa5a2597305a..ae5cd1b02086 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -19,8 +19,8 @@
>   #include "lapic.h"
>   #include "pmu.h"
>   
> -/* This keeps the total size of the filter under 4k. */
> -#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 63
> +/* This is enough to filter the vast majority of currently defined events. */
> +#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 300
>   
>   /* NOTE:
>    * - Each perf counter is defined as "struct kvm_pmc";
> @@ -206,12 +206,25 @@ void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 ctrl, int idx)
>   {
>   	unsigned en_field = ctrl & 0x3;
>   	bool pmi = ctrl & 0x8;
> +	struct kvm_pmu_event_filter *filter;
> +	struct kvm *kvm = pmc->vcpu->kvm;
> +

unnecessary white space here, other part looks good to me.

Reviewed-by: Wei Wang <wei.w.wang@xxxxxxxxx>

Best,
Wei