Re: [REPOST PATCH 08/16] selftests: KVM: aarch64: Consider PMU event filters for VM creation

Reiji Watanabe
2023-03-03T04:31:15Z

Hi Raghu,

On Tue, Feb 14, 2023 at 5:07 PM Raghavendra Rao Ananta
<rananta@google.com> wrote:
>
> Accept a list of KVM PMU event filters as an argument while creating
> a VM via create_vpmu_vm(). Upcoming patches would leverage this to
> test the event filters' functionality.
>
> No functional change intended.
>
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> ---
> .../testing/selftests/kvm/aarch64/vpmu_test.c | 64 +++++++++++++++++--
> 1 file changed, 60 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/aarch64/vpmu_test.c b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
> index 15aebc7d7dc94..2b3a4fa3afa9c 100644
> --- a/tools/testing/selftests/kvm/aarch64/vpmu_test.c
> +++ b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
> @@ -15,10 +15,14 @@
> #include <vgic.h>
> #include <asm/perf_event.h>
> #include <linux/bitfield.h>
> +#include <linux/bitmap.h>
>
> /* The max number of the PMU event counters (excluding the cycle counter) */
> #define ARMV8_PMU_MAX_GENERAL_COUNTERS (ARMV8_PMU_MAX_COUNTERS - 1)
>
> +/* The max number of event numbers that's supported */
> +#define ARMV8_PMU_MAX_EVENTS 64

The name and the comment would be a bit misleading.
(This sounds like a max number of events that are supported by ARMv8)

Perhaps 'MAX_EVENT_FILTER_BITS' would be more clear ?

> +
> /*
> * The macros and functions below for reading/writing PMEV{CNTR,TYPER}<n>_EL0
> * were basically copied from arch/arm64/kernel/perf_event.c.
> @@ -224,6 +228,8 @@ struct pmc_accessor pmc_accessors[] = {
> { read_sel_evcntr, write_pmevcntrn, read_sel_evtyper, write_pmevtypern },
> };
>
> +#define MAX_EVENT_FILTERS_PER_VM 10

(Looking at just this patch,) it appears 'PER_VM' in the name
might be rather misleading ?

> +
> #define INVALID_EC (-1ul)
> uint64_t expected_ec = INVALID_EC;
> uint64_t op_end_addr;
> @@ -232,6 +238,7 @@ struct vpmu_vm {
> struct kvm_vm *vm;
> struct kvm_vcpu *vcpu;
> int gic_fd;
> + unsigned long *pmu_filter;
> };
>
> enum test_stage {
> @@ -541,8 +548,51 @@ static void guest_code(void)
> #define GICD_BASE_GPA 0x8000000ULL
> #define GICR_BASE_GPA 0x80A0000ULL
>
> +static unsigned long *
> +set_event_filters(struct kvm_vcpu *vcpu, struct kvm_pmu_event_filter *pmu_event_filters)

Can you add a comment that explains the function ?
(especially for @pmu_event_filters and the return value ?)

> +{
> + int j;
> + unsigned long *pmu_filter;
> + struct kvm_device_attr filter_attr = {
> + .group = KVM_ARM_VCPU_PMU_V3_CTRL,
> + .attr = KVM_ARM_VCPU_PMU_V3_FILTER,
> + };
> +
> + /*
> + * Setting up of the bitmap is similar to what KVM does.
> + * If the first filter denys an event, default all the others to allow, and vice-versa.
> + */
> + pmu_filter = bitmap_zalloc(ARMV8_PMU_MAX_EVENTS);
> + TEST_ASSERT(pmu_filter, "Failed to allocate the pmu_filter");
> +
> + if (pmu_event_filters[0].action == KVM_PMU_EVENT_DENY)
> + bitmap_fill(pmu_filter, ARMV8_PMU_MAX_EVENTS);
> +
> + for (j = 0; j < MAX_EVENT_FILTERS_PER_VM; j++) {
> + struct kvm_pmu_event_filter *pmu_event_filter = &pmu_event_filters[j];
> +
> + if (!pmu_event_filter->nevents)

What does this mean ? (the end of the valid entry in the array ?)

> + break;
> +
> + pr_debug("Applying event filter:: event: 0x%x; action: %s\n",
> + pmu_event_filter->base_event,
> + pmu_event_filter->action == KVM_PMU_EVENT_ALLOW ? "ALLOW" : "DENY");
> +
> + filter_attr.addr = (uint64_t) pmu_event_filter;
> + vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &filter_attr);
> +
> + if (pmu_event_filter->action == KVM_PMU_EVENT_ALLOW)
> + __set_bit(pmu_event_filter->base_event, pmu_filter);
> + else
> + __clear_bit(pmu_event_filter->base_event, pmu_filter);
> + }
> +
> + return pmu_filter;
> +}
> +
> /* Create a VM that has one vCPU with PMUv3 configured. */
> -static struct vpmu_vm *create_vpmu_vm(void *guest_code)
> +static struct vpmu_vm *
> +create_vpmu_vm(void *guest_code, struct kvm_pmu_event_filter *pmu_event_filters)
> {
> struct kvm_vm *vm;
> struct kvm_vcpu *vcpu;
> @@ -586,6 +636,9 @@ static struct vpmu_vm *create_vpmu_vm(void *guest_code)
> "Unexpected PMUVER (0x%x) on the vCPU with PMUv3", pmuver);
>
> /* Initialize vPMU */
> + if (pmu_event_filters)
> + vpmu_vm->pmu_filter = set_event_filters(vcpu, pmu_event_filters);
> +
> vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &irq_attr);
> vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &init_attr);
>
> @@ -594,6 +647,8 @@ static struct vpmu_vm *create_vpmu_vm(void *guest_code)
>
> static void destroy_vpmu_vm(struct vpmu_vm *vpmu_vm)
> {
> + if (vpmu_vm->pmu_filter)
> + bitmap_free(vpmu_vm->pmu_filter);
> close(vpmu_vm->gic_fd);
> kvm_vm_free(vpmu_vm->vm);
> free(vpmu_vm);
> @@ -631,7 +686,7 @@ static void run_counter_access_test(uint64_t pmcr_n)
> guest_data.expected_pmcr_n = pmcr_n;
>
> pr_debug("Test with pmcr_n %lu\n", pmcr_n);
> - vpmu_vm = create_vpmu_vm(guest_code);
> + vpmu_vm = create_vpmu_vm(guest_code, NULL);
> vcpu = vpmu_vm->vcpu;
>
> /* Save the initial sp to restore them later to run the guest again */
> @@ -676,7 +731,7 @@ static void run_counter_access_error_test(uint64_t pmcr_n)
> guest_data.expected_pmcr_n = pmcr_n;
>
> pr_debug("Error test with pmcr_n %lu (larger than the host)\n", pmcr_n);
> - vpmu_vm = create_vpmu_vm(guest_code);
> + vpmu_vm = create_vpmu_vm(guest_code, NULL);
> vcpu = vpmu_vm->vcpu;
>
> /* Update the PMCR_EL0.N with @pmcr_n */
> @@ -719,9 +774,10 @@ static uint64_t get_pmcr_n_limit(void)
> struct vpmu_vm *vpmu_vm;
> uint64_t pmcr;
>
> - vpmu_vm = create_vpmu_vm(guest_code);
> + vpmu_vm = create_vpmu_vm(guest_code, NULL);
> vcpu_get_reg(vpmu_vm->vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), &pmcr);
> destroy_vpmu_vm(vpmu_vm);
> +
> return FIELD_GET(ARMV8_PMU_PMCR_N, pmcr);
> }

Thank you,
Reiji

>
> --
> 2.39.1.581.gbfd45094c4-goog
>