* [PATCH v3 1/6] KVM: x86/pmu: Use binary search to check filtered events
2022-01-15 5:24 [PATCH v3 0/6] KVM: x86/pmu: Use binary search to check filtered events Jim Mattson
@ 2022-01-15 5:24 ` Jim Mattson
2022-01-15 5:24 ` [PATCH v3 2/6] selftests: kvm/x86: Parameterize the CPUID vendor string check Jim Mattson
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: Jim Mattson @ 2022-01-15 5:24 UTC (permalink / raw)
To: kvm, pbonzini, like.xu.linux, daviddunn, cloudliang; +Cc: Jim Mattson
The PMU event filter may contain up to 300 events. Replace the linear
search in reprogram_gp_counter() with a binary search.
Signed-off-by: Jim Mattson <jmattson@google.com>
---
arch/x86/kvm/pmu.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index e632693a2266..2c98f3ee8df4 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -13,6 +13,8 @@
#include <linux/types.h>
#include <linux/kvm_host.h>
#include <linux/perf_event.h>
+#include <linux/bsearch.h>
+#include <linux/sort.h>
#include <asm/perf_event.h>
#include "x86.h"
#include "cpuid.h"
@@ -172,12 +174,16 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc)
return true;
}
+static int cmp_u64(const void *a, const void *b)
+{
+ return *(__u64 *)a - *(__u64 *)b;
+}
+
void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
{
unsigned config, type = PERF_TYPE_RAW;
struct kvm *kvm = pmc->vcpu->kvm;
struct kvm_pmu_event_filter *filter;
- int i;
bool allow_event = true;
if (eventsel & ARCH_PERFMON_EVENTSEL_PIN_CONTROL)
@@ -192,16 +198,13 @@ void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu);
if (filter) {
- for (i = 0; i < filter->nevents; i++)
- if (filter->events[i] ==
- (eventsel & AMD64_RAW_EVENT_MASK_NB))
- break;
- if (filter->action == KVM_PMU_EVENT_ALLOW &&
- i == filter->nevents)
- allow_event = false;
- if (filter->action == KVM_PMU_EVENT_DENY &&
- i < filter->nevents)
- allow_event = false;
+ __u64 key = eventsel & AMD64_RAW_EVENT_MASK_NB;
+
+ if (bsearch(&key, filter->events, filter->nevents,
+ sizeof(__u64), cmp_u64))
+ allow_event = filter->action == KVM_PMU_EVENT_ALLOW;
+ else
+ allow_event = filter->action == KVM_PMU_EVENT_DENY;
}
if (!allow_event)
return;
@@ -576,6 +579,11 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
/* Ensure nevents can't be changed between the user copies. */
*filter = tmp;
+ /*
+ * Sort the in-kernel list so that we can search it with bsearch.
+ */
+ sort(&filter->events, filter->nevents, sizeof(__u64), cmp_u64, NULL);
+
mutex_lock(&kvm->lock);
filter = rcu_replace_pointer(kvm->arch.pmu_event_filter, filter,
mutex_is_locked(&kvm->lock));
--
2.34.1.703.g22d0c6ccf7-goog
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH v3 6/6] selftests: kvm/x86: Add test for KVM_SET_PMU_EVENT_FILTER
2022-01-15 5:24 [PATCH v3 0/6] KVM: x86/pmu: Use binary search to check filtered events Jim Mattson
` (4 preceding siblings ...)
2022-01-15 5:24 ` [PATCH v3 5/6] selftests: kvm/x86: Introduce x86_model() Jim Mattson
@ 2022-01-15 5:24 ` Jim Mattson
5 siblings, 0 replies; 7+ messages in thread
From: Jim Mattson @ 2022-01-15 5:24 UTC (permalink / raw)
To: kvm, pbonzini, like.xu.linux, daviddunn, cloudliang; +Cc: Jim Mattson
Verify that the PMU event filter works as expected.
Note that the virtual PMU doesn't work as expected on AMD Zen CPUs (an
intercepted rdmsr is counted as a retired branch instruction), but the
PMU event filter does work.
Signed-off-by: Jim Mattson <jmattson@google.com>
---
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../kvm/x86_64/pmu_event_filter_test.c | 438 ++++++++++++++++++
3 files changed, 440 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 8c129961accf..7834e03ab159 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -22,6 +22,7 @@
/x86_64/mmio_warning_test
/x86_64/mmu_role_test
/x86_64/platform_info_test
+/x86_64/pmu_event_filter_test
/x86_64/set_boot_cpu_id
/x86_64/set_sregs_test
/x86_64/sev_migrate_tests
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c407ebbec2c1..899413a6588f 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -56,6 +56,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test
TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test
TEST_GEN_PROGS_x86_64 += x86_64/mmu_role_test
TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test
+TEST_GEN_PROGS_x86_64 += x86_64/pmu_event_filter_test
TEST_GEN_PROGS_x86_64 += x86_64/set_boot_cpu_id
TEST_GEN_PROGS_x86_64 += x86_64/set_sregs_test
TEST_GEN_PROGS_x86_64 += x86_64/smm_test
diff --git a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
new file mode 100644
index 000000000000..1cf697fca7aa
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
@@ -0,0 +1,438 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test for x86 KVM_SET_PMU_EVENT_FILTER.
+ *
+ * Copyright (C) 2022, Google LLC.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ *
+ * Verifies the expected behavior of allow lists and deny lists for
+ * virtual PMU events.
+ */
+
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+
+/*
+ * In lieu of copying perf_event.h into tools...
+ */
+#define ARCH_PERFMON_EVENTSEL_OS (1ULL << 17)
+#define ARCH_PERFMON_EVENTSEL_ENABLE (1ULL << 22)
+
+union cpuid10_eax {
+ struct {
+ unsigned int version_id:8;
+ unsigned int num_counters:8;
+ unsigned int bit_width:8;
+ unsigned int mask_length:8;
+ } split;
+ unsigned int full;
+};
+
+union cpuid10_ebx {
+ struct {
+ unsigned int no_unhalted_core_cycles:1;
+ unsigned int no_instructions_retired:1;
+ unsigned int no_unhalted_reference_cycles:1;
+ unsigned int no_llc_reference:1;
+ unsigned int no_llc_misses:1;
+ unsigned int no_branch_instruction_retired:1;
+ unsigned int no_branch_misses_retired:1;
+ } split;
+ unsigned int full;
+};
+
+/* End of stuff taken from perf_event.h. */
+
+/* Oddly, this isn't in perf_event.h. */
+#define ARCH_PERFMON_BRANCHES_RETIRED 5
+
+#define VCPU_ID 0
+#define NUM_BRANCHES 42
+
+/*
+ * This is how the event selector and unit mask are stored in an AMD
+ * core performance event-select register. Intel's format is similar,
+ * but the event selector is only 8 bits.
+ */
+#define EVENT(select, umask) ((select & 0xf00UL) << 24 | (select & 0xff) | \
+ (umask & 0xff) << 8)
+
+/*
+ * "Branch instructions retired", from the Intel SDM, volume 3,
+ * "Pre-defined Architectural Performance Events."
+ */
+
+#define INTEL_BR_RETIRED EVENT(0xc4, 0)
+
+/*
+ * "Retired branch instructions", from Processor Programming Reference
+ * (PPR) for AMD Family 17h Model 01h, Revision B1 Processors,
+ * Preliminary Processor Programming Reference (PPR) for AMD Family
+ * 17h Model 31h, Revision B0 Processors, and Preliminary Processor
+ * Programming Reference (PPR) for AMD Family 19h Model 01h, Revision
+ * B1 Processors Volume 1 of 2.
+ */
+
+#define AMD_ZEN_BR_RETIRED EVENT(0xc2, 0)
+
+/*
+ * This event list comprises Intel's eight architectural events plus
+ * AMD's "retired branch instructions" for Zen[123] (and possibly
+ * other AMD CPUs).
+ */
+static const uint64_t event_list[] = {
+ EVENT(0x3c, 0),
+ EVENT(0xc0, 0),
+ EVENT(0x3c, 1),
+ EVENT(0x2e, 0x4f),
+ EVENT(0x2e, 0x41),
+ EVENT(0xc4, 0),
+ EVENT(0xc5, 0),
+ EVENT(0xa4, 1),
+ AMD_ZEN_BR_RETIRED,
+};
+
+/*
+ * If we encounter a #GP during the guest PMU sanity check, then the guest
+ * PMU is not functional. Inform the hypervisor via GUEST_SYNC(0).
+ */
+static void guest_gp_handler(struct ex_regs *regs)
+{
+ GUEST_SYNC(0);
+}
+
+/*
+ * Check that we can write a new value to the given MSR and read it back.
+ * The caller should provide a non-empty set of bits that are safe to flip.
+ *
+ * Return on success. GUEST_SYNC(0) on error.
+ */
+static void check_msr(uint32_t msr, uint64_t bits_to_flip)
+{
+ uint64_t v = rdmsr(msr) ^ bits_to_flip;
+
+ wrmsr(msr, v);
+ if (rdmsr(msr) != v)
+ GUEST_SYNC(0);
+
+ v ^= bits_to_flip;
+ wrmsr(msr, v);
+ if (rdmsr(msr) != v)
+ GUEST_SYNC(0);
+}
+
+static void intel_guest_code(void)
+{
+ check_msr(MSR_CORE_PERF_GLOBAL_CTRL, 1);
+ check_msr(MSR_P6_EVNTSEL0, 0xffff);
+ check_msr(MSR_IA32_PMC0, 0xffff);
+ GUEST_SYNC(1);
+
+ for (;;) {
+ uint64_t br0, br1;
+
+ wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
+ wrmsr(MSR_P6_EVNTSEL0, ARCH_PERFMON_EVENTSEL_ENABLE |
+ ARCH_PERFMON_EVENTSEL_OS | INTEL_BR_RETIRED);
+ wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 1);
+ br0 = rdmsr(MSR_IA32_PMC0);
+ __asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));
+ br1 = rdmsr(MSR_IA32_PMC0);
+ GUEST_SYNC(br1 - br0);
+ }
+}
+
+/*
+ * To avoid needing a check for CPUID.80000001:ECX.PerfCtrExtCore[bit 23],
+ * this code uses the always-available, legacy K7 PMU MSRs, which alias to
+ * the first four of the six extended core PMU MSRs.
+ */
+static void amd_guest_code(void)
+{
+ check_msr(MSR_K7_EVNTSEL0, 0xffff);
+ check_msr(MSR_K7_PERFCTR0, 0xffff);
+ GUEST_SYNC(1);
+
+ for (;;) {
+ uint64_t br0, br1;
+
+ wrmsr(MSR_K7_EVNTSEL0, 0);
+ wrmsr(MSR_K7_EVNTSEL0, ARCH_PERFMON_EVENTSEL_ENABLE |
+ ARCH_PERFMON_EVENTSEL_OS | AMD_ZEN_BR_RETIRED);
+ br0 = rdmsr(MSR_K7_PERFCTR0);
+ __asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));
+ br1 = rdmsr(MSR_K7_PERFCTR0);
+ GUEST_SYNC(br1 - br0);
+ }
+}
+
+/*
+ * Run the VM to the next GUEST_SYNC(value), and return the value passed
+ * to the sync. Any other exit from the guest is fatal.
+ */
+static uint64_t run_vm_to_sync(struct kvm_vm *vm)
+{
+ struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+ struct ucall uc;
+
+ vcpu_run(vm, VCPU_ID);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+ "Exit_reason other than KVM_EXIT_IO: %u (%s)\n",
+ run->exit_reason,
+ exit_reason_str(run->exit_reason));
+ get_ucall(vm, VCPU_ID, &uc);
+ TEST_ASSERT(uc.cmd == UCALL_SYNC,
+ "Received ucall other than UCALL_SYNC: %lu", uc.cmd);
+ return uc.args[1];
+}
+
+/*
+ * In a nested environment or if the vPMU is disabled, the guest PMU
+ * might not work as architected (accessing the PMU MSRs may raise
+ * #GP, or writes could simply be discarded). In those situations,
+ * there is no point in running these tests. The guest code will perform
+ * a sanity check and then GUEST_SYNC(success). In the case of failure,
+ * the behavior of the guest on resumption is undefined.
+ */
+static bool sanity_check_pmu(struct kvm_vm *vm)
+{
+ bool success;
+
+ vm_install_exception_handler(vm, GP_VECTOR, guest_gp_handler);
+ success = run_vm_to_sync(vm);
+ vm_install_exception_handler(vm, GP_VECTOR, NULL);
+
+ return success;
+}
+
+static struct kvm_pmu_event_filter *make_pmu_event_filter(uint32_t nevents)
+{
+ struct kvm_pmu_event_filter *f;
+ int size = sizeof(*f) + nevents * sizeof(f->events[0]);
+
+ f = malloc(size);
+ TEST_ASSERT(f, "Out of memory");
+ memset(f, 0, size);
+ f->nevents = nevents;
+ return f;
+}
+
+static struct kvm_pmu_event_filter *event_filter(uint32_t action)
+{
+ struct kvm_pmu_event_filter *f;
+ int i;
+
+ f = make_pmu_event_filter(ARRAY_SIZE(event_list));
+ f->action = action;
+ for (i = 0; i < ARRAY_SIZE(event_list); i++)
+ f->events[i] = event_list[i];
+
+ return f;
+}
+
+/*
+ * Remove the first occurrence of 'event' (if any) from the filter's
+ * event list.
+ */
+static struct kvm_pmu_event_filter *remove_event(struct kvm_pmu_event_filter *f,
+ uint64_t event)
+{
+ bool found = false;
+ int i;
+
+ for (i = 0; i < f->nevents; i++) {
+ if (found)
+ f->events[i - 1] = f->events[i];
+ else
+ found = f->events[i] == event;
+ }
+ if (found)
+ f->nevents--;
+ return f;
+}
+
+static void test_without_filter(struct kvm_vm *vm)
+{
+ uint64_t count = run_vm_to_sync(vm);
+
+ if (count != NUM_BRANCHES)
+ pr_info("%s: Branch instructions retired = %lu (expected %u)\n",
+ __func__, count, NUM_BRANCHES);
+ TEST_ASSERT(count, "Allowed PMU event is not counting");
+}
+
+static uint64_t test_with_filter(struct kvm_vm *vm,
+ struct kvm_pmu_event_filter *f)
+{
+ vm_ioctl(vm, KVM_SET_PMU_EVENT_FILTER, (void *)f);
+ return run_vm_to_sync(vm);
+}
+
+static void test_member_deny_list(struct kvm_vm *vm)
+{
+ struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_DENY);
+ uint64_t count = test_with_filter(vm, f);
+
+ free(f);
+ if (count)
+ pr_info("%s: Branch instructions retired = %lu (expected 0)\n",
+ __func__, count);
+ TEST_ASSERT(!count, "Disallowed PMU Event is counting");
+}
+
+static void test_member_allow_list(struct kvm_vm *vm)
+{
+ struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_ALLOW);
+ uint64_t count = test_with_filter(vm, f);
+
+ free(f);
+ if (count != NUM_BRANCHES)
+ pr_info("%s: Branch instructions retired = %lu (expected %u)\n",
+ __func__, count, NUM_BRANCHES);
+ TEST_ASSERT(count, "Allowed PMU event is not counting");
+}
+
+static void test_not_member_deny_list(struct kvm_vm *vm)
+{
+ struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_DENY);
+ uint64_t count;
+
+ remove_event(f, INTEL_BR_RETIRED);
+ remove_event(f, AMD_ZEN_BR_RETIRED);
+ count = test_with_filter(vm, f);
+ free(f);
+ if (count != NUM_BRANCHES)
+ pr_info("%s: Branch instructions retired = %lu (expected %u)\n",
+ __func__, count, NUM_BRANCHES);
+ TEST_ASSERT(count, "Allowed PMU event is not counting");
+}
+
+static void test_not_member_allow_list(struct kvm_vm *vm)
+{
+ struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_ALLOW);
+ uint64_t count;
+
+ remove_event(f, INTEL_BR_RETIRED);
+ remove_event(f, AMD_ZEN_BR_RETIRED);
+ count = test_with_filter(vm, f);
+ free(f);
+ if (count)
+ pr_info("%s: Branch instructions retired = %lu (expected 0)\n",
+ __func__, count);
+ TEST_ASSERT(!count, "Disallowed PMU Event is counting");
+}
+
+/*
+ * Check for a non-zero PMU version, at least one general-purpose
+ * counter per logical processor, an EBX bit vector of length greater
+ * than 5, and EBX[5] clear.
+ */
+static bool check_intel_pmu_leaf(struct kvm_cpuid_entry2 *entry)
+{
+ union cpuid10_eax eax = { .full = entry->eax };
+ union cpuid10_ebx ebx = { .full = entry->ebx };
+
+ return eax.split.version_id && eax.split.num_counters > 0 &&
+ eax.split.mask_length > ARCH_PERFMON_BRANCHES_RETIRED &&
+ !ebx.split.no_branch_instruction_retired;
+}
+
+/*
+ * Note that CPUID leaf 0xa is Intel-specific. This leaf should be
+ * clear on AMD hardware.
+ */
+static bool use_intel_pmu(void)
+{
+ struct kvm_cpuid_entry2 *entry;
+ struct kvm_cpuid2 *cpuid;
+
+ cpuid = kvm_get_supported_cpuid();
+ entry = kvm_get_supported_cpuid_index(0xa, 0);
+ return is_intel_cpu() && entry && check_intel_pmu_leaf(entry);
+}
+
+static bool is_zen1(uint32_t eax)
+{
+ return x86_family(eax) == 0x17 && x86_model(eax) <= 0x0f;
+}
+
+static bool is_zen2(uint32_t eax)
+{
+ return x86_family(eax) == 0x17 &&
+ x86_model(eax) >= 0x30 && x86_model(eax) <= 0x3f;
+}
+
+static bool is_zen3(uint32_t eax)
+{
+ return x86_family(eax) == 0x19 && x86_model(eax) <= 0x0f;
+}
+
+/*
+ * Determining AMD support for a PMU event requires consulting the AMD
+ * PPR for the CPU or reference material derived therefrom. The AMD
+ * test code herein has been verified to work on Zen1, Zen2, and Zen3.
+ *
+ * Feel free to add more AMD CPUs that are documented to support event
+ * select 0xc2 umask 0 as "retired branch instructions."
+ */
+static bool use_amd_pmu(void)
+{
+ struct kvm_cpuid_entry2 *entry;
+ struct kvm_cpuid2 *cpuid;
+
+ cpuid = kvm_get_supported_cpuid();
+ entry = kvm_get_supported_cpuid_index(1, 0);
+ return is_amd_cpu() && entry &&
+ (is_zen1(entry->eax) ||
+ is_zen2(entry->eax) ||
+ is_zen3(entry->eax));
+}
+
+int main(int argc, char *argv[])
+{
+ void (*guest_code)(void) = NULL;
+ struct kvm_vm *vm;
+ int r;
+
+ /* Tell stdout not to buffer its content */
+ setbuf(stdout, NULL);
+
+ r = kvm_check_cap(KVM_CAP_PMU_EVENT_FILTER);
+ if (!r) {
+ print_skip("KVM_CAP_PMU_EVENT_FILTER not supported");
+ exit(KSFT_SKIP);
+ }
+
+ if (use_intel_pmu())
+ guest_code = intel_guest_code;
+ else if (use_amd_pmu())
+ guest_code = amd_guest_code;
+
+ if (!guest_code) {
+ print_skip("Don't know how to test this guest PMU");
+ exit(KSFT_SKIP);
+ }
+
+ vm = vm_create_default(VCPU_ID, 0, guest_code);
+
+ vm_init_descriptor_tables(vm);
+ vcpu_init_descriptor_tables(vm, VCPU_ID);
+
+ if (!sanity_check_pmu(vm)) {
+ print_skip("Guest PMU is not functional");
+ exit(KSFT_SKIP);
+ }
+
+ test_without_filter(vm);
+ test_member_deny_list(vm);
+ test_member_allow_list(vm);
+ test_not_member_deny_list(vm);
+ test_not_member_allow_list(vm);
+
+ kvm_vm_free(vm);
+
+ return 0;
+}
--
2.34.1.703.g22d0c6ccf7-goog
^ permalink raw reply related [flat|nested] 7+ messages in thread