All of lore.kernel.org
 help / color / mirror / Atom feed
From: Oliver Upton <oupton@google.com>
To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Marc Zyngier <maz@kernel.org>, Peter Shier <pshier@google.com>,
	Jim Mattson <jmattson@google.com>,
	David Matlack <dmatlack@google.com>,
	Ricardo Koller <ricarkol@google.com>,
	Jing Zhang <jingzhangos@google.com>,
	Raghavendra Rao Anata <rananta@google.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Oliver Upton <oupton@google.com>
Subject: [PATCH v2 12/12] selftests: KVM: Add counter emulation benchmark
Date: Fri, 16 Jul 2021 21:26:29 +0000	[thread overview]
Message-ID: <20210716212629.2232756-13-oupton@google.com> (raw)
In-Reply-To: <20210716212629.2232756-1-oupton@google.com>

Add a test case for counter emulation on arm64. A side effect of how KVM
handles physical counter offsetting on non-ECV systems is that the
virtual counter will always hit hardware and the physical could be
emulated. Force emulation by writing a nonzero offset to the physical
counter and compare the elapsed cycles to a direct read of the hardware
register.

Reviewed-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Oliver Upton <oupton@google.com>
---
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../kvm/aarch64/counter_emulation_benchmark.c | 215 ++++++++++++++++++
 3 files changed, 217 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 2752813d5090..1d811c6a769b 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 /aarch64/debug-exceptions
+/aarch64/counter_emulation_benchmark
 /aarch64/get-reg-list
 /aarch64/vgic_init
 /s390x/memop
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index d89908108c97..e560a3e74bc2 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -86,6 +86,7 @@ TEST_GEN_PROGS_x86_64 += kvm_binary_stats_test
 TEST_GEN_PROGS_x86_64 += system_counter_offset_test
 
 TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions
+TEST_GEN_PROGS_aarch64 += aarch64/counter_emulation_benchmark
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
 TEST_GEN_PROGS_aarch64 += demand_paging_test
diff --git a/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c b/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c
new file mode 100644
index 000000000000..73aeb6cdebfe
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * counter_emulation_benchmark.c -- test to measure the effects of counter
+ * emulation on guest reads of the physical counter.
+ *
+ * Copyright (c) 2021, Google LLC.
+ */
+
+#define _GNU_SOURCE
+#include <asm/kvm.h>
+#include <linux/kvm.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+#define VCPU_ID 0
+
+static struct counter_values {
+	uint64_t cntvct_start;
+	uint64_t cntpct;
+	uint64_t cntvct_end;
+} counter_values;
+
+static uint64_t nr_iterations = 1000;
+
+static void do_test(void)
+{
+	/*
+	 * Open-coded approach instead of using helper methods to keep a tight
+	 * interval around the physical counter read.
+	 */
+	asm volatile("isb\n\t"
+		     "mrs %[cntvct_start], cntvct_el0\n\t"
+		     "isb\n\t"
+		     "mrs %[cntpct], cntpct_el0\n\t"
+		     "isb\n\t"
+		     "mrs %[cntvct_end], cntvct_el0\n\t"
+		     "isb\n\t"
+		     : [cntvct_start] "=r"(counter_values.cntvct_start),
+		     [cntpct] "=r"(counter_values.cntpct),
+		     [cntvct_end] "=r"(counter_values.cntvct_end));
+}
+
+static void guest_main(void)
+{
+	int i;
+
+	for (i = 0; i < nr_iterations; i++) {
+		do_test();
+		GUEST_SYNC(i);
+	}
+
+	for (i = 0; i < nr_iterations; i++) {
+		do_test();
+		GUEST_SYNC(i);
+	}
+
+	GUEST_DONE();
+}
+
+static bool enter_guest(struct kvm_vm *vm)
+{
+	struct ucall uc;
+
+	vcpu_ioctl(vm, VCPU_ID, KVM_RUN, NULL);
+
+	switch (get_ucall(vm, VCPU_ID, &uc)) {
+	case UCALL_DONE:
+		return true;
+	case UCALL_SYNC:
+		break;
+	case UCALL_ABORT:
+		TEST_ASSERT(false, "%s at %s:%ld", (const char *)uc.args[0],
+			    __FILE__, uc.args[1]);
+		break;
+	default:
+		TEST_ASSERT(false, "unexpected exit: %s",
+			    exit_reason_str(vcpu_state(vm, VCPU_ID)->exit_reason));
+		break;
+	}
+
+	/* more work to do in the guest */
+	return false;
+}
+
+static double counter_frequency(void)
+{
+	uint32_t freq;
+
+	asm volatile("mrs %0, cntfrq_el0"
+		     : "=r" (freq));
+
+	return freq / 1000000.0;
+}
+
+static void log_csv(FILE *csv, bool trapped)
+{
+	double freq = counter_frequency();
+
+	fprintf(csv, "%s,%.02f,%lu,%lu,%lu\n",
+		trapped ? "true" : "false", freq,
+		counter_values.cntvct_start,
+		counter_values.cntpct,
+		counter_values.cntvct_end);
+}
+
+static double run_loop(struct kvm_vm *vm, FILE *csv, bool trapped)
+{
+	double avg = 0;
+	int i;
+
+	for (i = 0; i < nr_iterations; i++) {
+		uint64_t delta;
+
+		TEST_ASSERT(!enter_guest(vm), "guest exited unexpectedly");
+		sync_global_from_guest(vm, counter_values);
+
+		if (csv)
+			log_csv(csv, trapped);
+
+		delta = counter_values.cntvct_end - counter_values.cntvct_start;
+		avg = ((avg * i) + delta) / (i + 1);
+	}
+
+	return avg;
+}
+
+static void setup_counter(struct kvm_vm *vm, uint64_t offset)
+{
+	vcpu_access_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL,
+				KVM_ARM_VCPU_TIMER_OFFSET_PTIMER, &offset,
+				true);
+}
+
+static void run_tests(struct kvm_vm *vm, FILE *csv)
+{
+	double avg_trapped, avg_native, freq;
+
+	freq = counter_frequency();
+
+	if (csv)
+		fputs("trapped,freq_mhz,cntvct_start,cntpct,cntvct_end\n", csv);
+
+	/* no physical offsetting; kvm allows reads of cntpct_el0 */
+	setup_counter(vm, 0);
+	avg_native = run_loop(vm, csv, false);
+
+	/* force emulation of the physical counter */
+	setup_counter(vm, 1);
+	avg_trapped = run_loop(vm, csv, true);
+
+	TEST_ASSERT(enter_guest(vm), "guest didn't run to completion");
+	pr_info("%lu iterations: average cycles (@%.02fMHz) native: %.02f, trapped: %.02f\n",
+		nr_iterations, freq, avg_native, avg_trapped);
+}
+
+static void usage(const char *program_name)
+{
+	fprintf(stderr,
+		"Usage: %s [-h] [-o csv_file] [-n iterations]\n"
+		"  -h prints this message\n"
+		"  -n number of test iterations (default: %lu)\n"
+		"  -o csv file to write data\n",
+		program_name, nr_iterations);
+}
+
+int main(int argc, char **argv)
+{
+	struct kvm_vm *vm;
+	FILE *csv = NULL;
+	int opt;
+
+	while ((opt = getopt(argc, argv, "hn:o:")) != -1) {
+		switch (opt) {
+		case 'o':
+			csv = fopen(optarg, "w");
+			if (!csv) {
+				fprintf(stderr, "failed to open file '%s': %d\n",
+					optarg, errno);
+				exit(1);
+			}
+			break;
+		case 'n':
+			nr_iterations = strtoul(optarg, NULL, 0);
+			break;
+		default:
+			fprintf(stderr, "unrecognized option: '-%c'\n", opt);
+			/* fallthrough */
+		case 'h':
+			usage(argv[0]);
+			exit(1);
+		}
+	}
+
+	vm = vm_create_default(VCPU_ID, 0, guest_main);
+	sync_global_to_guest(vm, nr_iterations);
+	ucall_init(vm, NULL);
+
+	if (_vcpu_has_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL,
+				  KVM_ARM_VCPU_TIMER_OFFSET_PTIMER)) {
+		print_skip("KVM_ARM_VCPU_TIMER_OFFSET_PTIMER not supported.");
+		exit(KSFT_SKIP);
+	}
+
+	run_tests(vm, csv);
+	kvm_vm_free(vm);
+
+	if (csv)
+		fclose(csv);
+}
-- 
2.32.0.402.g57bb445576-goog


WARNING: multiple messages have this Message-ID (diff)
From: Oliver Upton <oupton@google.com>
To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: Marc Zyngier <maz@kernel.org>,
	Raghavendra Rao Anata <rananta@google.com>,
	Peter Shier <pshier@google.com>,
	Sean Christopherson <seanjc@google.com>,
	David Matlack <dmatlack@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	linux-arm-kernel@lists.infradead.org,
	Jim Mattson <jmattson@google.com>
Subject: [PATCH v2 12/12] selftests: KVM: Add counter emulation benchmark
Date: Fri, 16 Jul 2021 21:26:29 +0000	[thread overview]
Message-ID: <20210716212629.2232756-13-oupton@google.com> (raw)
In-Reply-To: <20210716212629.2232756-1-oupton@google.com>

Add a test case for counter emulation on arm64. A side effect of how KVM
handles physical counter offsetting on non-ECV systems is that the
virtual counter will always hit hardware and the physical could be
emulated. Force emulation by writing a nonzero offset to the physical
counter and compare the elapsed cycles to a direct read of the hardware
register.

Reviewed-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Oliver Upton <oupton@google.com>
---
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../kvm/aarch64/counter_emulation_benchmark.c | 215 ++++++++++++++++++
 3 files changed, 217 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 2752813d5090..1d811c6a769b 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 /aarch64/debug-exceptions
+/aarch64/counter_emulation_benchmark
 /aarch64/get-reg-list
 /aarch64/vgic_init
 /s390x/memop
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index d89908108c97..e560a3e74bc2 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -86,6 +86,7 @@ TEST_GEN_PROGS_x86_64 += kvm_binary_stats_test
 TEST_GEN_PROGS_x86_64 += system_counter_offset_test
 
 TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions
+TEST_GEN_PROGS_aarch64 += aarch64/counter_emulation_benchmark
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
 TEST_GEN_PROGS_aarch64 += demand_paging_test
diff --git a/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c b/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c
new file mode 100644
index 000000000000..73aeb6cdebfe
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * counter_emulation_benchmark.c -- test to measure the effects of counter
+ * emulation on guest reads of the physical counter.
+ *
+ * Copyright (c) 2021, Google LLC.
+ */
+
+#define _GNU_SOURCE
+#include <asm/kvm.h>
+#include <linux/kvm.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+#define VCPU_ID 0
+
+static struct counter_values {
+	uint64_t cntvct_start;
+	uint64_t cntpct;
+	uint64_t cntvct_end;
+} counter_values;
+
+static uint64_t nr_iterations = 1000;
+
+static void do_test(void)
+{
+	/*
+	 * Open-coded approach instead of using helper methods to keep a tight
+	 * interval around the physical counter read.
+	 */
+	asm volatile("isb\n\t"
+		     "mrs %[cntvct_start], cntvct_el0\n\t"
+		     "isb\n\t"
+		     "mrs %[cntpct], cntpct_el0\n\t"
+		     "isb\n\t"
+		     "mrs %[cntvct_end], cntvct_el0\n\t"
+		     "isb\n\t"
+		     : [cntvct_start] "=r"(counter_values.cntvct_start),
+		     [cntpct] "=r"(counter_values.cntpct),
+		     [cntvct_end] "=r"(counter_values.cntvct_end));
+}
+
+static void guest_main(void)
+{
+	int i;
+
+	for (i = 0; i < nr_iterations; i++) {
+		do_test();
+		GUEST_SYNC(i);
+	}
+
+	for (i = 0; i < nr_iterations; i++) {
+		do_test();
+		GUEST_SYNC(i);
+	}
+
+	GUEST_DONE();
+}
+
+static bool enter_guest(struct kvm_vm *vm)
+{
+	struct ucall uc;
+
+	vcpu_ioctl(vm, VCPU_ID, KVM_RUN, NULL);
+
+	switch (get_ucall(vm, VCPU_ID, &uc)) {
+	case UCALL_DONE:
+		return true;
+	case UCALL_SYNC:
+		break;
+	case UCALL_ABORT:
+		TEST_ASSERT(false, "%s at %s:%ld", (const char *)uc.args[0],
+			    __FILE__, uc.args[1]);
+		break;
+	default:
+		TEST_ASSERT(false, "unexpected exit: %s",
+			    exit_reason_str(vcpu_state(vm, VCPU_ID)->exit_reason));
+		break;
+	}
+
+	/* more work to do in the guest */
+	return false;
+}
+
+static double counter_frequency(void)
+{
+	uint32_t freq;
+
+	asm volatile("mrs %0, cntfrq_el0"
+		     : "=r" (freq));
+
+	return freq / 1000000.0;
+}
+
+static void log_csv(FILE *csv, bool trapped)
+{
+	double freq = counter_frequency();
+
+	fprintf(csv, "%s,%.02f,%lu,%lu,%lu\n",
+		trapped ? "true" : "false", freq,
+		counter_values.cntvct_start,
+		counter_values.cntpct,
+		counter_values.cntvct_end);
+}
+
+static double run_loop(struct kvm_vm *vm, FILE *csv, bool trapped)
+{
+	double avg = 0;
+	int i;
+
+	for (i = 0; i < nr_iterations; i++) {
+		uint64_t delta;
+
+		TEST_ASSERT(!enter_guest(vm), "guest exited unexpectedly");
+		sync_global_from_guest(vm, counter_values);
+
+		if (csv)
+			log_csv(csv, trapped);
+
+		delta = counter_values.cntvct_end - counter_values.cntvct_start;
+		avg = ((avg * i) + delta) / (i + 1);
+	}
+
+	return avg;
+}
+
+static void setup_counter(struct kvm_vm *vm, uint64_t offset)
+{
+	vcpu_access_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL,
+				KVM_ARM_VCPU_TIMER_OFFSET_PTIMER, &offset,
+				true);
+}
+
+static void run_tests(struct kvm_vm *vm, FILE *csv)
+{
+	double avg_trapped, avg_native, freq;
+
+	freq = counter_frequency();
+
+	if (csv)
+		fputs("trapped,freq_mhz,cntvct_start,cntpct,cntvct_end\n", csv);
+
+	/* no physical offsetting; kvm allows reads of cntpct_el0 */
+	setup_counter(vm, 0);
+	avg_native = run_loop(vm, csv, false);
+
+	/* force emulation of the physical counter */
+	setup_counter(vm, 1);
+	avg_trapped = run_loop(vm, csv, true);
+
+	TEST_ASSERT(enter_guest(vm), "guest didn't run to completion");
+	pr_info("%lu iterations: average cycles (@%.02fMHz) native: %.02f, trapped: %.02f\n",
+		nr_iterations, freq, avg_native, avg_trapped);
+}
+
+static void usage(const char *program_name)
+{
+	fprintf(stderr,
+		"Usage: %s [-h] [-o csv_file] [-n iterations]\n"
+		"  -h prints this message\n"
+		"  -n number of test iterations (default: %lu)\n"
+		"  -o csv file to write data\n",
+		program_name, nr_iterations);
+}
+
+int main(int argc, char **argv)
+{
+	struct kvm_vm *vm;
+	FILE *csv = NULL;
+	int opt;
+
+	while ((opt = getopt(argc, argv, "hn:o:")) != -1) {
+		switch (opt) {
+		case 'o':
+			csv = fopen(optarg, "w");
+			if (!csv) {
+				fprintf(stderr, "failed to open file '%s': %d\n",
+					optarg, errno);
+				exit(1);
+			}
+			break;
+		case 'n':
+			nr_iterations = strtoul(optarg, NULL, 0);
+			break;
+		default:
+			fprintf(stderr, "unrecognized option: '-%c'\n", opt);
+			/* fallthrough */
+		case 'h':
+			usage(argv[0]);
+			exit(1);
+		}
+	}
+
+	vm = vm_create_default(VCPU_ID, 0, guest_main);
+	sync_global_to_guest(vm, nr_iterations);
+	ucall_init(vm, NULL);
+
+	if (_vcpu_has_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL,
+				  KVM_ARM_VCPU_TIMER_OFFSET_PTIMER)) {
+		print_skip("KVM_ARM_VCPU_TIMER_OFFSET_PTIMER not supported.");
+		exit(KSFT_SKIP);
+	}
+
+	run_tests(vm, csv);
+	kvm_vm_free(vm);
+
+	if (csv)
+		fclose(csv);
+}
-- 
2.32.0.402.g57bb445576-goog

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Oliver Upton <oupton@google.com>
To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	 Marc Zyngier <maz@kernel.org>, Peter Shier <pshier@google.com>,
	Jim Mattson <jmattson@google.com>,
	 David Matlack <dmatlack@google.com>,
	Ricardo Koller <ricarkol@google.com>,
	 Jing Zhang <jingzhangos@google.com>,
	Raghavendra Rao Anata <rananta@google.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Oliver Upton <oupton@google.com>
Subject: [PATCH v2 12/12] selftests: KVM: Add counter emulation benchmark
Date: Fri, 16 Jul 2021 21:26:29 +0000	[thread overview]
Message-ID: <20210716212629.2232756-13-oupton@google.com> (raw)
In-Reply-To: <20210716212629.2232756-1-oupton@google.com>

Add a test case for counter emulation on arm64. A side effect of how KVM
handles physical counter offsetting on non-ECV systems is that the
virtual counter will always hit hardware and the physical could be
emulated. Force emulation by writing a nonzero offset to the physical
counter and compare the elapsed cycles to a direct read of the hardware
register.

Reviewed-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Oliver Upton <oupton@google.com>
---
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../kvm/aarch64/counter_emulation_benchmark.c | 215 ++++++++++++++++++
 3 files changed, 217 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 2752813d5090..1d811c6a769b 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 /aarch64/debug-exceptions
+/aarch64/counter_emulation_benchmark
 /aarch64/get-reg-list
 /aarch64/vgic_init
 /s390x/memop
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index d89908108c97..e560a3e74bc2 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -86,6 +86,7 @@ TEST_GEN_PROGS_x86_64 += kvm_binary_stats_test
 TEST_GEN_PROGS_x86_64 += system_counter_offset_test
 
 TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions
+TEST_GEN_PROGS_aarch64 += aarch64/counter_emulation_benchmark
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
 TEST_GEN_PROGS_aarch64 += demand_paging_test
diff --git a/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c b/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c
new file mode 100644
index 000000000000..73aeb6cdebfe
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * counter_emulation_benchmark.c -- test to measure the effects of counter
+ * emulation on guest reads of the physical counter.
+ *
+ * Copyright (c) 2021, Google LLC.
+ */
+
+#define _GNU_SOURCE
+#include <asm/kvm.h>
+#include <linux/kvm.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+#define VCPU_ID 0
+
+static struct counter_values {
+	uint64_t cntvct_start;
+	uint64_t cntpct;
+	uint64_t cntvct_end;
+} counter_values;
+
+static uint64_t nr_iterations = 1000;
+
+static void do_test(void)
+{
+	/*
+	 * Open-coded approach instead of using helper methods to keep a tight
+	 * interval around the physical counter read.
+	 */
+	asm volatile("isb\n\t"
+		     "mrs %[cntvct_start], cntvct_el0\n\t"
+		     "isb\n\t"
+		     "mrs %[cntpct], cntpct_el0\n\t"
+		     "isb\n\t"
+		     "mrs %[cntvct_end], cntvct_el0\n\t"
+		     "isb\n\t"
+		     : [cntvct_start] "=r"(counter_values.cntvct_start),
+		     [cntpct] "=r"(counter_values.cntpct),
+		     [cntvct_end] "=r"(counter_values.cntvct_end));
+}
+
+static void guest_main(void)
+{
+	int i;
+
+	for (i = 0; i < nr_iterations; i++) {
+		do_test();
+		GUEST_SYNC(i);
+	}
+
+	for (i = 0; i < nr_iterations; i++) {
+		do_test();
+		GUEST_SYNC(i);
+	}
+
+	GUEST_DONE();
+}
+
+static bool enter_guest(struct kvm_vm *vm)
+{
+	struct ucall uc;
+
+	vcpu_ioctl(vm, VCPU_ID, KVM_RUN, NULL);
+
+	switch (get_ucall(vm, VCPU_ID, &uc)) {
+	case UCALL_DONE:
+		return true;
+	case UCALL_SYNC:
+		break;
+	case UCALL_ABORT:
+		TEST_ASSERT(false, "%s at %s:%ld", (const char *)uc.args[0],
+			    __FILE__, uc.args[1]);
+		break;
+	default:
+		TEST_ASSERT(false, "unexpected exit: %s",
+			    exit_reason_str(vcpu_state(vm, VCPU_ID)->exit_reason));
+		break;
+	}
+
+	/* more work to do in the guest */
+	return false;
+}
+
+static double counter_frequency(void)
+{
+	uint32_t freq;
+
+	asm volatile("mrs %0, cntfrq_el0"
+		     : "=r" (freq));
+
+	return freq / 1000000.0;
+}
+
+static void log_csv(FILE *csv, bool trapped)
+{
+	double freq = counter_frequency();
+
+	fprintf(csv, "%s,%.02f,%lu,%lu,%lu\n",
+		trapped ? "true" : "false", freq,
+		counter_values.cntvct_start,
+		counter_values.cntpct,
+		counter_values.cntvct_end);
+}
+
+static double run_loop(struct kvm_vm *vm, FILE *csv, bool trapped)
+{
+	double avg = 0;
+	int i;
+
+	for (i = 0; i < nr_iterations; i++) {
+		uint64_t delta;
+
+		TEST_ASSERT(!enter_guest(vm), "guest exited unexpectedly");
+		sync_global_from_guest(vm, counter_values);
+
+		if (csv)
+			log_csv(csv, trapped);
+
+		delta = counter_values.cntvct_end - counter_values.cntvct_start;
+		avg = ((avg * i) + delta) / (i + 1);
+	}
+
+	return avg;
+}
+
+static void setup_counter(struct kvm_vm *vm, uint64_t offset)
+{
+	vcpu_access_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL,
+				KVM_ARM_VCPU_TIMER_OFFSET_PTIMER, &offset,
+				true);
+}
+
+static void run_tests(struct kvm_vm *vm, FILE *csv)
+{
+	double avg_trapped, avg_native, freq;
+
+	freq = counter_frequency();
+
+	if (csv)
+		fputs("trapped,freq_mhz,cntvct_start,cntpct,cntvct_end\n", csv);
+
+	/* no physical offsetting; kvm allows reads of cntpct_el0 */
+	setup_counter(vm, 0);
+	avg_native = run_loop(vm, csv, false);
+
+	/* force emulation of the physical counter */
+	setup_counter(vm, 1);
+	avg_trapped = run_loop(vm, csv, true);
+
+	TEST_ASSERT(enter_guest(vm), "guest didn't run to completion");
+	pr_info("%lu iterations: average cycles (@%.02fMHz) native: %.02f, trapped: %.02f\n",
+		nr_iterations, freq, avg_native, avg_trapped);
+}
+
+static void usage(const char *program_name)
+{
+	fprintf(stderr,
+		"Usage: %s [-h] [-o csv_file] [-n iterations]\n"
+		"  -h prints this message\n"
+		"  -n number of test iterations (default: %lu)\n"
+		"  -o csv file to write data\n",
+		program_name, nr_iterations);
+}
+
+int main(int argc, char **argv)
+{
+	struct kvm_vm *vm;
+	FILE *csv = NULL;
+	int opt;
+
+	while ((opt = getopt(argc, argv, "hn:o:")) != -1) {
+		switch (opt) {
+		case 'o':
+			csv = fopen(optarg, "w");
+			if (!csv) {
+				fprintf(stderr, "failed to open file '%s': %d\n",
+					optarg, errno);
+				exit(1);
+			}
+			break;
+		case 'n':
+			nr_iterations = strtoul(optarg, NULL, 0);
+			break;
+		default:
+			fprintf(stderr, "unrecognized option: '-%c'\n", opt);
+			/* fallthrough */
+		case 'h':
+			usage(argv[0]);
+			exit(1);
+		}
+	}
+
+	vm = vm_create_default(VCPU_ID, 0, guest_main);
+	sync_global_to_guest(vm, nr_iterations);
+	ucall_init(vm, NULL);
+
+	if (_vcpu_has_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL,
+				  KVM_ARM_VCPU_TIMER_OFFSET_PTIMER)) {
+		print_skip("KVM_ARM_VCPU_TIMER_OFFSET_PTIMER not supported.");
+		exit(KSFT_SKIP);
+	}
+
+	run_tests(vm, csv);
+	kvm_vm_free(vm);
+
+	if (csv)
+		fclose(csv);
+}
-- 
2.32.0.402.g57bb445576-goog


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-07-16 21:27 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-16 21:26 [PATCH v2 00/12] KVM: Add idempotent controls for migrating system counter state Oliver Upton
2021-07-16 21:26 ` Oliver Upton
2021-07-16 21:26 ` Oliver Upton
2021-07-16 21:26 ` [PATCH v2 01/12] KVM: x86: Report host tsc and realtime values in KVM_GET_CLOCK Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-18 20:02   ` kernel test robot
2021-07-18 20:02     ` kernel test robot
2021-07-18 20:02     ` kernel test robot
2021-07-18 22:30   ` kernel test robot
2021-07-18 22:30     ` kernel test robot
2021-07-18 22:30     ` kernel test robot
2021-07-19  0:48   ` kernel test robot
2021-07-19  0:48     ` kernel test robot
2021-07-19  0:48     ` kernel test robot
2021-07-16 21:26 ` [PATCH v2 02/12] KVM: x86: Refactor tsc synchronization code Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26 ` [PATCH v2 03/12] KVM: x86: Expose TSC offset controls to userspace Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-18 20:42   ` Paolo Bonzini
2021-07-18 20:42     ` Paolo Bonzini
2021-07-18 20:42     ` Paolo Bonzini
2021-07-18 20:50   ` kernel test robot
2021-07-18 20:50     ` kernel test robot
2021-07-18 20:50     ` kernel test robot
2021-07-16 21:26 ` [PATCH v2 04/12] tools: arch: x86: pull in pvclock headers Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26 ` [PATCH v2 05/12] selftests: KVM: Add test for KVM_{GET,SET}_CLOCK Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-21 14:58   ` Andrew Jones
2021-07-21 14:58     ` [PATCH v2 05/12] selftests: KVM: Add test for KVM_{GET, SET}_CLOCK Andrew Jones
2021-07-21 14:58     ` Andrew Jones
2021-07-16 21:26 ` [PATCH v2 06/12] selftests: KVM: Add helpers for vCPU device attributes Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-21 15:14   ` Andrew Jones
2021-07-21 15:14     ` Andrew Jones
2021-07-21 15:14     ` Andrew Jones
2021-07-16 21:26 ` [PATCH v2 07/12] selftests: KVM: Introduce system counter offset test Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-21 15:17   ` Andrew Jones
2021-07-21 15:17     ` Andrew Jones
2021-07-21 15:17     ` Andrew Jones
2021-07-16 21:26 ` [PATCH v2 08/12] KVM: arm64: Allow userspace to configure a vCPU's virtual offset Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26 ` [PATCH v2 09/12] selftests: KVM: Add support for aarch64 to system_counter_offset_test Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26 ` [PATCH v2 10/12] KVM: arm64: Provide userspace access to the physical counter offset Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26 ` [PATCH v2 11/12] selftests: KVM: Test physical counter offsetting Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:26 ` Oliver Upton [this message]
2021-07-16 21:26   ` [PATCH v2 12/12] selftests: KVM: Add counter emulation benchmark Oliver Upton
2021-07-16 21:26   ` Oliver Upton
2021-07-16 21:29 ` [PATCH v2 00/12] KVM: Add idempotent controls for migrating system counter state Oliver Upton
2021-07-16 21:29   ` Oliver Upton
2021-07-16 21:29   ` Oliver Upton
2021-07-21 15:28 ` Andrew Jones
2021-07-21 15:28   ` Andrew Jones
2021-07-21 15:28   ` Andrew Jones
2021-07-22 15:42   ` Oliver Upton
2021-07-22 15:42     ` Oliver Upton
2021-07-22 15:42     ` Oliver Upton

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210716212629.2232756-13-oupton@google.com \
    --to=oupton@google.com \
    --cc=alexandru.elisei@arm.com \
    --cc=dmatlack@google.com \
    --cc=james.morse@arm.com \
    --cc=jingzhangos@google.com \
    --cc=jmattson@google.com \
    --cc=kvm@vger.kernel.org \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=maz@kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=pshier@google.com \
    --cc=rananta@google.com \
    --cc=ricarkol@google.com \
    --cc=seanjc@google.com \
    --cc=suzuki.poulose@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.