| Message ID | 0343a9e4bfa8011fbb6bca0286cee7eab1f17d5d.1702371136.git.haibo1.xu@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | RISCV: Add kvm Sstc timer selftests | expand |
On Tue, Dec 12, 2023 at 05:31:20PM +0800, Haibo Xu wrote: > There are intermittent failures occured when stressing the > arch-timer test in a Qemu VM: > > Guest assert failed, vcpu 0; stage; 4; iter: 3 > ==== Test Assertion Failure ==== > aarch64/arch_timer.c:196: config_iter + 1 == irq_iter > pid=4048 tid=4049 errno=4 - Interrupted system call > 1 0x000000000040253b: test_vcpu_run at arch_timer.c:248 > 2 0x0000ffffb60dd5c7: ?? ??:0 > 3 0x0000ffffb6145d1b: ?? ??:0 > 0x3 != 0x2 (config_iter + 1 != irq_iter)e > > Further test and debug show that the timeout for an interrupt > to arrive do have random high fluctuation, espectially when > testing in an virtual environment. > > To alleviate this issue, just expose the timeout value as user > configurable and print some hint message to increase the value > when hitting the failure.. > > Signed-off-by: Haibo Xu <haibo1.xu@intel.com> > --- > .../selftests/kvm/aarch64/arch_timer.c | 8 +++++-- > tools/testing/selftests/kvm/arch_timer.c | 22 +++++++++++++------ > .../selftests/kvm/include/timer_test.h | 1 + > .../testing/selftests/kvm/riscv/arch_timer.c | 8 +++++-- > 4 files changed, 28 insertions(+), 11 deletions(-) > > diff --git a/tools/testing/selftests/kvm/aarch64/arch_timer.c b/tools/testing/selftests/kvm/aarch64/arch_timer.c > index 4b421d421c3f..139eecbf77e7 100644 > --- a/tools/testing/selftests/kvm/aarch64/arch_timer.c > +++ b/tools/testing/selftests/kvm/aarch64/arch_timer.c > @@ -131,10 +131,14 @@ static void guest_run_stage(struct test_vcpu_shared_data *shared_data, > > /* Setup a timeout for the interrupt to arrive */ > udelay(msecs_to_usecs(test_args.timer_period_ms) + > - TIMER_TEST_ERR_MARGIN_US); > + test_args.timer_err_margin_us); > > irq_iter = READ_ONCE(shared_data->nr_iter); > - GUEST_ASSERT_EQ(config_iter + 1, irq_iter); > + __GUEST_ASSERT(config_iter + 1 == irq_iter, > + "config_iter + 1 = 0x%lx, irq_iter = 0x%lx.\n" > + " Guest timer interrupt was not trigged within the specified\n" > + " interval, try to increase the error margin by [-e] option.\n", > + config_iter + 1, irq_iter); > } > } > > diff --git a/tools/testing/selftests/kvm/arch_timer.c b/tools/testing/selftests/kvm/arch_timer.c > index 60963fce16f2..5050022fd345 100644 > --- a/tools/testing/selftests/kvm/arch_timer.c > +++ b/tools/testing/selftests/kvm/arch_timer.c > @@ -5,16 +5,17 @@ > * The guest's main thread configures the timer interrupt and waits > * for it to fire, with a timeout equal to the timer period. > * It asserts that the timeout doesn't exceed the timer period plus > - * an error margin of 100us. > + * an user configurable error margin(default to 100us). > * > * On the other hand, upon receipt of an interrupt, the guest's interrupt > * handler validates the interrupt by checking if the architectural state > * is in compliance with the specifications. > * > * The test provides command-line options to configure the timer's > - * period (-p), number of vCPUs (-n), and iterations per stage (-i). > - * To stress-test the timer stack even more, an option to migrate the > - * vCPUs across pCPUs (-m), at a particular rate, is also provided. > + * period (-p), number of vCPUs (-n), iterations per stage (-i), and timer > + * interrupt arrival error margin (-e). To stress-test the timer stack even > + * more, an option to migrate the vCPUs across pCPUs (-m), at a particular > + * rate, is also provided. > * > * Copyright (c) 2021, Google LLC. > */ > @@ -34,6 +35,7 @@ struct test_args test_args = { > .nr_iter = NR_TEST_ITERS_DEF, > .timer_period_ms = TIMER_TEST_PERIOD_MS_DEF, > .migration_freq_ms = TIMER_TEST_MIGRATION_FREQ_MS, > + .timer_err_margin_us = TIMER_TEST_ERR_MARGIN_US, > .reserved = 1, > }; > > @@ -179,8 +181,9 @@ static void test_run(struct kvm_vm *vm) > > static void test_print_help(char *name) > { > - pr_info("Usage: %s [-h] [-n nr_vcpus] [-i iterations] [-p timer_period_ms]\n", > - name); > + pr_info("Usage: %s [-h] [-n nr_vcpus] [-i iterations] [-p timer_period_ms]\n" > + "\t\t [-m migration_freq_ms] [-o counter_offset]\n" > + "\t\t [-e timer_err_margin_us]\n", name); > pr_info("\t-n: Number of vCPUs to configure (default: %u; max: %u)\n", > NR_VCPUS_DEF, KVM_MAX_VCPUS); > pr_info("\t-i: Number of iterations per stage (default: %u)\n", > @@ -190,6 +193,8 @@ static void test_print_help(char *name) > pr_info("\t-m: Frequency (in ms) of vCPUs to migrate to different pCPU. 0 to turn off (default: %u)\n", > TIMER_TEST_MIGRATION_FREQ_MS); > pr_info("\t-o: Counter offset (in counter cycles, default: 0) [aarch64-only]\n"); > + pr_info("\t-e: Interrupt arrival error margin(in us) of the guest timer (default: %u)\n", ^ need space here > + TIMER_TEST_ERR_MARGIN_US); > pr_info("\t-h: print this help screen\n"); > } > > @@ -197,7 +202,7 @@ static bool parse_args(int argc, char *argv[]) > { > int opt; > > - while ((opt = getopt(argc, argv, "hn:i:p:m:o:")) != -1) { > + while ((opt = getopt(argc, argv, "hn:i:p:m:o:e:")) != -1) { > switch (opt) { > case 'n': > test_args.nr_vcpus = atoi_positive("Number of vCPUs", optarg); > @@ -216,6 +221,9 @@ static bool parse_args(int argc, char *argv[]) > case 'm': > test_args.migration_freq_ms = atoi_non_negative("Frequency", optarg); > break; > + case 'e': > + test_args.timer_err_margin_us = atoi_non_negative("Error Margin", optarg); > + break; > case 'o': > test_args.counter_offset = strtol(optarg, NULL, 0); > test_args.reserved = 0; > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h > index 968257b893a7..b1d405e7157d 100644 > --- a/tools/testing/selftests/kvm/include/timer_test.h > +++ b/tools/testing/selftests/kvm/include/timer_test.h > @@ -22,6 +22,7 @@ struct test_args { > int nr_iter; > int timer_period_ms; > int migration_freq_ms; > + int timer_err_margin_us; > /* Members of struct kvm_arm_counter_offset */ > uint64_t counter_offset; > uint64_t reserved; > diff --git a/tools/testing/selftests/kvm/riscv/arch_timer.c b/tools/testing/selftests/kvm/riscv/arch_timer.c > index 13bf184d1ff5..45a139dc7ce3 100644 > --- a/tools/testing/selftests/kvm/riscv/arch_timer.c > +++ b/tools/testing/selftests/kvm/riscv/arch_timer.c > @@ -55,10 +55,14 @@ static void guest_run(struct test_vcpu_shared_data *shared_data) > > /* Setup a timeout for the interrupt to arrive */ > udelay(msecs_to_usecs(test_args.timer_period_ms) + > - TIMER_TEST_ERR_MARGIN_US); > + test_args.timer_err_margin_us); > > irq_iter = READ_ONCE(shared_data->nr_iter); > - GUEST_ASSERT_EQ(config_iter + 1, irq_iter); > + __GUEST_ASSERT(config_iter + 1 == irq_iter, > + "config_iter + 1 = 0x%lx, irq_iter = 0x%lx.\n" > + " Guest timer interrupt was not trigged within the specified\n" > + " interval, try to increase the error margin by [-e] option.\n", > + config_iter + 1, irq_iter); > } > } > > -- > 2.34.1 > I probably would have started the series with this patch since you said you could reproduce the problem on aarch64. Starting the series with this patch would allow just this patch to get picked up to fix aarch64, if that's necessary, and also avoids touching a couple places twice with the code split for riscv. But anyway, other than the missing space in the help text, Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Thanks, drew
Hi Marc, Hi Oliver, On Tue, Dec 12, 2023 at 2:52 PM Haibo Xu <haibo1.xu@intel.com> wrote: > > There are intermittent failures occured when stressing the > arch-timer test in a Qemu VM: > > Guest assert failed, vcpu 0; stage; 4; iter: 3 > ==== Test Assertion Failure ==== > aarch64/arch_timer.c:196: config_iter + 1 == irq_iter > pid=4048 tid=4049 errno=4 - Interrupted system call > 1 0x000000000040253b: test_vcpu_run at arch_timer.c:248 > 2 0x0000ffffb60dd5c7: ?? ??:0 > 3 0x0000ffffb6145d1b: ?? ??:0 > 0x3 != 0x2 (config_iter + 1 != irq_iter)e > > Further test and debug show that the timeout for an interrupt > to arrive do have random high fluctuation, espectially when > testing in an virtual environment. > > To alleviate this issue, just expose the timeout value as user > configurable and print some hint message to increase the value > when hitting the failure.. > > Signed-off-by: Haibo Xu <haibo1.xu@intel.com> Can you please review this patch ? We want to take this entire series through the KVM RISC-V tree. Regards, Anup > --- > .../selftests/kvm/aarch64/arch_timer.c | 8 +++++-- > tools/testing/selftests/kvm/arch_timer.c | 22 +++++++++++++------ > .../selftests/kvm/include/timer_test.h | 1 + > .../testing/selftests/kvm/riscv/arch_timer.c | 8 +++++-- > 4 files changed, 28 insertions(+), 11 deletions(-) > > diff --git a/tools/testing/selftests/kvm/aarch64/arch_timer.c b/tools/testing/selftests/kvm/aarch64/arch_timer.c > index 4b421d421c3f..139eecbf77e7 100644 > --- a/tools/testing/selftests/kvm/aarch64/arch_timer.c > +++ b/tools/testing/selftests/kvm/aarch64/arch_timer.c > @@ -131,10 +131,14 @@ static void guest_run_stage(struct test_vcpu_shared_data *shared_data, > > /* Setup a timeout for the interrupt to arrive */ > udelay(msecs_to_usecs(test_args.timer_period_ms) + > - TIMER_TEST_ERR_MARGIN_US); > + test_args.timer_err_margin_us); > > irq_iter = READ_ONCE(shared_data->nr_iter); > - GUEST_ASSERT_EQ(config_iter + 1, irq_iter); > + __GUEST_ASSERT(config_iter + 1 == irq_iter, > + "config_iter + 1 = 0x%lx, irq_iter = 0x%lx.\n" > + " Guest timer interrupt was not trigged within the specified\n" > + " interval, try to increase the error margin by [-e] option.\n", > + config_iter + 1, irq_iter); > } > } > > diff --git a/tools/testing/selftests/kvm/arch_timer.c b/tools/testing/selftests/kvm/arch_timer.c > index 60963fce16f2..5050022fd345 100644 > --- a/tools/testing/selftests/kvm/arch_timer.c > +++ b/tools/testing/selftests/kvm/arch_timer.c > @@ -5,16 +5,17 @@ > * The guest's main thread configures the timer interrupt and waits > * for it to fire, with a timeout equal to the timer period. > * It asserts that the timeout doesn't exceed the timer period plus > - * an error margin of 100us. > + * an user configurable error margin(default to 100us). > * > * On the other hand, upon receipt of an interrupt, the guest's interrupt > * handler validates the interrupt by checking if the architectural state > * is in compliance with the specifications. > * > * The test provides command-line options to configure the timer's > - * period (-p), number of vCPUs (-n), and iterations per stage (-i). > - * To stress-test the timer stack even more, an option to migrate the > - * vCPUs across pCPUs (-m), at a particular rate, is also provided. > + * period (-p), number of vCPUs (-n), iterations per stage (-i), and timer > + * interrupt arrival error margin (-e). To stress-test the timer stack even > + * more, an option to migrate the vCPUs across pCPUs (-m), at a particular > + * rate, is also provided. > * > * Copyright (c) 2021, Google LLC. > */ > @@ -34,6 +35,7 @@ struct test_args test_args = { > .nr_iter = NR_TEST_ITERS_DEF, > .timer_period_ms = TIMER_TEST_PERIOD_MS_DEF, > .migration_freq_ms = TIMER_TEST_MIGRATION_FREQ_MS, > + .timer_err_margin_us = TIMER_TEST_ERR_MARGIN_US, > .reserved = 1, > }; > > @@ -179,8 +181,9 @@ static void test_run(struct kvm_vm *vm) > > static void test_print_help(char *name) > { > - pr_info("Usage: %s [-h] [-n nr_vcpus] [-i iterations] [-p timer_period_ms]\n", > - name); > + pr_info("Usage: %s [-h] [-n nr_vcpus] [-i iterations] [-p timer_period_ms]\n" > + "\t\t [-m migration_freq_ms] [-o counter_offset]\n" > + "\t\t [-e timer_err_margin_us]\n", name); > pr_info("\t-n: Number of vCPUs to configure (default: %u; max: %u)\n", > NR_VCPUS_DEF, KVM_MAX_VCPUS); > pr_info("\t-i: Number of iterations per stage (default: %u)\n", > @@ -190,6 +193,8 @@ static void test_print_help(char *name) > pr_info("\t-m: Frequency (in ms) of vCPUs to migrate to different pCPU. 0 to turn off (default: %u)\n", > TIMER_TEST_MIGRATION_FREQ_MS); > pr_info("\t-o: Counter offset (in counter cycles, default: 0) [aarch64-only]\n"); > + pr_info("\t-e: Interrupt arrival error margin(in us) of the guest timer (default: %u)\n", > + TIMER_TEST_ERR_MARGIN_US); > pr_info("\t-h: print this help screen\n"); > } > > @@ -197,7 +202,7 @@ static bool parse_args(int argc, char *argv[]) > { > int opt; > > - while ((opt = getopt(argc, argv, "hn:i:p:m:o:")) != -1) { > + while ((opt = getopt(argc, argv, "hn:i:p:m:o:e:")) != -1) { > switch (opt) { > case 'n': > test_args.nr_vcpus = atoi_positive("Number of vCPUs", optarg); > @@ -216,6 +221,9 @@ static bool parse_args(int argc, char *argv[]) > case 'm': > test_args.migration_freq_ms = atoi_non_negative("Frequency", optarg); > break; > + case 'e': > + test_args.timer_err_margin_us = atoi_non_negative("Error Margin", optarg); > + break; > case 'o': > test_args.counter_offset = strtol(optarg, NULL, 0); > test_args.reserved = 0; > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h > index 968257b893a7..b1d405e7157d 100644 > --- a/tools/testing/selftests/kvm/include/timer_test.h > +++ b/tools/testing/selftests/kvm/include/timer_test.h > @@ -22,6 +22,7 @@ struct test_args { > int nr_iter; > int timer_period_ms; > int migration_freq_ms; > + int timer_err_margin_us; > /* Members of struct kvm_arm_counter_offset */ > uint64_t counter_offset; > uint64_t reserved; > diff --git a/tools/testing/selftests/kvm/riscv/arch_timer.c b/tools/testing/selftests/kvm/riscv/arch_timer.c > index 13bf184d1ff5..45a139dc7ce3 100644 > --- a/tools/testing/selftests/kvm/riscv/arch_timer.c > +++ b/tools/testing/selftests/kvm/riscv/arch_timer.c > @@ -55,10 +55,14 @@ static void guest_run(struct test_vcpu_shared_data *shared_data) > > /* Setup a timeout for the interrupt to arrive */ > udelay(msecs_to_usecs(test_args.timer_period_ms) + > - TIMER_TEST_ERR_MARGIN_US); > + test_args.timer_err_margin_us); > > irq_iter = READ_ONCE(shared_data->nr_iter); > - GUEST_ASSERT_EQ(config_iter + 1, irq_iter); > + __GUEST_ASSERT(config_iter + 1 == irq_iter, > + "config_iter + 1 = 0x%lx, irq_iter = 0x%lx.\n" > + " Guest timer interrupt was not trigged within the specified\n" > + " interval, try to increase the error margin by [-e] option.\n", > + config_iter + 1, irq_iter); > } > } > > -- > 2.34.1 >
On Tue, 12 Dec 2023 09:31:20 +0000, Haibo Xu <haibo1.xu@intel.com> wrote: > > @@ -216,6 +221,9 @@ static bool parse_args(int argc, char *argv[]) > case 'm': > test_args.migration_freq_ms = atoi_non_negative("Frequency", optarg); > break; > + case 'e': > + test_args.timer_err_margin_us = atoi_non_negative("Error Margin", optarg); > + break; So your error margin is always unsigned... > case 'o': > test_args.counter_offset = strtol(optarg, NULL, 0); > test_args.reserved = 0; > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h > index 968257b893a7..b1d405e7157d 100644 > --- a/tools/testing/selftests/kvm/include/timer_test.h > +++ b/tools/testing/selftests/kvm/include/timer_test.h > @@ -22,6 +22,7 @@ struct test_args { > int nr_iter; > int timer_period_ms; > int migration_freq_ms; > + int timer_err_margin_us; ... except that you are storing it as a signed value. Some consistency wouldn't hurt, really, and would avoid issues when passing large values. M.
On Wed, Dec 20, 2023 at 2:22 AM Marc Zyngier <maz@kernel.org> wrote: > > On Tue, 12 Dec 2023 09:31:20 +0000, > Haibo Xu <haibo1.xu@intel.com> wrote: > > > @@ -216,6 +221,9 @@ static bool parse_args(int argc, char *argv[]) > > case 'm': > > test_args.migration_freq_ms = atoi_non_negative("Frequency", optarg); > > break; > > + case 'e': > > + test_args.timer_err_margin_us = atoi_non_negative("Error Margin", optarg); > > + break; > > So your error margin is always unsigned... > The error margin was supposed to be a non-negative [0, INT_MAX]. (May be need to define a Max for the input, instead of INT_MAX) > > case 'o': > > test_args.counter_offset = strtol(optarg, NULL, 0); > > test_args.reserved = 0; > > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h > > index 968257b893a7..b1d405e7157d 100644 > > --- a/tools/testing/selftests/kvm/include/timer_test.h > > +++ b/tools/testing/selftests/kvm/include/timer_test.h > > @@ -22,6 +22,7 @@ struct test_args { > > int nr_iter; > > int timer_period_ms; > > int migration_freq_ms; > > + int timer_err_margin_us; > > ... except that you are storing it as a signed value. Some consistency > wouldn't hurt, really, and would avoid issues when passing large > values. > Yes, it's more proper to use an unsigned int for the non-negative error margin. Storing as signed here is just to keep the type consistent with that of timer_period_ms since there will be '+' operation in other places. tools/testing/selftests/kvm/aarch64/arch_timer.c /* Setup a timeout for the interrupt to arrive */ udelay(msecs_to_usecs(test_args.timer_period_ms) + test_args.timer_err_margin_us); Thanks, Haibo > M. > > -- > Without deviation from the norm, progress is not possible.
On 2023-12-20 06:50, Haibo Xu wrote: > On Wed, Dec 20, 2023 at 2:22 AM Marc Zyngier <maz@kernel.org> wrote: >> >> On Tue, 12 Dec 2023 09:31:20 +0000, >> Haibo Xu <haibo1.xu@intel.com> wrote: >> > > @@ -216,6 +221,9 @@ static bool parse_args(int argc, char *argv[]) >> > case 'm': >> > test_args.migration_freq_ms = atoi_non_negative("Frequency", optarg); >> > break; >> > + case 'e': >> > + test_args.timer_err_margin_us = atoi_non_negative("Error Margin", optarg); >> > + break; >> >> So your error margin is always unsigned... >> > > The error margin was supposed to be a non-negative [0, INT_MAX]. > (May be need to define a Max for the input, instead of INT_MAX) > >> > case 'o': >> > test_args.counter_offset = strtol(optarg, NULL, 0); >> > test_args.reserved = 0; >> > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h >> > index 968257b893a7..b1d405e7157d 100644 >> > --- a/tools/testing/selftests/kvm/include/timer_test.h >> > +++ b/tools/testing/selftests/kvm/include/timer_test.h >> > @@ -22,6 +22,7 @@ struct test_args { >> > int nr_iter; >> > int timer_period_ms; >> > int migration_freq_ms; >> > + int timer_err_margin_us; >> >> ... except that you are storing it as a signed value. Some consistency >> wouldn't hurt, really, and would avoid issues when passing large >> values. >> > > Yes, it's more proper to use an unsigned int for the non-negative error > margin. > Storing as signed here is just to keep the type consistent with that > of timer_period_ms > since there will be '+' operation in other places. > > tools/testing/selftests/kvm/aarch64/arch_timer.c > /* Setup a timeout for the interrupt to arrive */ > udelay(msecs_to_usecs(test_args.timer_period_ms) + > test_args.timer_err_margin_us); But that's exactly why using a signed quantity is wrong. What does it mean to have a huge *negative* margin? I don't see how you can justify this. M.
On Wed, Dec 20, 2023 at 5:00 PM Marc Zyngier <maz@kernel.org> wrote: > > On 2023-12-20 06:50, Haibo Xu wrote: > > On Wed, Dec 20, 2023 at 2:22 AM Marc Zyngier <maz@kernel.org> wrote: > >> > >> On Tue, 12 Dec 2023 09:31:20 +0000, > >> Haibo Xu <haibo1.xu@intel.com> wrote: > >> > > @@ -216,6 +221,9 @@ static bool parse_args(int argc, char *argv[]) > >> > case 'm': > >> > test_args.migration_freq_ms = atoi_non_negative("Frequency", optarg); > >> > break; > >> > + case 'e': > >> > + test_args.timer_err_margin_us = atoi_non_negative("Error Margin", optarg); > >> > + break; > >> > >> So your error margin is always unsigned... > >> > > > > The error margin was supposed to be a non-negative [0, INT_MAX]. > > (May be need to define a Max for the input, instead of INT_MAX) > > > >> > case 'o': > >> > test_args.counter_offset = strtol(optarg, NULL, 0); > >> > test_args.reserved = 0; > >> > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h > >> > index 968257b893a7..b1d405e7157d 100644 > >> > --- a/tools/testing/selftests/kvm/include/timer_test.h > >> > +++ b/tools/testing/selftests/kvm/include/timer_test.h > >> > @@ -22,6 +22,7 @@ struct test_args { > >> > int nr_iter; > >> > int timer_period_ms; > >> > int migration_freq_ms; > >> > + int timer_err_margin_us; > >> > >> ... except that you are storing it as a signed value. Some consistency > >> wouldn't hurt, really, and would avoid issues when passing large > >> values. > >> > > > > Yes, it's more proper to use an unsigned int for the non-negative error > > margin. > > Storing as signed here is just to keep the type consistent with that > > of timer_period_ms > > since there will be '+' operation in other places. > > > > tools/testing/selftests/kvm/aarch64/arch_timer.c > > /* Setup a timeout for the interrupt to arrive */ > > udelay(msecs_to_usecs(test_args.timer_period_ms) + > > test_args.timer_err_margin_us); > > But that's exactly why using a signed quantity is wrong. > What does it mean to have a huge *negative* margin? > Hi Marc, I agree that negative values are meaningless for the margin. If I understand correctly, the negative margin should be filtered by assertion in atoi_non_negative(). Thanks, Haibo > I don't see how you can justify this. > > M. > -- > Jazz is not dead. It just smells funny...
On Wed, 20 Dec 2023 13:51:24 +0000, Haibo Xu <xiaobo55x@gmail.com> wrote: > > On Wed, Dec 20, 2023 at 5:00 PM Marc Zyngier <maz@kernel.org> wrote: > > > > On 2023-12-20 06:50, Haibo Xu wrote: > > > On Wed, Dec 20, 2023 at 2:22 AM Marc Zyngier <maz@kernel.org> wrote: > > >> > > >> On Tue, 12 Dec 2023 09:31:20 +0000, > > >> Haibo Xu <haibo1.xu@intel.com> wrote: > > >> > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h > > >> > index 968257b893a7..b1d405e7157d 100644 > > >> > --- a/tools/testing/selftests/kvm/include/timer_test.h > > >> > +++ b/tools/testing/selftests/kvm/include/timer_test.h > > >> > @@ -22,6 +22,7 @@ struct test_args { > > >> > int nr_iter; > > >> > int timer_period_ms; > > >> > int migration_freq_ms; > > >> > + int timer_err_margin_us; > > >> > > >> ... except that you are storing it as a signed value. Some consistency > > >> wouldn't hurt, really, and would avoid issues when passing large > > >> values. > > >> > > > > > > Yes, it's more proper to use an unsigned int for the non-negative error > > > margin. > > > Storing as signed here is just to keep the type consistent with that > > > of timer_period_ms > > > since there will be '+' operation in other places. > > > > > > tools/testing/selftests/kvm/aarch64/arch_timer.c > > > /* Setup a timeout for the interrupt to arrive */ > > > udelay(msecs_to_usecs(test_args.timer_period_ms) + > > > test_args.timer_err_margin_us); > > > > But that's exactly why using a signed quantity is wrong. > > What does it mean to have a huge *negative* margin? > > > > Hi Marc, > > I agree that negative values are meaningless for the margin. > If I understand correctly, the negative margin should be filtered by > assertion in atoi_non_negative(). No. Please. atoi_non_negative() returns a uint32_t, which is what it should do. The bug is squarely in the use of an 'int' to store such value, and it is the *storage* that turns a positive value into a negative one. M.
On Wed, Dec 20, 2023 at 9:58 PM Marc Zyngier <maz@kernel.org> wrote: > > On Wed, 20 Dec 2023 13:51:24 +0000, > Haibo Xu <xiaobo55x@gmail.com> wrote: > > > > On Wed, Dec 20, 2023 at 5:00 PM Marc Zyngier <maz@kernel.org> wrote: > > > > > > On 2023-12-20 06:50, Haibo Xu wrote: > > > > On Wed, Dec 20, 2023 at 2:22 AM Marc Zyngier <maz@kernel.org> wrote: > > > >> > > > >> On Tue, 12 Dec 2023 09:31:20 +0000, > > > >> Haibo Xu <haibo1.xu@intel.com> wrote: > > > >> > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h > > > >> > index 968257b893a7..b1d405e7157d 100644 > > > >> > --- a/tools/testing/selftests/kvm/include/timer_test.h > > > >> > +++ b/tools/testing/selftests/kvm/include/timer_test.h > > > >> > @@ -22,6 +22,7 @@ struct test_args { > > > >> > int nr_iter; > > > >> > int timer_period_ms; > > > >> > int migration_freq_ms; > > > >> > + int timer_err_margin_us; > > > >> > > > >> ... except that you are storing it as a signed value. Some consistency > > > >> wouldn't hurt, really, and would avoid issues when passing large > > > >> values. > > > >> > > > > > > > > Yes, it's more proper to use an unsigned int for the non-negative error > > > > margin. > > > > Storing as signed here is just to keep the type consistent with that > > > > of timer_period_ms > > > > since there will be '+' operation in other places. > > > > > > > > tools/testing/selftests/kvm/aarch64/arch_timer.c > > > > /* Setup a timeout for the interrupt to arrive */ > > > > udelay(msecs_to_usecs(test_args.timer_period_ms) + > > > > test_args.timer_err_margin_us); > > > > > > But that's exactly why using a signed quantity is wrong. > > > What does it mean to have a huge *negative* margin? > > > > > > > Hi Marc, > > > > I agree that negative values are meaningless for the margin. > > If I understand correctly, the negative margin should be filtered by > > assertion in atoi_non_negative(). > > No. Please. > > atoi_non_negative() returns a uint32_t, which is what it should do. > The bug is squarely in the use of an 'int' to store such value, and it > is the *storage* that turns a positive value into a negative one. > Thanks for the detailed info! May I understand that your concern is mainly for a platform with 64bit int type, which may trigger the positive to negative convert? If so, I think we may need to do a clean up for the test code since several other places have the same issue. Regards, Haibo > M. > > -- > Without deviation from the norm, progress is not possible.
On Thu, 21 Dec 2023 02:58:40 +0000, Haibo Xu <xiaobo55x@gmail.com> wrote: > > On Wed, Dec 20, 2023 at 9:58 PM Marc Zyngier <maz@kernel.org> wrote: > > > > On Wed, 20 Dec 2023 13:51:24 +0000, > > Haibo Xu <xiaobo55x@gmail.com> wrote: > > > > > > On Wed, Dec 20, 2023 at 5:00 PM Marc Zyngier <maz@kernel.org> wrote: > > > > > > > > On 2023-12-20 06:50, Haibo Xu wrote: > > > > > On Wed, Dec 20, 2023 at 2:22 AM Marc Zyngier <maz@kernel.org> wrote: > > > > >> > > > > >> On Tue, 12 Dec 2023 09:31:20 +0000, > > > > >> Haibo Xu <haibo1.xu@intel.com> wrote: > > > > >> > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h > > > > >> > index 968257b893a7..b1d405e7157d 100644 > > > > >> > --- a/tools/testing/selftests/kvm/include/timer_test.h > > > > >> > +++ b/tools/testing/selftests/kvm/include/timer_test.h > > > > >> > @@ -22,6 +22,7 @@ struct test_args { > > > > >> > int nr_iter; > > > > >> > int timer_period_ms; > > > > >> > int migration_freq_ms; > > > > >> > + int timer_err_margin_us; > > > > >> > > > > >> ... except that you are storing it as a signed value. Some consistency > > > > >> wouldn't hurt, really, and would avoid issues when passing large > > > > >> values. > > > > >> > > > > > > > > > > Yes, it's more proper to use an unsigned int for the non-negative error > > > > > margin. > > > > > Storing as signed here is just to keep the type consistent with that > > > > > of timer_period_ms > > > > > since there will be '+' operation in other places. > > > > > > > > > > tools/testing/selftests/kvm/aarch64/arch_timer.c > > > > > /* Setup a timeout for the interrupt to arrive */ > > > > > udelay(msecs_to_usecs(test_args.timer_period_ms) + > > > > > test_args.timer_err_margin_us); > > > > > > > > But that's exactly why using a signed quantity is wrong. > > > > What does it mean to have a huge *negative* margin? > > > > > > > > > > Hi Marc, > > > > > > I agree that negative values are meaningless for the margin. > > > If I understand correctly, the negative margin should be filtered by > > > assertion in atoi_non_negative(). > > > > No. Please. > > > > atoi_non_negative() returns a uint32_t, which is what it should do. > > The bug is squarely in the use of an 'int' to store such value, and it > > is the *storage* that turns a positive value into a negative one. > > > > Thanks for the detailed info! > > May I understand that your concern is mainly for a platform with > 64bit int type, which may trigger the positive to negative convert? No. It specifically applies to architectures with a 32bit int type, which is... *EVERYTHING*. Here's a basic example: <quote> #include <stdio.h> int main(int argc, char *argv[]) { int x = 1U << 31; printf("%d (%d)\n", x, sizeof(x)); return 0; } </quote> which returns "-2147483648 (4)" on any platform. This really is basic C, and I am very worried that you don't see the issue. I strongly suggest that you go and read about the C type system before touching this code. M.
On Thu, Dec 21, 2023 at 10:58:40AM +0800, Haibo Xu wrote: > On Wed, Dec 20, 2023 at 9:58 PM Marc Zyngier <maz@kernel.org> wrote: > > > > On Wed, 20 Dec 2023 13:51:24 +0000, > > Haibo Xu <xiaobo55x@gmail.com> wrote: > > > > > > On Wed, Dec 20, 2023 at 5:00 PM Marc Zyngier <maz@kernel.org> wrote: > > > > > > > > On 2023-12-20 06:50, Haibo Xu wrote: > > > > > On Wed, Dec 20, 2023 at 2:22 AM Marc Zyngier <maz@kernel.org> wrote: > > > > >> > > > > >> On Tue, 12 Dec 2023 09:31:20 +0000, > > > > >> Haibo Xu <haibo1.xu@intel.com> wrote: > > > > >> > diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h > > > > >> > index 968257b893a7..b1d405e7157d 100644 > > > > >> > --- a/tools/testing/selftests/kvm/include/timer_test.h > > > > >> > +++ b/tools/testing/selftests/kvm/include/timer_test.h > > > > >> > @@ -22,6 +22,7 @@ struct test_args { > > > > >> > int nr_iter; > > > > >> > int timer_period_ms; > > > > >> > int migration_freq_ms; > > > > >> > + int timer_err_margin_us; > > > > >> > > > > >> ... except that you are storing it as a signed value. Some consistency > > > > >> wouldn't hurt, really, and would avoid issues when passing large > > > > >> values. > > > > >> > > > > > > > > > > Yes, it's more proper to use an unsigned int for the non-negative error > > > > > margin. > > > > > Storing as signed here is just to keep the type consistent with that > > > > > of timer_period_ms > > > > > since there will be '+' operation in other places. > > > > > > > > > > tools/testing/selftests/kvm/aarch64/arch_timer.c > > > > > /* Setup a timeout for the interrupt to arrive */ > > > > > udelay(msecs_to_usecs(test_args.timer_period_ms) + > > > > > test_args.timer_err_margin_us); > > > > > > > > But that's exactly why using a signed quantity is wrong. > > > > What does it mean to have a huge *negative* margin? > > > > > > > > > > Hi Marc, > > > > > > I agree that negative values are meaningless for the margin. > > > If I understand correctly, the negative margin should be filtered by > > > assertion in atoi_non_negative(). > > > > No. Please. > > > > atoi_non_negative() returns a uint32_t, which is what it should do. > > The bug is squarely in the use of an 'int' to store such value, and it > > is the *storage* that turns a positive value into a negative one. > > > > Thanks for the detailed info! > > May I understand that your concern is mainly for a platform with 64bit int type, > which may trigger the positive to negative convert? > > If so, I think we may need to do a clean up for the test code since > several other > places have the same issue. Yes, I think we should do that cleanup. While there are probably several offenders scattered throughout kvm selftests, we can keep the scope of this series focused on arch_timer.c. Let's audit all uses of signed types and convert them to unsigned as necessary with some separate patch(es) before splitting the test, so both aarch64 and riscv get the cleanups. Thanks, drew
diff --git a/tools/testing/selftests/kvm/aarch64/arch_timer.c b/tools/testing/selftests/kvm/aarch64/arch_timer.c index 4b421d421c3f..139eecbf77e7 100644 --- a/tools/testing/selftests/kvm/aarch64/arch_timer.c +++ b/tools/testing/selftests/kvm/aarch64/arch_timer.c @@ -131,10 +131,14 @@ static void guest_run_stage(struct test_vcpu_shared_data *shared_data, /* Setup a timeout for the interrupt to arrive */ udelay(msecs_to_usecs(test_args.timer_period_ms) + - TIMER_TEST_ERR_MARGIN_US); + test_args.timer_err_margin_us); irq_iter = READ_ONCE(shared_data->nr_iter); - GUEST_ASSERT_EQ(config_iter + 1, irq_iter); + __GUEST_ASSERT(config_iter + 1 == irq_iter, + "config_iter + 1 = 0x%lx, irq_iter = 0x%lx.\n" + " Guest timer interrupt was not trigged within the specified\n" + " interval, try to increase the error margin by [-e] option.\n", + config_iter + 1, irq_iter); } } diff --git a/tools/testing/selftests/kvm/arch_timer.c b/tools/testing/selftests/kvm/arch_timer.c index 60963fce16f2..5050022fd345 100644 --- a/tools/testing/selftests/kvm/arch_timer.c +++ b/tools/testing/selftests/kvm/arch_timer.c @@ -5,16 +5,17 @@ * The guest's main thread configures the timer interrupt and waits * for it to fire, with a timeout equal to the timer period. * It asserts that the timeout doesn't exceed the timer period plus - * an error margin of 100us. + * an user configurable error margin(default to 100us). * * On the other hand, upon receipt of an interrupt, the guest's interrupt * handler validates the interrupt by checking if the architectural state * is in compliance with the specifications. * * The test provides command-line options to configure the timer's - * period (-p), number of vCPUs (-n), and iterations per stage (-i). - * To stress-test the timer stack even more, an option to migrate the - * vCPUs across pCPUs (-m), at a particular rate, is also provided. + * period (-p), number of vCPUs (-n), iterations per stage (-i), and timer + * interrupt arrival error margin (-e). To stress-test the timer stack even + * more, an option to migrate the vCPUs across pCPUs (-m), at a particular + * rate, is also provided. * * Copyright (c) 2021, Google LLC. */ @@ -34,6 +35,7 @@ struct test_args test_args = { .nr_iter = NR_TEST_ITERS_DEF, .timer_period_ms = TIMER_TEST_PERIOD_MS_DEF, .migration_freq_ms = TIMER_TEST_MIGRATION_FREQ_MS, + .timer_err_margin_us = TIMER_TEST_ERR_MARGIN_US, .reserved = 1, }; @@ -179,8 +181,9 @@ static void test_run(struct kvm_vm *vm) static void test_print_help(char *name) { - pr_info("Usage: %s [-h] [-n nr_vcpus] [-i iterations] [-p timer_period_ms]\n", - name); + pr_info("Usage: %s [-h] [-n nr_vcpus] [-i iterations] [-p timer_period_ms]\n" + "\t\t [-m migration_freq_ms] [-o counter_offset]\n" + "\t\t [-e timer_err_margin_us]\n", name); pr_info("\t-n: Number of vCPUs to configure (default: %u; max: %u)\n", NR_VCPUS_DEF, KVM_MAX_VCPUS); pr_info("\t-i: Number of iterations per stage (default: %u)\n", @@ -190,6 +193,8 @@ static void test_print_help(char *name) pr_info("\t-m: Frequency (in ms) of vCPUs to migrate to different pCPU. 0 to turn off (default: %u)\n", TIMER_TEST_MIGRATION_FREQ_MS); pr_info("\t-o: Counter offset (in counter cycles, default: 0) [aarch64-only]\n"); + pr_info("\t-e: Interrupt arrival error margin(in us) of the guest timer (default: %u)\n", + TIMER_TEST_ERR_MARGIN_US); pr_info("\t-h: print this help screen\n"); } @@ -197,7 +202,7 @@ static bool parse_args(int argc, char *argv[]) { int opt; - while ((opt = getopt(argc, argv, "hn:i:p:m:o:")) != -1) { + while ((opt = getopt(argc, argv, "hn:i:p:m:o:e:")) != -1) { switch (opt) { case 'n': test_args.nr_vcpus = atoi_positive("Number of vCPUs", optarg); @@ -216,6 +221,9 @@ static bool parse_args(int argc, char *argv[]) case 'm': test_args.migration_freq_ms = atoi_non_negative("Frequency", optarg); break; + case 'e': + test_args.timer_err_margin_us = atoi_non_negative("Error Margin", optarg); + break; case 'o': test_args.counter_offset = strtol(optarg, NULL, 0); test_args.reserved = 0; diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h index 968257b893a7..b1d405e7157d 100644 --- a/tools/testing/selftests/kvm/include/timer_test.h +++ b/tools/testing/selftests/kvm/include/timer_test.h @@ -22,6 +22,7 @@ struct test_args { int nr_iter; int timer_period_ms; int migration_freq_ms; + int timer_err_margin_us; /* Members of struct kvm_arm_counter_offset */ uint64_t counter_offset; uint64_t reserved; diff --git a/tools/testing/selftests/kvm/riscv/arch_timer.c b/tools/testing/selftests/kvm/riscv/arch_timer.c index 13bf184d1ff5..45a139dc7ce3 100644 --- a/tools/testing/selftests/kvm/riscv/arch_timer.c +++ b/tools/testing/selftests/kvm/riscv/arch_timer.c @@ -55,10 +55,14 @@ static void guest_run(struct test_vcpu_shared_data *shared_data) /* Setup a timeout for the interrupt to arrive */ udelay(msecs_to_usecs(test_args.timer_period_ms) + - TIMER_TEST_ERR_MARGIN_US); + test_args.timer_err_margin_us); irq_iter = READ_ONCE(shared_data->nr_iter); - GUEST_ASSERT_EQ(config_iter + 1, irq_iter); + __GUEST_ASSERT(config_iter + 1 == irq_iter, + "config_iter + 1 = 0x%lx, irq_iter = 0x%lx.\n" + " Guest timer interrupt was not trigged within the specified\n" + " interval, try to increase the error margin by [-e] option.\n", + config_iter + 1, irq_iter); } }
There are intermittent failures occured when stressing the arch-timer test in a Qemu VM: Guest assert failed, vcpu 0; stage; 4; iter: 3 ==== Test Assertion Failure ==== aarch64/arch_timer.c:196: config_iter + 1 == irq_iter pid=4048 tid=4049 errno=4 - Interrupted system call 1 0x000000000040253b: test_vcpu_run at arch_timer.c:248 2 0x0000ffffb60dd5c7: ?? ??:0 3 0x0000ffffb6145d1b: ?? ??:0 0x3 != 0x2 (config_iter + 1 != irq_iter)e Further test and debug show that the timeout for an interrupt to arrive do have random high fluctuation, espectially when testing in an virtual environment. To alleviate this issue, just expose the timeout value as user configurable and print some hint message to increase the value when hitting the failure.. Signed-off-by: Haibo Xu <haibo1.xu@intel.com> --- .../selftests/kvm/aarch64/arch_timer.c | 8 +++++-- tools/testing/selftests/kvm/arch_timer.c | 22 +++++++++++++------ .../selftests/kvm/include/timer_test.h | 1 + .../testing/selftests/kvm/riscv/arch_timer.c | 8 +++++-- 4 files changed, 28 insertions(+), 11 deletions(-)