subject:"\\\\\\\[PATCH v4\\\\\\\] KVM\\\\\\\: selftests\\\\\\\: Fix target thread to be migrated in rseq

Re: [PATCH v4] KVM: selftests: Fix target thread to be migrated in rseq_test

2022-07-19 Thread Paolo Bonzini


On 7/19/22 04:08, Gavin Shan wrote:

In rseq_test, there are two threads, which are vCPU thread and migration
worker separately. Unfortunately, the test has the wrong PID passed to
sched_setaffinity() in the migration worker. It forces migration on the
migration worker because zeroed PID represents the calling thread, which
is the migration worker itself. It means the vCPU thread is never enforced
to migration and it can migrate at any time, which eventually leads to
failure as the following logs show.

   host# uname -r
   5.19.0-rc6-gavin+
   host# # cat /proc/cpuinfo | grep processor | tail -n 1
   processor: 223
   host# pwd
   /home/gavin/sandbox/linux.main/tools/testing/selftests/kvm
   host# for i in `seq 1 100`; do \
 echo "> $i"; ./rseq_test; done
   > 1
   > 2
   > 3
   > 4
   > 5
   > 6
    Test Assertion Failure 
 rseq_test.c:265: rseq_cpu == cpu
 pid=3925 tid=3925 errno=4 - Interrupted system call
1  0x00401963: main at rseq_test.c:265 (discriminator 2)
2  0xb044affb: ?? ??:0
3  0xb044b0c7: ?? ??:0
4  0x00401a6f: _start at ??:?
 rseq CPU = 4, sched CPU = 27

Fix the issue by passing correct parameter, TID of the vCPU thread, to
sched_setaffinity() in the migration worker.

Fixes: 61e52f1630f5 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect task 
migration bugs")
Suggested-by: Sean Christopherson 
Signed-off-by: Gavin Shan 
Reviewed-by: Oliver Upton 
---
v4: Pick the code change as Sean suggested.
---
  tools/testing/selftests/kvm/rseq_test.c | 8 +---
  1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/kvm/rseq_test.c 
b/tools/testing/selftests/kvm/rseq_test.c
index 4158da0da2bb..2237d1aac801 100644
--- a/tools/testing/selftests/kvm/rseq_test.c
+++ b/tools/testing/selftests/kvm/rseq_test.c
@@ -82,8 +82,9 @@ static int next_cpu(int cpu)
return cpu;
  }
  
-static void *migration_worker(void *ign)

+static void *migration_worker(void *__rseq_tid)
  {
+   pid_t rseq_tid = (pid_t)(unsigned long)__rseq_tid;
cpu_set_t allowed_mask;
int r, i, cpu;
  
@@ -106,7 +107,7 @@ static void *migration_worker(void *ign)

 * stable, i.e. while changing affinity is in-progress.
 */
smp_wmb();
-   r = sched_setaffinity(0, sizeof(allowed_mask), _mask);
+   r = sched_setaffinity(rseq_tid, sizeof(allowed_mask), 
_mask);
TEST_ASSERT(!r, "sched_setaffinity failed, errno = %d (%s)",
errno, strerror(errno));
smp_wmb();
@@ -231,7 +232,8 @@ int main(int argc, char *argv[])
vm = vm_create_default(VCPU_ID, 0, guest_code);
ucall_init(vm, NULL);
  
-	pthread_create(_thread, NULL, migration_worker, 0);

+   pthread_create(_thread, NULL, migration_worker,
+  (void *)(unsigned long)gettid());
  
  	for (i = 0; !done; i++) {

vcpu_run(vm, VCPU_ID);


Queued, thanks.

Paolo

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

Re: [PATCH v4] KVM: selftests: Fix target thread to be migrated in rseq_test

2022-07-19 Thread Andrew Jones

On Tue, Jul 19, 2022 at 10:08:30AM +0800, Gavin Shan wrote:
> In rseq_test, there are two threads, which are vCPU thread and migration
> worker separately. Unfortunately, the test has the wrong PID passed to
> sched_setaffinity() in the migration worker. It forces migration on the
> migration worker because zeroed PID represents the calling thread, which
> is the migration worker itself. It means the vCPU thread is never enforced
> to migration and it can migrate at any time, which eventually leads to
> failure as the following logs show.
> 
>   host# uname -r
>   5.19.0-rc6-gavin+
>   host# # cat /proc/cpuinfo | grep processor | tail -n 1
>   processor: 223
>   host# pwd
>   /home/gavin/sandbox/linux.main/tools/testing/selftests/kvm
>   host# for i in `seq 1 100`; do \
> echo "> $i"; ./rseq_test; done
>   > 1
>   > 2
>   > 3
>   > 4
>   > 5
>   > 6
>    Test Assertion Failure 
> rseq_test.c:265: rseq_cpu == cpu
> pid=3925 tid=3925 errno=4 - Interrupted system call
>1  0x00401963: main at rseq_test.c:265 (discriminator 2)
>2  0xb044affb: ?? ??:0
>3  0xb044b0c7: ?? ??:0
>4  0x00401a6f: _start at ??:?
> rseq CPU = 4, sched CPU = 27
> 
> Fix the issue by passing correct parameter, TID of the vCPU thread, to
> sched_setaffinity() in the migration worker.
> 
> Fixes: 61e52f1630f5 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect 
> task migration bugs")
> Suggested-by: Sean Christopherson 
> Signed-off-by: Gavin Shan 
> Reviewed-by: Oliver Upton 
> ---
> v4: Pick the code change as Sean suggested.
> ---
>  tools/testing/selftests/kvm/rseq_test.c | 8 +---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/rseq_test.c 
> b/tools/testing/selftests/kvm/rseq_test.c
> index 4158da0da2bb..2237d1aac801 100644
> --- a/tools/testing/selftests/kvm/rseq_test.c
> +++ b/tools/testing/selftests/kvm/rseq_test.c
> @@ -82,8 +82,9 @@ static int next_cpu(int cpu)
>   return cpu;
>  }
>  
> -static void *migration_worker(void *ign)
> +static void *migration_worker(void *__rseq_tid)
>  {
> + pid_t rseq_tid = (pid_t)(unsigned long)__rseq_tid;
>   cpu_set_t allowed_mask;
>   int r, i, cpu;
>  
> @@ -106,7 +107,7 @@ static void *migration_worker(void *ign)
>* stable, i.e. while changing affinity is in-progress.
>*/
>   smp_wmb();
> - r = sched_setaffinity(0, sizeof(allowed_mask), _mask);
> + r = sched_setaffinity(rseq_tid, sizeof(allowed_mask), 
> _mask);
>   TEST_ASSERT(!r, "sched_setaffinity failed, errno = %d (%s)",
>   errno, strerror(errno));
>   smp_wmb();
> @@ -231,7 +232,8 @@ int main(int argc, char *argv[])
>   vm = vm_create_default(VCPU_ID, 0, guest_code);
>   ucall_init(vm, NULL);
>  
> - pthread_create(_thread, NULL, migration_worker, 0);
> + pthread_create(_thread, NULL, migration_worker,
> +(void *)(unsigned long)gettid());
>  
>   for (i = 0; !done; i++) {
>   vcpu_run(vm, VCPU_ID);
> -- 
> 2.23.0

Thanks for figuring this out Gavin and Sean!

Reviewed-by: Andrew Jones 
___
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

[PATCH v4] KVM: selftests: Fix target thread to be migrated in rseq_test

2022-07-18 Thread Gavin Shan

In rseq_test, there are two threads, which are vCPU thread and migration
worker separately. Unfortunately, the test has the wrong PID passed to
sched_setaffinity() in the migration worker. It forces migration on the
migration worker because zeroed PID represents the calling thread, which
is the migration worker itself. It means the vCPU thread is never enforced
to migration and it can migrate at any time, which eventually leads to
failure as the following logs show.

  host# uname -r
  5.19.0-rc6-gavin+
  host# # cat /proc/cpuinfo | grep processor | tail -n 1
  processor: 223
  host# pwd
  /home/gavin/sandbox/linux.main/tools/testing/selftests/kvm
  host# for i in `seq 1 100`; do \
echo "> $i"; ./rseq_test; done
  > 1
  > 2
  > 3
  > 4
  > 5
  > 6
   Test Assertion Failure 
rseq_test.c:265: rseq_cpu == cpu
pid=3925 tid=3925 errno=4 - Interrupted system call
   1  0x00401963: main at rseq_test.c:265 (discriminator 2)
   2  0xb044affb: ?? ??:0
   3  0xb044b0c7: ?? ??:0
   4  0x00401a6f: _start at ??:?
rseq CPU = 4, sched CPU = 27

Fix the issue by passing correct parameter, TID of the vCPU thread, to
sched_setaffinity() in the migration worker.

Fixes: 61e52f1630f5 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect 
task migration bugs")
Suggested-by: Sean Christopherson 
Signed-off-by: Gavin Shan 
Reviewed-by: Oliver Upton 
---
v4: Pick the code change as Sean suggested.
---
 tools/testing/selftests/kvm/rseq_test.c | 8 +---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/kvm/rseq_test.c 
b/tools/testing/selftests/kvm/rseq_test.c
index 4158da0da2bb..2237d1aac801 100644
--- a/tools/testing/selftests/kvm/rseq_test.c
+++ b/tools/testing/selftests/kvm/rseq_test.c
@@ -82,8 +82,9 @@ static int next_cpu(int cpu)
return cpu;
 }
 
-static void *migration_worker(void *ign)
+static void *migration_worker(void *__rseq_tid)
 {
+   pid_t rseq_tid = (pid_t)(unsigned long)__rseq_tid;
cpu_set_t allowed_mask;
int r, i, cpu;
 
@@ -106,7 +107,7 @@ static void *migration_worker(void *ign)
 * stable, i.e. while changing affinity is in-progress.
 */
smp_wmb();
-   r = sched_setaffinity(0, sizeof(allowed_mask), _mask);
+   r = sched_setaffinity(rseq_tid, sizeof(allowed_mask), 
_mask);
TEST_ASSERT(!r, "sched_setaffinity failed, errno = %d (%s)",
errno, strerror(errno));
smp_wmb();
@@ -231,7 +232,8 @@ int main(int argc, char *argv[])
vm = vm_create_default(VCPU_ID, 0, guest_code);
ucall_init(vm, NULL);
 
-   pthread_create(_thread, NULL, migration_worker, 0);
+   pthread_create(_thread, NULL, migration_worker,
+  (void *)(unsigned long)gettid());
 
for (i = 0; !done; i++) {
vcpu_run(vm, VCPU_ID);
-- 
2.23.0

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

Re: [PATCH v4] KVM: selftests: Fix target thread to be migrated in rseq_test

Re: [PATCH v4] KVM: selftests: Fix target thread to be migrated in rseq_test

[PATCH v4] KVM: selftests: Fix target thread to be migrated in rseq_test

3 matches

Site Navigation

Mail list logo

Footer information