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From: Peter Xu <peterx@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	peterx@redhat.com, Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: [PATCH RFC 15/15] KVM: selftests: Test dirty ring waitqueue
Date: Fri, 29 Nov 2019 16:35:05 -0500
Message-ID: <20191129213505.18472-16-peterx@redhat.com> (raw)
In-Reply-To: <20191129213505.18472-1-peterx@redhat.com>

This is a bit tricky, but should still be reasonable.

Firstly we introduce a totally new dirty log test type, because we
need to force vcpu to go into a blocked state by dead loop on vcpu_run
even if it wants to quit to userspace.

Here the tricky part is we need to read the procfs to make sure the
vcpu thread is TASK_UNINTERRUPTIBLE.

After that, we reset the ring and the reset should kick the vcpu again
by moving out of that state.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 tools/testing/selftests/kvm/dirty_log_test.c | 101 +++++++++++++++++++
 1 file changed, 101 insertions(+)

diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index c9db136a1f12..41bc015131e1 100644
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -16,6 +16,7 @@
 #include <sys/types.h>
 #include <signal.h>
 #include <errno.h>
+#include <sys/syscall.h>
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
 #include <asm/barrier.h>
@@ -151,12 +152,16 @@ enum log_mode_t {
 	/* Use dirty ring for logging */
 	LOG_MODE_DIRTY_RING = 2,
 
+	/* Dirty ring test but tailored for the waitqueue */
+	LOG_MODE_DIRTY_RING_WP = 3,
+
 	LOG_MODE_NUM,
 };
 
 /* Mode of logging.  Default is LOG_MODE_DIRTY_LOG */
 static enum log_mode_t host_log_mode;
 pthread_t vcpu_thread;
+pid_t vcpu_thread_tid;
 static uint32_t test_dirty_ring_count = TEST_DIRTY_RING_COUNT;
 
 /* Only way to pass this to the signal handler */
@@ -221,6 +226,18 @@ static void dirty_ring_create_vm_done(struct kvm_vm *vm)
 			     sizeof(struct kvm_dirty_gfn));
 }
 
+static void dirty_ring_wq_create_vm_done(struct kvm_vm *vm)
+{
+	/*
+	 * Force to use a relatively small ring size, so easier to get
+	 * full.  Better bigger than PML size, hence 1024.
+	 */
+	test_dirty_ring_count = 1024;
+	DEBUG("Forcing ring size: %u\n", test_dirty_ring_count);
+	vm_enable_dirty_ring(vm, test_dirty_ring_count *
+			     sizeof(struct kvm_dirty_gfn));
+}
+
 static uint32_t dirty_ring_collect_one(struct kvm_dirty_gfn *dirty_gfns,
 				       struct kvm_dirty_ring_indexes *indexes,
 				       int slot, void *bitmap,
@@ -295,6 +312,81 @@ static void dirty_ring_collect_dirty_pages(struct kvm_vm *vm, int slot,
 	DEBUG("Iteration %ld collected %u pages\n", iteration, count);
 }
 
+/*
+ * Return 'D' for uninterruptible, 'R' for running, 'S' for
+ * interruptible, etc.
+ */
+static char read_tid_status_char(unsigned int tid)
+{
+	int fd, ret, line = 0;
+	char buf[128], *c;
+
+	snprintf(buf, sizeof(buf) - 1, "/proc/%u/status", tid);
+	fd = open(buf, O_RDONLY);
+	TEST_ASSERT(fd >= 0, "open status file failed: %s", buf);
+	ret = read(fd, buf, sizeof(buf) - 1);
+	TEST_ASSERT(ret > 0, "read status file failed: %d, %d", ret, errno);
+	close(fd);
+
+	/* Skip 2 lines */
+	for (c = buf; c < buf + sizeof(buf) && line < 2; c++) {
+		if (*c == '\n') {
+			line++;
+			continue;
+		}
+	}
+
+	/* Skip "Status:  " */
+	while (*c != ':') c++;
+	c++;
+	while (*c == ' ') c++;
+	c++;
+
+	return *c;
+}
+
+static void dirty_ring_wq_collect_dirty_pages(struct kvm_vm *vm, int slot,
+					      void *bitmap, uint32_t num_pages)
+{
+	uint32_t count = test_dirty_ring_count;
+	struct kvm_run *state = vcpu_state(vm, VCPU_ID);
+	struct kvm_dirty_ring_indexes *indexes = &state->vcpu_ring_indexes;
+	uint32_t avail;
+
+	while (count--) {
+		/*
+		 * Force vcpu to run enough time to make sure we
+		 * trigger the ring full case
+		 */
+		sem_post(&dirty_ring_vcpu_cont);
+	}
+
+	/* Make sure it's stuck */
+	TEST_ASSERT(vcpu_thread_tid, "TID not inited");
+        /*
+	 * Wait for /proc/pid/status "Status:" changes to "D". "D"
+	 * stands for "D (disk sleep)", TASK_UNINTERRUPTIBLE
+	 */
+	while (read_tid_status_char(vcpu_thread_tid) != 'D') {
+		usleep(1000);
+	}
+	DEBUG("Now VCPU thread dirty ring full\n");
+
+	avail = READ_ONCE(indexes->avail_index);
+	/* Assuming we've consumed all */
+	WRITE_ONCE(indexes->fetch_index, avail);
+
+	kvm_vm_reset_dirty_ring(vm);
+
+	/* Wait for it to be awake */
+	while (read_tid_status_char(vcpu_thread_tid) == 'D') {
+		usleep(1000);
+	}
+	DEBUG("VCPU Thread is successfully waked up\n");
+
+	exit(0);
+}
+
 static void dirty_ring_after_vcpu_run(struct kvm_vm *vm, int ret, int err)
 {
 	struct kvm_run *run = vcpu_state(vm, VCPU_ID);
@@ -353,6 +445,12 @@ struct log_mode {
 		.before_vcpu_join = dirty_ring_before_vcpu_join,
 		.after_vcpu_run = dirty_ring_after_vcpu_run,
 	},
+	{
+		.name = "dirty-ring-wait-queue",
+		.create_vm_done = dirty_ring_wq_create_vm_done,
+		.collect_dirty_pages = dirty_ring_wq_collect_dirty_pages,
+		.after_vcpu_run = dirty_ring_after_vcpu_run,
+	},
 };
 
 /*
@@ -422,6 +520,9 @@ static void *vcpu_worker(void *data)
 	uint64_t *guest_array;
 	struct sigaction sigact;
 
+	vcpu_thread_tid = syscall(SYS_gettid);
+	printf("VCPU Thread ID: %u\n", vcpu_thread_tid);
+
 	current_vm = vm;
 	memset(&sigact, 0, sizeof(sigact));
 	sigact.sa_handler = vcpu_sig_handler;
-- 
2.21.0


  parent reply index

Thread overview: 121+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-29 21:34 [PATCH RFC 00/15] KVM: Dirty ring interface Peter Xu
2019-11-29 21:34 ` [PATCH RFC 01/15] KVM: Move running VCPU from ARM to common code Peter Xu
2019-12-03 19:01   ` Sean Christopherson
2019-12-04  9:42     ` Paolo Bonzini
2019-12-09 22:05       ` Peter Xu
2019-11-29 21:34 ` [PATCH RFC 02/15] KVM: Add kvm/vcpu argument to mark_dirty_page_in_slot Peter Xu
2019-12-02 19:32   ` Sean Christopherson
2019-12-02 20:49     ` Peter Xu
2019-11-29 21:34 ` [PATCH RFC 03/15] KVM: Add build-time error check on kvm_run size Peter Xu
2019-12-02 19:30   ` Sean Christopherson
2019-12-02 20:53     ` Peter Xu
2019-12-02 22:19       ` Sean Christopherson
2019-12-02 22:40         ` Peter Xu
2019-12-03  5:50           ` Sean Christopherson
2019-12-03 13:41         ` Paolo Bonzini
2019-12-03 17:04           ` Peter Xu
2019-11-29 21:34 ` [PATCH RFC 04/15] KVM: Implement ring-based dirty memory tracking Peter Xu
2019-12-02 20:10   ` Sean Christopherson
2019-12-02 21:16     ` Peter Xu
2019-12-02 21:50       ` Sean Christopherson
2019-12-02 23:09         ` Peter Xu
2019-12-03 13:48         ` Paolo Bonzini
2019-12-03 18:46           ` Sean Christopherson
2019-12-04 10:05             ` Paolo Bonzini
2019-12-07  0:29               ` Sean Christopherson
2019-12-09  9:37                 ` Paolo Bonzini
2019-12-09 21:54               ` Peter Xu
2019-12-10 10:07                 ` Paolo Bonzini
2019-12-10 15:52                   ` Peter Xu
2019-12-10 17:09                     ` Paolo Bonzini
2019-12-15 17:21                       ` Peter Xu
2019-12-16 10:08                         ` Paolo Bonzini
2019-12-16 18:54                           ` Peter Xu
2019-12-17  9:01                             ` Paolo Bonzini
2019-12-17 16:24                               ` Peter Xu
2019-12-17 16:28                                 ` Paolo Bonzini
2019-12-18 21:58                                   ` Peter Xu
2019-12-18 22:24                                     ` Sean Christopherson
2019-12-18 22:37                                       ` Paolo Bonzini
2019-12-18 22:49                                         ` Peter Xu
2019-12-17  2:28                           ` Tian, Kevin
2019-12-17 16:18                             ` Alex Williamson
2019-12-17 16:30                               ` Paolo Bonzini
2019-12-18  0:29                                 ` Tian, Kevin
     [not found]                           ` <AADFC41AFE54684AB9EE6CBC0274A5D19D645E5F@SHSMSX104.ccr.corp.intel.com>
2019-12-17  5:17                             ` Tian, Kevin
2019-12-17  5:25                               ` Yan Zhao
2019-12-17 16:24                                 ` Alex Williamson
2019-12-03 19:13   ` Sean Christopherson
2019-12-04 10:14     ` Paolo Bonzini
2019-12-04 14:33       ` Sean Christopherson
2019-12-04 10:38   ` Jason Wang
2019-12-04 11:04     ` Paolo Bonzini
2019-12-04 19:52       ` Peter Xu
2019-12-05  6:51         ` Jason Wang
2019-12-05 12:08           ` Peter Xu
2019-12-05 13:12             ` Jason Wang
2019-12-10 13:25       ` Michael S. Tsirkin
2019-12-10 13:31         ` Paolo Bonzini
2019-12-10 16:02           ` Peter Xu
2019-12-10 21:53             ` Michael S. Tsirkin
2019-12-11  9:05               ` Paolo Bonzini
2019-12-11 13:04                 ` Michael S. Tsirkin
2019-12-11 14:54                   ` Peter Xu
2019-12-10 21:48           ` Michael S. Tsirkin
2019-12-11 12:53   ` Michael S. Tsirkin
2019-12-11 14:14     ` Paolo Bonzini
2019-12-11 20:59     ` Peter Xu
2019-12-11 22:57       ` Michael S. Tsirkin
2019-12-12  0:08         ` Paolo Bonzini
2019-12-12  7:36           ` Michael S. Tsirkin
2019-12-12  8:12             ` Paolo Bonzini
2019-12-12 10:38               ` Michael S. Tsirkin
2019-12-15 17:33           ` Peter Xu
2019-12-16  9:47             ` Michael S. Tsirkin
2019-12-16 15:07               ` Peter Xu
2019-12-16 15:33                 ` Michael S. Tsirkin
2019-12-16 15:47                   ` Peter Xu
2019-12-11 17:24   ` Christophe de Dinechin
2019-12-13 20:23     ` Peter Xu
2019-12-14  7:57       ` Paolo Bonzini
2019-12-14 16:26         ` Peter Xu
2019-12-16  9:29           ` Paolo Bonzini
2019-12-16 15:26             ` Peter Xu
2019-12-16 15:31               ` Paolo Bonzini
2019-12-16 15:43                 ` Peter Xu
2019-12-17 12:16         ` Christophe de Dinechin
2019-12-17 12:19           ` Paolo Bonzini
2019-12-17 15:38             ` Peter Xu
2019-12-17 16:31               ` Paolo Bonzini
2019-12-17 16:42                 ` Peter Xu
2019-12-17 16:48                   ` Paolo Bonzini
2019-12-17 19:41                     ` Peter Xu
2019-12-18  0:33                       ` Paolo Bonzini
2019-12-18 16:32                         ` Peter Xu
2019-12-18 16:41                           ` Paolo Bonzini
2019-12-20 18:19       ` Peter Xu
2019-11-29 21:34 ` [PATCH RFC 05/15] KVM: Make dirty ring exclusive to dirty bitmap log Peter Xu
2019-11-29 21:34 ` [PATCH RFC 06/15] KVM: Introduce dirty ring wait queue Peter Xu
2019-11-29 21:34 ` [PATCH RFC 07/15] KVM: X86: Implement ring-based dirty memory tracking Peter Xu
2019-11-29 21:34 ` [PATCH RFC 08/15] KVM: selftests: Always clear dirty bitmap after iteration Peter Xu
2019-11-29 21:34 ` [PATCH RFC 09/15] KVM: selftests: Sync uapi/linux/kvm.h to tools/ Peter Xu
2019-11-29 21:35 ` [PATCH RFC 10/15] KVM: selftests: Use a single binary for dirty/clear log test Peter Xu
2019-11-29 21:35 ` [PATCH RFC 11/15] KVM: selftests: Introduce after_vcpu_run hook for dirty " Peter Xu
2019-11-29 21:35 ` [PATCH RFC 12/15] KVM: selftests: Add dirty ring buffer test Peter Xu
2019-11-29 21:35 ` [PATCH RFC 13/15] KVM: selftests: Let dirty_log_test async for dirty ring test Peter Xu
2019-11-29 21:35 ` [PATCH RFC 14/15] KVM: selftests: Add "-c" parameter to dirty log test Peter Xu
2019-11-29 21:35 ` Peter Xu [this message]
2019-11-30  8:29 ` [PATCH RFC 00/15] KVM: Dirty ring interface Paolo Bonzini
2019-12-02  2:13   ` Peter Xu
2019-12-03 13:59     ` Paolo Bonzini
2019-12-05 19:30       ` Peter Xu
2019-12-05 19:59         ` Paolo Bonzini
2019-12-05 20:52           ` Peter Xu
2019-12-02 20:21   ` Sean Christopherson
2019-12-02 20:43     ` Peter Xu
2019-12-04 10:39 ` Jason Wang
2019-12-04 19:33   ` Peter Xu
2019-12-05  6:49     ` Jason Wang
2019-12-11 13:41 ` Christophe de Dinechin
2019-12-11 14:16   ` Paolo Bonzini
2019-12-11 17:15     ` Peter Xu

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