KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

4 files changed, 279 insertions, 0 deletions

diff --git a/tools/testing/selftests/ipc/.gitignore b/tools/testing/selftests/ipc/.gitignore
new file mode 100644
index 000000000..9ed280e4c
--- /dev/null
+++ b/tools/testing/selftests/ipc/.gitignore
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+msgque_test
+msgque
diff --git a/tools/testing/selftests/ipc/Makefile b/tools/testing/selftests/ipc/Makefile
new file mode 100644
index 000000000..fad10f2bb
--- /dev/null
+++ b/tools/testing/selftests/ipc/Makefile
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0
+ARCH ?= $(shell uname -m 2>/dev/null || echo not)
+override ARCH := $(shell echo $(ARCH) | sed -e s/i.86/i386/)
+ifeq ($(ARCH),i386)
+        override ARCH := x86
+	CFLAGS := -DCONFIG_X86_32 -D__i386__
+endif
+ifeq ($(ARCH),x86_64)
+        override ARCH := x86
+	CFLAGS := -DCONFIG_X86_64 -D__x86_64__
+endif
+
+CFLAGS += $(KHDR_INCLUDES)
+
+TEST_GEN_PROGS := msgque
+
+include ../lib.mk
+
diff --git a/tools/testing/selftests/ipc/config b/tools/testing/selftests/ipc/config
new file mode 100644
index 000000000..070244710
--- /dev/null
+++ b/tools/testing/selftests/ipc/config
@@ -0,0 +1,2 @@
+CONFIG_EXPERT=y
+CONFIG_CHECKPOINT_RESTORE=y
diff --git a/tools/testing/selftests/ipc/msgque.c b/tools/testing/selftests/ipc/msgque.c
new file mode 100644
index 000000000..4b4c1abfa
--- /dev/null
+++ b/tools/testing/selftests/ipc/msgque.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/msg.h>
+#include <fcntl.h>
+
+#include "kselftest.h"
+
+#define MAX_MSG_SIZE		32
+
+struct msg1 {
+	int msize;
+	long mtype;
+	char mtext[MAX_MSG_SIZE];
+};
+
+#define TEST_STRING "Test sysv5 msg"
+#define MSG_TYPE 1
+
+#define ANOTHER_TEST_STRING "Yet another test sysv5 msg"
+#define ANOTHER_MSG_TYPE 26538
+
+struct msgque_data {
+	key_t key;
+	int msq_id;
+	int qbytes;
+	int qnum;
+	int mode;
+	struct msg1 *messages;
+};
+
+int restore_queue(struct msgque_data *msgque)
+{
+	int fd, ret, id, i;
+	char buf[32];
+
+	fd = open("/proc/sys/kernel/msg_next_id", O_WRONLY);
+	if (fd == -1) {
+		ksft_test_result_fail("Failed to open /proc/sys/kernel/msg_next_id\n");
+		return -errno;
+	}
+	sprintf(buf, "%d", msgque->msq_id);
+
+	ret = write(fd, buf, strlen(buf));
+	if (ret != strlen(buf)) {
+		ksft_test_result_fail("Failed to write to /proc/sys/kernel/msg_next_id\n");
+		return -errno;
+	}
+
+	id = msgget(msgque->key, msgque->mode | IPC_CREAT | IPC_EXCL);
+	if (id == -1) {
+		ksft_test_result_fail("Failed to create queue\n");
+		return -errno;
+	}
+
+	if (id != msgque->msq_id) {
+		ksft_test_result_fail("Restored queue has wrong id (%d instead of %d)\n"
+								, id, msgque->msq_id);
+		ret = -EFAULT;
+		goto destroy;
+	}
+
+	for (i = 0; i < msgque->qnum; i++) {
+		if (msgsnd(msgque->msq_id, &msgque->messages[i].mtype,
+			   msgque->messages[i].msize, IPC_NOWAIT) != 0) {
+			ksft_test_result_fail("msgsnd failed (%m)\n");
+			ret = -errno;
+			goto destroy;
+		}
+	}
+	return 0;
+
+destroy:
+	if (msgctl(id, IPC_RMID, NULL))
+		printf("Failed to destroy queue: %d\n", -errno);
+	return ret;
+}
+
+int check_and_destroy_queue(struct msgque_data *msgque)
+{
+	struct msg1 message;
+	int cnt = 0, ret;
+
+	while (1) {
+		ret = msgrcv(msgque->msq_id, &message.mtype, MAX_MSG_SIZE,
+				0, IPC_NOWAIT);
+		if (ret < 0) {
+			if (errno == ENOMSG)
+				break;
+			ksft_test_result_fail("Failed to read IPC message: %m\n");
+			ret = -errno;
+			goto err;
+		}
+		if (ret != msgque->messages[cnt].msize) {
+			ksft_test_result_fail("Wrong message size: %d (expected %d)\n", ret, msgque->messages[cnt].msize);
+			ret = -EINVAL;
+			goto err;
+		}
+		if (message.mtype != msgque->messages[cnt].mtype) {
+			ksft_test_result_fail("Wrong message type\n");
+			ret = -EINVAL;
+			goto err;
+		}
+		if (memcmp(message.mtext, msgque->messages[cnt].mtext, ret)) {
+			ksft_test_result_fail("Wrong message content\n");
+			ret = -EINVAL;
+			goto err;
+		}
+		cnt++;
+	}
+
+	if (cnt != msgque->qnum) {
+		ksft_test_result_fail("Wrong message number\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	ret = 0;
+err:
+	if (msgctl(msgque->msq_id, IPC_RMID, NULL)) {
+		printf("Failed to destroy queue: %d\n", -errno);
+		return -errno;
+	}
+	return ret;
+}
+
+int dump_queue(struct msgque_data *msgque)
+{
+	struct msqid_ds ds;
+	int kern_id;
+	int i, ret;
+
+	for (kern_id = 0; kern_id < 256; kern_id++) {
+		ret = msgctl(kern_id, MSG_STAT, &ds);
+		if (ret < 0) {
+			if (errno == EINVAL)
+				continue;
+			ksft_test_result_fail("Failed to get stats for IPC queue with id %d\n",
+					kern_id);
+			return -errno;
+		}
+
+		if (ret == msgque->msq_id)
+			break;
+	}
+
+	msgque->messages = malloc(sizeof(struct msg1) * ds.msg_qnum);
+	if (msgque->messages == NULL) {
+		ksft_test_result_fail("Failed to get stats for IPC queue\n");
+		return -ENOMEM;
+	}
+
+	msgque->qnum = ds.msg_qnum;
+	msgque->mode = ds.msg_perm.mode;
+	msgque->qbytes = ds.msg_qbytes;
+
+	for (i = 0; i < msgque->qnum; i++) {
+		ret = msgrcv(msgque->msq_id, &msgque->messages[i].mtype,
+				MAX_MSG_SIZE, i, IPC_NOWAIT | MSG_COPY);
+		if (ret < 0) {
+			if (errno == EOPNOTSUPP)
+				ksft_exit_skip("MSG_COPY not supported\n");
+
+			ksft_test_result_fail("Failed to copy IPC message: %m (%d)\n", errno);
+			return -errno;
+		}
+		msgque->messages[i].msize = ret;
+	}
+	return 0;
+}
+
+int fill_msgque(struct msgque_data *msgque)
+{
+	struct msg1 msgbuf;
+
+	msgbuf.mtype = MSG_TYPE;
+	memcpy(msgbuf.mtext, TEST_STRING, sizeof(TEST_STRING));
+	if (msgsnd(msgque->msq_id, &msgbuf.mtype, sizeof(TEST_STRING),
+				IPC_NOWAIT) != 0) {
+		ksft_test_result_fail("First message send failed (%m)\n");
+		return -errno;
+	}
+
+	msgbuf.mtype = ANOTHER_MSG_TYPE;
+	memcpy(msgbuf.mtext, ANOTHER_TEST_STRING, sizeof(ANOTHER_TEST_STRING));
+	if (msgsnd(msgque->msq_id, &msgbuf.mtype, sizeof(ANOTHER_TEST_STRING),
+				IPC_NOWAIT) != 0) {
+		ksft_test_result_fail("Second message send failed (%m)\n");
+		return -errno;
+	}
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int err;
+	struct msgque_data msgque;
+
+	if (getuid() != 0)
+		ksft_exit_skip("Please run the test as root - Exiting.\n");
+
+	msgque.key = ftok(argv[0], 822155650);
+	if (msgque.key == -1) {
+		ksft_test_result_fail("Can't make key: %d\n", -errno);
+		ksft_exit_fail();
+	}
+
+	msgque.msq_id = msgget(msgque.key, IPC_CREAT | IPC_EXCL | 0666);
+	if (msgque.msq_id == -1) {
+		err = -errno;
+		ksft_test_result_fail("Can't create queue: %d\n", err);
+		goto err_out;
+	}
+
+	err = fill_msgque(&msgque);
+	if (err) {
+		ksft_test_result_fail("Failed to fill queue: %d\n", err);
+		goto err_destroy;
+	}
+
+	err = dump_queue(&msgque);
+	if (err) {
+		ksft_test_result_fail("Failed to dump queue: %d\n", err);
+		goto err_destroy;
+	}
+
+	err = check_and_destroy_queue(&msgque);
+	if (err) {
+		ksft_test_result_fail("Failed to check and destroy queue: %d\n", err);
+		goto err_out;
+	}
+
+	err = restore_queue(&msgque);
+	if (err) {
+		ksft_test_result_fail("Failed to restore queue: %d\n", err);
+		goto err_destroy;
+	}
+
+	err = check_and_destroy_queue(&msgque);
+	if (err) {
+		ksft_test_result_fail("Failed to test queue: %d\n", err);
+		goto err_out;
+	}
+	ksft_exit_pass();
+
+err_destroy:
+	if (msgctl(msgque.msq_id, IPC_RMID, NULL)) {
+		printf("Failed to destroy queue: %d\n", -errno);
+		ksft_exit_fail();
+	}
+err_out:
+	ksft_exit_fail();
+}