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>

1 files changed, 95 insertions, 0 deletions

diff --git a/sound/soc/sof/ipc4-telemetry.c b/sound/soc/sof/ipc4-telemetry.c
new file mode 100644
index 000000000..ddc3bc494
--- /dev/null
+++ b/sound/soc/sof/ipc4-telemetry.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
+//
+// This file is provided under a dual BSD/GPLv2 license.  When using or
+// redistributing this file, you may do so under either license.
+//
+// Copyright(c) 2018-2023 Intel Corporation
+//
+
+#include <linux/debugfs.h>
+#include <linux/io.h>
+#include <linux/pm_runtime.h>
+#include <sound/sof/debug.h>
+#include <sound/sof/ipc4/header.h>
+#include "sof-priv.h"
+#include "ops.h"
+#include "ipc4-telemetry.h"
+#include "ipc4-priv.h"
+
+static void __iomem *sof_ipc4_query_exception_address(struct snd_sof_dev *sdev)
+{
+	u32 type = SOF_IPC4_DEBUG_SLOT_TELEMETRY;
+	size_t telemetry_slot_offset;
+	u32 offset;
+
+	telemetry_slot_offset = sof_ipc4_find_debug_slot_offset_by_type(sdev, type);
+	if (!telemetry_slot_offset)
+		return NULL;
+
+	/* skip the first separator magic number */
+	offset = telemetry_slot_offset + sizeof(u32);
+
+	return sdev->bar[sdev->mailbox_bar] + offset;
+}
+
+static ssize_t sof_telemetry_entry_read(struct file *file, char __user *buffer,
+					size_t count, loff_t *ppos)
+{
+	struct snd_sof_dfsentry *dfse = file->private_data;
+	struct snd_sof_dev *sdev = dfse->sdev;
+	void __iomem *io_addr;
+	loff_t pos = *ppos;
+	size_t size_ret;
+	u8 *buf;
+
+	if (pos < 0)
+		return -EINVAL;
+	/* skip the first separator magic number */
+	if (pos >= SOF_IPC4_DEBUG_SLOT_SIZE - 4 || !count)
+		return 0;
+	if (count > SOF_IPC4_DEBUG_SLOT_SIZE - 4 - pos)
+		count = SOF_IPC4_DEBUG_SLOT_SIZE - 4 - pos;
+
+	io_addr = sof_ipc4_query_exception_address(sdev);
+	if (!io_addr)
+		return -EFAULT;
+
+	buf = kzalloc(SOF_IPC4_DEBUG_SLOT_SIZE - 4, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	memcpy_fromio(buf, io_addr, SOF_IPC4_DEBUG_SLOT_SIZE - 4);
+	size_ret = copy_to_user(buffer, buf + pos, count);
+	if (size_ret) {
+		kfree(buf);
+		return -EFAULT;
+	}
+
+	*ppos = pos + count;
+	kfree(buf);
+
+	return count;
+}
+
+static const struct file_operations sof_telemetry_fops = {
+	.open = simple_open,
+	.read = sof_telemetry_entry_read,
+};
+
+void sof_ipc4_create_exception_debugfs_node(struct snd_sof_dev *sdev)
+{
+	struct snd_sof_dfsentry *dfse;
+
+	dfse = devm_kzalloc(sdev->dev, sizeof(*dfse), GFP_KERNEL);
+	if (!dfse)
+		return;
+
+	dfse->type = SOF_DFSENTRY_TYPE_IOMEM;
+	dfse->size = SOF_IPC4_DEBUG_SLOT_SIZE - 4;
+	dfse->access_type = SOF_DEBUGFS_ACCESS_ALWAYS;
+	dfse->sdev = sdev;
+
+	list_add(&dfse->list, &sdev->dfsentry_list);
+
+	debugfs_create_file("exception", 0444, sdev->debugfs_root, dfse, &sof_telemetry_fops);
+}