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, 108 insertions, 0 deletions

diff --git a/include/uapi/sound/tlv.h b/include/uapi/sound/tlv.h
new file mode 100644
index 000000000..5bb55c80e
--- /dev/null
+++ b/include/uapi/sound/tlv.h
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+
+#ifndef __UAPI_SOUND_TLV_H
+#define __UAPI_SOUND_TLV_H
+
+#define SNDRV_CTL_TLVT_CONTAINER 0	/* one level down - group of TLVs */
+#define SNDRV_CTL_TLVT_DB_SCALE	1       /* dB scale */
+#define SNDRV_CTL_TLVT_DB_LINEAR 2	/* linear volume */
+#define SNDRV_CTL_TLVT_DB_RANGE 3	/* dB range container */
+#define SNDRV_CTL_TLVT_DB_MINMAX 4	/* dB scale with min/max */
+#define SNDRV_CTL_TLVT_DB_MINMAX_MUTE 5	/* dB scale with min/max with mute */
+
+/*
+ * channel-mapping TLV items
+ *  TLV length must match with num_channels
+ */
+#define SNDRV_CTL_TLVT_CHMAP_FIXED	0x101	/* fixed channel position */
+#define SNDRV_CTL_TLVT_CHMAP_VAR	0x102	/* channels freely swappable */
+#define SNDRV_CTL_TLVT_CHMAP_PAIRED	0x103	/* pair-wise swappable */
+
+#define SNDRV_CTL_TLVT_FCP_CHANNEL_LABELS	0x110	/* channel labels */
+
+/*
+ * TLV structure is right behind the struct snd_ctl_tlv:
+ *   unsigned int type  	- see SNDRV_CTL_TLVT_*
+ *   unsigned int length
+ *   .... data aligned to sizeof(unsigned int), use
+ *        block_length = (length + (sizeof(unsigned int) - 1)) &
+ *                       ~(sizeof(unsigned int) - 1)) ....
+ */
+#define SNDRV_CTL_TLVD_ITEM(type, ...) \
+	(type), SNDRV_CTL_TLVD_LENGTH(__VA_ARGS__), __VA_ARGS__
+#define SNDRV_CTL_TLVD_LENGTH(...) \
+	((unsigned int)sizeof((const unsigned int[]) { __VA_ARGS__ }))
+
+/* Accessor offsets for TLV data items */
+#define SNDRV_CTL_TLVO_TYPE		0
+#define SNDRV_CTL_TLVO_LEN		1
+
+#define SNDRV_CTL_TLVD_CONTAINER_ITEM(...) \
+	SNDRV_CTL_TLVD_ITEM(SNDRV_CTL_TLVT_CONTAINER, __VA_ARGS__)
+#define SNDRV_CTL_TLVD_DECLARE_CONTAINER(name, ...) \
+	unsigned int name[] = { \
+		SNDRV_CTL_TLVD_CONTAINER_ITEM(__VA_ARGS__) \
+	}
+
+#define SNDRV_CTL_TLVD_DB_SCALE_MASK	0xffff
+#define SNDRV_CTL_TLVD_DB_SCALE_MUTE	0x10000
+#define SNDRV_CTL_TLVD_DB_SCALE_ITEM(min, step, mute) \
+	SNDRV_CTL_TLVD_ITEM(SNDRV_CTL_TLVT_DB_SCALE, \
+			    (min), \
+			    ((step) & SNDRV_CTL_TLVD_DB_SCALE_MASK) | \
+			     ((mute) ? SNDRV_CTL_TLVD_DB_SCALE_MUTE : 0))
+#define SNDRV_CTL_TLVD_DECLARE_DB_SCALE(name, min, step, mute) \
+	unsigned int name[] = { \
+		SNDRV_CTL_TLVD_DB_SCALE_ITEM(min, step, mute) \
+	}
+
+/* Accessor offsets for min, mute and step items in dB scale type TLV */
+#define SNDRV_CTL_TLVO_DB_SCALE_MIN		2
+#define SNDRV_CTL_TLVO_DB_SCALE_MUTE_AND_STEP	3
+
+/* dB scale specified with min/max values instead of step */
+#define SNDRV_CTL_TLVD_DB_MINMAX_ITEM(min_dB, max_dB) \
+	SNDRV_CTL_TLVD_ITEM(SNDRV_CTL_TLVT_DB_MINMAX, (min_dB), (max_dB))
+#define SNDRV_CTL_TLVD_DB_MINMAX_MUTE_ITEM(min_dB, max_dB) \
+	SNDRV_CTL_TLVD_ITEM(SNDRV_CTL_TLVT_DB_MINMAX_MUTE, (min_dB), (max_dB))
+#define SNDRV_CTL_TLVD_DECLARE_DB_MINMAX(name, min_dB, max_dB) \
+	unsigned int name[] = { \
+		SNDRV_CTL_TLVD_DB_MINMAX_ITEM(min_dB, max_dB) \
+	}
+#define SNDRV_CTL_TLVD_DECLARE_DB_MINMAX_MUTE(name, min_dB, max_dB) \
+	unsigned int name[] = { \
+		SNDRV_CTL_TLVD_DB_MINMAX_MUTE_ITEM(min_dB, max_dB) \
+	}
+
+/* Accessor offsets for min, max items in db-minmax types of TLV. */
+#define SNDRV_CTL_TLVO_DB_MINMAX_MIN	2
+#define SNDRV_CTL_TLVO_DB_MINMAX_MAX	3
+
+/* linear volume between min_dB and max_dB (.01dB unit) */
+#define SNDRV_CTL_TLVD_DB_LINEAR_ITEM(min_dB, max_dB) \
+	SNDRV_CTL_TLVD_ITEM(SNDRV_CTL_TLVT_DB_LINEAR, (min_dB), (max_dB))
+#define SNDRV_CTL_TLVD_DECLARE_DB_LINEAR(name, min_dB, max_dB) \
+	unsigned int name[] = { \
+		SNDRV_CTL_TLVD_DB_LINEAR_ITEM(min_dB, max_dB) \
+	}
+
+/* Accessor offsets for min, max items in db-linear type of TLV. */
+#define SNDRV_CTL_TLVO_DB_LINEAR_MIN	2
+#define SNDRV_CTL_TLVO_DB_LINEAR_MAX	3
+
+/* dB range container:
+ * Items in dB range container must be ordered by their values and by their
+ * dB values. This implies that larger values must correspond with larger
+ * dB values (which is also required for all other mixer controls).
+ */
+/* Each item is: <min> <max> <TLV> */
+#define SNDRV_CTL_TLVD_DB_RANGE_ITEM(...) \
+	SNDRV_CTL_TLVD_ITEM(SNDRV_CTL_TLVT_DB_RANGE, __VA_ARGS__)
+#define SNDRV_CTL_TLVD_DECLARE_DB_RANGE(name, ...) \
+	unsigned int name[] = { \
+		SNDRV_CTL_TLVD_DB_RANGE_ITEM(__VA_ARGS__) \
+	}
+
+#define SNDRV_CTL_TLVD_DB_GAIN_MUTE	-9999999
+
+#endif