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, 49 insertions, 0 deletions

diff --git a/include/sound/sdw.h b/include/sound/sdw.h
new file mode 100644
index 000000000..6dcdb3228
--- /dev/null
+++ b/include/sound/sdw.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * linux/sound/sdw.h -- SoundWire helpers for ALSA/ASoC
+ *
+ * Copyright (c) 2022 Cirrus Logic Inc.
+ *
+ * Author: Charles Keepax <ckeepax@opensource.cirrus.com>
+ */
+
+#include <linux/soundwire/sdw.h>
+#include <sound/asound.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+#ifndef __INCLUDE_SOUND_SDW_H
+#define __INCLUDE_SOUND_SDW_H
+
+/**
+ * snd_sdw_params_to_config() - Conversion from hw_params to SoundWire config
+ *
+ * @substream: Pointer to the PCM substream structure
+ * @params: Pointer to the hardware params structure
+ * @stream_config: Stream configuration for the SoundWire audio stream
+ * @port_config: Port configuration for the SoundWire audio stream
+ *
+ * This function provides a basic conversion from the hw_params structure to
+ * SoundWire configuration structures. The user will at a minimum need to also
+ * set the port number in the port config, but may also override more of the
+ * setup, or in the case of a complex user, not use this helper at all and
+ * open-code everything.
+ */
+static inline void snd_sdw_params_to_config(struct snd_pcm_substream *substream,
+					    struct snd_pcm_hw_params *params,
+					    struct sdw_stream_config *stream_config,
+					    struct sdw_port_config *port_config)
+{
+	stream_config->frame_rate = params_rate(params);
+	stream_config->ch_count = params_channels(params);
+	stream_config->bps = snd_pcm_format_width(params_format(params));
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		stream_config->direction = SDW_DATA_DIR_RX;
+	else
+		stream_config->direction = SDW_DATA_DIR_TX;
+
+	port_config->ch_mask = GENMASK(stream_config->ch_count - 1, 0);
+}
+
+#endif