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, 103 insertions, 0 deletions

diff --git a/include/soc/tegra/ivc.h b/include/soc/tegra/ivc.h
new file mode 100644
index 000000000..be45d5f5a
--- /dev/null
+++ b/include/soc/tegra/ivc.h
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#ifndef __TEGRA_IVC_H
+#define __TEGRA_IVC_H
+
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/iosys-map.h>
+#include <linux/types.h>
+
+struct tegra_ivc_header;
+
+struct tegra_ivc {
+	struct device *peer;
+
+	struct {
+		struct iosys_map map;
+		unsigned int position;
+		dma_addr_t phys;
+	} rx, tx;
+
+	void (*notify)(struct tegra_ivc *ivc, void *data);
+	void *notify_data;
+
+	unsigned int num_frames;
+	size_t frame_size;
+};
+
+/**
+ * tegra_ivc_read_get_next_frame - Peek at the next frame to receive
+ * @ivc		pointer of the IVC channel
+ *
+ * Peek at the next frame to be received, without removing it from
+ * the queue.
+ *
+ * Returns a pointer to the frame, or an error encoded pointer.
+ */
+int tegra_ivc_read_get_next_frame(struct tegra_ivc *ivc, struct iosys_map *map);
+
+/**
+ * tegra_ivc_read_advance - Advance the read queue
+ * @ivc		pointer of the IVC channel
+ *
+ * Advance the read queue
+ *
+ * Returns 0, or a negative error value if failed.
+ */
+int tegra_ivc_read_advance(struct tegra_ivc *ivc);
+
+/**
+ * tegra_ivc_write_get_next_frame - Poke at the next frame to transmit
+ * @ivc		pointer of the IVC channel
+ *
+ * Get access to the next frame.
+ *
+ * Returns a pointer to the frame, or an error encoded pointer.
+ */
+int tegra_ivc_write_get_next_frame(struct tegra_ivc *ivc, struct iosys_map *map);
+
+/**
+ * tegra_ivc_write_advance - Advance the write queue
+ * @ivc		pointer of the IVC channel
+ *
+ * Advance the write queue
+ *
+ * Returns 0, or a negative error value if failed.
+ */
+int tegra_ivc_write_advance(struct tegra_ivc *ivc);
+
+/**
+ * tegra_ivc_notified - handle internal messages
+ * @ivc		pointer of the IVC channel
+ *
+ * This function must be called following every notification.
+ *
+ * Returns 0 if the channel is ready for communication, or -EAGAIN if a channel
+ * reset is in progress.
+ */
+int tegra_ivc_notified(struct tegra_ivc *ivc);
+
+/**
+ * tegra_ivc_reset - initiates a reset of the shared memory state
+ * @ivc		pointer of the IVC channel
+ *
+ * This function must be called after a channel is reserved before it is used
+ * for communication. The channel will be ready for use when a subsequent call
+ * to notify the remote of the channel reset.
+ */
+void tegra_ivc_reset(struct tegra_ivc *ivc);
+
+size_t tegra_ivc_align(size_t size);
+unsigned tegra_ivc_total_queue_size(unsigned queue_size);
+int tegra_ivc_init(struct tegra_ivc *ivc, struct device *peer, const struct iosys_map *rx,
+		   dma_addr_t rx_phys, const struct iosys_map *tx, dma_addr_t tx_phys,
+		   unsigned int num_frames, size_t frame_size,
+		   void (*notify)(struct tegra_ivc *ivc, void *data),
+		   void *data);
+void tegra_ivc_cleanup(struct tegra_ivc *ivc);
+
+#endif /* __TEGRA_IVC_H */