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, 196 insertions, 0 deletions

diff --git a/drivers/media/common/uvc.c b/drivers/media/common/uvc.c
new file mode 100644
index 000000000..0107cedd0
--- /dev/null
+++ b/drivers/media/common/uvc.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/usb/uvc.h>
+#include <linux/videodev2.h>
+
+/* ------------------------------------------------------------------------
+ * Video formats
+ */
+
+static const struct uvc_format_desc uvc_fmts[] = {
+	{
+		.guid		= UVC_GUID_FORMAT_YUY2,
+		.fcc		= V4L2_PIX_FMT_YUYV,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_YUY2_ISIGHT,
+		.fcc		= V4L2_PIX_FMT_YUYV,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_NV12,
+		.fcc		= V4L2_PIX_FMT_NV12,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_MJPEG,
+		.fcc		= V4L2_PIX_FMT_MJPEG,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_YV12,
+		.fcc		= V4L2_PIX_FMT_YVU420,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_I420,
+		.fcc		= V4L2_PIX_FMT_YUV420,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_M420,
+		.fcc		= V4L2_PIX_FMT_M420,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_P010,
+		.fcc		= V4L2_PIX_FMT_P010,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_UYVY,
+		.fcc		= V4L2_PIX_FMT_UYVY,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_Y800,
+		.fcc		= V4L2_PIX_FMT_GREY,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_Y8,
+		.fcc		= V4L2_PIX_FMT_GREY,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_D3DFMT_L8,
+		.fcc		= V4L2_PIX_FMT_GREY,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_KSMEDIA_L8_IR,
+		.fcc		= V4L2_PIX_FMT_GREY,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_Y10,
+		.fcc		= V4L2_PIX_FMT_Y10,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_Y12,
+		.fcc		= V4L2_PIX_FMT_Y12,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_Y16,
+		.fcc		= V4L2_PIX_FMT_Y16,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_BY8,
+		.fcc		= V4L2_PIX_FMT_SBGGR8,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_BA81,
+		.fcc		= V4L2_PIX_FMT_SBGGR8,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_GBRG,
+		.fcc		= V4L2_PIX_FMT_SGBRG8,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_GRBG,
+		.fcc		= V4L2_PIX_FMT_SGRBG8,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_RGGB,
+		.fcc		= V4L2_PIX_FMT_SRGGB8,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_RGBP,
+		.fcc		= V4L2_PIX_FMT_RGB565,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_D3DFMT_R5G6B5,
+		.fcc		= V4L2_PIX_FMT_RGB565,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_BGR3,
+		.fcc		= V4L2_PIX_FMT_BGR24,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_BGR4,
+		.fcc		= V4L2_PIX_FMT_XBGR32,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_H264,
+		.fcc		= V4L2_PIX_FMT_H264,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_H265,
+		.fcc		= V4L2_PIX_FMT_HEVC,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_Y8I,
+		.fcc		= V4L2_PIX_FMT_Y8I,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_Y12I,
+		.fcc		= V4L2_PIX_FMT_Y12I,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_Y16I,
+		.fcc		= V4L2_PIX_FMT_Y16I,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_Z16,
+		.fcc		= V4L2_PIX_FMT_Z16,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_RW10,
+		.fcc		= V4L2_PIX_FMT_SRGGB10P,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_BG16,
+		.fcc		= V4L2_PIX_FMT_SBGGR16,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_GB16,
+		.fcc		= V4L2_PIX_FMT_SGBRG16,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_RG16,
+		.fcc		= V4L2_PIX_FMT_SRGGB16,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_GR16,
+		.fcc		= V4L2_PIX_FMT_SGRBG16,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_INVZ,
+		.fcc		= V4L2_PIX_FMT_Z16,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_INVI,
+		.fcc		= V4L2_PIX_FMT_Y10,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_INZI,
+		.fcc		= V4L2_PIX_FMT_INZI,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_CNF4,
+		.fcc		= V4L2_PIX_FMT_CNF4,
+	},
+	{
+		.guid		= UVC_GUID_FORMAT_HEVC,
+		.fcc		= V4L2_PIX_FMT_HEVC,
+	},
+};
+
+const struct uvc_format_desc *uvc_format_by_guid(const u8 guid[16])
+{
+	unsigned int len = ARRAY_SIZE(uvc_fmts);
+	unsigned int i;
+
+	for (i = 0; i < len; ++i) {
+		if (memcmp(guid, uvc_fmts[i].guid, 16) == 0)
+			return &uvc_fmts[i];
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(uvc_format_by_guid);
+
+MODULE_DESCRIPTION("USB Video Class common code");
+MODULE_LICENSE("GPL");