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, 26 insertions, 0 deletions

diff --git a/drivers/video/nomodeset.c b/drivers/video/nomodeset.c
new file mode 100644
index 000000000..13cc8b719
--- /dev/null
+++ b/drivers/video/nomodeset.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include <video/nomodeset.h>
+
+static bool video_nomodeset;
+
+bool video_firmware_drivers_only(void)
+{
+	return video_nomodeset;
+}
+EXPORT_SYMBOL(video_firmware_drivers_only);
+
+static int __init disable_modeset(char *str)
+{
+	video_nomodeset = true;
+
+	pr_warn("Booted with the nomodeset parameter. Only the system framebuffer will be available\n");
+
+	return 1;
+}
+
+/* Disable kernel modesetting */
+__setup("nomodeset", disable_modeset);