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, 43 insertions, 0 deletions

diff --git a/arch/powerpc/boot/ofconsole.c b/arch/powerpc/boot/ofconsole.c
new file mode 100644
index 000000000..8eb0f1c45
--- /dev/null
+++ b/arch/powerpc/boot/ofconsole.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * OF console routines
+ *
+ * Copyright (C) Paul Mackerras 1997.
+ */
+#include <stddef.h>
+#include "types.h"
+#include "elf.h"
+#include "string.h"
+#include "stdio.h"
+#include "page.h"
+#include "ops.h"
+
+#include "of.h"
+
+static unsigned int of_stdout_handle;
+
+static int of_console_open(void)
+{
+	void *devp;
+
+	if (((devp = of_finddevice("/chosen")) != NULL)
+	    && (of_getprop(devp, "stdout", &of_stdout_handle,
+			   sizeof(of_stdout_handle))
+		== sizeof(of_stdout_handle))) {
+		of_stdout_handle = be32_to_cpu(of_stdout_handle);
+		return 0;
+	}
+
+	return -1;
+}
+
+static void of_console_write(const char *buf, int len)
+{
+	of_call_prom("write", 3, 1, of_stdout_handle, buf, len);
+}
+
+void of_console_init(void)
+{
+	console_ops.open = of_console_open;
+	console_ops.write = of_console_write;
+}