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, 41 insertions, 0 deletions

diff --git a/arch/arm/mach-shmobile/timer.c b/arch/arm/mach-shmobile/timer.c
new file mode 100644
index 000000000..2335311b5
--- /dev/null
+++ b/arch/arm/mach-shmobile/timer.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SH-Mobile Timer
+ *
+ * Copyright (C) 2010  Magnus Damm
+ * Copyright (C) 2002 - 2009  Paul Mundt
+ */
+#include <linux/platform_device.h>
+#include <linux/clocksource.h>
+#include <linux/delay.h>
+#include <linux/of_address.h>
+
+#include "common.h"
+
+void __init shmobile_init_delay(void)
+{
+	struct device_node *np;
+	u32 max_freq = 0;
+
+	for_each_of_cpu_node(np) {
+		u32 freq;
+
+		if (!of_property_read_u32(np, "clock-frequency", &freq))
+			max_freq = max(max_freq, freq);
+	}
+
+	if (!max_freq)
+		return;
+
+	/*
+	 * Calculate a worst-case loops-per-jiffy value
+	 * based on maximum cpu core hz setting and the
+	 * __delay() implementation in arch/arm/lib/delay.S.
+	 *
+	 * This will result in a longer delay than expected
+	 * when the cpu core runs on lower frequencies.
+	 */
+
+	if (!preset_lpj)
+		preset_lpj = max_freq / HZ;
+}