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, 62 insertions, 0 deletions

diff --git a/arch/mips/sgi-ip30/ip30-timer.c b/arch/mips/sgi-ip30/ip30-timer.c
new file mode 100644
index 000000000..294e1f7e6
--- /dev/null
+++ b/arch/mips/sgi-ip30/ip30-timer.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ip30-timer.c: Clocksource/clockevent support for the
+ *               HEART chip in SGI Octane (IP30) systems.
+ *
+ * Copyright (C) 2004-2007 Stanislaw Skowronek <skylark@unaligned.org>
+ * Copyright (C) 2009 Johannes Dickgreber <tanzy@gmx.de>
+ * Copyright (C) 2011 Joshua Kinard <linux@kumba.dev>
+ */
+
+#include <linux/clocksource.h>
+#include <linux/cpumask.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/percpu.h>
+#include <linux/sched_clock.h>
+
+#include <asm/time.h>
+#include <asm/cevt-r4k.h>
+#include <asm/sgi/heart.h>
+
+static u64 ip30_heart_counter_read(struct clocksource *cs)
+{
+	return heart_read(&heart_regs->count);
+}
+
+struct clocksource ip30_heart_clocksource = {
+	.name	= "HEART",
+	.rating	= 400,
+	.read	= ip30_heart_counter_read,
+	.mask	= CLOCKSOURCE_MASK(52),
+	.flags	= (CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_VALID_FOR_HRES),
+};
+
+static u64 notrace ip30_heart_read_sched_clock(void)
+{
+	return heart_read(&heart_regs->count);
+}
+
+static void __init ip30_heart_clocksource_init(void)
+{
+	struct clocksource *cs = &ip30_heart_clocksource;
+
+	clocksource_register_hz(cs, HEART_CYCLES_PER_SEC);
+
+	sched_clock_register(ip30_heart_read_sched_clock, 52,
+			     HEART_CYCLES_PER_SEC);
+}
+
+void __init plat_time_init(void)
+{
+	int irq = get_c0_compare_int();
+
+	cp0_timer_irq_installed = 1;
+	irq_set_handler(irq, handle_percpu_devid_irq);
+	irq_set_percpu_devid(irq);
+	WARN_ON(request_percpu_irq(irq, c0_compare_interrupt,
+				   "timer", &mips_clockevent_device));
+	enable_percpu_irq(irq, IRQ_TYPE_NONE);
+
+	ip30_heart_clocksource_init();
+}