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, 74 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
new file mode 100644
index 000000000..5c907c2c0
--- /dev/null
+++ b/arch/arm/mach-tegra/hotplug.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Copyright (C) 2002 ARM Ltd.
+ *  All Rights Reserved
+ *  Copyright (c) 2010, 2012-2013, NVIDIA Corporation. All rights reserved.
+ */
+
+#include <linux/clk/tegra.h>
+#include <linux/kernel.h>
+#include <linux/smp.h>
+
+#include <soc/tegra/common.h>
+#include <soc/tegra/fuse.h>
+
+#include <asm/smp_plat.h>
+
+#include "common.h"
+#include "sleep.h"
+
+static void (*tegra_hotplug_shutdown)(void);
+
+int tegra_cpu_kill(unsigned cpu)
+{
+	cpu = cpu_logical_map(cpu);
+
+	/* Clock gate the CPU */
+	tegra_wait_cpu_in_reset(cpu);
+	tegra_disable_cpu_clock(cpu);
+
+	return 1;
+}
+
+/*
+ * platform-specific code to shutdown a CPU
+ *
+ * Called with IRQs disabled
+ */
+void tegra_cpu_die(unsigned int cpu)
+{
+	if (!tegra_hotplug_shutdown) {
+		WARN(1, "hotplug is not yet initialized\n");
+		return;
+	}
+
+	/* Clean L1 data cache */
+	tegra_disable_clean_inv_dcache(TEGRA_FLUSH_CACHE_LOUIS);
+
+	/* Shut down the current CPU. */
+	tegra_hotplug_shutdown();
+
+	/* Should never return here. */
+	BUG();
+}
+
+static int __init tegra_hotplug_init(void)
+{
+	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+		return 0;
+
+	if (!soc_is_tegra())
+		return 0;
+
+	if (IS_ENABLED(CONFIG_ARCH_TEGRA_2x_SOC) && tegra_get_chip_id() == TEGRA20)
+		tegra_hotplug_shutdown = tegra20_hotplug_shutdown;
+	if (IS_ENABLED(CONFIG_ARCH_TEGRA_3x_SOC) && tegra_get_chip_id() == TEGRA30)
+		tegra_hotplug_shutdown = tegra30_hotplug_shutdown;
+	if (IS_ENABLED(CONFIG_ARCH_TEGRA_114_SOC) && tegra_get_chip_id() == TEGRA114)
+		tegra_hotplug_shutdown = tegra30_hotplug_shutdown;
+	if (IS_ENABLED(CONFIG_ARCH_TEGRA_124_SOC) && tegra_get_chip_id() == TEGRA124)
+		tegra_hotplug_shutdown = tegra30_hotplug_shutdown;
+
+	return 0;
+}
+pure_initcall(tegra_hotplug_init);