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, 47 insertions, 0 deletions

diff --git a/arch/arm/mach-imx/hotplug.c b/arch/arm/mach-imx/hotplug.c
new file mode 100644
index 000000000..e24a46dc5
--- /dev/null
+++ b/arch/arm/mach-imx/hotplug.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2011 Freescale Semiconductor, Inc.
+ * Copyright 2011 Linaro Ltd.
+ */
+
+#include <linux/errno.h>
+#include <linux/jiffies.h>
+#include <asm/cacheflush.h>
+#include <asm/cp15.h>
+#include <asm/proc-fns.h>
+
+#include "common.h"
+#include "hardware.h"
+
+/*
+ * platform-specific code to shutdown a CPU
+ *
+ * Called with IRQs disabled
+ */
+void imx_cpu_die(unsigned int cpu)
+{
+	v7_exit_coherency_flush(louis);
+	/*
+	 * We use the cpu jumping argument register to sync with
+	 * imx_cpu_kill() which is running on cpu0 and waiting for
+	 * the register being cleared to kill the cpu.
+	 */
+	imx_set_cpu_arg(cpu, ~0);
+
+	while (1)
+		cpu_do_idle();
+}
+
+int imx_cpu_kill(unsigned int cpu)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(50);
+
+	while (imx_get_cpu_arg(cpu) == 0)
+		if (time_after(jiffies, timeout))
+			return 0;
+	imx_enable_cpu(cpu, false);
+	imx_set_cpu_arg(cpu, 0);
+	if (cpu_is_imx7d())
+		imx_gpcv2_set_core1_pdn_pup_by_software(true);
+	return 1;
+}