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, 85 insertions, 0 deletions

diff --git a/drivers/firmware/imx/sm-cpu.c b/drivers/firmware/imx/sm-cpu.c
new file mode 100644
index 000000000..091b014f7
--- /dev/null
+++ b/drivers/firmware/imx/sm-cpu.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2025 NXP
+ */
+
+#include <linux/firmware/imx/sm.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/scmi_protocol.h>
+#include <linux/scmi_imx_protocol.h>
+
+static const struct scmi_imx_cpu_proto_ops *imx_cpu_ops;
+static struct scmi_protocol_handle *ph;
+
+int scmi_imx_cpu_reset_vector_set(u32 cpuid, u64 vector, bool start, bool boot,
+				  bool resume)
+{
+	if (!ph)
+		return -EPROBE_DEFER;
+
+	return imx_cpu_ops->cpu_reset_vector_set(ph, cpuid, vector, start,
+						 boot, resume);
+}
+EXPORT_SYMBOL(scmi_imx_cpu_reset_vector_set);
+
+int scmi_imx_cpu_start(u32 cpuid, bool start)
+{
+	if (!ph)
+		return -EPROBE_DEFER;
+
+	if (start)
+		return imx_cpu_ops->cpu_start(ph, cpuid, true);
+
+	return imx_cpu_ops->cpu_start(ph, cpuid, false);
+};
+EXPORT_SYMBOL(scmi_imx_cpu_start);
+
+int scmi_imx_cpu_started(u32 cpuid, bool *started)
+{
+	if (!ph)
+		return -EPROBE_DEFER;
+
+	if (!started)
+		return -EINVAL;
+
+	return imx_cpu_ops->cpu_started(ph, cpuid, started);
+};
+EXPORT_SYMBOL(scmi_imx_cpu_started);
+
+static int scmi_imx_cpu_probe(struct scmi_device *sdev)
+{
+	const struct scmi_handle *handle = sdev->handle;
+
+	if (!handle)
+		return -ENODEV;
+
+	if (imx_cpu_ops) {
+		dev_err(&sdev->dev, "sm cpu already initialized\n");
+		return -EEXIST;
+	}
+
+	imx_cpu_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_IMX_CPU, &ph);
+	if (IS_ERR(imx_cpu_ops))
+		return PTR_ERR(imx_cpu_ops);
+
+	return 0;
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+	{ SCMI_PROTOCOL_IMX_CPU, "imx-cpu" },
+	{ },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_imx_cpu_driver = {
+	.name = "scmi-imx-cpu",
+	.probe = scmi_imx_cpu_probe,
+	.id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_imx_cpu_driver);
+
+MODULE_AUTHOR("Peng Fan <peng.fan@nxp.com>");
+MODULE_DESCRIPTION("IMX SM CPU driver");
+MODULE_LICENSE("GPL");