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, 78 insertions, 0 deletions

diff --git a/arch/powerpc/boot/mpc8xx.c b/arch/powerpc/boot/mpc8xx.c
new file mode 100644
index 000000000..e19ef64df
--- /dev/null
+++ b/arch/powerpc/boot/mpc8xx.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MPC8xx support functions
+ *
+ * Author: Scott Wood <scottwood@freescale.com>
+ *
+ * Copyright (c) 2007 Freescale Semiconductor, Inc.
+ */
+
+#include "ops.h"
+#include "types.h"
+#include "fsl-soc.h"
+#include "mpc8xx.h"
+#include "stdio.h"
+#include "io.h"
+
+#define MPC8XX_PLPRCR (0x284/4) /* PLL and Reset Control Register */
+
+/* Return system clock from crystal frequency */
+u32 mpc885_get_clock(u32 crystal)
+{
+	u32 *immr;
+	u32 plprcr;
+	int mfi, mfn, mfd, pdf;
+	u32 ret;
+
+	immr = fsl_get_immr();
+	if (!immr) {
+		printf("mpc885_get_clock: Couldn't get IMMR base.\r\n");
+		return 0;
+	}
+
+	plprcr = in_be32(&immr[MPC8XX_PLPRCR]);
+
+	mfi = (plprcr >> 16) & 15;
+	if (mfi < 5) {
+		printf("Warning: PLPRCR[MFI] value of %d out-of-bounds\r\n",
+		       mfi);
+		mfi = 5;
+	}
+
+	pdf = (plprcr >> 1) & 0xf;
+	mfd = (plprcr >> 22) & 0x1f;
+	mfn = (plprcr >> 27) & 0x1f;
+
+	ret = crystal * mfi;
+
+	if (mfn != 0)
+		ret += crystal * mfn / (mfd + 1);
+
+	return ret / (pdf + 1);
+}
+
+/* Set common device tree fields based on the given clock frequencies. */
+void mpc8xx_set_clocks(u32 sysclk)
+{
+	void *node;
+
+	dt_fixup_cpu_clocks(sysclk, sysclk / 16, sysclk);
+
+	node = finddevice("/soc/cpm");
+	if (node)
+		setprop(node, "clock-frequency", &sysclk, 4);
+
+	node = finddevice("/soc/cpm/brg");
+	if (node)
+		setprop(node, "clock-frequency", &sysclk, 4);
+}
+
+int mpc885_fixup_clocks(u32 crystal)
+{
+	u32 sysclk = mpc885_get_clock(crystal);
+	if (!sysclk)
+		return 0;
+
+	mpc8xx_set_clocks(sysclk);
+	return 1;
+}