Re: [PATCH 2/8] pseries: phyp dump: reserve-release proof-of-concept

Index: 2.6.25-rc1/arch/powerpc/platforms/pseries/phyp_dump.c
===================================================================

--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2.6.25-rc1/arch/powerpc/platforms/pseries/phyp_dump.c	2008-02-28 21:57:52.000000000 -0600

@@ -0,0 +1,105 @@
+/*
+ * Hypervisor-assisted dump
+ *
+ * Linas Vepstas, Manish Ahuja 2008
+ * Copyright 2008 IBM Corp.
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/pfn.h>
+#include <linux/swap.h>
+
+#include <asm/page.h>
+#include <asm/phyp_dump.h>
+#include <asm/machdep.h>
+#include <asm/prom.h>
+
+/* Global, used to communicate data between early boot and late boot */
+static struct phyp_dump phyp_dump_global;
+struct phyp_dump *phyp_dump_info = &phyp_dump_global;

+
+/**
+ * release_memory_range -- release memory previously lmb_reserved
+ * @start_pfn: starting physical frame number
+ * @nr_pages: number of pages to free.
+ *
+ * This routine will release memory that had been previously
+ * lmb_reserved in early boot. The released memory becomes
+ * available for genreal use.
+ */
+static void
+release_memory_range(unsigned long start_pfn, unsigned long nr_pages)
+{
+	struct page *rpage;
+	unsigned long end_pfn;
+	long i;
+
+	end_pfn = start_pfn + nr_pages;
+
+	for (i = start_pfn; i <= end_pfn; i++) {
+		rpage = pfn_to_page(i);
+		if (PageReserved(rpage)) {
+			ClearPageReserved(rpage);
+			init_page_count(rpage);
+			__free_page(rpage);
+			totalram_pages++;
+		}
+	}
+}
+
+static int __init phyp_dump_setup(void)
+{
+	unsigned long start_pfn, nr_pages;
+
+	/* If no memory was reserved in early boot, there is nothing to do */
+	if (phyp_dump_info->init_reserve_size == 0)
+		return 0;
+
+	/* Release memory that was reserved in early boot */
+	start_pfn = PFN_DOWN(phyp_dump_info->init_reserve_start);
+	nr_pages = PFN_DOWN(phyp_dump_info->init_reserve_size);
+	release_memory_range(start_pfn, nr_pages);
+
+	return 0;
+}
+machine_subsys_initcall(pseries, phyp_dump_setup);
+
+int __init early_init_dt_scan_phyp_dump(unsigned long node,
+		const char *uname, int depth, void *data)
+{
+#ifdef CONFIG_PHYP_DUMP
+	const unsigned int *sizes;
+
+	phyp_dump_info->phyp_dump_configured = 0;
+	phyp_dump_info->phyp_dump_is_active = 0;
+
+	if (depth != 1 || strcmp(uname, "rtas") != 0)
+		return 0;
+
+	if (of_get_flat_dt_prop(node, "ibm,configure-kernel-dump", NULL))
+		phyp_dump_info->phyp_dump_configured++;
+
+	if (of_get_flat_dt_prop(node, "ibm,dump-kernel", NULL))
+		phyp_dump_info->phyp_dump_is_active++;
+
+	sizes = of_get_flat_dt_prop(node, "ibm,configure-kernel-dump-sizes",
+									NULL);
+	if (!sizes)
+		return 0;
+
+	if (sizes[0] == 1)
+		phyp_dump_info->cpu_state_size = *((unsigned long *)&sizes[1]);
+
+	if (sizes[3] == 2)
+		phyp_dump_info->hpte_region_size =
+						*((unsigned long *)&sizes[4]);
+#endif

Index: 2.6.25-rc1/arch/powerpc/kernel/prom.c
===================================================================

--- 2.6.25-rc1.orig/arch/powerpc/kernel/prom.c	2008-02-28 21:54:57.000000000 -0600
+++ 2.6.25-rc1/arch/powerpc/kernel/prom.c	2008-02-28 21:55:27.000000000 -0600

@@ -1039,6 +1040,51 @@ static void __init early_reserve_mem(voi
 #endif
 }
 
+#ifdef CONFIG_PHYP_DUMP
+/**
+ * reserve_crashed_mem() - reserve all not-yet-dumped mmemory
+ *
+ * This routine may reserve memory regions in the kernel only
+ * if the system is supported and a dump was taken in last
+ * boot instance or if the hardware is supported and the
+ * scratch area needs to be setup. In other instances it returns
+ * without reserving anything. The memory in case of dump being
+ * active is freed when the dump is collected (by userland tools).
+ */
+static void __init reserve_crashed_mem(void)

+{
+	unsigned long base, size;
+	if (!phyp_dump_info->phyp_dump_configured) {
+		printk(KERN_ERR "Phyp-dump not supported on this hardware\n");
+		return;
+	}
+
+	if (phyp_dump_info->phyp_dump_is_active) {
+		/* Reserve *everything* above RMR.Area freed by userland tools*/
+		base = PHYP_DUMP_RMR_END;
+		size = lmb_end_of_DRAM() - base;
+
+		/* XXX crashed_ram_end is wrong, since it may be beyond
+		 * the memory_limit, it will need to be adjusted. */
+		lmb_reserve(base, size);
+
+		phyp_dump_info->init_reserve_start = base;
+		phyp_dump_info->init_reserve_size = size;
+	} else {
+		size = phyp_dump_info->cpu_state_size +
+			phyp_dump_info->hpte_region_size +
+			PHYP_DUMP_RMR_END;
+		base = lmb_end_of_DRAM() - size;
+		lmb_reserve(base, size);
+		phyp_dump_info->init_reserve_start = base;
+		phyp_dump_info->init_reserve_size = size;
+	}
+}
+#else
+static inline void __init reserve_crashed_mem(void) {}
+#endif /* CONFIG_PHYP_DUMP  && CONFIG_PPC_RTAS */