x86/boot: Parse SRAT table and count immovable memory regions

Parse SRAT for the immovable memory regions and use that information to
control which offset KASLR selects so that it doesn't overlap with any
movable region.

 [ bp:
   - Move struct mem_vector where it is visible so that it builds.
   - Correct comments.
   - Rewrite commit message.
   ]
Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: <caoj.fnst@cn.fujitsu.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <indou.takao@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: <kasong@redhat.com>
Cc: <keescook@chromium.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <msys.mizuma@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190123110850.12433-7-fanc.fnst@cn.fujitsu.com

arch/x86/boot/compressed/acpi.c

@@ -4,9 +4,22 @@
 #include "error.h"
 #include "../string.h"
 
+#include <linux/numa.h>
 #include <linux/efi.h>
 #include <asm/efi.h>
 
+/*
+ * Longest parameter of 'acpi=' is 'copy_dsdt', plus an extra '\0'
+ * for termination.
+ */
+#define MAX_ACPI_ARG_LENGTH 10
+
+/*
+ * Immovable memory regions representation. Max amount of memory regions is
+ * MAX_NUMNODES*2.
+ */
+struct mem_vector immovable_mem[MAX_NUMNODES*2];
+
 /*
  * Max length of 64-bit hex address string is 19, prefix "0x" + 16 hex
  * digits, and '\0' for termination.
@@ -203,3 +216,111 @@ acpi_physical_address get_rsdp_addr(void)
 
 	return pa;
 }
+
+#if defined(CONFIG_RANDOMIZE_BASE) && defined(CONFIG_MEMORY_HOTREMOVE)
+/* Compute SRAT address from RSDP. */
+static unsigned long get_acpi_srat_table(void)
+{
+	unsigned long root_table, acpi_table;
+	struct acpi_table_header *header;
+	struct acpi_table_rsdp *rsdp;
+	u32 num_entries, size, len;
+	char arg[10];
+	u8 *entry;
+
+	rsdp = (struct acpi_table_rsdp *)(long)boot_params->acpi_rsdp_addr;
+	if (!rsdp)
+		return 0;
+
+	/* Get ACPI root table from RSDP.*/
+	if (!(cmdline_find_option("acpi", arg, sizeof(arg)) == 4 &&
+	    !strncmp(arg, "rsdt", 4)) &&
+	    rsdp->xsdt_physical_address &&
+	    rsdp->revision > 1) {
+		root_table = rsdp->xsdt_physical_address;
+		size = ACPI_XSDT_ENTRY_SIZE;
+	} else {
+		root_table = rsdp->rsdt_physical_address;
+		size = ACPI_RSDT_ENTRY_SIZE;
+	}
+
+	if (!root_table)
+		return 0;
+
+	header = (struct acpi_table_header *)root_table;
+	len = header->length;
+	if (len < sizeof(struct acpi_table_header) + size)
+		return 0;
+
+	num_entries = (len - sizeof(struct acpi_table_header)) / size;
+	entry = (u8 *)(root_table + sizeof(struct acpi_table_header));
+
+	while (num_entries--) {
+		if (size == ACPI_RSDT_ENTRY_SIZE)
+			acpi_table = *(u32 *)entry;
+		else
+			acpi_table = *(u64 *)entry;
+
+		if (acpi_table) {
+			header = (struct acpi_table_header *)acpi_table;
+
+			if (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_SRAT))
+				return acpi_table;
+		}
+		entry += size;
+	}
+	return 0;
+}
+
+/**
+ * count_immovable_mem_regions - Parse SRAT and cache the immovable
+ * memory regions into the immovable_mem array.
+ *
+ * Return the number of immovable memory regions on success, 0 on failure:
+ *
+ * - Too many immovable memory regions
+ * - ACPI off or no SRAT found
+ * - No immovable memory region found.
+ */
+int count_immovable_mem_regions(void)
+{
+	unsigned long table_addr, table_end, table;
+	struct acpi_subtable_header *sub_table;
+	struct acpi_table_header *table_header;
+	char arg[MAX_ACPI_ARG_LENGTH];
+	int num = 0;
+
+	if (cmdline_find_option("acpi", arg, sizeof(arg)) == 3 &&
+	    !strncmp(arg, "off", 3))
+		return 0;
+
+	table_addr = get_acpi_srat_table();
+	if (!table_addr)
+		return 0;
+
+	table_header = (struct acpi_table_header *)table_addr;
+	table_end = table_addr + table_header->length;
+	table = table_addr + sizeof(struct acpi_table_srat);
+
+	while (table + sizeof(struct acpi_subtable_header) < table_end) {
+		sub_table = (struct acpi_subtable_header *)table;
+		if (sub_table->type == ACPI_SRAT_TYPE_MEMORY_AFFINITY) {
+			struct acpi_srat_mem_affinity *ma;
+
+			ma = (struct acpi_srat_mem_affinity *)sub_table;
+			if (!(ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) && ma->length) {
+				immovable_mem[num].start = ma->base_address;
+				immovable_mem[num].size = ma->length;
+				num++;
+			}
+
+			if (num >= MAX_NUMNODES*2) {
+				debug_putstr("Too many immovable memory regions, aborting.\n");
+				return 0;
+			}
+		}
+		table += sub_table->length;
+	}
+	return num;
+}
+#endif /* CONFIG_RANDOMIZE_BASE && CONFIG_MEMORY_HOTREMOVE */

arch/x86/boot/compressed/kaslr.c

@@ -87,10 +87,6 @@ static unsigned long get_boot_seed(void)
 #define KASLR_COMPRESSED_BOOT
 #include "../../lib/kaslr.c"
 
-struct mem_vector {
-	unsigned long long start;
-	unsigned long long size;
-};
 
 /* Only supporting at most 4 unusable memmap regions with kaslr */
 #define MAX_MEMMAP_REGIONS	4

arch/x86/boot/compressed/misc.h

@@ -72,6 +72,10 @@ int cmdline_find_option(const char *option, char *buffer, int bufsize);
 int cmdline_find_option_bool(const char *option);
 #endif
 
+struct mem_vector {
+	unsigned long long start;
+	unsigned long long size;
+};
 
 #if CONFIG_RANDOMIZE_BASE
 /* kaslr.c */
@@ -126,3 +130,9 @@ acpi_physical_address get_rsdp_addr(void);
 #else
 static inline acpi_physical_address get_rsdp_addr(void) { return 0; }
 #endif
+
+#if defined(CONFIG_RANDOMIZE_BASE) && defined(CONFIG_MEMORY_HOTREMOVE)
+int count_immovable_mem_regions(void);
+#else
+static inline int count_immovable_mem_regions(void) { return 0; }
+#endif