1 files changed, 222 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/unaccepted_memory.c b/drivers/firmware/efi/libstub/unaccepted_memory.c
new file mode 100644
index 000000000000..ca61f4733ea5
--- /dev/null
+++ b/drivers/firmware/efi/libstub/unaccepted_memory.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+#include "efistub.h"
+
+struct efi_unaccepted_memory *unaccepted_table;
+
+efi_status_t allocate_unaccepted_bitmap(__u32 nr_desc,
+					struct efi_boot_memmap *map)
+{
+	efi_guid_t unaccepted_table_guid = LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID;
+	u64 unaccepted_start = ULLONG_MAX, unaccepted_end = 0, bitmap_size;
+	efi_status_t status;
+	int i;
+
+	/* Check if the table is already installed */
+	unaccepted_table = get_efi_config_table(unaccepted_table_guid);
+	if (unaccepted_table) {
+		if (unaccepted_table->version != 1) {
+			efi_err("Unknown version of unaccepted memory table\n");
+			return EFI_UNSUPPORTED;
+		}
+		return EFI_SUCCESS;
+	}
+
+	/* Check if there's any unaccepted memory and find the max address */
+	for (i = 0; i < nr_desc; i++) {
+		efi_memory_desc_t *d;
+		unsigned long m = (unsigned long)map->map;
+
+		d = efi_early_memdesc_ptr(m, map->desc_size, i);
+		if (d->type != EFI_UNACCEPTED_MEMORY)
+			continue;
+
+		unaccepted_start = min(unaccepted_start, d->phys_addr);
+		unaccepted_end = max(unaccepted_end,
+				     d->phys_addr + d->num_pages * PAGE_SIZE);
+	}
+
+	if (unaccepted_start == ULLONG_MAX)
+		return EFI_SUCCESS;
+
+	unaccepted_start = round_down(unaccepted_start,
+				      EFI_UNACCEPTED_UNIT_SIZE);
+	unaccepted_end = round_up(unaccepted_end, EFI_UNACCEPTED_UNIT_SIZE);
+
+	/*
+	 * If unaccepted memory is present, allocate a bitmap to track what
+	 * memory has to be accepted before access.
+	 *
+	 * One bit in the bitmap represents 2MiB in the address space:
+	 * A 4k bitmap can track 64GiB of physical address space.
+	 *
+	 * In the worst case scenario -- a huge hole in the middle of the
+	 * address space -- It needs 256MiB to handle 4PiB of the address
+	 * space.
+	 *
+	 * The bitmap will be populated in setup_e820() according to the memory
+	 * map after efi_exit_boot_services().
+	 */
+	bitmap_size = DIV_ROUND_UP(unaccepted_end - unaccepted_start,
+				   EFI_UNACCEPTED_UNIT_SIZE * BITS_PER_BYTE);
+
+	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
+			     sizeof(*unaccepted_table) + bitmap_size,
+			     (void **)&unaccepted_table);
+	if (status != EFI_SUCCESS) {
+		efi_err("Failed to allocate unaccepted memory config table\n");
+		return status;
+	}
+
+	unaccepted_table->version = 1;
+	unaccepted_table->unit_size = EFI_UNACCEPTED_UNIT_SIZE;
+	unaccepted_table->phys_base = unaccepted_start;
+	unaccepted_table->size = bitmap_size;
+	memset(unaccepted_table->bitmap, 0, bitmap_size);
+
+	status = efi_bs_call(install_configuration_table,
+			     &unaccepted_table_guid, unaccepted_table);
+	if (status != EFI_SUCCESS) {
+		efi_bs_call(free_pool, unaccepted_table);
+		efi_err("Failed to install unaccepted memory config table!\n");
+	}
+
+	return status;
+}
+
+/*
+ * The accepted memory bitmap only works at unit_size granularity.  Take
+ * unaligned start/end addresses and either:
+ *  1. Accepts the memory immediately and in its entirety
+ *  2. Accepts unaligned parts, and marks *some* aligned part unaccepted
+ *
+ * The function will never reach the bitmap_set() with zero bits to set.
+ */
+void process_unaccepted_memory(u64 start, u64 end)
+{
+	u64 unit_size = unaccepted_table->unit_size;
+	u64 unit_mask = unaccepted_table->unit_size - 1;
+	u64 bitmap_size = unaccepted_table->size;
+
+	/*
+	 * Ensure that at least one bit will be set in the bitmap by
+	 * immediately accepting all regions under 2*unit_size.  This is
+	 * imprecise and may immediately accept some areas that could
+	 * have been represented in the bitmap.  But, results in simpler
+	 * code below
+	 *
+	 * Consider case like this (assuming unit_size == 2MB):
+	 *
+	 * | 4k | 2044k |    2048k   |
+	 * ^ 0x0        ^ 2MB        ^ 4MB
+	 *
+	 * Only the first 4k has been accepted. The 0MB->2MB region can not be
+	 * represented in the bitmap. The 2MB->4MB region can be represented in
+	 * the bitmap. But, the 0MB->4MB region is <2*unit_size and will be
+	 * immediately accepted in its entirety.
+	 */
+	if (end - start < 2 * unit_size) {
+		arch_accept_memory(start, end);
+		return;
+	}
+
+	/*
+	 * No matter how the start and end are aligned, at least one unaccepted
+	 * unit_size area will remain to be marked in the bitmap.
+	 */
+
+	/* Immediately accept a <unit_size piece at the start: */
+	if (start & unit_mask) {
+		arch_accept_memory(start, round_up(start, unit_size));
+		start = round_up(start, unit_size);
+	}
+
+	/* Immediately accept a <unit_size piece at the end: */
+	if (end & unit_mask) {
+		arch_accept_memory(round_down(end, unit_size), end);
+		end = round_down(end, unit_size);
+	}
+
+	/*
+	 * Accept part of the range that before phys_base and cannot be recorded
+	 * into the bitmap.
+	 */
+	if (start < unaccepted_table->phys_base) {
+		arch_accept_memory(start,
+				   min(unaccepted_table->phys_base, end));
+		start = unaccepted_table->phys_base;
+	}
+
+	/* Nothing to record */
+	if (end < unaccepted_table->phys_base)
+		return;
+
+	/* Translate to offsets from the beginning of the bitmap */
+	start -= unaccepted_table->phys_base;
+	end -= unaccepted_table->phys_base;
+
+	/* Accept memory that doesn't fit into bitmap */
+	if (end > bitmap_size * unit_size * BITS_PER_BYTE) {
+		unsigned long phys_start, phys_end;
+
+		phys_start = bitmap_size * unit_size * BITS_PER_BYTE +
+			     unaccepted_table->phys_base;
+		phys_end = end + unaccepted_table->phys_base;
+
+		arch_accept_memory(phys_start, phys_end);
+		end = bitmap_size * unit_size * BITS_PER_BYTE;
+	}
+
+	/*
+	 * 'start' and 'end' are now both unit_size-aligned.
+	 * Record the range as being unaccepted:
+	 */
+	bitmap_set(unaccepted_table->bitmap,
+		   start / unit_size, (end - start) / unit_size);
+}
+
+void accept_memory(phys_addr_t start, phys_addr_t end)
+{
+	unsigned long range_start, range_end;
+	unsigned long bitmap_size;
+	u64 unit_size;
+
+	if (!unaccepted_table)
+		return;
+
+	unit_size = unaccepted_table->unit_size;
+
+	/*
+	 * Only care for the part of the range that is represented
+	 * in the bitmap.
+	 */
+	if (start < unaccepted_table->phys_base)
+		start = unaccepted_table->phys_base;
+	if (end < unaccepted_table->phys_base)
+		return;
+
+	/* Translate to offsets from the beginning of the bitmap */
+	start -= unaccepted_table->phys_base;
+	end -= unaccepted_table->phys_base;
+
+	/* Make sure not to overrun the bitmap */
+	if (end > unaccepted_table->size * unit_size * BITS_PER_BYTE)
+		end = unaccepted_table->size * unit_size * BITS_PER_BYTE;
+
+	range_start = start / unit_size;
+	bitmap_size = DIV_ROUND_UP(end, unit_size);
+
+	for_each_set_bitrange_from(range_start, range_end,
+				   unaccepted_table->bitmap, bitmap_size) {
+		unsigned long phys_start, phys_end;
+
+		phys_start = range_start * unit_size + unaccepted_table->phys_base;
+		phys_end = range_end * unit_size + unaccepted_table->phys_base;
+
+		arch_accept_memory(phys_start, phys_end);
+		bitmap_clear(unaccepted_table->bitmap,
+			     range_start, range_end - range_start);
+	}
+}