Merge tag 'efi-next-26032025' of https://source.denx.de/u-boot/custodians/u-boot-tpm into next

When trying to boot an OS installer or a live image via EFI HTTP the
following happens
- U-Boot downloads the image and mounts it in memory
- The EFI subsystem is invoked and the image is started
- The OS calls ExitBootServices and the memory that holds the mounted
  image might get overwritten

This results in installers complaining that they can't find installer
medium or live images complaining they can't find the root filesystem.

ACPI already deals with it by having NFIT and NVDIMM to provide ramdisks
that need to be preserved by the OS. Linux and device trees have support
for persistent memory devices (pmem).

We can use them and inject a pmem node in the DT to preserve memory across the
entire boot sequence. Linux will just create a block device over the reserved
memory and installers/images can re-discover it.

This is what it looks like from the OS perspective:

nd_pmem namespace0.0: unable to guarantee persistence of writes
pmem0: p1 p2 p3
EXT4-fs (pmem0p3): mounted filesystem f40f64a4-5b41-4828-856e-caaae2c1c2a0 r/w with ordered data mode. Quota mode: disabled.
EXT4-fs (pmem0p3): re-mounted f40f64a4-5b41-4828-856e-caaae2c1c2a0 r/w. Quota mode: disabled.
Adding 45052k swap on /dev/pmem0p2.  Priority:-2 extents:1 across:45052k SS
root@genericarm64:~# mount | grep pmem
/dev/pmem0p3 on / type ext4 (rw,relatime)
/dev/pmem0p1 on /boot type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)

It's worth noting that Linux behaves differently with reserved memory
(at least on arm64) and that depends on kernel config options.
CONFIG_ZONE_DEVICES and CONFIG_ARM64_PMEM are such options. It boils down to
how the kernel tries to map pages. If devm_memremap_pages() gets called instead
of devm_memremap() mapping the memory fails.

The only safe way is to remove the memory from the EFI memory map,
rather than defining it as /reserved no-map;/ in the DT.

12 files changed, 310 insertions, 48 deletions

diff --git a/boot/fdt_support.c b/boot/fdt_support.c
index 49efeec3681..92f2f534ee0 100644
--- a/boot/fdt_support.c
+++ b/boot/fdt_support.c
@@ -18,6 +18,7 @@
 #include <dm/ofnode.h>
 #include <linux/ctype.h>
 #include <linux/types.h>
+#include <linux/sizes.h>
 #include <asm/global_data.h>
 #include <asm/unaligned.h>
 #include <linux/libfdt.h>
@@ -464,7 +465,6 @@ void do_fixup_by_compat_u32(void *fdt, const char *compat,
 	do_fixup_by_compat(fdt, compat, prop, &tmp, 4, create);
 }
 
-#ifdef CONFIG_ARCH_FIXUP_FDT_MEMORY
 /*
  * fdt_pack_reg - pack address and size array into the "reg"-suitable stream
  */
@@ -493,6 +493,7 @@ static int fdt_pack_reg(const void *fdt, void *buf, u64 *address, u64 *size,
 	return p - (char *)buf;
 }
 
+#ifdef CONFIG_ARCH_FIXUP_FDT_MEMORY
 #if CONFIG_NR_DRAM_BANKS > 4
 #define MEMORY_BANKS_MAX CONFIG_NR_DRAM_BANKS
 #else
@@ -2222,3 +2223,39 @@ int fdt_valid(struct fdt_header **blobp)
 	}
 	return 1;
 }
+
+int fdt_fixup_pmem_region(void *fdt, u64 pmem_start, u64 pmem_size)
+{
+	char node_name[32];
+	int nodeoffset, len;
+	int err;
+	u8 tmp[4 * 16]; /* Up to 64-bit address + 64-bit size */
+
+	if (!IS_ALIGNED(pmem_start, SZ_2M) ||
+	    !IS_ALIGNED(pmem_start + pmem_size, SZ_2M)) {
+		printf("Start and end address must be 2MiB aligned\n");
+		return -1;
+	}
+
+	snprintf(node_name, sizeof(node_name), "pmem@%llx", pmem_start);
+	nodeoffset = fdt_find_or_add_subnode(fdt, 0, node_name);
+	if (nodeoffset < 0)
+		return nodeoffset;
+
+	err = fdt_setprop_string(fdt, nodeoffset, "compatible", "pmem-region");
+	if (err)
+		return err;
+	err = fdt_setprop_empty(fdt, nodeoffset, "volatile");
+	if (err)
+		return err;
+
+	len = fdt_pack_reg(fdt, tmp, &pmem_start, &pmem_size, 1);
+	err = fdt_setprop(fdt, nodeoffset, "reg", tmp, len);
+	if (err < 0) {
+		printf("WARNING: could not set pmem %s %s.\n", "reg",
+		       fdt_strerror(err));
+		return err;
+	}
+
+	return 0;
+}
diff --git a/boot/image-fdt.c b/boot/image-fdt.c
index 9d1598b1a93..8f718ad29f6 100644
--- a/boot/image-fdt.c
+++ b/boot/image-fdt.c
@@ -11,6 +11,7 @@
 #include <command.h>
 #include <fdt_support.h>
 #include <fdtdec.h>
+#include <efi.h>
 #include <env.h>
 #include <errno.h>
 #include <image.h>
@@ -649,6 +650,12 @@ int image_setup_libfdt(struct bootm_headers *images, void *blob, bool lmb)
 	if (!ft_verify_fdt(blob))
 		goto err;
 
+	if (CONFIG_IS_ENABLED(BLKMAP) && CONFIG_IS_ENABLED(EFI_LOADER)) {
+		fdt_ret = fdt_efi_pmem_setup(blob);
+		if (fdt_ret)
+			goto err;
+	}
+
 	/* after here we are using a livetree */
 	if (!of_live_active() && CONFIG_IS_ENABLED(EVENT)) {
 		struct event_ft_fixup fixup;
diff --git a/cmd/blkmap.c b/cmd/blkmap.c
index 164f80f1387..86a123b1cd3 100644
--- a/cmd/blkmap.c
+++ b/cmd/blkmap.c
@@ -62,13 +62,18 @@ static int do_blkmap_map_mem(struct map_ctx *ctx, int argc, char *const argv[])
 {
 	phys_addr_t addr;
 	int err;
+	bool preserve = false;
 
 	if (argc < 2)
 		return CMD_RET_USAGE;
 
 	addr = hextoul(argv[1], NULL);
 
-	err = blkmap_map_pmem(ctx->dev, ctx->blknr, ctx->blkcnt, addr);
+	if (argc == 3 && !strcmp(argv[2], "preserve"))
+		preserve = true;
+
+	err = blkmap_map_pmem(ctx->dev, ctx->blknr, ctx->blkcnt, addr,
+			      preserve);
 	if (err) {
 		printf("Unable to map %#llx at block 0x" LBAF ": %d\n",
 		       (unsigned long long)addr, ctx->blknr, err);
@@ -221,7 +226,7 @@ U_BOOT_CMD_WITH_SUBCMDS(
 	"blkmap create <label> - create device\n"
 	"blkmap destroy <label> - destroy device\n"
 	"blkmap map <label> <blk#> <cnt> linear <interface> <dev> <blk#> - device mapping\n"
-	"blkmap map <label> <blk#> <cnt> mem <addr> - memory mapping\n",
+	"blkmap map <label> <blk#> <cnt> mem <addr> [preserve] - memory mapping\n",
 	U_BOOT_SUBCMD_MKENT(info, 2, 1, do_blkmap_common),
 	U_BOOT_SUBCMD_MKENT(part, 2, 1, do_blkmap_common),
 	U_BOOT_SUBCMD_MKENT(dev, 4, 1, do_blkmap_common),
diff --git a/drivers/block/blkmap.c b/drivers/block/blkmap.c
index 34eed1380dc..473c65b5911 100644
--- a/drivers/block/blkmap.c
+++ b/drivers/block/blkmap.c
@@ -17,6 +17,30 @@
 struct blkmap;
 
 /**
+ * define BLKMAP_SLICE_LINEAR - Linear mapping to another block device
+ *
+ * This blkmap slice type is used for mapping to other existing block
+ * devices.
+ */
+#define BLKMAP_SLICE_LINEAR	BIT(0)
+
+/**
+ * define BLKMAP_SLICE_MEM - Linear mapping to memory based block device
+ *
+ * This blkmap slice type is used for mapping to memory based block
+ * devices, like ramdisks.
+ */
+#define BLKMAP_SLICE_MEM	BIT(1)
+
+/**
+ * define BLKMAP_SLICE_PRESERVE - Preserved blkmap slice
+ *
+ * This blkmap slice is intended to be preserved, and it's
+ * information passed on to a later stage, like OS.
+ */
+#define BLKMAP_SLICE_PRESERVE	BIT(2)
+
+/**
  * struct blkmap_slice - Region mapped to a blkmap
  *
  * Common data for a region mapped to a blkmap, specialized by each
@@ -25,12 +49,14 @@ struct blkmap;
  * @node: List node used to associate this slice with a blkmap
  * @blknr: Start block number of the mapping
  * @blkcnt: Number of blocks covered by this mapping
+ * @attr: Attributes of blkmap slice
  */
 struct blkmap_slice {
 	struct list_head node;
 
 	lbaint_t blknr;
 	lbaint_t blkcnt;
+	uint     attr;
 
 	/**
 	 * @read: - Read from slice
@@ -169,6 +195,7 @@ int blkmap_map_linear(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
 		.slice = {
 			.blknr = blknr,
 			.blkcnt = blkcnt,
+			.attr = BLKMAP_SLICE_LINEAR,
 
 			.read = blkmap_linear_read,
 			.write = blkmap_linear_write,
@@ -234,7 +261,7 @@ static void blkmap_mem_destroy(struct blkmap *bm, struct blkmap_slice *bms)
 }
 
 int __blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
-		     void *addr, bool remapped)
+		     void *addr, bool remapped, bool preserve)
 {
 	struct blkmap *bm = dev_get_plat(dev);
 	struct blkmap_mem *bmm;
@@ -248,6 +275,7 @@ int __blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
 		.slice = {
 			.blknr = blknr,
 			.blkcnt = blkcnt,
+			.attr = BLKMAP_SLICE_MEM,
 
 			.read = blkmap_mem_read,
 			.write = blkmap_mem_write,
@@ -258,6 +286,9 @@ int __blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
 		.remapped = remapped,
 	};
 
+	if (preserve)
+		bmm->slice.attr |= BLKMAP_SLICE_PRESERVE;
+
 	err = blkmap_slice_add(bm, &bmm->slice);
 	if (err)
 		free(bmm);
@@ -268,11 +299,11 @@ int __blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
 int blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
 		   void *addr)
 {
-	return __blkmap_map_mem(dev, blknr, blkcnt, addr, false);
+	return __blkmap_map_mem(dev, blknr, blkcnt, addr, false, false);
 }
 
 int blkmap_map_pmem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
-		    phys_addr_t paddr)
+		    phys_addr_t paddr, bool preserve)
 {
 	struct blkmap *bm = dev_get_plat(dev);
 	struct blk_desc *bd = dev_get_uclass_plat(bm->blk);
@@ -283,7 +314,7 @@ int blkmap_map_pmem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
 	if (!addr)
 		return -ENOMEM;
 
-	err = __blkmap_map_mem(dev, blknr, blkcnt, addr, true);
+	err = __blkmap_map_mem(dev, blknr, blkcnt, addr, true, preserve);
 	if (err)
 		unmap_sysmem(addr);
 
@@ -486,6 +517,49 @@ err:
 	return err;
 }
 
+static bool blkmap_mem_preserve_slice(struct blkmap_slice *bms)
+{
+	return (bms->attr & (BLKMAP_SLICE_MEM | BLKMAP_SLICE_PRESERVE)) ==
+		(BLKMAP_SLICE_MEM | BLKMAP_SLICE_PRESERVE);
+}
+
+int blkmap_get_preserved_pmem_slices(int (*cb)(void *ctx, u64 addr,
+					       u64 size), void *ctx)
+{
+	int ret;
+	u64 addr, size;
+	struct udevice *dev;
+	struct uclass *uc;
+	struct blkmap *bm;
+	struct blkmap_mem *bmm;
+	struct blkmap_slice *bms;
+	struct blk_desc *bd;
+
+	if (!cb) {
+		log_debug("%s: No callback passed to the function\n", __func__);
+		return 0;
+	}
+
+	uclass_id_foreach_dev(UCLASS_BLKMAP, dev, uc) {
+		bm = dev_get_plat(dev);
+		bd = dev_get_uclass_plat(bm->blk);
+
+		list_for_each_entry(bms, &bm->slices, node) {
+			if (!blkmap_mem_preserve_slice(bms))
+				continue;
+
+			bmm = container_of(bms, struct blkmap_mem, slice);
+			addr = (u64)(uintptr_t)bmm->addr;
+			size = (u64)bms->blkcnt << bd->log2blksz;
+			ret = cb(ctx, addr, size);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return 0;
+}
+
 int blkmap_destroy(struct udevice *dev)
 {
 	int err;
diff --git a/drivers/block/blkmap_helper.c b/drivers/block/blkmap_helper.c
index bfba14110d2..2f1bc28ee5d 100644
--- a/drivers/block/blkmap_helper.c
+++ b/drivers/block/blkmap_helper.c
@@ -28,7 +28,7 @@ int blkmap_create_ramdisk(const char *label, ulong image_addr, ulong image_size,
 	bm = dev_get_plat(bm_dev);
 	desc = dev_get_uclass_plat(bm->blk);
 	blknum = image_size >> desc->log2blksz;
-	ret = blkmap_map_pmem(bm_dev, 0, blknum, image_addr);
+	ret = blkmap_map_pmem(bm_dev, 0, blknum, image_addr, true);
 	if (ret) {
 		log_err("Unable to map %#llx at block %d : %d\n",
 			(unsigned long long)image_addr, 0, ret);
diff --git a/include/blkmap.h b/include/blkmap.h
index d53095437fa..57555fda4fb 100644
--- a/include/blkmap.h
+++ b/include/blkmap.h
@@ -7,6 +7,7 @@
 #ifndef _BLKMAP_H
 #define _BLKMAP_H
 
+#include <blk.h>
 #include <dm/lists.h>
 
 /**
@@ -60,10 +61,12 @@ int blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
  * @blknr: Start block number of the mapping
  * @blkcnt: Number of blocks to map
  * @paddr: The target physical memory address of the mapping
+ * @preserve: Mapping intended to be preserved for subsequent stages,
+ *		like the OS (e.g. ISO installer)
  * Returns: 0 on success, negative error code on failure
  */
 int blkmap_map_pmem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
-		    phys_addr_t paddr);
+		    phys_addr_t paddr, bool preserve);
 
 /**
  * blkmap_from_label() - Find blkmap from label
@@ -102,4 +105,32 @@ int blkmap_destroy(struct udevice *dev);
 int blkmap_create_ramdisk(const char *label, ulong image_addr, ulong image_size,
 			  struct udevice **devp);
 
+/**
+ * blkmap_get_preserved_pmem_slices() - Look for memory mapped preserved slices
+ * @cb: Callback function to call for the blkmap slice
+ * @ctx: Argument to be passed to the callback function
+ *
+ * The function is used to iterate through all the blkmap slices, looking
+ * specifically for memory mapped blkmap mapping which has been
+ * created with the preserve attribute. The function looks for such slices
+ * with the relevant attributes and then calls the callback function which
+ * then does additional configuration as needed. The callback function is
+ * invoked for all the discovered slices, unless there is an error returned
+ * by the callback, in which case the function returns that error.
+ *
+ * The callback function has the following arguments
+ * @ctx:	Argument to be passed to the callback function
+ * @addr:	Start address of the memory mapped slice
+ * @size:	Size of the memory mapped slice
+ *
+ * Typically, the callback will perform some configuration needed for the
+ * information passed on to it. An example of this would be setting up the
+ * pmem node in a device-tree(passed through the ctx argument) with the
+ * parameters passed on to the callback.
+ *
+ * Return: 0 on success, negative error on failure
+ */
+int blkmap_get_preserved_pmem_slices(int (*cb)(void *ctx, u64 addr,
+					       u64 size), void *ctx);
+
 #endif	/* _BLKMAP_H */
diff --git a/include/efi.h b/include/efi.h
index d005cb6181e..f9bbb175c3a 100644
--- a/include/efi.h
+++ b/include/efi.h
@@ -705,4 +705,17 @@ static inline bool efi_use_host_arch(void)
  */
 int efi_get_pxe_arch(void);
 
+/**
+ * fdt_efi_pmem_setup() - Pmem setup in DT and EFI memory map
+ * @fdt: Devicetree to add the pmem nodes to
+ *
+ * Iterate through all the blkmap devices, look for BLKMAP_MEM devices,
+ * and add pmem nodes corresponding to the blkmap slice to the
+ * devicetree along with removing the corresponding region from the
+ * EFI memory map.
+ *
+ * Returns: 0 on success, negative error on failure
+ */
+int fdt_efi_pmem_setup(void *fdt);
+
 #endif /* _LINUX_EFI_H */
diff --git a/include/efi_loader.h b/include/efi_loader.h
index e9c10819ba2..5f769786786 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -878,6 +878,21 @@ efi_status_t efi_get_memory_map(efi_uintn_t *memory_map_size,
 /* Adds a range into the EFI memory map */
 efi_status_t efi_add_memory_map(u64 start, u64 size, int memory_type);
 
+/**
+ * efi_update_memory_map() - update the memory map by adding/removing pages
+ *
+ * @start:			start address, must be a multiple of
+ *				EFI_PAGE_SIZE
+ * @pages:			number of pages to add
+ * @memory_type:		type of memory added
+ * @overlap_conventional:	region may only overlap free(conventional)
+ *				memory
+ * @remove:			remove memory map
+ * Return:			status code
+ */
+efi_status_t efi_update_memory_map(u64 start, u64 pages, int memory_type,
+				   bool overlap_conventional, bool remove);
+
 /* Called by board init to initialize the EFI drivers */
 efi_status_t efi_driver_init(void);
 /* Called when a block device is added */
diff --git a/include/fdt_support.h b/include/fdt_support.h
index f0ad2e6b365..049190cf3d7 100644
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -471,6 +471,20 @@ int fdt_valid(struct fdt_header **blobp);
  */
 int fdt_get_cells_len(const void *blob, char *nr_cells_name);
 
+/**
+ * fdt_fixup_pmem_region() - add a pmem node on the device tree
+ *
+ * This functions adds/updates a pmem node to the device tree.
+ * Usually used with EFI installers to preserve installer
+ * images
+ *
+ * @fdt:	device tree provided by caller
+ * @addr:	start address of the pmem node
+ * @size:	size of the memory of the pmem node
+ * Return:	0 on success or < 0 on failure
+ */
+int fdt_fixup_pmem_region(void *fdt, u64 pmem_start, u64 pmem_size);
+
 #endif /* !USE_HOSTCC */
 
 #ifdef USE_HOSTCC
diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
index c6124c590d9..f9534ef85ed 100644
--- a/lib/efi_loader/efi_bootmgr.c
+++ b/lib/efi_loader/efi_bootmgr.c
@@ -18,6 +18,8 @@
 #include <efi_loader.h>
 #include <efi_variable.h>
 #include <asm/unaligned.h>
+#include <linux/kernel.h>
+#include <linux/sizes.h>
 
 static const struct efi_boot_services *bs;
 static const struct efi_runtime_services *rs;
@@ -348,6 +350,7 @@ static efi_status_t prepare_loaded_image(u16 *label, ulong addr, ulong size,
 					 struct efi_device_path **dp,
 					 struct udevice **blk)
 {
+	u64 pages;
 	efi_status_t ret;
 	struct udevice *ramdisk_blk;
 
@@ -362,13 +365,18 @@ static efi_status_t prepare_loaded_image(u16 *label, ulong addr, ulong size,
 	}
 
 	/*
-	 * TODO: expose the ramdisk to OS.
-	 * Need to pass the ramdisk information by the architecture-specific
-	 * methods such as 'pmem' device-tree node.
+	 * Linux supports 'pmem' which allows OS installers to find, reclaim
+	 * the mounted images and continue the installation since the contents
+	 * of the pmem region are treated as local media.
+	 *
+	 * The memory regions used for it needs to be carved out of the EFI
+	 * memory map.
 	 */
-	ret = efi_add_memory_map(addr, size, EFI_RESERVED_MEMORY_TYPE);
+	pages = efi_size_in_pages(size + (addr & EFI_PAGE_MASK));
+	ret = efi_update_memory_map(addr, pages, EFI_CONVENTIONAL_MEMORY,
+				    false, true);
 	if (ret != EFI_SUCCESS) {
-		log_err("Memory reservation failed\n");
+		log_err("Failed to reserve memory\n");
 		goto err;
 	}
 
@@ -490,6 +498,13 @@ static efi_status_t try_load_from_uri_path(struct efi_device_path_uri *uridp,
 		ret = EFI_INVALID_PARAMETER;
 		goto err;
 	}
+	/*
+	 * Depending on the kernel configuration, pmem memory areas must be
+	 * page aligned or 2MiB aligned. PowerPC is an exception here and
+	 * requires 16MiB alignment, but since we don't have EFI support for
+	 * it, limit the alignment to 2MiB.
+	 */
+	image_size = ALIGN(image_size, SZ_2M);
 
 	/*
 	 * If the file extension is ".iso" or ".img", mount it and try to load
diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c
index 04b2efc4a3b..8c32059edda 100644
--- a/lib/efi_loader/efi_helper.c
+++ b/lib/efi_loader/efi_helper.c
@@ -5,6 +5,7 @@
 
 #define LOG_CATEGORY LOGC_EFI
 
+#include <blkmap.h>
 #include <bootm.h>
 #include <env.h>
 #include <image.h>
@@ -454,22 +455,29 @@ efi_status_t efi_env_set_load_options(efi_handle_t handle,
  */
 static efi_status_t copy_fdt(void **fdtp)
 {
-	unsigned long fdt_ram_start = -1L, fdt_pages;
 	efi_status_t ret = 0;
 	void *fdt, *new_fdt;
-	u64 new_fdt_addr;
-	uint fdt_size;
-	int i;
+	static u64 new_fdt_addr;
+	static efi_uintn_t fdt_pages;
+	ulong fdt_size;
 
-	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
-		u64 ram_start = gd->bd->bi_dram[i].start;
-		u64 ram_size = gd->bd->bi_dram[i].size;
+	/*
+	 * Remove the configuration table that might already be
+	 * installed, ignoring EFI_NOT_FOUND if no device-tree
+	 * is installed
+	 */
+	efi_install_configuration_table(&efi_guid_fdt, NULL);
 
-		if (!ram_size)
-			continue;
+	if (new_fdt_addr) {
+		log_debug("%s: Found allocated memory at %#llx, with %#zx pages\n",
+			  __func__, new_fdt_addr, fdt_pages);
 
-		if (ram_start < fdt_ram_start)
-			fdt_ram_start = ram_start;
+		ret = efi_free_pages(new_fdt_addr, fdt_pages);
+		if (ret != EFI_SUCCESS)
+			log_err("Unable to free up existing FDT memory region\n");
+
+		new_fdt_addr = 0;
+		fdt_pages = 0;
 	}
 
 	/*
@@ -485,15 +493,18 @@ static efi_status_t copy_fdt(void **fdtp)
 				 &new_fdt_addr);
 	if (ret != EFI_SUCCESS) {
 		log_err("Failed to reserve space for FDT\n");
-		goto done;
+		return ret;
 	}
+	log_debug("%s: Allocated memory at %#llx, with %#zx pages\n",
+		  __func__, new_fdt_addr, fdt_pages);
+
 	new_fdt = (void *)(uintptr_t)new_fdt_addr;
 	memcpy(new_fdt, fdt, fdt_totalsize(fdt));
 	fdt_set_totalsize(new_fdt, fdt_size);
 
-	*fdtp = (void *)(uintptr_t)new_fdt_addr;
-done:
-	return ret;
+	*fdtp = new_fdt;
+
+	return EFI_SUCCESS;
 }
 
 /**
@@ -546,9 +557,6 @@ efi_status_t efi_install_fdt(void *fdt)
 		const char *fdt_opt;
 		uintptr_t fdt_addr;
 
-		/* Look for device tree that is already installed */
-		if (efi_get_configuration_table(&efi_guid_fdt))
-			return EFI_SUCCESS;
 		/* Check if there is a hardware device tree */
 		fdt_opt = env_get("fdt_addr");
 		/* Use our own device tree as fallback */
@@ -680,3 +688,44 @@ out:
 
 	return ret;
 }
+
+/**
+ * pmem_node_efi_memmap_setup() - Add pmem node and tweak EFI memmap
+ * @fdt: The devicetree to which pmem node is added
+ * @addr: start address of the pmem node
+ * @size: size of the memory of the pmem node
+ *
+ * The function adds the pmem node to the device-tree along with removing
+ * the corresponding region from the EFI memory map. Used primarily to
+ * pass the information of a RAM based ISO image to the OS.
+ *
+ * Return: 0 on success, -ve value on error
+ */
+static int pmem_node_efi_memmap_setup(void *fdt, u64 addr, u64 size)
+{
+	int ret;
+	u64 pages;
+	efi_status_t status;
+
+	ret = fdt_fixup_pmem_region(fdt, addr, size);
+	if (ret) {
+		log_err("Failed to setup pmem node for addr %#llx, size %#llx, err %d\n",
+			addr, size, ret);
+		return ret;
+	}
+
+	/* Remove the pmem region from the EFI memory map */
+	pages = efi_size_in_pages(size + (addr & EFI_PAGE_MASK));
+	status = efi_update_memory_map(addr, pages, EFI_CONVENTIONAL_MEMORY,
+				       false, true);
+	if (status != EFI_SUCCESS)
+		return -1;
+
+	return 0;
+}
+
+int fdt_efi_pmem_setup(void *fdt)
+{
+	return blkmap_get_preserved_pmem_slices(pmem_node_efi_memmap_setup,
+						fdt);
+}
diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index c39b53922bb..0abb1f6159a 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -258,7 +258,7 @@ static s64 efi_mem_carve_out(struct efi_mem_list *map,
 }
 
 /**
- * efi_add_memory_map_pg() - add pages to the memory map
+ * efi_update_memory_map() - update the memory map by adding/removing pages
  *
  * @start:			start address, must be a multiple of
  *				EFI_PAGE_SIZE
@@ -266,12 +266,11 @@ static s64 efi_mem_carve_out(struct efi_mem_list *map,
  * @memory_type:		type of memory added
  * @overlap_conventional:	region may only overlap free(conventional)
  *				memory
+ * @remove:			remove memory map
  * Return:			status code
  */
-static
-efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
-				   int memory_type,
-				   bool overlap_conventional)
+efi_status_t efi_update_memory_map(u64 start, u64 pages, int memory_type,
+				   bool overlap_conventional, bool remove)
 {
 	struct efi_mem_list *lmem;
 	struct efi_mem_list *newlist;
@@ -279,9 +278,9 @@ efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
 	uint64_t carved_pages = 0;
 	struct efi_event *evt;
 
-	EFI_PRINT("%s: 0x%llx 0x%llx %d %s\n", __func__,
+	EFI_PRINT("%s: 0x%llx 0x%llx %d %s %s\n", __func__,
 		  start, pages, memory_type, overlap_conventional ?
-		  "yes" : "no");
+		  "yes" : "no", remove ? "remove" : "add");
 
 	if (memory_type >= EFI_MAX_MEMORY_TYPE)
 		return EFI_INVALID_PARAMETER;
@@ -364,7 +363,10 @@ efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
 	}
 
 	/* Add our new map */
-        list_add_tail(&newlist->link, &efi_mem);
+	if (!remove)
+		list_add_tail(&newlist->link, &efi_mem);
+	else
+		free(newlist);
 
 	/* And make sure memory is listed in descending order */
 	efi_mem_sort();
@@ -401,7 +403,7 @@ efi_status_t efi_add_memory_map(u64 start, u64 size, int memory_type)
 	pages = efi_size_in_pages(size + (start & EFI_PAGE_MASK));
 	start &= ~EFI_PAGE_MASK;
 
-	return efi_add_memory_map_pg(start, pages, memory_type, false);
+	return efi_update_memory_map(start, pages, memory_type, false, false);
 }
 
 /**
@@ -501,7 +503,7 @@ efi_status_t efi_allocate_pages(enum efi_allocate_type type,
 
 	efi_addr = (u64)(uintptr_t)map_sysmem(addr, 0);
 	/* Reserve that map in our memory maps */
-	ret = efi_add_memory_map_pg(efi_addr, pages, memory_type, true);
+	ret = efi_update_memory_map(efi_addr, pages, memory_type, true, false);
 	if (ret != EFI_SUCCESS) {
 		/* Map would overlap, bail out */
 		lmb_free_flags(addr, (u64)pages << EFI_PAGE_SHIFT, flags);
@@ -822,8 +824,8 @@ static void add_u_boot_and_runtime(void)
 		       uboot_stack_size) & ~EFI_PAGE_MASK;
 	uboot_pages = ((uintptr_t)map_sysmem(gd->ram_top - 1, 0) -
 		       uboot_start + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
-	efi_add_memory_map_pg(uboot_start, uboot_pages, EFI_BOOT_SERVICES_CODE,
-			      false);
+	efi_update_memory_map(uboot_start, uboot_pages, EFI_BOOT_SERVICES_CODE,
+			      false, false);
 #if defined(__aarch64__)
 	/*
 	 * Runtime Services must be 64KiB aligned according to the
@@ -841,8 +843,8 @@ static void add_u_boot_and_runtime(void)
 	runtime_end = (uintptr_t)__efi_runtime_stop;
 	runtime_end = (runtime_end + runtime_mask) & ~runtime_mask;
 	runtime_pages = (runtime_end - runtime_start) >> EFI_PAGE_SHIFT;
-	efi_add_memory_map_pg(runtime_start, runtime_pages,
-			      EFI_RUNTIME_SERVICES_CODE, false);
+	efi_update_memory_map(runtime_start, runtime_pages,
+			      EFI_RUNTIME_SERVICES_CODE, false, false);
 }
 
 int efi_memory_init(void)
@@ -877,11 +879,11 @@ int efi_map_update_notify(phys_addr_t addr, phys_size_t size,
 	pages = efi_size_in_pages(size + (efi_addr & EFI_PAGE_MASK));
 	efi_addr &= ~EFI_PAGE_MASK;
 
-	status = efi_add_memory_map_pg(efi_addr, pages,
+	status = efi_update_memory_map(efi_addr, pages,
 				       op == LMB_MAP_OP_RESERVE ?
 				       EFI_BOOT_SERVICES_DATA :
 				       EFI_CONVENTIONAL_MEMORY,
-				       false);
+				       false, false);
 	if (status != EFI_SUCCESS) {
 		log_err("LMB Map notify failure %lu\n",
 			status & ~EFI_ERROR_MASK);