[RFC PATCH 6/9] x86/efi: Do not rely on EFI_MEMORY_RUNTIME bit and avoid entry splitting

[Ard Biesheuvel <ardb+git@google.com>]

From: Ard Biesheuvel <ardb@kernel.org>

Now that efi_mem_reserve() has been updated to rely on RSRV_KERN
memblock reservations, it is no longer needed to mark memblock reserved
regions as EFI_MEMORY_RUNTIME. This means that it is no longer needed to
split existing entries in the EFI memory map, removing the need to
re-allocate/copy/remap the entire EFI memory map on every call to
efi_mem_reserve().

So drop this functionality - it is no longer needed.

Note that, for the time being, this requires the E820 map to be
consulted when deciding whether or not an entry with the
EFI_MEMORY_RUNTIME cleared needs to be preserved in the runtime map or
not. However, this will be superseded and removed by a subsequent patch,
which combines the map compaction with the actual freeing, in which case
the freeing logic can answer this question directly.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/include/asm/efi.h     |   4 -
 arch/x86/platform/efi/memmap.c | 138 --------------------
 arch/x86/platform/efi/quirks.c |  60 +--------
 3 files changed, 5 insertions(+), 197 deletions(-)

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 51b4cdbea061..b01dd639bf62 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -396,10 +396,6 @@ extern int __init efi_memmap_alloc(unsigned int num_entries,
 				   struct efi_memory_map_data *data);
 
 extern int __init efi_memmap_install(struct efi_memory_map_data *data);
-extern int __init efi_memmap_split_count(efi_memory_desc_t *md,
-					 struct range *range);
-extern void __init efi_memmap_insert(struct efi_memory_map *old_memmap,
-				     void *buf, struct efi_mem_range *mem);
 
 extern enum efi_secureboot_mode __x86_ima_efi_boot_mode(void);
 
diff --git a/arch/x86/platform/efi/memmap.c b/arch/x86/platform/efi/memmap.c
index 023697c88910..8ef45014c7e7 100644
--- a/arch/x86/platform/efi/memmap.c
+++ b/arch/x86/platform/efi/memmap.c
@@ -110,141 +110,3 @@ int __init efi_memmap_install(struct efi_memory_map_data *data)
 	__efi_memmap_free(phys, size, flags);
 	return 0;
 }
-
-/**
- * efi_memmap_split_count - Count number of additional EFI memmap entries
- * @md: EFI memory descriptor to split
- * @range: Address range (start, end) to split around
- *
- * Returns the number of additional EFI memmap entries required to
- * accommodate @range.
- */
-int __init efi_memmap_split_count(efi_memory_desc_t *md, struct range *range)
-{
-	u64 m_start, m_end;
-	u64 start, end;
-	int count = 0;
-
-	start = md->phys_addr;
-	end = start + (md->num_pages << EFI_PAGE_SHIFT) - 1;
-
-	/* modifying range */
-	m_start = range->start;
-	m_end = range->end;
-
-	if (m_start <= start) {
-		/* split into 2 parts */
-		if (start < m_end && m_end < end)
-			count++;
-	}
-
-	if (start < m_start && m_start < end) {
-		/* split into 3 parts */
-		if (m_end < end)
-			count += 2;
-		/* split into 2 parts */
-		if (end <= m_end)
-			count++;
-	}
-
-	return count;
-}
-
-/**
- * efi_memmap_insert - Insert a memory region in an EFI memmap
- * @old_memmap: The existing EFI memory map structure
- * @buf: Address of buffer to store new map
- * @mem: Memory map entry to insert
- *
- * It is suggested that you call efi_memmap_split_count() first
- * to see how large @buf needs to be.
- */
-void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
-			      struct efi_mem_range *mem)
-{
-	u64 m_start, m_end, m_attr;
-	efi_memory_desc_t *md;
-	u64 start, end;
-	void *old, *new;
-
-	/* modifying range */
-	m_start = mem->range.start;
-	m_end = mem->range.end;
-	m_attr = mem->attribute;
-
-	/*
-	 * The EFI memory map deals with regions in EFI_PAGE_SIZE
-	 * units. Ensure that the region described by 'mem' is aligned
-	 * correctly.
-	 */
-	if (!IS_ALIGNED(m_start, EFI_PAGE_SIZE) ||
-	    !IS_ALIGNED(m_end + 1, EFI_PAGE_SIZE)) {
-		WARN_ON(1);
-		return;
-	}
-
-	for (old = old_memmap->map, new = buf;
-	     old < old_memmap->map_end;
-	     old += old_memmap->desc_size, new += old_memmap->desc_size) {
-
-		/* copy original EFI memory descriptor */
-		memcpy(new, old, old_memmap->desc_size);
-		md = new;
-		start = md->phys_addr;
-		end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
-
-		if (m_start <= start && end <= m_end)
-			md->attribute |= m_attr;
-
-		if (m_start <= start &&
-		    (start < m_end && m_end < end)) {
-			/* first part */
-			md->attribute |= m_attr;
-			md->num_pages = (m_end - md->phys_addr + 1) >>
-				EFI_PAGE_SHIFT;
-			/* latter part */
-			new += old_memmap->desc_size;
-			memcpy(new, old, old_memmap->desc_size);
-			md = new;
-			md->phys_addr = m_end + 1;
-			md->num_pages = (end - md->phys_addr + 1) >>
-				EFI_PAGE_SHIFT;
-		}
-
-		if ((start < m_start && m_start < end) && m_end < end) {
-			/* first part */
-			md->num_pages = (m_start - md->phys_addr) >>
-				EFI_PAGE_SHIFT;
-			/* middle part */
-			new += old_memmap->desc_size;
-			memcpy(new, old, old_memmap->desc_size);
-			md = new;
-			md->attribute |= m_attr;
-			md->phys_addr = m_start;
-			md->num_pages = (m_end - m_start + 1) >>
-				EFI_PAGE_SHIFT;
-			/* last part */
-			new += old_memmap->desc_size;
-			memcpy(new, old, old_memmap->desc_size);
-			md = new;
-			md->phys_addr = m_end + 1;
-			md->num_pages = (end - m_end) >>
-				EFI_PAGE_SHIFT;
-		}
-
-		if ((start < m_start && m_start < end) &&
-		    (end <= m_end)) {
-			/* first part */
-			md->num_pages = (m_start - md->phys_addr) >>
-				EFI_PAGE_SHIFT;
-			/* latter part */
-			new += old_memmap->desc_size;
-			memcpy(new, old, old_memmap->desc_size);
-			md = new;
-			md->phys_addr = m_start;
-			md->num_pages = (end - md->phys_addr + 1) >>
-				EFI_PAGE_SHIFT;
-			md->attribute |= m_attr;
-		}
-	}
-}
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index e72e8b23598e..8a4a0c6b64bc 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -239,63 +239,9 @@ EXPORT_SYMBOL_GPL(efi_query_variable_store);
  * buggy implementations we reserve boot services region during EFI
  * init and make sure it stays executable. Then, after
  * SetVirtualAddressMap(), it is discarded.
- *
- * However, some boot services regions contain data that is required
- * by drivers, so we need to track which memory ranges can never be
- * freed. This is done by tagging those regions with the
- * EFI_MEMORY_RUNTIME attribute.
- *
- * Any driver that wants to mark a region as reserved must use
- * efi_mem_reserve() which will insert a new EFI memory descriptor
- * into efi.memmap (splitting existing regions if necessary) and tag
- * it with EFI_MEMORY_RUNTIME.
  */
 void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size)
 {
-	struct efi_memory_map_data data = { 0 };
-	struct efi_mem_range mr;
-	efi_memory_desc_t md;
-	int num_entries;
-	void *new;
-
-	if (efi_mem_desc_lookup(addr, &md) ||
-	    md.type != EFI_BOOT_SERVICES_DATA) {
-		pr_err("Failed to lookup EFI memory descriptor for %pa\n", &addr);
-		return;
-	}
-
-	if (addr + size > md.phys_addr + (md.num_pages << EFI_PAGE_SHIFT)) {
-		pr_err("Region spans EFI memory descriptors, %pa\n", &addr);
-		return;
-	}
-
-	size += addr % EFI_PAGE_SIZE;
-	size = round_up(size, EFI_PAGE_SIZE);
-	addr = round_down(addr, EFI_PAGE_SIZE);
-
-	mr.range.start = addr;
-	mr.range.end = addr + size - 1;
-	mr.attribute = md.attribute | EFI_MEMORY_RUNTIME;
-
-	num_entries = efi_memmap_split_count(&md, &mr.range);
-	num_entries += efi.memmap.nr_map;
-
-	if (efi_memmap_alloc(num_entries, &data) != 0) {
-		pr_err("Could not allocate boot services memmap\n");
-		return;
-	}
-
-	new = early_memremap_prot(data.phys_map, data.size,
-				  pgprot_val(pgprot_encrypted(FIXMAP_PAGE_NORMAL)));
-	if (!new) {
-		pr_err("Failed to map new boot services memmap\n");
-		return;
-	}
-
-	efi_memmap_insert(&efi.memmap, new, &mr);
-	early_memunmap(new, data.size);
-
-	efi_memmap_install(&data);
 	e820__range_update(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED);
 	e820__update_table(e820_table);
 }
@@ -509,8 +455,12 @@ void __init efi_unmap_boot_services(void)
 	for_each_efi_memory_desc(md) {
 		if (!(md->attribute & EFI_MEMORY_RUNTIME) &&
 		    (md->type == EFI_BOOT_SERVICES_CODE ||
-		     md->type == EFI_BOOT_SERVICES_DATA))
+		     md->type == EFI_BOOT_SERVICES_DATA) &&
+		    !e820__mapped_any(md->phys_addr,
+				      md->phys_addr + md->num_pages * EFI_PAGE_SIZE,
+				      E820_TYPE_RESERVED)) {
 			continue;
+		}
 
 		memcpy(new_md, md, efi.memmap.desc_size);
 		new_md += efi.memmap.desc_size;
-- 
2.53.0.473.g4a7958ca14-goog