[PATCH v3 12/17] x86/efi: Clean the memory map using iterator and filter API

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

From: Ard Biesheuvel <ardb@kernel.org>

Instead of open coding the iteration logic, use the existing iterator
API to iterate over all valid entries in the EFI memory map.

In addition, break out the logic that iterates over and conditionally
suppresses memory map entries so it can be reused later, as something
similar is happening two more times during boot.

Note that actually reinstalling the EFI memory map, which involves
unmapping and remapping it, is no longer needed, given that the number
of valid entries can only go down. So omit efi_memmap_install() and just
update the number of valid entries.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/platform/efi/efi.c | 30 +++++++++-----------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index edbf6efe3947..459b5c13167a 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -266,36 +266,32 @@ static bool __init efi_memmap_entry_valid(const efi_memory_desc_t *md, int i)
 	return false;
 }
 
-static void __init efi_clean_memmap(void)
+static int __init
+efi_memmap_filter_entries(bool (*callback)(const efi_memory_desc_t *, int))
 {
 	efi_memory_desc_t *out = efi.memmap.map;
 	const efi_memory_desc_t *in = out;
-	const efi_memory_desc_t *end = efi.memmap.map_end;
-	int i, n_removal;
+	int i = 0, filtered = 0;
 
-	for (i = n_removal = 0; in < end; i++) {
-		if (efi_memmap_entry_valid(in, i)) {
+	for_each_efi_memory_desc(in) {
+		if (callback(in, i++)) {
 			if (out != in)
 				memcpy(out, in, efi.memmap.desc_size);
 			out = (void *)out + efi.memmap.desc_size;
 		} else {
-			n_removal++;
+			filtered++;
 		}
-		in = (void *)in + efi.memmap.desc_size;
 	}
+	efi.memmap.num_valid_entries -= filtered;
+	return filtered;
+}
 
-	if (n_removal > 0) {
-		struct efi_memory_map_data data = {
-			.phys_map	= efi.memmap.phys_map,
-			.desc_version	= efi.memmap.desc_version,
-			.desc_size	= efi.memmap.desc_size,
-			.size		= efi.memmap.desc_size * (efi.memmap.num_valid_entries - n_removal),
-			.flags		= 0,
-		};
+static void __init efi_clean_memmap(void)
+{
+	int n_removal = efi_memmap_filter_entries(efi_memmap_entry_valid);
 
+	if (n_removal > 0)
 		pr_warn("Removing %d invalid memory map entries.\n", n_removal);
-		efi_memmap_install(&data);
-	}
 }
 
 /*
-- 
2.54.0.rc2.544.gc7ae2d5bb8-goog