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From: Andrew Bresticker <abrestic@rivosinc.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	linux-efi@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-riscv@lists.infradead.org,
	Andrew Bresticker <abrestic@rivosinc.com>
Subject: [PATCH 2/2] efi: Don't add memblocks for unusable memory
Date: Fri,  2 Feb 2024 08:34:33 -0800
Message-Id: <20240202163433.786581-3-abrestic@rivosinc.com>
In-Reply-To: <20240202163433.786581-1-abrestic@rivosinc.com>
References: <20240202163433.786581-1-abrestic@rivosinc.com>
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Adding memblocks (even if nomap) for such regions unnecessarily consumes
resources by creating struct pages for memory that may never be used or,
in the case of soft-reserved regions, prevents the memory from later
being hotplugged in by dax_kmem. This is also consistent with how x86
handles unusable memory found in the EFI memory map.

Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
---
 drivers/firmware/efi/efi-init.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/drivers/firmware/efi/efi-init.c b/drivers/firmware/efi/efi-init.c
index d4987d013080..f05bacac89b7 100644
--- a/drivers/firmware/efi/efi-init.c
+++ b/drivers/firmware/efi/efi-init.c
@@ -24,13 +24,6 @@
 
 unsigned long __initdata screen_info_table = EFI_INVALID_TABLE_ADDR;
 
-static int __init is_memory(efi_memory_desc_t *md)
-{
-	if (md->attribute & (EFI_MEMORY_WB|EFI_MEMORY_WT|EFI_MEMORY_WC))
-		return 1;
-	return 0;
-}
-
 /*
  * Translate a EFI virtual address into a physical address: this is necessary,
  * as some data members of the EFI system table are virtually remapped after
@@ -195,12 +188,9 @@ static __init void reserve_regions(void)
 		memrange_efi_to_native(&paddr, &npages);
 		size = npages << PAGE_SHIFT;
 
-		if (is_memory(md)) {
+		if (is_usable_memory(md)) {
 			early_init_dt_add_memory_arch(paddr, size);
 
-			if (!is_usable_memory(md))
-				memblock_mark_nomap(paddr, size);
-
 			/* keep ACPI reclaim memory intact for kexec etc. */
 			if (md->type == EFI_ACPI_RECLAIM_MEMORY)
 				memblock_reserve(paddr, size);
-- 
2.34.1