Commit 2053bc57 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Borislav Petkov (AMD)
Browse files

efi: Add unaccepted memory support 



efi_config_parse_tables() reserves memory that holds unaccepted memory
configuration table so it won't be reused by page allocator.

Core-mm requires few helpers to support unaccepted memory:

 - accept_memory() checks the range of addresses against the bitmap and
   accept memory if needed.

 - range_contains_unaccepted_memory() checks if anything within the
   range requires acceptance.

Architectural code has to provide efi_get_unaccepted_table() that
returns pointer to the unaccepted memory configuration table.

arch_accept_memory() handles arch-specific part of memory acceptance.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarArd Biesheuvel <ardb@kernel.org>
Reviewed-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20230606142637.5171-6-kirill.shutemov@linux.intel.com
parent 3fd1239a

arch/x86/platform/efi/efi.c

+3 −0
Original line number Diff line number Diff line
@@ -96,6 +96,9 @@ static const unsigned long * const efi_tables[] = { 
#ifdef CONFIG_EFI_COCO_SECRET

	&efi.coco_secret,

#endif

#ifdef CONFIG_UNACCEPTED_MEMORY

	&efi.unaccepted,

#endif

};



u64 efi_setup;		/* efi setup_data physical address */

drivers/firmware/efi/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -41,3 +41,4 @@ obj-$(CONFIG_EFI_CAPSULE_LOADER) += capsule-loader.o 
obj-$(CONFIG_EFI_EARLYCON)		+= earlycon.o

obj-$(CONFIG_UEFI_CPER_ARM)		+= cper-arm.o

obj-$(CONFIG_UEFI_CPER_X86)		+= cper-x86.o

obj-$(CONFIG_UNACCEPTED_MEMORY)		+= unaccepted_memory.o

drivers/firmware/efi/efi.c

+25 −0
Original line number Diff line number Diff line
@@ -50,6 +50,9 @@ struct efi __read_mostly efi = { 
#ifdef CONFIG_EFI_COCO_SECRET

	.coco_secret		= EFI_INVALID_TABLE_ADDR,

#endif

#ifdef CONFIG_UNACCEPTED_MEMORY

	.unaccepted		= EFI_INVALID_TABLE_ADDR,

#endif

};

EXPORT_SYMBOL(efi);
@@ -605,6 +608,9 @@ static const efi_config_table_type_t common_tables[] __initconst = { 
#ifdef CONFIG_EFI_COCO_SECRET

	{LINUX_EFI_COCO_SECRET_AREA_GUID,	&efi.coco_secret,	"CocoSecret"	},

#endif

#ifdef CONFIG_UNACCEPTED_MEMORY

	{LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID,	&efi.unaccepted,	"Unaccepted"	},

#endif

#ifdef CONFIG_EFI_GENERIC_STUB

	{LINUX_EFI_SCREEN_INFO_TABLE_GUID,	&screen_info_table			},

#endif
@@ -759,6 +765,25 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables, 
		}

	}



	if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY) &&

	    efi.unaccepted != EFI_INVALID_TABLE_ADDR) {

		struct efi_unaccepted_memory *unaccepted;



		unaccepted = early_memremap(efi.unaccepted, sizeof(*unaccepted));

		if (unaccepted) {

			unsigned long size;



			if (unaccepted->version == 1) {

				size = sizeof(*unaccepted) + unaccepted->size;

				memblock_reserve(efi.unaccepted, size);

			} else {

				efi.unaccepted = EFI_INVALID_TABLE_ADDR;

			}



			early_memunmap(unaccepted, sizeof(*unaccepted));

		}

	}



	return 0;

}

drivers/firmware/efi/unaccepted_memory.c

0 → 100644
+112 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only



#include <linux/efi.h>

#include <linux/memblock.h>

#include <linux/spinlock.h>

#include <asm/unaccepted_memory.h>



/* Protects unaccepted memory bitmap */

static DEFINE_SPINLOCK(unaccepted_memory_lock);



/*

 * accept_memory() -- Consult bitmap and accept the memory if needed.

 *

 * Only memory that is explicitly marked as unaccepted in the bitmap requires

 * an action. All the remaining memory is implicitly accepted and doesn't need

 * acceptance.

 *

 * No need to accept:

 *  - anything if the system has no unaccepted table;

 *  - memory that is below phys_base;

 *  - memory that is above the memory that addressable by the bitmap;

 */

void accept_memory(phys_addr_t start, phys_addr_t end)

{

	struct efi_unaccepted_memory *unaccepted;

	unsigned long range_start, range_end;

	unsigned long flags;

	u64 unit_size;



	unaccepted = efi_get_unaccepted_table();

	if (!unaccepted)

		return;



	unit_size = unaccepted->unit_size;



	/*

	 * Only care for the part of the range that is represented

	 * in the bitmap.

	 */

	if (start < unaccepted->phys_base)

		start = unaccepted->phys_base;

	if (end < unaccepted->phys_base)

		return;



	/* Translate to offsets from the beginning of the bitmap */

	start -= unaccepted->phys_base;

	end -= unaccepted->phys_base;



	/* Make sure not to overrun the bitmap */

	if (end > unaccepted->size * unit_size * BITS_PER_BYTE)

		end = unaccepted->size * unit_size * BITS_PER_BYTE;



	range_start = start / unit_size;



	spin_lock_irqsave(&unaccepted_memory_lock, flags);

	for_each_set_bitrange_from(range_start, range_end, unaccepted->bitmap,

				   DIV_ROUND_UP(end, unit_size)) {

		unsigned long phys_start, phys_end;

		unsigned long len = range_end - range_start;



		phys_start = range_start * unit_size + unaccepted->phys_base;

		phys_end = range_end * unit_size + unaccepted->phys_base;



		arch_accept_memory(phys_start, phys_end);

		bitmap_clear(unaccepted->bitmap, range_start, len);

	}

	spin_unlock_irqrestore(&unaccepted_memory_lock, flags);

}



bool range_contains_unaccepted_memory(phys_addr_t start, phys_addr_t end)

{

	struct efi_unaccepted_memory *unaccepted;

	unsigned long flags;

	bool ret = false;

	u64 unit_size;



	unaccepted = efi_get_unaccepted_table();

	if (!unaccepted)

		return false;



	unit_size = unaccepted->unit_size;



	/*

	 * Only care for the part of the range that is represented

	 * in the bitmap.

	 */

	if (start < unaccepted->phys_base)

		start = unaccepted->phys_base;

	if (end < unaccepted->phys_base)

		return false;



	/* Translate to offsets from the beginning of the bitmap */

	start -= unaccepted->phys_base;

	end -= unaccepted->phys_base;



	/* Make sure not to overrun the bitmap */

	if (end > unaccepted->size * unit_size * BITS_PER_BYTE)

		end = unaccepted->size * unit_size * BITS_PER_BYTE;



	spin_lock_irqsave(&unaccepted_memory_lock, flags);

	while (start < end) {

		if (test_bit(start / unit_size, unaccepted->bitmap)) {

			ret = true;

			break;

		}



		start += unit_size;

	}

	spin_unlock_irqrestore(&unaccepted_memory_lock, flags);



	return ret;

}

include/linux/efi.h

+1 −0
Original line number Diff line number Diff line
@@ -646,6 +646,7 @@ extern struct efi { 
	unsigned long			tpm_final_log;		/* TPM2 Final Events Log table */

	unsigned long			mokvar_table;		/* MOK variable config table */

	unsigned long			coco_secret;		/* Confidential computing secret table */

	unsigned long			unaccepted;		/* Unaccepted memory table */



	efi_get_time_t			*get_time;

	efi_set_time_t			*set_time;