The patch titled
Subject: x86/boot/compressed: handle unaccepted memory
has been added to the -mm mm-unstable branch. Its filename is
x86-boot-compressed-handle-unaccepted-memory.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/x86-boot-compressed-handle-unaccepted-memory.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: x86/boot/compressed: handle unaccepted memory
Date: Thu, 1 Jun 2023 21:25:38 +0300
The firmware will pre-accept the memory used to run the stub. But, the
stub is responsible for accepting the memory into which it decompresses
the main kernel. Accept memory just before decompression starts.
The stub is also responsible for choosing a physical address in which to
place the decompressed kernel image. The KASLR mechanism will randomize
this physical address. Since the accepted memory region is relatively
small, KASLR would be quite ineffective if it only used the pre-accepted
area (EFI_CONVENTIONAL_MEMORY). Ensure that KASLR randomizes among the
entire physical address space by also including EFI_UNACCEPTED_MEMORY.
Link: https://lkml.kernel.org/r/20230601182543.19036-5-kirill.shutemov@xxxxxxxxxxxxxxx
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Liam Merwick <liam.merwick@xxxxxxxxxx>
Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Dario Faggioli <dfaggioli@xxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Joerg Roedel <jroedel@xxxxxxx>
Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
Cc: Marcelo Henrique Cerri <marcelo.cerri@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tim Gardner <tim.gardner@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/boot/compressed/efi.h | 10 ++++++++
arch/x86/boot/compressed/kaslr.c | 35 +++++++++++++++++++----------
arch/x86/boot/compressed/mem.c | 31 +++++++++++++++++++++++++
arch/x86/boot/compressed/misc.c | 7 +++++
arch/x86/boot/compressed/misc.h | 6 ++++
5 files changed, 77 insertions(+), 12 deletions(-)
--- a/arch/x86/boot/compressed/efi.h~x86-boot-compressed-handle-unaccepted-memory
+++ a/arch/x86/boot/compressed/efi.h
@@ -16,6 +16,7 @@ typedef guid_t efi_guid_t __aligned(__al
#define ACPI_TABLE_GUID EFI_GUID(0xeb9d2d30, 0x2d88, 0x11d3, 0x9a, 0x16, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
#define ACPI_20_TABLE_GUID EFI_GUID(0x8868e871, 0xe4f1, 0x11d3, 0xbc, 0x22, 0x00, 0x80, 0xc7, 0x3c, 0x88, 0x81)
#define EFI_CC_BLOB_GUID EFI_GUID(0x067b1f5f, 0xcf26, 0x44c5, 0x85, 0x54, 0x93, 0xd7, 0x77, 0x91, 0x2d, 0x42)
+#define LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID EFI_GUID(0xd5d1de3c, 0x105c, 0x44f9, 0x9e, 0xa9, 0xbc, 0xef, 0x98, 0x12, 0x00, 0x31)
#define EFI32_LOADER_SIGNATURE "EL32"
#define EFI64_LOADER_SIGNATURE "EL64"
@@ -32,6 +33,7 @@ typedef struct {
} efi_table_hdr_t;
#define EFI_CONVENTIONAL_MEMORY 7
+#define EFI_UNACCEPTED_MEMORY 15
#define EFI_MEMORY_MORE_RELIABLE \
((u64)0x0000000000010000ULL) /* higher reliability */
@@ -104,6 +106,14 @@ struct efi_setup_data {
u64 reserved[8];
};
+struct efi_unaccepted_memory {
+ u32 version;
+ u32 unit_size;
+ u64 phys_base;
+ u64 size;
+ unsigned long bitmap[];
+};
+
static inline int efi_guidcmp (efi_guid_t left, efi_guid_t right)
{
return memcmp(&left, &right, sizeof (efi_guid_t));
--- a/arch/x86/boot/compressed/kaslr.c~x86-boot-compressed-handle-unaccepted-memory
+++ a/arch/x86/boot/compressed/kaslr.c
@@ -672,6 +672,28 @@ static bool process_mem_region(struct me
}
#ifdef CONFIG_EFI
+
+/*
+ * Only EFI_CONVENTIONAL_MEMORY and EFI_UNACCEPTED_MEMORY (if supported) are
+ * guaranteed to be free.
+ *
+ * It is more conservative in picking free memory than the EFI spec allows:
+ *
+ * According to the spec, EFI_BOOT_SERVICES_{CODE|DATA} are also free memory
+ * and thus available to place the kernel image into, but in practice there's
+ * firmware where using that memory leads to crashes.
+ */
+static inline bool memory_type_is_free(efi_memory_desc_t *md)
+{
+ if (md->type == EFI_CONVENTIONAL_MEMORY)
+ return true;
+
+ if (md->type == EFI_UNACCEPTED_MEMORY)
+ return IS_ENABLED(CONFIG_UNACCEPTED_MEMORY);
+
+ return false;
+}
+
/*
* Returns true if we processed the EFI memmap, which we prefer over the E820
* table if it is available.
@@ -716,18 +738,7 @@ process_efi_entries(unsigned long minimu
for (i = 0; i < nr_desc; i++) {
md = efi_early_memdesc_ptr(pmap, e->efi_memdesc_size, i);
- /*
- * Here we are more conservative in picking free memory than
- * the EFI spec allows:
- *
- * According to the spec, EFI_BOOT_SERVICES_{CODE|DATA} are also
- * free memory and thus available to place the kernel image into,
- * but in practice there's firmware where using that memory leads
- * to crashes.
- *
- * Only EFI_CONVENTIONAL_MEMORY is guaranteed to be free.
- */
- if (md->type != EFI_CONVENTIONAL_MEMORY)
+ if (!memory_type_is_free(md))
continue;
if (efi_soft_reserve_enabled() &&
--- a/arch/x86/boot/compressed/mem.c~x86-boot-compressed-handle-unaccepted-memory
+++ a/arch/x86/boot/compressed/mem.c
@@ -1,9 +1,40 @@
// SPDX-License-Identifier: GPL-2.0-only
#include "error.h"
+#include "misc.h"
void arch_accept_memory(phys_addr_t start, phys_addr_t end)
{
/* Platform-specific memory-acceptance call goes here */
error("Cannot accept memory");
}
+
+void init_unaccepted_memory(void)
+{
+ guid_t guid = LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID;
+ struct efi_unaccepted_memory *unaccepted_table;
+ unsigned long cfg_table_pa;
+ unsigned int cfg_table_len;
+ enum efi_type et;
+ int ret;
+
+ et = efi_get_type(boot_params);
+ if (et == EFI_TYPE_NONE)
+ return;
+
+ ret = efi_get_conf_table(boot_params, &cfg_table_pa, &cfg_table_len);
+ if (ret)
+ error("EFI config table not found.");
+
+ unaccepted_table = (void *)efi_find_vendor_table(boot_params,
+ cfg_table_pa,
+ cfg_table_len,
+ guid);
+ if (!unaccepted_table)
+ return;
+
+ if (unaccepted_table->version != 1)
+ error("Unknown version of unaccepted memory table\n");
+
+ set_unaccepted_table(unaccepted_table);
+}
--- a/arch/x86/boot/compressed/misc.c~x86-boot-compressed-handle-unaccepted-memory
+++ a/arch/x86/boot/compressed/misc.c
@@ -455,6 +455,13 @@ asmlinkage __visible void *extract_kerne
#endif
debug_putstr("\nDecompressing Linux... ");
+
+ if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY)) {
+ debug_putstr("Accepting memory... ");
+ init_unaccepted_memory();
+ accept_memory(__pa(output), __pa(output) + needed_size);
+ }
+
__decompress(input_data, input_len, NULL, NULL, output, output_len,
NULL, error);
entry_offset = parse_elf(output);
--- a/arch/x86/boot/compressed/misc.h~x86-boot-compressed-handle-unaccepted-memory
+++ a/arch/x86/boot/compressed/misc.h
@@ -247,4 +247,10 @@ static inline unsigned long efi_find_ven
}
#endif /* CONFIG_EFI */
+void init_unaccepted_memory(void);
+
+/* Implemented in EFI stub */
+void set_unaccepted_table(struct efi_unaccepted_memory *table);
+void accept_memory(phys_addr_t start, phys_addr_t end);
+
#endif /* BOOT_COMPRESSED_MISC_H */
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
mm-add-support-for-unaccepted-memory.patch
efi-x86-get-full-memory-map-in-allocate_e820.patch
efi-libstub-implement-support-for-unaccepted-memory.patch
x86-boot-compressed-handle-unaccepted-memory.patch
efi-add-unaccepted-memory-support.patch
efi-unaccepted-avoid-load_unaligned_zeropad-stepping-into-unaccepted-memory.patch
x86-tdx-make-_tdx_hypercall-and-__tdx_module_call-available-in-boot-stub.patch
x86-tdx-refactor-try_accept_one.patch
x86-tdx-add-unaccepted-memory-support.patch
