UEFI 2.8 defines an EFI_MEMORY_SP attribute bit to augment the
interpretation of the EFI Memory Types as "reserved for a specific
purpose".
The proposed Linux behavior for specific purpose memory is that it is
reserved for direct-access (device-dax) by default and not available for
any kernel usage, not even as an OOM fallback. Later, through udev
scripts or another init mechanism, these device-dax claimed ranges can
be reconfigured and hot-added to the available System-RAM with a unique
node identifier. This device-dax management scheme implements "soft" in
the "soft reserved" designation by allowing some or all of the
reservation to be recovered as typical memory. This policy can be
disabled at compile-time with CONFIG_EFI_SOFT_RESERVE=n, or runtime with
efi=nosoftreserve.
This patch introduces 2 new concepts at once given the entanglement
between early boot enumeration relative to memory that can optionally be
reserved from the kernel page allocator by default. The new concepts
are:
- E820_TYPE_SOFT_RESERVED: Upon detecting the EFI_MEMORY_SP
attribute on EFI_CONVENTIONAL memory, update the E820 map with this
new type. Only perform this classification if the
CONFIG_EFI_SOFT_RESERVE=y policy is enabled, otherwise treat it as
typical ram.
- IORES_DESC_SOFT_RESERVED: Add a new I/O resource descriptor for
a device driver to search iomem resources for application specific
memory. Teach the iomem code to identify such ranges as "Soft Reserved".
A follow-on change integrates parsing of the ACPI HMAT to identify the
node and sub-range boundaries of EFI_MEMORY_SP designated memory. For
now, just identify and reserve memory of this type.
The translation of EFI_CONVENTIONAL_MEMORY + EFI_MEMORY_SP to "soft
reserved" is x86/E820-only, but other archs could choose to publish
IORES_DESC_SOFT_RESERVED resources from their platform-firmware memory
map handlers. Other EFI-capable platforms would need to go audit their
local usages of EFI_CONVENTIONAL_MEMORY to consider the soft reserved
case.
Cc: <x86@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Darren Hart <dvhart@xxxxxxxxxxxxx>
Cc: Andy Shevchenko <andy@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Reviewed-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 19 +++++++--
arch/x86/Kconfig | 21 +++++++++
arch/x86/boot/compressed/eboot.c | 7 +++
arch/x86/boot/compressed/kaslr.c | 4 ++
arch/x86/include/asm/e820/types.h | 8 ++++
arch/x86/include/asm/efi-stub.h | 11 +++++
arch/x86/kernel/e820.c | 12 +++++
arch/x86/platform/efi/efi.c | 51 +++++++++++++++++++++--
drivers/firmware/efi/efi.c | 3 +
drivers/firmware/efi/libstub/efi-stub-helper.c | 12 +++++
include/linux/efi.h | 1
include/linux/ioport.h | 1
12 files changed, 139 insertions(+), 11 deletions(-)
create mode 100644 arch/x86/include/asm/efi-stub.h
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1c67acd1df65..dd28f0726309 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1152,7 +1152,8 @@
Format: {"off" | "on" | "skip[mbr]"}
efi= [EFI]
- Format: { "old_map", "nochunk", "noruntime", "debug" }
+ Format: { "old_map", "nochunk", "noruntime", "debug",
+ "nosoftreserve" }
old_map [X86-64]: switch to the old ioremap-based EFI
runtime services mapping. 32-bit still uses this one by
default.
@@ -1161,6 +1162,12 @@
firmware implementations.
noruntime : disable EFI runtime services support
debug: enable misc debug output
+ nosoftreserve: The EFI_MEMORY_SP (Specific Purpose)
+ attribute may cause the kernel to reserve the
+ memory range for a memory mapping driver to
+ claim. Specify efi=nosoftreserve to disable this
+ reservation and treat the memory by its base type
+ (i.e. EFI_CONVENTIONAL_MEMORY / "System RAM").
efi_no_storage_paranoia [EFI; X86]
Using this parameter you can use more than 50% of
@@ -1173,15 +1180,21 @@
updating original EFI memory map.
Region of memory which aa attribute is added to is
from ss to ss+nn.
+
If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
attribute is added to range 0x100000000-0x180000000 and
0x10a0000000-0x1120000000.
+ If efi_fake_mem=8G@9G:0x40000 is specified, the
+ EFI_MEMORY_SP(0x40000) attribute is added to
+ range 0x240000000-0x43fffffff.
+
Using this parameter you can do debugging of EFI memmap
- related feature. For example, you can do debugging of
+ related features. For example, you can do debugging of
Address Range Mirroring feature even if your box
- doesn't support it.
+ doesn't support it, or mark specific memory as
+ "soft reserved".
efivar_ssdt= [EFI; X86] Name of an EFI variable that contains an SSDT
that is to be dynamically loaded by Linux. If there are
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4195f44c6a09..bced13503bb1 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1981,6 +1981,27 @@ config EFI_MIXED
If unsure, say N.
+config EFI_SOFT_RESERVE
+ bool "Reserve EFI Specific Purpose Memory"
+ depends on EFI && ACPI_HMAT
+ default ACPI_HMAT
+ ---help---
+ On systems that have mixed performance classes of memory EFI
+ may indicate specific purpose memory with an attribute (See
+ EFI_MEMORY_SP in UEFI 2.8). A memory range tagged with this
+ attribute may have unique performance characteristics compared
+ to the system's general purpose "System RAM" pool. On the
+ expectation that such memory has application specific usage,
+ and its base EFI memory type is "conventional" answer Y to
+ arrange for the kernel to reserve it as a "Soft Reserved"
+ resource, and set aside for direct-access (device-dax) by
+ default. The memory range can later be optionally assigned to
+ the page allocator by system administrator policy via the
+ device-dax kmem facility. Say N to have the kernel treat this
+ memory as "System RAM" by default.
+
+ If unsure, say Y.
+
config SECCOMP
def_bool y
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index d6662fdef300..f2dc5896d770 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -10,6 +10,7 @@
#include <linux/pci.h>
#include <asm/efi.h>
+#include <asm/efi-stub.h>
#include <asm/e820/types.h>
#include <asm/setup.h>
#include <asm/desc.h>
@@ -553,7 +554,11 @@ setup_e820(struct boot_params *params, struct setup_data *e820ext, u32 e820ext_s
case EFI_BOOT_SERVICES_CODE:
case EFI_BOOT_SERVICES_DATA:
case EFI_CONVENTIONAL_MEMORY:
- e820_type = E820_TYPE_RAM;
+ if (!efi_nosoftreserve
+ && (d->attribute & EFI_MEMORY_SP))
+ e820_type = E820_TYPE_SOFT_RESERVED;
+ else
+ e820_type = E820_TYPE_RAM;
break;
case EFI_ACPI_MEMORY_NVS:
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 2e53c056ba20..093e84e28b7a 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -38,6 +38,7 @@
#include <linux/efi.h>
#include <generated/utsrelease.h>
#include <asm/efi.h>
+#include <asm/efi-stub.h>
/* Macros used by the included decompressor code below. */
#define STATIC
@@ -760,6 +761,9 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
if (md->type != EFI_CONVENTIONAL_MEMORY)
continue;
+ if (!efi_nosoftreserve && (md->attribute & EFI_MEMORY_SP))
+ continue;
+
if (efi_mirror_found &&
!(md->attribute & EFI_MEMORY_MORE_RELIABLE))
continue;
diff --git a/arch/x86/include/asm/e820/types.h b/arch/x86/include/asm/e820/types.h
index c3aa4b5e49e2..314f75d886d0 100644
--- a/arch/x86/include/asm/e820/types.h
+++ b/arch/x86/include/asm/e820/types.h
@@ -28,6 +28,14 @@ enum e820_type {
*/
E820_TYPE_PRAM = 12,
+ /*
+ * Special-purpose memory is indicated to the system via the
+ * EFI_MEMORY_SP attribute. Define an e820 translation of this
+ * memory type for the purpose of reserving this range and
+ * marking it with the IORES_DESC_SOFT_RESERVED designation.
+ */
+ E820_TYPE_SOFT_RESERVED = 0xefffffff,
+
/*
* Reserved RAM used by the kernel itself if
* CONFIG_INTEL_TXT=y is enabled, memory of this type
diff --git a/arch/x86/include/asm/efi-stub.h b/arch/x86/include/asm/efi-stub.h
new file mode 100644
index 000000000000..16ebd036387b
--- /dev/null
+++ b/arch/x86/include/asm/efi-stub.h
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef _X86_EFI_STUB_H_
+#define _X86_EFI_STUB_H_
+
+#ifdef CONFIG_EFI_STUB
+extern bool efi_nosoftreserve;
+#else
+#define efi_nosoftreserve (1)
+#endif
+
+#endif /* _X86_EFI_STUB_H_ */
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 7da2bcd2b8eb..9976106b57ec 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -190,6 +190,7 @@ static void __init e820_print_type(enum e820_type type)
case E820_TYPE_RAM: /* Fall through: */
case E820_TYPE_RESERVED_KERN: pr_cont("usable"); break;
case E820_TYPE_RESERVED: pr_cont("reserved"); break;
+ case E820_TYPE_SOFT_RESERVED: pr_cont("soft reserved"); break;
case E820_TYPE_ACPI: pr_cont("ACPI data"); break;
case E820_TYPE_NVS: pr_cont("ACPI NVS"); break;
case E820_TYPE_UNUSABLE: pr_cont("unusable"); break;
@@ -1037,6 +1038,7 @@ static const char *__init e820_type_to_string(struct e820_entry *entry)
case E820_TYPE_PRAM: return "Persistent Memory (legacy)";
case E820_TYPE_PMEM: return "Persistent Memory";
case E820_TYPE_RESERVED: return "Reserved";
+ case E820_TYPE_SOFT_RESERVED: return "Soft Reserved";
default: return "Unknown E820 type";
}
}
@@ -1052,6 +1054,7 @@ static unsigned long __init e820_type_to_iomem_type(struct e820_entry *entry)
case E820_TYPE_PRAM: /* Fall-through: */
case E820_TYPE_PMEM: /* Fall-through: */
case E820_TYPE_RESERVED: /* Fall-through: */
+ case E820_TYPE_SOFT_RESERVED: /* Fall-through: */
default: return IORESOURCE_MEM;
}
}
@@ -1064,6 +1067,7 @@ static unsigned long __init e820_type_to_iores_desc(struct e820_entry *entry)
case E820_TYPE_PMEM: return IORES_DESC_PERSISTENT_MEMORY;
case E820_TYPE_PRAM: return IORES_DESC_PERSISTENT_MEMORY_LEGACY;
case E820_TYPE_RESERVED: return IORES_DESC_RESERVED;
+ case E820_TYPE_SOFT_RESERVED: return IORES_DESC_SOFT_RESERVED;
case E820_TYPE_RESERVED_KERN: /* Fall-through: */
case E820_TYPE_RAM: /* Fall-through: */
case E820_TYPE_UNUSABLE: /* Fall-through: */
@@ -1078,11 +1082,12 @@ static bool __init do_mark_busy(enum e820_type type, struct resource *res)
return true;
/*
- * Treat persistent memory like device memory, i.e. reserve it
- * for exclusive use of a driver
+ * Treat persistent memory and other special memory ranges like
+ * device memory, i.e. reserve it for exclusive use of a driver
*/
switch (type) {
case E820_TYPE_RESERVED:
+ case E820_TYPE_SOFT_RESERVED:
case E820_TYPE_PRAM:
case E820_TYPE_PMEM:
return false;
@@ -1285,6 +1290,9 @@ void __init e820__memblock_setup(void)
if (end != (resource_size_t)end)
continue;
+ if (entry->type == E820_TYPE_SOFT_RESERVED)
+ memblock_reserve(entry->addr, entry->size);
+
if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN)
continue;
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 0bb58eb33ca0..9cfb7f1cf25d 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -151,10 +151,18 @@ void __init efi_find_mirror(void)
* more than the max 128 entries that can fit in the e820 legacy
* (zeropage) memory map.
*/
+enum add_efi_mode {
+ ADD_EFI_ALL,
+ ADD_EFI_SOFT_RESERVED,
+};
-static void __init do_add_efi_memmap(void)
+static void __init do_add_efi_memmap(enum add_efi_mode mode)
{
efi_memory_desc_t *md;
+ int add = 0;
+
+ if (!efi_enabled(EFI_MEMMAP))
+ return;
for_each_efi_memory_desc(md) {
unsigned long long start = md->phys_addr;
@@ -167,7 +175,10 @@ static void __init do_add_efi_memmap(void)
case EFI_BOOT_SERVICES_CODE:
case EFI_BOOT_SERVICES_DATA:
case EFI_CONVENTIONAL_MEMORY:
- if (md->attribute & EFI_MEMORY_WB)
+ if (efi_enabled(EFI_MEM_SOFT_RESERVE)
+ && (md->attribute & EFI_MEMORY_SP))
+ e820_type = E820_TYPE_SOFT_RESERVED;
+ else if (md->attribute & EFI_MEMORY_WB)
e820_type = E820_TYPE_RAM;
else
e820_type = E820_TYPE_RESERVED;
@@ -193,9 +204,17 @@ static void __init do_add_efi_memmap(void)
e820_type = E820_TYPE_RESERVED;
break;
}
+
+ if (e820_type == E820_TYPE_SOFT_RESERVED)
+ /* always add E820_TYPE_SOFT_RESERVED */;
+ else if (mode == ADD_EFI_SOFT_RESERVED)
+ continue;
+
+ add++;
e820__range_add(start, size, e820_type);
}
- e820__update_table(e820_table);
+ if (add)
+ e820__update_table(e820_table);
}
int __init efi_memblock_x86_reserve_range(void)
@@ -227,8 +246,18 @@ int __init efi_memblock_x86_reserve_range(void)
if (rv)
return rv;
- if (add_efi_memmap)
- do_add_efi_memmap();
+ if (add_efi_memmap) {
+ do_add_efi_memmap(ADD_EFI_ALL);
+ } else {
+ /*
+ * Given add_efi_memmap defaults to 0 and there there is no e820
+ * mechanism for soft-reserved memory. Explicitly scan for
+ * soft-reserved memory. Otherwise, the mechanism to disable the
+ * kernel's consideration of EFI_MEMORY_SP is the
+ * efi=nosoftreserve option.
+ */
+ do_add_efi_memmap(ADD_EFI_SOFT_RESERVED);
+ }
WARN(efi.memmap.desc_version != 1,
"Unexpected EFI_MEMORY_DESCRIPTOR version %ld",
@@ -781,6 +810,15 @@ static bool should_map_region(efi_memory_desc_t *md)
if (IS_ENABLED(CONFIG_X86_32))
return false;
+ /*
+ * EFI specific purpose memory may be reserved by default
+ * depending on kernel config and boot options.
+ */
+ if (md->type == EFI_CONVENTIONAL_MEMORY
+ && efi_enabled(EFI_MEM_SOFT_RESERVE)
+ && (md->attribute & EFI_MEMORY_SP))
+ return false;
+
/*
* Map all of RAM so that we can access arguments in the 1:1
* mapping when making EFI runtime calls.
@@ -1072,6 +1110,9 @@ static int __init arch_parse_efi_cmdline(char *str)
if (parse_option_str(str, "old_map"))
set_bit(EFI_OLD_MEMMAP, &efi.flags);
+ if (parse_option_str(str, "nosoftreserve"))
+ clear_bit(EFI_MEM_SOFT_RESERVE, &efi.flags);
+
return 0;
}
early_param("efi", arch_parse_efi_cmdline);
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 363bb9d00fa5..6d54d5c74347 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -52,6 +52,9 @@ struct efi __read_mostly efi = {
.tpm_log = EFI_INVALID_TABLE_ADDR,
.tpm_final_log = EFI_INVALID_TABLE_ADDR,
.mem_reserve = EFI_INVALID_TABLE_ADDR,
+#ifdef CONFIG_EFI_SOFT_RESERVE
+ .flags = 1UL << EFI_MEM_SOFT_RESERVE,
+#endif
};
EXPORT_SYMBOL(efi);
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index 3caae7f2cf56..35ee98a2c00c 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -28,6 +28,7 @@
#define EFI_READ_CHUNK_SIZE (1024 * 1024)
static unsigned long __chunk_size = EFI_READ_CHUNK_SIZE;
+bool efi_nosoftreserve;
static int __section(.data) __nokaslr;
static int __section(.data) __quiet;
@@ -211,6 +212,9 @@ efi_status_t efi_high_alloc(efi_system_table_t *sys_table_arg,
if (desc->type != EFI_CONVENTIONAL_MEMORY)
continue;
+ if (!efi_nosoftreserve && (desc->attribute & EFI_MEMORY_SP))
+ continue;
+
if (desc->num_pages < nr_pages)
continue;
@@ -305,6 +309,9 @@ efi_status_t efi_low_alloc(efi_system_table_t *sys_table_arg,
if (desc->type != EFI_CONVENTIONAL_MEMORY)
continue;
+ if (!efi_nosoftreserve && (desc->attribute & EFI_MEMORY_SP))
+ continue;
+
if (desc->num_pages < nr_pages)
continue;
@@ -489,6 +496,11 @@ efi_status_t efi_parse_options(char const *cmdline)
__novamap = 1;
}
+ if (!strncmp(str, "nosoftreserve", 7)) {
+ str += strlen("nosoftreserve");
+ efi_nosoftreserve = 1;
+ }
+
/* Group words together, delimited by "," */
while (*str && *str != ' ' && *str != ',')
str++;
diff --git a/include/linux/efi.h b/include/linux/efi.h
index acc2b8982ed2..f50e0f01a5ed 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1201,6 +1201,7 @@ extern int __init efi_setup_pcdp_console(char *);
#define EFI_DBG 8 /* Print additional debug info at runtime */
#define EFI_NX_PE_DATA 9 /* Can runtime data regions be mapped non-executable? */
#define EFI_MEM_ATTR 10 /* Did firmware publish an EFI_MEMORY_ATTRIBUTES table? */
+#define EFI_MEM_SOFT_RESERVE 11 /* Is the kernel configured to honor soft reservations? */
#ifdef CONFIG_EFI
/*
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 5b6a7121c9f0..17d9b1abc2f0 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -134,6 +134,7 @@ enum {
IORES_DESC_PERSISTENT_MEMORY_LEGACY = 5,
IORES_DESC_DEVICE_PRIVATE_MEMORY = 6,
IORES_DESC_RESERVED = 7,
+ IORES_DESC_SOFT_RESERVED = 8,
};
/*
