UEFI 2.8 defines an EFI_MEMORY_SP attribute bit to augment the interpretation of the EFI Memory Types as "reserved for a special purpose".
The proposed Linux behavior for special 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. A follow-on patch integrates parsing of the ACPI HMAT to identify the node and sub-range boundaries of EFI_MEMORY_SP designated memory. For now, arrange for EFI_MEMORY_SP memory to be reserved. Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Ard Biesheuvel <[email protected]> Cc: Darren Hart <[email protected]> Cc: Andy Shevchenko <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- arch/x86/Kconfig | 18 ++++++++++++++++++ arch/x86/boot/compressed/eboot.c | 5 ++++- arch/x86/boot/compressed/kaslr.c | 2 +- arch/x86/include/asm/e820/types.h | 9 +++++++++ arch/x86/kernel/e820.c | 9 +++++++-- arch/x86/platform/efi/efi.c | 10 +++++++++- include/linux/efi.h | 14 ++++++++++++++ include/linux/ioport.h | 1 + 8 files changed, 63 insertions(+), 5 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index c1f9b3cf437c..cb9ca27de7a5 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1961,6 +1961,24 @@ config EFI_MIXED If unsure, say N. +config EFI_SPECIAL_MEMORY + bool "EFI Special Purpose Memory Support" + depends on EFI + ---help--- + On systems that have mixed performance classes of memory EFI + may indicate special 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 + answer Y to arrange for the kernel to reserve it for + direct-access (device-dax) by default. The memory range can + later be optionally assigned to the page allocator by system + administrator policy. Say N to have the kernel treat this + memory as general purpose 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 544ac4fafd11..9b90fae21abe 100644 --- a/arch/x86/boot/compressed/eboot.c +++ b/arch/x86/boot/compressed/eboot.c @@ -560,7 +560,10 @@ 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 (is_efi_special(d)) + e820_type = E820_TYPE_SPECIAL; + 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..897e46eb9714 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -757,7 +757,7 @@ process_efi_entries(unsigned long minimum, unsigned long image_size) * * Only EFI_CONVENTIONAL_MEMORY is guaranteed to be free. */ - if (md->type != EFI_CONVENTIONAL_MEMORY) + if (md->type != EFI_CONVENTIONAL_MEMORY || is_efi_special(md)) continue; if (efi_mirror_found && diff --git a/arch/x86/include/asm/e820/types.h b/arch/x86/include/asm/e820/types.h index c3aa4b5e49e2..0ab8abae2e8b 100644 --- a/arch/x86/include/asm/e820/types.h +++ b/arch/x86/include/asm/e820/types.h @@ -28,6 +28,15 @@ enum e820_type { */ E820_TYPE_PRAM = 12, + /* + * Special-purpose / application-specific 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_APPLICATION_RESERVED designation. + */ + E820_TYPE_SPECIAL = 0xefffffff, + /* * Reserved RAM used by the kernel itself if * CONFIG_INTEL_TXT=y is enabled, memory of this type diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 2879e234e193..9f50dd0bbb04 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -176,6 +176,7 @@ static void __init e820_print_type(enum e820_type type) switch (type) { case E820_TYPE_RAM: /* Fall through: */ case E820_TYPE_RESERVED_KERN: pr_cont("usable"); break; + case E820_TYPE_SPECIAL: /* Fall through: */ case E820_TYPE_RESERVED: pr_cont("reserved"); break; case E820_TYPE_ACPI: pr_cont("ACPI data"); break; case E820_TYPE_NVS: pr_cont("ACPI NVS"); break; @@ -1023,6 +1024,7 @@ static const char *__init e820_type_to_string(struct e820_entry *entry) case E820_TYPE_UNUSABLE: return "Unusable memory"; case E820_TYPE_PRAM: return "Persistent Memory (legacy)"; case E820_TYPE_PMEM: return "Persistent Memory"; + case E820_TYPE_SPECIAL: /* Fall-through: */ case E820_TYPE_RESERVED: return "Reserved"; default: return "Unknown E820 type"; } @@ -1038,6 +1040,7 @@ static unsigned long __init e820_type_to_iomem_type(struct e820_entry *entry) case E820_TYPE_UNUSABLE: /* Fall-through: */ case E820_TYPE_PRAM: /* Fall-through: */ case E820_TYPE_PMEM: /* Fall-through: */ + case E820_TYPE_SPECIAL: /* Fall-through: */ case E820_TYPE_RESERVED: /* Fall-through: */ default: return IORESOURCE_MEM; } @@ -1050,6 +1053,7 @@ static unsigned long __init e820_type_to_iores_desc(struct e820_entry *entry) case E820_TYPE_NVS: return IORES_DESC_ACPI_NV_STORAGE; case E820_TYPE_PMEM: return IORES_DESC_PERSISTENT_MEMORY; case E820_TYPE_PRAM: return IORES_DESC_PERSISTENT_MEMORY_LEGACY; + case E820_TYPE_SPECIAL: return IORES_DESC_APPLICATION_RESERVED; case E820_TYPE_RESERVED_KERN: /* Fall-through: */ case E820_TYPE_RAM: /* Fall-through: */ case E820_TYPE_UNUSABLE: /* Fall-through: */ @@ -1065,13 +1069,14 @@ 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_PRAM: case E820_TYPE_PMEM: + case E820_TYPE_SPECIAL: return false; case E820_TYPE_RESERVED_KERN: case E820_TYPE_RAM: diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index e1cb01a22fa8..d227751f331b 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -139,7 +139,9 @@ 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 (is_efi_special(md)) + e820_type = E820_TYPE_SPECIAL; + else if (md->attribute & EFI_MEMORY_WB) e820_type = E820_TYPE_RAM; else e820_type = E820_TYPE_RESERVED; @@ -753,6 +755,12 @@ static bool should_map_region(efi_memory_desc_t *md) if (IS_ENABLED(CONFIG_X86_32)) return false; + /* + * Special purpose memory is not mapped by default. + */ + if (is_efi_special(md)) + return false; + /* * Map all of RAM so that we can access arguments in the 1:1 * mapping when making EFI runtime calls. diff --git a/include/linux/efi.h b/include/linux/efi.h index 54357a258b35..cecbc2bda1da 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -112,6 +112,7 @@ typedef struct { #define EFI_MEMORY_MORE_RELIABLE \ ((u64)0x0000000000010000ULL) /* higher reliability */ #define EFI_MEMORY_RO ((u64)0x0000000000020000ULL) /* read-only */ +#define EFI_MEMORY_SP ((u64)0x0000000000040000ULL) /* special purpose */ #define EFI_MEMORY_RUNTIME ((u64)0x8000000000000000ULL) /* range requires runtime mapping */ #define EFI_MEMORY_DESCRIPTOR_VERSION 1 @@ -128,6 +129,19 @@ typedef struct { u64 attribute; } efi_memory_desc_t; +#ifdef CONFIG_EFI_SPECIAL_MEMORY +static inline bool is_efi_special(efi_memory_desc_t *md) +{ + return md->type == EFI_CONVENTIONAL_MEMORY + && (md->attribute & EFI_MEMORY_SP); +} +#else +static inline bool is_efi_special(efi_memory_desc_t *md) +{ + return false; +} +#endif + typedef struct { efi_guid_t guid; u32 headersize; diff --git a/include/linux/ioport.h b/include/linux/ioport.h index da0ebaec25f0..2d79841ee9b9 100644 --- a/include/linux/ioport.h +++ b/include/linux/ioport.h @@ -133,6 +133,7 @@ enum { IORES_DESC_PERSISTENT_MEMORY_LEGACY = 5, IORES_DESC_DEVICE_PRIVATE_MEMORY = 6, IORES_DESC_DEVICE_PUBLIC_MEMORY = 7, + IORES_DESC_APPLICATION_RESERVED = 8, }; /* helpers to define resources */ _______________________________________________ Linux-nvdimm mailing list [email protected] https://lists.01.org/mailman/listinfo/linux-nvdimm
