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 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_APPLICATION_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_SPECIFIC_DAX=y policy is enabled, otherwise treat it as typical ram. - IORES_DESC_APPLICATION_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 "Application 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. Cc: <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Darren Hart <[email protected]> Cc: Andy Shevchenko <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ard Biesheuvel <[email protected]> Reported-by: kbuild test robot <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- arch/x86/Kconfig | 21 +++++++++++++++++++++ arch/x86/boot/compressed/eboot.c | 5 ++++- arch/x86/boot/compressed/kaslr.c | 3 ++- arch/x86/include/asm/e820/types.h | 9 +++++++++ arch/x86/include/asm/efi.h | 14 ++++++++++++++ arch/x86/kernel/e820.c | 12 ++++++++++-- arch/x86/kernel/setup.c | 1 + arch/x86/platform/efi/efi.c | 37 +++++++++++++++++++++++++++++++++---- include/linux/ioport.h | 1 + 9 files changed, 95 insertions(+), 8 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 2bbbd4d1ba31..a786f72905e5 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1955,6 +1955,27 @@ config EFI_MIXED If unsure, say N. +config EFI_APPLICATION_RESERVED + bool "Reserve EFI Specific Purpose Memory" + depends on EFI + ---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 an "Application + 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 544ac4fafd11..a6c96eb6e633 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_application_reserved(d)) + e820_type = E820_TYPE_APPLICATION_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..e8306f452182 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -757,7 +757,8 @@ 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_application_reserved(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..41193c116a1f 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_APPLICATION_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.h b/arch/x86/include/asm/efi.h index 606a4b6a9812..a8a3be68cd61 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -121,6 +121,7 @@ extern void __iomem *__init efi_ioremap(unsigned long addr, unsigned long size, extern struct efi_scratch efi_scratch; extern void __init efi_set_executable(efi_memory_desc_t *md, bool executable); extern int __init efi_memblock_x86_reserve_range(void); +extern void __init efi_find_application_reserved(void); extern pgd_t * __init efi_call_phys_prolog(void); extern void __init efi_call_phys_epilog(pgd_t *save_pgd); extern void __init efi_print_memmap(void); @@ -142,6 +143,19 @@ extern void efi_recover_from_page_fault(unsigned long phys_addr); extern void efi_free_boot_services(void); extern void efi_reserve_boot_services(void); +#ifdef CONFIG_EFI_APPLICATION_RESERVED +static inline bool is_efi_application_reserved(efi_memory_desc_t *md) +{ + return md->type == EFI_CONVENTIONAL_MEMORY + && (md->attribute & EFI_MEMORY_SP); +} +#else +static inline bool is_efi_application_reserved(efi_memory_desc_t *md) +{ + return false; +} +#endif + struct efi_setup_data { u64 fw_vendor; u64 runtime; diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 8f32e705a980..c5b91c2d0661 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -189,6 +189,7 @@ 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_APPLICATION_RESERVED: pr_cont("application reserved"); break; 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; @@ -1036,6 +1037,7 @@ 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_APPLICATION_RESERVED: return "Application Reserved"; case E820_TYPE_RESERVED: return "Reserved"; default: return "Unknown E820 type"; } @@ -1051,6 +1053,7 @@ 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_APPLICATION_RESERVED: /* Fall-through: */ case E820_TYPE_RESERVED: /* Fall-through: */ default: return IORESOURCE_MEM; } @@ -1063,6 +1066,7 @@ 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_APPLICATION_RESERVED: return IORES_DESC_APPLICATION_RESERVED; case E820_TYPE_RESERVED_KERN: /* Fall-through: */ case E820_TYPE_RAM: /* Fall-through: */ case E820_TYPE_UNUSABLE: /* Fall-through: */ @@ -1078,13 +1082,14 @@ 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_APPLICATION_RESERVED: return false; case E820_TYPE_RESERVED_KERN: case E820_TYPE_RAM: @@ -1285,6 +1290,9 @@ void __init e820__memblock_setup(void) if (end != (resource_size_t)end) continue; + if (entry->type == E820_TYPE_APPLICATION_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/kernel/setup.c b/arch/x86/kernel/setup.c index b68fd57a8d26..3b9001b7c951 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1104,6 +1104,7 @@ void __init setup_arch(char **cmdline_p) memblock_set_current_limit(ISA_END_ADDRESS); + efi_find_application_reserved(); e820__memblock_setup(); reserve_bios_regions(); diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 4e8458b1ca30..4b4a9eb6d2c9 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -126,10 +126,18 @@ 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_APPLICATION_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; @@ -142,7 +150,9 @@ 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_application_reserved(md)) + e820_type = E820_TYPE_APPLICATION_RESERVED; + else if (md->attribute & EFI_MEMORY_WB) e820_type = E820_TYPE_RAM; else e820_type = E820_TYPE_RESERVED; @@ -168,9 +178,22 @@ static void __init do_add_efi_memmap(void) e820_type = E820_TYPE_RESERVED; break; } + + if (e820_type == E820_TYPE_APPLICATION_RESERVED) + /* always add E820_TYPE_APPLICATION_RESERVED */; + else if (mode != ADD_EFI_APPLICATION_RESERVED) + continue; + + add++; e820__range_add(start, size, e820_type); } - e820__update_table(e820_table); + if (add) + e820__update_table(e820_table); +} + +void __init efi_find_application_reserved(void) +{ + do_add_efi_memmap(ADD_EFI_APPLICATION_RESERVED); } int __init efi_memblock_x86_reserve_range(void) @@ -203,7 +226,7 @@ int __init efi_memblock_x86_reserve_range(void) return rv; if (add_efi_memmap) - do_add_efi_memmap(); + do_add_efi_memmap(ADD_EFI_ALL); WARN(efi.memmap.desc_version != 1, "Unexpected EFI_MEMORY_DESCRIPTOR version %ld", @@ -756,6 +779,12 @@ static bool should_map_region(efi_memory_desc_t *md) if (IS_ENABLED(CONFIG_X86_32)) return false; + /* + * Specific purpose memory is reserved by default. + */ + if (is_efi_application_reserved(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/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 */
