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: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20230606142637.5171-6-kirill.shutemov@linux.intel.com

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index f3f2d87..e9f99c5 100644 (file)
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -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 */

diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index b51f2a4..e489fef 100644 (file)
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -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

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 7dce06e..d817e7a 100644 (file)
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -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;
 }
 

diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/efi/unaccepted_memory.c
new file mode 100644 (file)
index 0000000..08a9a84
--- /dev/null
+++ b/drivers/firmware/efi/unaccepted_memory.c
@@ -0,0 +1,112 @@
+// 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;
+}

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8ffe451..67cb72d 100644 (file)
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -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;