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@xxxxxxxxxxxxxxx>
Reviewed-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
arch/x86/platform/efi/efi.c | 3 +
drivers/firmware/efi/Makefile | 1 +
drivers/firmware/efi/efi.c | 25 +++++
drivers/firmware/efi/unaccepted_memory.c | 112 +++++++++++++++++++++++
include/linux/efi.h | 1 +
5 files changed, 142 insertions(+)
create mode 100644 drivers/firmware/efi/unaccepted_memory.c
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index f3f2d87cce1b..e9f99c56f3ce 100644
--- 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 b51f2a4c821e..e489fefd23da 100644
--- 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 7dce06e419c5..d817e7afd266 100644
--- 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
index 000000000000..08a9a843550a
--- /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 29cc622910da..9864f9c00da2 100644
--- 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;
--
2.39.3
