[PATCH 0/2] efi: Add support for EFI_MEMORY_HOT_PLUGGABLE

[PATCH 0/2] efi: Add support for EFI_MEMORY_HOT_PLUGGABLE

[Ard Biesheuvel]

From: Ard Biesheuvel <ardb@kernel.org>

Adopt the EFI_MEMORY_HOT_PLUGGABLE memory attribute definition from UEFI
2.11 and test for it where appropriate.

Ard Biesheuvel (2):
  efi: Avoid cold plugged memory for placing the kernel
  efi: Use BIT_ULL() constants for memory attributes

 drivers/firmware/efi/efi.c                 |  6 ++--
 drivers/firmware/efi/libstub/randomalloc.c |  3 ++
 drivers/firmware/efi/libstub/relocate.c    |  3 ++
 include/linux/efi.h                        | 31 ++++++++++----------
 4 files changed, 26 insertions(+), 17 deletions(-)

-- 
2.48.1.362.g079036d154-goog

[PATCH 1/2] efi: Avoid cold plugged memory for placing the kernel

[Ard Biesheuvel]

From: Ard Biesheuvel <ardb@kernel.org>

UEFI 2.11 introduced EFI_MEMORY_HOT_PLUGGABLE to annotate system memory
regions that are 'cold plugged' at boot, i.e., hot pluggable memory that
is available from early boot, and described as system RAM by the
firmware.

Existing loaders and EFI applications running in the boot context will
happily use this memory for allocating data structures that cannot be
freed or moved at runtime, and this prevents the memory from being
unplugged. Going forward, the new EFI_MEMORY_HOT_PLUGGABLE attribute
should be tested, and memory annotated as such should be avoided for
such allocations.

In the EFI stub, there are a couple of occurrences where, instead of the
high-level AllocatePages() UEFI boot service, a low-level code sequence
is used that traverses the EFI memory map and carves out the requested
number of pages from a free region. This is needed, e.g., for allocating
as low as possible, or for allocating pages at random.

While AllocatePages() should presumably avoid special purpose memory and
cold plugged regions, this manual approach needs to incorporate this
logic itself, in order to prevent the kernel itself from ending up in a
hot unpluggable region, preventing it from being unplugged.

So add the EFI_MEMORY_HOTPLUGGABLE macro definition, and check for it
where appropriate.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/firmware/efi/efi.c                 | 6 ++++--
 drivers/firmware/efi/libstub/randomalloc.c | 3 +++
 drivers/firmware/efi/libstub/relocate.c    | 3 +++
 include/linux/efi.h                        | 1 +
 4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 8296bf985d1d..7309394b8fc9 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -934,13 +934,15 @@ char * __init efi_md_typeattr_format(char *buf, size_t size,
 		     EFI_MEMORY_WB | EFI_MEMORY_UCE | EFI_MEMORY_RO |
 		     EFI_MEMORY_WP | EFI_MEMORY_RP | EFI_MEMORY_XP |
 		     EFI_MEMORY_NV | EFI_MEMORY_SP | EFI_MEMORY_CPU_CRYPTO |
-		     EFI_MEMORY_RUNTIME | EFI_MEMORY_MORE_RELIABLE))
+		     EFI_MEMORY_MORE_RELIABLE | EFI_MEMORY_HOT_PLUGGABLE |
+		     EFI_MEMORY_RUNTIME))
 		snprintf(pos, size, "|attr=0x%016llx]",
 			 (unsigned long long)attr);
 	else
 		snprintf(pos, size,
-			 "|%3s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
+			 "|%3s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
 			 attr & EFI_MEMORY_RUNTIME		? "RUN" : "",
+			 attr & EFI_MEMORY_HOT_PLUGGABLE	? "HP"  : "",
 			 attr & EFI_MEMORY_MORE_RELIABLE	? "MR"  : "",
 			 attr & EFI_MEMORY_CPU_CRYPTO   	? "CC"  : "",
 			 attr & EFI_MEMORY_SP			? "SP"  : "",
diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c
index e5872e38d9a4..5a732018be36 100644
--- a/drivers/firmware/efi/libstub/randomalloc.c
+++ b/drivers/firmware/efi/libstub/randomalloc.c
@@ -25,6 +25,9 @@ static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
 	if (md->type != EFI_CONVENTIONAL_MEMORY)
 		return 0;
 
+	if (md->attribute & EFI_MEMORY_HOT_PLUGGABLE)
+		return 0;
+
 	if (efi_soft_reserve_enabled() &&
 	    (md->attribute & EFI_MEMORY_SP))
 		return 0;
diff --git a/drivers/firmware/efi/libstub/relocate.c b/drivers/firmware/efi/libstub/relocate.c
index 99b45d1cd624..d4264bfb6dc1 100644
--- a/drivers/firmware/efi/libstub/relocate.c
+++ b/drivers/firmware/efi/libstub/relocate.c
@@ -53,6 +53,9 @@ efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
 		if (desc->type != EFI_CONVENTIONAL_MEMORY)
 			continue;
 
+		if (desc->attribute & EFI_MEMORY_HOT_PLUGGABLE)
+			continue;
+
 		if (efi_soft_reserve_enabled() &&
 		    (desc->attribute & EFI_MEMORY_SP))
 			continue;
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 053c57e61869..db293d7de686 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -128,6 +128,7 @@ typedef	struct {
 #define EFI_MEMORY_RO		((u64)0x0000000000020000ULL)	/* read-only */
 #define EFI_MEMORY_SP		((u64)0x0000000000040000ULL)	/* soft reserved */
 #define EFI_MEMORY_CPU_CRYPTO	((u64)0x0000000000080000ULL)	/* supports encryption */
+#define EFI_MEMORY_HOT_PLUGGABLE	BIT_ULL(20)	/* supports unplugging at runtime */
 #define EFI_MEMORY_RUNTIME	((u64)0x8000000000000000ULL)	/* range requires runtime mapping */
 #define EFI_MEMORY_DESCRIPTOR_VERSION	1
 
-- 
2.48.1.362.g079036d154-goog

[PATCH 2/2] efi: Use BIT_ULL() constants for memory attributes

[Ard Biesheuvel]

From: Ard Biesheuvel <ardb@kernel.org>

For legibility, use the existing BIT_ULL() to generate the u64 type EFI
memory attribute macros.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 include/linux/efi.h | 30 ++++++++++----------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/include/linux/efi.h b/include/linux/efi.h
index db293d7de686..7d63d1d75f22 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -114,22 +114,22 @@ typedef	struct {
 #define EFI_MAX_MEMORY_TYPE		16
 
 /* Attribute values: */
-#define EFI_MEMORY_UC		((u64)0x0000000000000001ULL)	/* uncached */
-#define EFI_MEMORY_WC		((u64)0x0000000000000002ULL)	/* write-coalescing */
-#define EFI_MEMORY_WT		((u64)0x0000000000000004ULL)	/* write-through */
-#define EFI_MEMORY_WB		((u64)0x0000000000000008ULL)	/* write-back */
-#define EFI_MEMORY_UCE		((u64)0x0000000000000010ULL)	/* uncached, exported */
-#define EFI_MEMORY_WP		((u64)0x0000000000001000ULL)	/* write-protect */
-#define EFI_MEMORY_RP		((u64)0x0000000000002000ULL)	/* read-protect */
-#define EFI_MEMORY_XP		((u64)0x0000000000004000ULL)	/* execute-protect */
-#define EFI_MEMORY_NV		((u64)0x0000000000008000ULL)	/* non-volatile */
-#define EFI_MEMORY_MORE_RELIABLE \
-				((u64)0x0000000000010000ULL)	/* higher reliability */
-#define EFI_MEMORY_RO		((u64)0x0000000000020000ULL)	/* read-only */
-#define EFI_MEMORY_SP		((u64)0x0000000000040000ULL)	/* soft reserved */
-#define EFI_MEMORY_CPU_CRYPTO	((u64)0x0000000000080000ULL)	/* supports encryption */
+#define EFI_MEMORY_UC			BIT_ULL(0)	/* uncached */
+#define EFI_MEMORY_WC			BIT_ULL(1)	/* write-coalescing */
+#define EFI_MEMORY_WT			BIT_ULL(2)	/* write-through */
+#define EFI_MEMORY_WB			BIT_ULL(3)	/* write-back */
+#define EFI_MEMORY_UCE			BIT_ULL(4)	/* uncached, exported */
+#define EFI_MEMORY_WP			BIT_ULL(12)	/* write-protect */
+#define EFI_MEMORY_RP			BIT_ULL(13)	/* read-protect */
+#define EFI_MEMORY_XP			BIT_ULL(14)	/* execute-protect */
+#define EFI_MEMORY_NV			BIT_ULL(15)	/* non-volatile */
+#define EFI_MEMORY_MORE_RELIABLE	BIT_ULL(16)	/* higher reliability */
+#define EFI_MEMORY_RO			BIT_ULL(17)	/* read-only */
+#define EFI_MEMORY_SP			BIT_ULL(18)	/* soft reserved */
+#define EFI_MEMORY_CPU_CRYPTO		BIT_ULL(19)	/* supports encryption */
 #define EFI_MEMORY_HOT_PLUGGABLE	BIT_ULL(20)	/* supports unplugging at runtime */
-#define EFI_MEMORY_RUNTIME	((u64)0x8000000000000000ULL)	/* range requires runtime mapping */
+#define EFI_MEMORY_RUNTIME		BIT_ULL(63)	/* range requires runtime mapping */
+
 #define EFI_MEMORY_DESCRIPTOR_VERSION	1
 
 #define EFI_PAGE_SHIFT		12
-- 
2.48.1.362.g079036d154-goog