Re: [PATCH 0/2] arm64: Support to find mirrored memory ranges

Re: [PATCH 0/2] arm64: Support to find mirrored memory ranges

[Ard Biesheuvel]

On Thu, 20 Feb 2020 at 04:43, Jing Xiangfeng <jingxiangfeng@huawei.com> wrote:
>
> This series enable finding mirrored memory ranges
> functionality on arm64 platform. This feature has been
> implemented on the x86 platform, so we move some
> functions from x86.
>

Hello Jing Xiangfeng,

Could you explain your use case a bit better? Usually, the firmware is
a better place to make modifications to the EFI memory map.

The reason I am asking is that currently, on ARM and arm64, we never
make *any* changes to the firmware provided tables (EFI system table,
EFI memory map, DT/ACPI/SMBIOS tables etc), in order to ensure that
kexec is idempotent, i.e., it will always see the exact same state as
far as the firmware is concerned. This is a bit different from x86,
where the memory map is already modified for various other reasons, so
using it for fake memory regions is not such a big deal.

Do you see a use case for this in production?

> Jing Xiangfeng (2):
>   efi: allow EFI_FAKE_MEMMAP on arm64 platform
>   arm64/efi: support to find mirrored memory ranges
>
>  arch/x86/include/asm/efi.h      |  5 -----
>  arch/x86/platform/efi/efi.c     | 39 ---------------------------------------
>  drivers/firmware/efi/Kconfig    |  2 +-
>  drivers/firmware/efi/arm-init.c |  2 ++
>  drivers/firmware/efi/efi.c      | 23 +++++++++++++++++++++++
>  drivers/firmware/efi/memmap.c   | 16 ++++++++++++++++
>  include/linux/efi.h             |  5 +++++
>  7 files changed, 47 insertions(+), 45 deletions(-)
>
> --
> 1.8.3.1
>

[PATCH 0/2] arm64: Support to find mirrored memory ranges

[Jing Xiangfeng]

This series enable finding mirrored memory ranges
functionality on arm64 platform. This feature has been
implemented on the x86 platform, so we move some
functions from x86.

Jing Xiangfeng (2):
  efi: allow EFI_FAKE_MEMMAP on arm64 platform
  arm64/efi: support to find mirrored memory ranges

 arch/x86/include/asm/efi.h      |  5 -----
 arch/x86/platform/efi/efi.c     | 39 ---------------------------------------
 drivers/firmware/efi/Kconfig    |  2 +-
 drivers/firmware/efi/arm-init.c |  2 ++
 drivers/firmware/efi/efi.c      | 23 +++++++++++++++++++++++
 drivers/firmware/efi/memmap.c   | 16 ++++++++++++++++
 include/linux/efi.h             |  5 +++++
 7 files changed, 47 insertions(+), 45 deletions(-)

-- 
1.8.3.1

[PATCH 1/2] efi: allow EFI_FAKE_MEMMAP on arm64 platform

[Jing Xiangfeng]

Add a efi_fake_memmap call in efi_init on arm64.This is useful for
debugging of Address Range Mirroring feature on arm64 platform.

Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com>
---
 arch/x86/include/asm/efi.h      |  1 -
 arch/x86/platform/efi/efi.c     | 16 ----------------
 drivers/firmware/efi/Kconfig    |  2 +-
 drivers/firmware/efi/arm-init.c |  1 +
 drivers/firmware/efi/memmap.c   | 16 ++++++++++++++++
 include/linux/efi.h             |  1 +
 6 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 86169a2..127977f 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -158,7 +158,6 @@ 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_print_memmap(void);
 extern void __init efi_memory_uc(u64 addr, unsigned long size);
 extern void __init efi_map_region(efi_memory_desc_t *md);
 extern void __init efi_map_region_fixed(efi_memory_desc_t *md);
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index ae923ee..4c8793d 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -317,22 +317,6 @@ static void __init efi_clean_memmap(void)
 	}
 }
 
-void __init efi_print_memmap(void)
-{
-	efi_memory_desc_t *md;
-	int i = 0;
-
-	for_each_efi_memory_desc(md) {
-		char buf[64];
-
-		pr_info("mem%02u: %s range=[0x%016llx-0x%016llx] (%lluMB)\n",
-			i++, efi_md_typeattr_format(buf, sizeof(buf), md),
-			md->phys_addr,
-			md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1,
-			(md->num_pages >> (20 - EFI_PAGE_SHIFT)));
-	}
-}
-
 static int __init efi_systab_init(u64 phys)
 {
 	int size = efi_enabled(EFI_64BIT) ? sizeof(efi_system_table_64_t)
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index ecc83e2..9cf9a96 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -55,7 +55,7 @@ config EFI_RUNTIME_MAP
 
 config EFI_FAKE_MEMMAP
 	bool "Enable EFI fake memory map"
-	depends on EFI && X86
+	depends on EFI && (X86 || ARM64)
 	default n
 	help
 	  Saying Y here will enable "efi_fake_mem" boot option.
diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
index d99f5b0..ac00e7c 100644
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -265,6 +265,7 @@ void __init efi_init(void)
 	}
 
 	reserve_regions();
+	efi_fake_memmap();
 	efi_esrt_init();
 
 	memblock_reserve(params.mmap & PAGE_MASK,
diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
index 2ff1883..0155bf0 100644
--- a/drivers/firmware/efi/memmap.c
+++ b/drivers/firmware/efi/memmap.c
@@ -376,3 +376,19 @@ void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
 		}
 	}
 }
+
+void __init efi_print_memmap(void)
+{
+	efi_memory_desc_t *md;
+	int i = 0;
+
+	for_each_efi_memory_desc(md) {
+		char buf[64];
+
+		pr_info("mem%02u: %s range=[0x%016llx-0x%016llx] (%lluMB)\n",
+			i++, efi_md_typeattr_format(buf, sizeof(buf), md),
+			md->phys_addr,
+			md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1,
+			(md->num_pages >> (20 - EFI_PAGE_SHIFT)));
+	}
+}
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 7efd707..bf101e5 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1142,6 +1142,7 @@ static inline bool __pure efi_soft_reserve_enabled(void)
 	return IS_ENABLED(CONFIG_EFI_SOFT_RESERVE)
 		&& __efi_soft_reserve_enabled();
 }
+extern void __init efi_print_memmap(void);
 #else
 static inline bool efi_enabled(int feature)
 {
-- 
1.8.3.1

[PATCH 2/2] arm64/efi: support to find mirrored memory ranges

[Jing Xiangfeng]

Commit b05b9f5f9dcf ("x86, mirror: x86 enabling - find
mirrored memory ranges") introduced the efi_find_mirror
on x86. Now we can scan the memory map and find  mirrored
memory ranges by calling efi_find_mirror on arm64 platform.

For example, if "efi_fake_mem=4G@1G:0x10000,4G@7G:0x10000"
is specified, the original (firmware provided) EFI memmap will be
updated so that the specified memory regions have
EFI_MEMORY_MORE_RELIABLE attribute (0x10000):

 <original>
   efi: mem02: [Conventional Memory|   |  |  |  |  |  |  |  |   |WB|
	|  |  ] range=[0x0000000040000000-0x00000001b5035fff] (5968MB)

   efi: mem28: [Conventional Memory|   |  |  |  |  |  |  |  |   |WB|
	|  |  ] range=[0x00000001c0000000-0x00000002843fffff] (3140MB)
   efi: mem29: [Loader Data        |   |  |  |  |  |  |  |  |   |WB|
	|  |  ] range=[0x0000000284400000-0x0000000285f18fff] (27MB)
   efi: mem30: [Conventional Memory|   |  |  |  |  |  |  |  |   |WB|
	|  |  ] range=[0x0000000285f19000-0x000000033fbfffff] (2972MB)
 <updated>
   efi: mem02: [Conventional Memory|   |MR|  |  |  |  |  |  |   |WB|
	|  |  ] range=[0x0000000040000000-0x000000013fffffff] (4096MB)
   efi: mem03: [Conventional Memory|   |  |  |  |  |  |  |  |   |WB|
	|  |  ] range=[0x0000000140000000-0x00000001b5035fff] (1872MB)

   efi: mem29: [Conventional Memory|   |MR|  |  |  |  |  |  |   |WB|
	|  |  ] range=[0x00000001c0000000-0x00000002843fffff] (3140MB)
   efi: mem30: [Loader Data        |   |MR|  |  |  |  |  |  |   |WB|
	|  |  ] range=[0x0000000284400000-0x0000000285f18fff] (27MB)
   efi: mem31: [Conventional Memory|   |MR|  |  |  |  |  |  |   |WB|
	|  |  ] range=[0x0000000285f19000-0x00000002bfffffff] (928MB)

And you will find that the following message is output:

   efi: Memory: 8192M/12352M mirrored memory

Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com>
---
 arch/x86/include/asm/efi.h      |  4 ----
 arch/x86/platform/efi/efi.c     | 23 -----------------------
 drivers/firmware/efi/arm-init.c |  1 +
 drivers/firmware/efi/efi.c      | 23 +++++++++++++++++++++++
 include/linux/efi.h             |  4 ++++
 5 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 127977f..24fa6a9 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -330,7 +330,6 @@ static inline void *efi64_zero_upper(void *p)
 extern bool efi_reboot_required(void);
 extern bool efi_is_table_address(unsigned long phys_addr);
 
-extern void efi_find_mirror(void);
 extern void efi_reserve_boot_services(void);
 #else
 static inline void parse_efi_setup(u64 phys_addr, u32 data_len) {}
@@ -342,9 +341,6 @@ static inline  bool efi_is_table_address(unsigned long phys_addr)
 {
 	return false;
 }
-static inline void efi_find_mirror(void)
-{
-}
 static inline void efi_reserve_boot_services(void)
 {
 }
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 4c8793d..c06603d 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -97,29 +97,6 @@ static int __init setup_add_efi_memmap(char *arg)
 }
 early_param("add_efi_memmap", setup_add_efi_memmap);
 
-void __init efi_find_mirror(void)
-{
-	efi_memory_desc_t *md;
-	u64 mirror_size = 0, total_size = 0;
-
-	if (!efi_enabled(EFI_MEMMAP))
-		return;
-
-	for_each_efi_memory_desc(md) {
-		unsigned long long start = md->phys_addr;
-		unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
-
-		total_size += size;
-		if (md->attribute & EFI_MEMORY_MORE_RELIABLE) {
-			memblock_mark_mirror(start, size);
-			mirror_size += size;
-		}
-	}
-	if (mirror_size)
-		pr_info("Memory: %lldM/%lldM mirrored memory\n",
-			mirror_size>>20, total_size>>20);
-}
-
 /*
  * Tell the kernel about the EFI memory map.  This might include
  * more than the max 128 entries that can fit in the passed in e820
diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
index ac00e7c..f86e73e 100644
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -266,6 +266,7 @@ void __init efi_init(void)
 
 	reserve_regions();
 	efi_fake_memmap();
+	efi_find_mirror();
 	efi_esrt_init();
 
 	memblock_reserve(params.mmap & PAGE_MASK,
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 621220a..664d01d 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -394,6 +394,29 @@ static int __init efisubsys_init(void)
 
 subsys_initcall(efisubsys_init);
 
+void __init efi_find_mirror(void)
+{
+	efi_memory_desc_t *md;
+	u64 mirror_size = 0, total_size = 0;
+
+	if (!efi_enabled(EFI_MEMMAP))
+		return;
+
+	for_each_efi_memory_desc(md) {
+		unsigned long long start = md->phys_addr;
+		unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
+
+		total_size += size;
+		if (md->attribute & EFI_MEMORY_MORE_RELIABLE) {
+			memblock_mark_mirror(start, size);
+			mirror_size += size;
+		}
+	}
+	if (mirror_size)
+		pr_info("Memory: %lldM/%lldM mirrored memory\n",
+			mirror_size>>20, total_size>>20);
+}
+
 /*
  * Find the efi memory descriptor for a given physical address.  Given a
  * physical address, determine if it exists within an EFI Memory Map entry,
diff --git a/include/linux/efi.h b/include/linux/efi.h
index bf101e5..bb32e37 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1143,6 +1143,7 @@ static inline bool __pure efi_soft_reserve_enabled(void)
 		&& __efi_soft_reserve_enabled();
 }
 extern void __init efi_print_memmap(void);
+extern void efi_find_mirror(void);
 #else
 static inline bool efi_enabled(int feature)
 {
@@ -1161,6 +1162,9 @@ static inline bool efi_soft_reserve_enabled(void)
 {
 	return false;
 }
+static inline void efi_find_mirror(void)
+{
+}
 #endif
 
 extern int efi_status_to_err(efi_status_t status);
-- 
1.8.3.1