[PATCH 0/3] efi/memattr: Improve the efi_memattr_init function.

[PATCH 0/3] efi/memattr: Improve the efi_memattr_init function.

[Breno Leitao]

After 8fbe4c49c0ccac ("efi/memattr: Ignore table if the size is clearly
bogus") landed, we are seeing a lot of firmware bugs in the Meta fleet.

There is an indication that this might be related to kexec, but, more on
this later.

While debugging the current issue, I modified the efi_memattr_init()
function in a way that I think it might be useful upstream.

The changes will help to detect EFI problems at scale, by making it more
verbose and easy to categorize early FW bugs.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
Breno Leitao (3):
      efi/memattr: Convert efi_memattr_init() return type to void
      efi/memattr: Add FW_BUG prefix to firmware error messages
      efi/memattr: Include EFI memmap size in corruption warnings

 drivers/firmware/efi/memattr.c | 20 ++++++++++----------
 include/linux/efi.h            |  2 +-
 2 files changed, 11 insertions(+), 11 deletions(-)
---
base-commit: c8e17339185951589d109ba81e8854513ab3d26f
change-id: 20250106-efi_fw_bug-2b62e9a41899

Best regards,
-- 
Breno Leitao <leitao@debian.org>

[PATCH 1/3] efi/memattr: Convert efi_memattr_init() return type to void

[Breno Leitao]

The efi_memattr_init() function's return values (0 and -ENOMEM) are never
checked by callers. Convert the function to return void since the return
status is unused.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 drivers/firmware/efi/memattr.c | 7 +++----
 include/linux/efi.h            | 2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
index c38b1a335590d4f6b75012414a936e66f22dcd9a..e727cc5909cb676c47d787ab0d7754b6fdcb493d 100644
--- a/drivers/firmware/efi/memattr.c
+++ b/drivers/firmware/efi/memattr.c
@@ -19,19 +19,19 @@ unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;
  * Reserve the memory associated with the Memory Attributes configuration
  * table, if it exists.
  */
-int __init efi_memattr_init(void)
+void __init efi_memattr_init(void)
 {
 	efi_memory_attributes_table_t *tbl;
 	unsigned long size;
 
 	if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)
-		return 0;
+		return;
 
 	tbl = early_memremap(efi_mem_attr_table, sizeof(*tbl));
 	if (!tbl) {
 		pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
 		       efi_mem_attr_table);
-		return -ENOMEM;
+		return;
 	}
 
 	if (tbl->version > 2) {
@@ -61,7 +61,6 @@ int __init efi_memattr_init(void)
 
 unmap:
 	early_memunmap(tbl, sizeof(*tbl));
-	return 0;
 }
 
 /*
diff --git a/include/linux/efi.h b/include/linux/efi.h
index e5815867aba971a64091bf0ea017d95f21115124..5404939df81bdc870f6ee5d0fb7cbb53394a2304 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -771,7 +771,7 @@ extern unsigned long efi_mem_attr_table;
  */
 typedef int (*efi_memattr_perm_setter)(struct mm_struct *, efi_memory_desc_t *, bool);
 
-extern int efi_memattr_init(void);
+extern void efi_memattr_init(void);
 extern int efi_memattr_apply_permissions(struct mm_struct *mm,
 					 efi_memattr_perm_setter fn);
 

-- 
2.43.5

[PATCH 2/3] efi/memattr: Add FW_BUG prefix to firmware error messages

[Breno Leitao]

Tag firmware-related error messages with FW_BUG in efi_memattr_init() to
make EFI firmware issues more discoverable and consistent with kernel
error reporting conventions.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 drivers/firmware/efi/memattr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
index e727cc5909cb676c47d787ab0d7754b6fdcb493d..5f83cdea88b05cb325e9f90c14a0048131e53cfa 100644
--- a/drivers/firmware/efi/memattr.c
+++ b/drivers/firmware/efi/memattr.c
@@ -29,13 +29,13 @@ void __init efi_memattr_init(void)
 
 	tbl = early_memremap(efi_mem_attr_table, sizeof(*tbl));
 	if (!tbl) {
-		pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
+		pr_err(FW_BUG "Failed to map EFI Memory Attributes table @ 0x%lx\n",
 		       efi_mem_attr_table);
 		return;
 	}
 
 	if (tbl->version > 2) {
-		pr_warn("Unexpected EFI Memory Attributes table version %d\n",
+		pr_warn(FW_BUG "Unexpected EFI Memory Attributes table version %d\n",
 			tbl->version);
 		goto unmap;
 	}

-- 
2.43.5

[PATCH 3/3] efi/memattr: Include EFI memmap size in corruption warnings

[Breno Leitao]

Add EFI memory map size to warning messages when a corrupted Memory
Attributes Table is detected, making it easier to diagnose firmware issues.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 drivers/firmware/efi/memattr.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
index 5f83cdea88b05cb325e9f90c14a0048131e53cfa..2c276bcc0df48352bec6cd96b69edf67a16f6069 100644
--- a/drivers/firmware/efi/memattr.c
+++ b/drivers/firmware/efi/memattr.c
@@ -22,7 +22,7 @@ unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;
 void __init efi_memattr_init(void)
 {
 	efi_memory_attributes_table_t *tbl;
-	unsigned long size;
+	unsigned long size, efi_map_size;
 
 	if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)
 		return;
@@ -49,9 +49,10 @@ void __init efi_memattr_init(void)
 	 * just be ignored altogether.
 	 */
 	size = tbl->num_entries * tbl->desc_size;
-	if (size > 3 * efi.memmap.nr_map * efi.memmap.desc_size) {
-		pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u)\n",
-			tbl->version, tbl->desc_size, tbl->num_entries);
+	efi_map_size = efi.memmap.nr_map * efi.memmap.desc_size;
+	if (size > 3 * efi_map_size) {
+		pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u, efi_map_size == %lu)\n",
+			tbl->version, tbl->desc_size, tbl->num_entries, efi_map_size);
 		goto unmap;
 	}
 

-- 
2.43.5

Re: [PATCH 1/3] efi/memattr: Convert efi_memattr_init() return type to void

[Ard Biesheuvel]

Hello Breno,

On Mon, 6 Jan 2025 at 20:03, Breno Leitao <leitao@debian.org> wrote:
>
> The efi_memattr_init() function's return values (0 and -ENOMEM) are never
> checked by callers. Convert the function to return void since the return
> status is unused.
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  drivers/firmware/efi/memattr.c | 7 +++----
>  include/linux/efi.h            | 2 +-
>  2 files changed, 4 insertions(+), 5 deletions(-)
>

Acked-by: Ard Biesheuvel <ardb@kernel.org>

> diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
> index c38b1a335590d4f6b75012414a936e66f22dcd9a..e727cc5909cb676c47d787ab0d7754b6fdcb493d 100644
> --- a/drivers/firmware/efi/memattr.c
> +++ b/drivers/firmware/efi/memattr.c
> @@ -19,19 +19,19 @@ unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;
>   * Reserve the memory associated with the Memory Attributes configuration
>   * table, if it exists.
>   */
> -int __init efi_memattr_init(void)
> +void __init efi_memattr_init(void)
>  {
>         efi_memory_attributes_table_t *tbl;
>         unsigned long size;
>
>         if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)
> -               return 0;
> +               return;
>
>         tbl = early_memremap(efi_mem_attr_table, sizeof(*tbl));
>         if (!tbl) {
>                 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
>                        efi_mem_attr_table);
> -               return -ENOMEM;
> +               return;
>         }
>
>         if (tbl->version > 2) {
> @@ -61,7 +61,6 @@ int __init efi_memattr_init(void)
>
>  unmap:
>         early_memunmap(tbl, sizeof(*tbl));
> -       return 0;
>  }
>
>  /*
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index e5815867aba971a64091bf0ea017d95f21115124..5404939df81bdc870f6ee5d0fb7cbb53394a2304 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -771,7 +771,7 @@ extern unsigned long efi_mem_attr_table;
>   */
>  typedef int (*efi_memattr_perm_setter)(struct mm_struct *, efi_memory_desc_t *, bool);
>
> -extern int efi_memattr_init(void);
> +extern void efi_memattr_init(void);
>  extern int efi_memattr_apply_permissions(struct mm_struct *mm,
>                                          efi_memattr_perm_setter fn);
>
>
> --
> 2.43.5
>
>

Re: [PATCH 2/3] efi/memattr: Add FW_BUG prefix to firmware error messages

[Ard Biesheuvel]

On Mon, 6 Jan 2025 at 20:03, Breno Leitao <leitao@debian.org> wrote:
>
> Tag firmware-related error messages with FW_BUG in efi_memattr_init() to
> make EFI firmware issues more discoverable and consistent with kernel
> error reporting conventions.
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  drivers/firmware/efi/memattr.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
> index e727cc5909cb676c47d787ab0d7754b6fdcb493d..5f83cdea88b05cb325e9f90c14a0048131e53cfa 100644
> --- a/drivers/firmware/efi/memattr.c
> +++ b/drivers/firmware/efi/memattr.c
> @@ -29,13 +29,13 @@ void __init efi_memattr_init(void)
>
>         tbl = early_memremap(efi_mem_attr_table, sizeof(*tbl));
>         if (!tbl) {
> -               pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
> +               pr_err(FW_BUG "Failed to map EFI Memory Attributes table @ 0x%lx\n",
>                        efi_mem_attr_table);
>                 return;
>         }
>
>         if (tbl->version > 2) {
> -               pr_warn("Unexpected EFI Memory Attributes table version %d\n",
> +               pr_warn(FW_BUG "Unexpected EFI Memory Attributes table version %d\n",
>                         tbl->version);
>                 goto unmap;
>         }
>

Neither of these are firmware bugs, so we shouldn't report them as such.

(A future version of the table could be > 2, and we wouldn't know how
to deal with that. That doesn't mean there is anything wrong with the
firmware, it only means the kernel is too old)

Re: [PATCH 3/3] efi/memattr: Include EFI memmap size in corruption warnings

[Ard Biesheuvel]

On Mon, 6 Jan 2025 at 20:03, Breno Leitao <leitao@debian.org> wrote:
>
> Add EFI memory map size to warning messages when a corrupted Memory
> Attributes Table is detected, making it easier to diagnose firmware issues.
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  drivers/firmware/efi/memattr.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
> index 5f83cdea88b05cb325e9f90c14a0048131e53cfa..2c276bcc0df48352bec6cd96b69edf67a16f6069 100644
> --- a/drivers/firmware/efi/memattr.c
> +++ b/drivers/firmware/efi/memattr.c
> @@ -22,7 +22,7 @@ unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;
>  void __init efi_memattr_init(void)
>  {
>         efi_memory_attributes_table_t *tbl;
> -       unsigned long size;
> +       unsigned long size, efi_map_size;
>
>         if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)
>                 return;
> @@ -49,9 +49,10 @@ void __init efi_memattr_init(void)
>          * just be ignored altogether.
>          */
>         size = tbl->num_entries * tbl->desc_size;
> -       if (size > 3 * efi.memmap.nr_map * efi.memmap.desc_size) {
> -               pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u)\n",
> -                       tbl->version, tbl->desc_size, tbl->num_entries);
> +       efi_map_size = efi.memmap.nr_map * efi.memmap.desc_size;
> +       if (size > 3 * efi_map_size) {
> +               pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u, efi_map_size == %lu)\n",
> +                       tbl->version, tbl->desc_size, tbl->num_entries, efi_map_size);
>                 goto unmap;
>         }
>
>

Hello Breno,

I don't mind the patch per se, but I don't think it is terribly useful either.

Could you explain how this helps?

Re: [PATCH 3/3] efi/memattr: Include EFI memmap size in corruption warnings

[Breno Leitao]

Hello Ard,

On Tue, Jan 07, 2025 at 12:24:03PM +0100, Ard Biesheuvel wrote:
> On Mon, 6 Jan 2025 at 20:03, Breno Leitao <leitao@debian.org> wrote:
> >
> > Add EFI memory map size to warning messages when a corrupted Memory
> > Attributes Table is detected, making it easier to diagnose firmware issues.
> >
> > Signed-off-by: Breno Leitao <leitao@debian.org>
> > ---
> >  drivers/firmware/efi/memattr.c | 9 +++++----
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
> > index 5f83cdea88b05cb325e9f90c14a0048131e53cfa..2c276bcc0df48352bec6cd96b69edf67a16f6069 100644
> > --- a/drivers/firmware/efi/memattr.c
> > +++ b/drivers/firmware/efi/memattr.c
> > @@ -22,7 +22,7 @@ unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;
> >  void __init efi_memattr_init(void)
> >  {
> >         efi_memory_attributes_table_t *tbl;
> > -       unsigned long size;
> > +       unsigned long size, efi_map_size;
> >
> >         if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)
> >                 return;
> > @@ -49,9 +49,10 @@ void __init efi_memattr_init(void)
> >          * just be ignored altogether.
> >          */
> >         size = tbl->num_entries * tbl->desc_size;
> > -       if (size > 3 * efi.memmap.nr_map * efi.memmap.desc_size) {
> > -               pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u)\n",
> > -                       tbl->version, tbl->desc_size, tbl->num_entries);
> > +       efi_map_size = efi.memmap.nr_map * efi.memmap.desc_size;
> > +       if (size > 3 * efi_map_size) {
> > +               pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u, efi_map_size == %lu)\n",
> > +                       tbl->version, tbl->desc_size, tbl->num_entries, efi_map_size);
> >                 goto unmap;
> >         }
> >
> >
> 
> Hello Breno,
> 
> I don't mind the patch per se, but I don't think it is terribly useful either.
> 
> Could you explain how this helps?

We are seeing a bunch of `Corrupted EFI Memory Attributes Table
detected!` in the Meta fleet, and this is something we are
investigating.

We highly think this is related to some kexec overwrites, and when we
get here, the EFI table is completely garbage. I haven't seen this
problem on cold boot.

Here are sof the instances I see:

	efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 0, desc_size == 18058, num_entries == 33554432)
	efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 1, desc_size == 2072184435, num_entries == 3248688968)
	efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 0, desc_size == 83886080, num_entries == 304)
	efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 2, desc_size == 48, num_entries == 40)	

Anyway, back to you question, this patch helped us to narrow down and
find where the problem was, by printing all variables taken in
consideration to get the conclusion that the firmware is buggy.

Regarding the problem, Usama and I are suspecting that it might be
related to some 77d48d39e99170 ("efistub/tpm: Use ACPI reclaim memory for
event log to avoid corruption"), but at this time with memattr table, where it
might not preserved during kexec(?).

Thanks,
--breno

Re: [PATCH 3/3] efi/memattr: Include EFI memmap size in corruption warnings

[Ard Biesheuvel]

On Tue, 7 Jan 2025 at 13:05, Breno Leitao <leitao@debian.org> wrote:
>
> Hello Ard,
>
> On Tue, Jan 07, 2025 at 12:24:03PM +0100, Ard Biesheuvel wrote:
> > On Mon, 6 Jan 2025 at 20:03, Breno Leitao <leitao@debian.org> wrote:
> > >
> > > Add EFI memory map size to warning messages when a corrupted Memory
> > > Attributes Table is detected, making it easier to diagnose firmware issues.
> > >
> > > Signed-off-by: Breno Leitao <leitao@debian.org>
> > > ---
> > >  drivers/firmware/efi/memattr.c | 9 +++++----
> > >  1 file changed, 5 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
> > > index 5f83cdea88b05cb325e9f90c14a0048131e53cfa..2c276bcc0df48352bec6cd96b69edf67a16f6069 100644
> > > --- a/drivers/firmware/efi/memattr.c
> > > +++ b/drivers/firmware/efi/memattr.c
> > > @@ -22,7 +22,7 @@ unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;
> > >  void __init efi_memattr_init(void)
> > >  {
> > >         efi_memory_attributes_table_t *tbl;
> > > -       unsigned long size;
> > > +       unsigned long size, efi_map_size;
> > >
> > >         if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)
> > >                 return;
> > > @@ -49,9 +49,10 @@ void __init efi_memattr_init(void)
> > >          * just be ignored altogether.
> > >          */
> > >         size = tbl->num_entries * tbl->desc_size;
> > > -       if (size > 3 * efi.memmap.nr_map * efi.memmap.desc_size) {
> > > -               pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u)\n",
> > > -                       tbl->version, tbl->desc_size, tbl->num_entries);
> > > +       efi_map_size = efi.memmap.nr_map * efi.memmap.desc_size;
> > > +       if (size > 3 * efi_map_size) {
> > > +               pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u, efi_map_size == %lu)\n",
> > > +                       tbl->version, tbl->desc_size, tbl->num_entries, efi_map_size);
> > >                 goto unmap;
> > >         }
> > >
> > >
> >
> > Hello Breno,
> >
> > I don't mind the patch per se, but I don't think it is terribly useful either.
> >
> > Could you explain how this helps?
>
> We are seeing a bunch of `Corrupted EFI Memory Attributes Table
> detected!` in the Meta fleet, and this is something we are
> investigating.
>
> We highly think this is related to some kexec overwrites, and when we
> get here, the EFI table is completely garbage. I haven't seen this
> problem on cold boot.
>

It likely means the memory is not reserved correctly.

Could you check whether this

--- a/drivers/firmware/efi/memattr.c
+++ b/drivers/firmware/efi/memattr.c
@@ -56,7 +56,7 @@ int __init efi_memattr_init(void)
        }

        tbl_size = sizeof(*tbl) + size;
-       memblock_reserve(efi_mem_attr_table, tbl_size);
+       efi_mem_reserve(efi_mem_attr_table, tbl_size);
        set_bit(EFI_MEM_ATTR, &efi.flags);

 unmap:


makes any difference?


> Here are sof the instances I see:
>
>         efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 0, desc_size == 18058, num_entries == 33554432)
>         efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 1, desc_size == 2072184435, num_entries == 3248688968)
>         efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 0, desc_size == 83886080, num_entries == 304)
>         efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 2, desc_size == 48, num_entries == 40)
>

The last one looks like a false positive: each of those values seems
perfectly reasonable.

Any chance you could dump the memory map and this table (boot using
efi=debug) on this system?


> Anyway, back to you question, this patch helped us to narrow down and
> find where the problem was, by printing all variables taken in
> consideration to get the conclusion that the firmware is buggy.
>

Fair enough.

> Regarding the problem, Usama and I are suspecting that it might be
> related to some 77d48d39e99170 ("efistub/tpm: Use ACPI reclaim memory for
> event log to avoid corruption"), but at this time with memattr table, where it
> might not preserved during kexec(?).
>

Please see the suggestion above.

Re: [PATCH 3/3] efi/memattr: Include EFI memmap size in corruption warnings

[Usama Arif]

On 09/01/2025 14:48, Ard Biesheuvel wrote:
> On Tue, 7 Jan 2025 at 13:05, Breno Leitao <leitao@debian.org> wrote:
>>
>> Hello Ard,
>>
>> On Tue, Jan 07, 2025 at 12:24:03PM +0100, Ard Biesheuvel wrote:
>>> On Mon, 6 Jan 2025 at 20:03, Breno Leitao <leitao@debian.org> wrote:
>>>>
>>>> Add EFI memory map size to warning messages when a corrupted Memory
>>>> Attributes Table is detected, making it easier to diagnose firmware issues.
>>>>
>>>> Signed-off-by: Breno Leitao <leitao@debian.org>
>>>> ---
>>>>  drivers/firmware/efi/memattr.c | 9 +++++----
>>>>  1 file changed, 5 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
>>>> index 5f83cdea88b05cb325e9f90c14a0048131e53cfa..2c276bcc0df48352bec6cd96b69edf67a16f6069 100644
>>>> --- a/drivers/firmware/efi/memattr.c
>>>> +++ b/drivers/firmware/efi/memattr.c
>>>> @@ -22,7 +22,7 @@ unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;
>>>>  void __init efi_memattr_init(void)
>>>>  {
>>>>         efi_memory_attributes_table_t *tbl;
>>>> -       unsigned long size;
>>>> +       unsigned long size, efi_map_size;
>>>>
>>>>         if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)
>>>>                 return;
>>>> @@ -49,9 +49,10 @@ void __init efi_memattr_init(void)
>>>>          * just be ignored altogether.
>>>>          */
>>>>         size = tbl->num_entries * tbl->desc_size;
>>>> -       if (size > 3 * efi.memmap.nr_map * efi.memmap.desc_size) {
>>>> -               pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u)\n",
>>>> -                       tbl->version, tbl->desc_size, tbl->num_entries);
>>>> +       efi_map_size = efi.memmap.nr_map * efi.memmap.desc_size;
>>>> +       if (size > 3 * efi_map_size) {
>>>> +               pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u, efi_map_size == %lu)\n",
>>>> +                       tbl->version, tbl->desc_size, tbl->num_entries, efi_map_size);
>>>>                 goto unmap;
>>>>         }
>>>>
>>>>
>>>
>>> Hello Breno,
>>>
>>> I don't mind the patch per se, but I don't think it is terribly useful either.
>>>
>>> Could you explain how this helps?
>>
>> We are seeing a bunch of `Corrupted EFI Memory Attributes Table
>> detected!` in the Meta fleet, and this is something we are
>> investigating.
>>
>> We highly think this is related to some kexec overwrites, and when we
>> get here, the EFI table is completely garbage. I haven't seen this
>> problem on cold boot.
>>
> 
> It likely means the memory is not reserved correctly.
> 
> Could you check whether this
> 
> --- a/drivers/firmware/efi/memattr.c
> +++ b/drivers/firmware/efi/memattr.c
> @@ -56,7 +56,7 @@ int __init efi_memattr_init(void)
>         }
> 
>         tbl_size = sizeof(*tbl) + size;
> -       memblock_reserve(efi_mem_attr_table, tbl_size);
> +       efi_mem_reserve(efi_mem_attr_table, tbl_size);
>         set_bit(EFI_MEM_ATTR, &efi.flags);
> 
>  unmap:
> 
> 
> makes any difference?
> 
Hi Ard,

Thanks for the reply!

I have further explained the problems and possible solutions in
https://lore.kernel.org/all/20250108215957.3437660-1-usamaarif642@gmail.com/.

I am assuming the above diff is to solve problem 2 that I have described in the patches.
I haven't tested it, because its a bit difficult to reproduce problem 2, but I think
the above diff might not make a difference? efi_mem_reserve changes e820_table,
while /sys/firmware/memmap uses e820_table_firmware. An alternate solution might be
to change /sys/firmware/memmap to e820_table. I didnt go down that route because,
you would be changing what the kernel exposes to userspace, which might not be the
right thing.

Thanks,
Usama


> 
>> Here are sof the instances I see:
>>
>>         efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 0, desc_size == 18058, num_entries == 33554432)
>>         efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 1, desc_size == 2072184435, num_entries == 3248688968)
>>         efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 0, desc_size == 83886080, num_entries == 304)
>>         efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 2, desc_size == 48, num_entries == 40)
>>
> 
> The last one looks like a false positive: each of those values seems
> perfectly reasonable.
> 
> Any chance you could dump the memory map and this table (boot using
> efi=debug) on this system?
> 
> 
>> Anyway, back to you question, this patch helped us to narrow down and
>> find where the problem was, by printing all variables taken in
>> consideration to get the conclusion that the firmware is buggy.
>>
> 
> Fair enough.
> 
>> Regarding the problem, Usama and I are suspecting that it might be
>> related to some 77d48d39e99170 ("efistub/tpm: Use ACPI reclaim memory for
>> event log to avoid corruption"), but at this time with memattr table, where it
>> might not preserved during kexec(?).
>>
> 
> Please see the suggestion above.

Re: [PATCH 3/3] efi/memattr: Include EFI memmap size in corruption warnings

[Breno Leitao]

On Thu, Jan 09, 2025 at 03:48:56PM +0100, Ard Biesheuvel wrote:
> On Tue, 7 Jan 2025 at 13:05, Breno Leitao <leitao@debian.org> wrote:
> > On Tue, Jan 07, 2025 at 12:24:03PM +0100, Ard Biesheuvel wrote:


> > We are seeing a bunch of `Corrupted EFI Memory Attributes Table
> > detected!` in the Meta fleet, and this is something we are
> > investigating.
> >
> > We highly think this is related to some kexec overwrites, and when we
> > get here, the EFI table is completely garbage. I haven't seen this
> > problem on cold boot.
> >
> 
> It likely means the memory is not reserved correctly.
> 
> Could you check whether this
> 
> --- a/drivers/firmware/efi/memattr.c
> +++ b/drivers/firmware/efi/memattr.c
> @@ -56,7 +56,7 @@ int __init efi_memattr_init(void)
>         }
> 
>         tbl_size = sizeof(*tbl) + size;
> -       memblock_reserve(efi_mem_attr_table, tbl_size);
> +       efi_mem_reserve(efi_mem_attr_table, tbl_size);
>         set_bit(EFI_MEM_ATTR, &efi.flags);
> 
>  unmap:
> 
> 
> makes any difference?

It doesn't seem so. This is how I tested it.

I've cherry-picked it on top of Linus' master eea6e4b4dfb8 ("Merge tag
'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi"), 
and booted a system with this kernel.

From cold boot, we never see any firmware bug (as usual). Then I kexec
the same kernel, and then I got the problem twice (I tested it 2 times
and same results):

	[    0.000000] APIC: Static calls initialized
	[    0.000000] e820: update [mem 0x107fff9400-0x107fff940f] usable ==> usable
	[    0.000000] e820: update [mem 0x107fff93e0-0x107fff93ff] usable ==> usable
	[    0.000000] e820: update [mem 0x107fff9370-0x107fff93df] usable ==> usable
	[    0.000000] extended physical RAM map:
	[    0.000000] reserve setup_data: [mem 0x0000000000000000-0x000000000009ffff] usable
	[    0.000000] reserve setup_data: [mem 0x00000000000a0000-0x00000000000fffff] reserved
	[    0.000000] reserve setup_data: [mem 0x0000000000100000-0x0000000069cd5fff] usable
	[    0.000000] reserve setup_data: [mem 0x0000000069cd6000-0x000000006bdd5fff] reserved
	[    0.000000] reserve setup_data: [mem 0x000000006bdd6000-0x000000006be90fff] ACPI data
	[    0.000000] reserve setup_data: [mem 0x000000006be91000-0x000000006c9eafff] ACPI NVS
	[    0.000000] reserve setup_data: [mem 0x000000006c9eb000-0x000000006ebedfff] reserved
	[    0.000000] reserve setup_data: [mem 0x000000006ebee000-0x000000006fffffff] usable
	[    0.000000] reserve setup_data: [mem 0x0000000070000000-0x000000008fffffff] reserved
	[    0.000000] reserve setup_data: [mem 0x00000000fd000000-0x00000000fe7fffff] reserved
	[    0.000000] reserve setup_data: [mem 0x00000000fed20000-0x00000000fed44fff] reserved
	[    0.000000] reserve setup_data: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
	[    0.000000] reserve setup_data: [mem 0x0000000100000000-0x000000107fff936f] usable
	[    0.000000] reserve setup_data: [mem 0x000000107fff9370-0x000000107fff940f] usable
	[    0.000000] reserve setup_data: [mem 0x000000107fff9410-0x000000107fffffff] usable
	[    0.000000] efi: EFI v2.6 by American Megatrends
	[    0.000000] efi: ACPI 2.0=0x6c61e000 ACPI=0x6c61e000 TPMFinalLog=0x6c9b9000 SMBIOS=0x6e69d000 SMBIOS 3.0=0x6e69c000 MEMATTR=0x64ef1018 ESRT=0x67dc9918 TPMEventLog=0x6be8e018
	[    0.000000] efi: memattr: [Firmware Bug]: Corrupted EFI Memory Attributes Table detected! (version == 1, desc_size == 48, num_entries == 50)
	[    0.000000] efi: Remove mem00: MMIO range=[0xff000000-0xffffffff] (16MB) from e820 map
	[    0.000000] e820: remove [mem 0xff000000-0xffffffff] reserved
	[    0.000000] efi: Not removing mem01: MMIO range=[0xfed20000-0xfed44fff] (148KB) from e820 map
	[    0.000000] efi: Remove mem02: MMIO range=[0xfd000000-0xfe7fffff] (24MB) from e820 map
	[    0.000000] e820: remove [mem 0xfd000000-0xfe7fffff] reserved
	[    0.000000] efi: Remove mem03: MMIO range=[0x80000000-0x8fffffff] (256MB) from e820 map
	[    0.000000] e820: remove [mem 0x80000000-0x8fffffff] reserved
	[    0.000000] SMBIOS 3.1.1 present.