Skip to contentSkip to conversation

arm64: efi: Call SetVaMap() with a 1:1 mapping

PATCH In review Ard Biesheuvel 3 participants 9 messages Jan 17, 2023 – Feb 27, 2023

Subsystems (2)
arm64 EFI
lore
Share & tools
lore

Ard Biesheuvel

author maintainer
#0 lore raw

cover arm64: efi: Call SetVaMap() with a 1:1 mapping

Linux on arm64 is now in the same boat as x86, where supporting laptops that were built to run Windows and never tested beyond what is required for the Windows Logo certification need workarounds for all kinds of bizarre behaviors.

On Snapdragon laptops, we cannot call SetVirtualAddressMap() from the stub, because the firmware will crash while trying to access memory via the virtual addresses being installed, which is explicitly unsupported by the EFI spec.

However, not calling SetVirtualAddressMap() results in other problems:
on Ampere Altra, it causes SetTime() to crash. On Surface and Flex5g Windows-on-ARM laptops, it causes ResetSystem() to crash.

So let's try to work around this while not making too much of a mess.

First of all, install a 1:1 mapping instead of avoiding SetVaMap() altogether - from the EFI spec pov, this should amount to the same thing.

Then, given that we already use a SMBIOS based hack for Altra to force the use of SetVirtualAddressMap(), let's check for Surface systems in the same way.

Please test, and please report the SMBIOS type 1 family field for which this workaround is needed.

Also, note that these changes will not make a difference if the EFI_RT_PROPERTIES_TABLE lists SetVirtualAddressMap() as not implemented.

Nathan, I would appreciate it if you could give this a spin on your Altra box (only patch #1 should make a difference), and for good measure, double check that hwclock still works as it should.

Cc Johan Hovold <[email protected]>
Cc Maximilian Luz <[email protected]>
Cc Nathan Chancellor <[email protected]>
Cc Steev Klimaszewski <[email protected]>
Cc Shawn Guo <[email protected]>

Ard Biesheuvel (2):
arm64: efi: Prefer a flat virtual mapping of the runtime services
arm64: efi: Force use of SetVirtualAddressMap() on MS Surface

 arch/arm64/include/asm/efi.h            | 2 ++
 drivers/firmware/efi/libstub/arm64.c    | 3 ++-
 drivers/firmware/efi/libstub/efi-stub.c | 6 +++++-
 3 files changed, 9 insertions(+), 2 deletions(-)
Signature · 7 lines
2.39.0


_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
author maintainer
#1 lore raw

PATCH 1/2 arm64: efi: Prefer a flat virtual mapping of the runtime services

With some systems, we cannot omit the boot time call to SetVirtualAddressMap() even if the kernel VA space is sufficiently large, because some buggy EFI implementations exist that misbehave if SetVirtualAddressMap() is never called.

However, this does not mean we must reshuffle the EFI memory map: we can simply invoke SetVirtualAddressMap() with a memory map that places each EFI runtime region at the same virtual address that it takes up in the physical address map.

Signed-off-by Ard Biesheuvel <[email protected]>
---
 arch/arm64/include/asm/efi.h            | 2 ++
 drivers/firmware/efi/libstub/efi-stub.c | 6 +++++-
 2 files changed, 7 insertions(+), 1 deletion(-)
arch/arm64/include/asm/efi.h +2 -0
index de4ff90785b2c96a..98c4dc4da5a90e8c 100644
@@ -114,6 +114,8 @@ static inline unsigned long efi_get_kimg_min_align(void)
 #define EFI_ALLOC_ALIGN		SZ_64K
 #define EFI_ALLOC_LIMIT		((1UL << 48) - 1)
 
+#define EFI_USE_FLAT_VA_MAPPING	(VA_BITS_MIN >= 48)
+
 /*
  * On ARM systems, virtually remapped UEFI runtime services are set up in two
  * distinct stages:
drivers/firmware/efi/libstub/efi-stub.c +5 -1
index 2955c1ac6a36ee00..40869320d601492a 100644
@@ -44,8 +44,12 @@
 #define EFI_RT_VIRTUAL_OFFSET	0
 #endif
 
+#ifndef EFI_USE_FLAT_VA_MAPPING
+#define EFI_USE_FLAT_VA_MAPPING	(EFI_RT_VIRTUAL_OFFSET != 0)
+#endif
+
 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
-static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);
+static bool flat_va_mapping = EFI_USE_FLAT_VA_MAPPING;
 
 struct screen_info * __weak alloc_screen_info(void)
 {
Signature · 7 lines
2.39.0


_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
author maintainer
#2 lore raw

PATCH 2/2 arm64: efi: Force use of SetVirtualAddressMap() on MS Surface

In reply to Ard Biesheuvel

Qualcomm Snapdragon based Surface machines crash in the ResetSystem() EFI runtime service if SetVirtualAddressMap() has not been called prior.

Unfortunately, SetVirtualAddressMap() itself crashes at boot time unless the mapping being installed is a 1:1 mapping, as these firmware implementations violate the EFI spec by accessing the new mapping before SetVirtualAddressMap() completes.

Now that we have worked around the latter issue by always using a 1:1 map when the size of the VA space permits it, we can safely call SetVirtualAddressMap() in such cases.

Signed-off-by Ard Biesheuvel <[email protected]>
---
 drivers/firmware/efi/libstub/arm64.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
drivers/firmware/efi/libstub/arm64.c +2 -1
index ff2d18c42ee74979..cc3757fc29bdda24 100644
@@ -22,7 +22,8 @@ static bool system_needs_vamap(void)
 	 * Ampere Altra machines crash in SetTime() if SetVirtualAddressMap()
 	 * has not been called prior.
 	 */
-	if (!type1_family || strcmp(type1_family, "Altra"))
+	if (!type1_family ||
+	    (strcmp(type1_family, "Altra") && strcmp(type1_family, "Surface")))
 		return false;
 
 	efi_warn("Working around broken SetVirtualAddressMap()\n");
Signature · 7 lines
2.39.0


_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
author maintainer
#3 lore raw
In reply to Ard Biesheuvel
Quoted 41 lines · Ard Biesheuvel

Linux on arm64 is now in the same boat as x86, where supporting laptops that were built to run Windows and never tested beyond what is required for the Windows Logo certification need workarounds for all kinds of bizarre behaviors.

On Snapdragon laptops, we cannot call SetVirtualAddressMap() from the stub, because the firmware will crash while trying to access memory via the virtual addresses being installed, which is explicitly unsupported by the EFI spec.

However, not calling SetVirtualAddressMap() results in other problems:
on Ampere Altra, it causes SetTime() to crash. On Surface and Flex5g Windows-on-ARM laptops, it causes ResetSystem() to crash.

So let's try to work around this while not making too much of a mess.

First of all, install a 1:1 mapping instead of avoiding SetVaMap() altogether - from the EFI spec pov, this should amount to the same thing.

Then, given that we already use a SMBIOS based hack for Altra to force the use of SetVirtualAddressMap(), let's check for Surface systems in the same way.

Please test, and please report the SMBIOS type 1 family field for which this workaround is needed.

Also, note that these changes will not make a difference if the EFI_RT_PROPERTIES_TABLE lists SetVirtualAddressMap() as not implemented.

Nathan, I would appreciate it if you could give this a spin on your Altra box (only patch #1 should make a difference), and for good measure, double check that hwclock still works as it should.

Cc Johan Hovold <[email protected]>
Cc Maximilian Luz <[email protected]>
Cc Nathan Chancellor <[email protected]>
Cc Steev Klimaszewski <[email protected]>
Cc Shawn Guo <[email protected]>
Quoted 4 lines

Ard Biesheuvel (2):
arm64: efi: Prefer a flat virtual mapping of the runtime services
arm64: efi: Force use of SetVirtualAddressMap() on MS Surface

Bah this does not even work on Yoga C630, so this is not going to help us.

If we want ResetSystem() on these machines, we'll have to retain other memory ranges and map the in the EFI runtime map. Yuck.

Nathan - still interested in whether patch #1 works on Altra,

Tested-by
#4 lore raw
Quoted 47 lines · Ard Biesheuvel
Quoted 41 lines · Ard Biesheuvel

Linux on arm64 is now in the same boat as x86, where supporting laptops that were built to run Windows and never tested beyond what is required for the Windows Logo certification need workarounds for all kinds of bizarre behaviors.

On Snapdragon laptops, we cannot call SetVirtualAddressMap() from the stub, because the firmware will crash while trying to access memory via the virtual addresses being installed, which is explicitly unsupported by the EFI spec.

However, not calling SetVirtualAddressMap() results in other problems:
on Ampere Altra, it causes SetTime() to crash. On Surface and Flex5g Windows-on-ARM laptops, it causes ResetSystem() to crash.

So let's try to work around this while not making too much of a mess.

First of all, install a 1:1 mapping instead of avoiding SetVaMap() altogether - from the EFI spec pov, this should amount to the same thing.

Then, given that we already use a SMBIOS based hack for Altra to force the use of SetVirtualAddressMap(), let's check for Surface systems in the same way.

Please test, and please report the SMBIOS type 1 family field for which this workaround is needed.

Also, note that these changes will not make a difference if the EFI_RT_PROPERTIES_TABLE lists SetVirtualAddressMap() as not implemented.

Nathan, I would appreciate it if you could give this a spin on your Altra box (only patch #1 should make a difference), and for good measure, double check that hwclock still works as it should.

Cc Johan Hovold <[email protected]>
Cc Maximilian Luz <[email protected]>
Cc Nathan Chancellor <[email protected]>
Cc Steev Klimaszewski <[email protected]>
Cc Shawn Guo <[email protected]>
Quoted 4 lines

Ard Biesheuvel (2):
arm64: efi: Prefer a flat virtual mapping of the runtime services
arm64: efi: Force use of SetVirtualAddressMap() on MS Surface

Quoted 6 lines

Bah this does not even work on Yoga C630, so this is not going to help us.

If we want ResetSystem() on these machines, we'll have to retain other memory ranges and map the in the EFI runtime map. Yuck.

Nathan - still interested in whether patch #1 works on Altra,

I applied patch 1 on top of commit 6e50979a9c87 ("Merge tag 'mm-hotfixes-stable-2023-01-16-15-23' of
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm") in Linus' tree and everything still appears to be okay with hwclock. If there is any more specific testing that I should do, please let me know. Feel free to add

Tested-by Nathan Chancellor <[email protected]>

to patch 1 in future revisions, and I am happy to test anything else that you might need in this series or future ones.

Mainline:

# uname -mr
6.2.0-rc4-00031-g6e50979a9c87 aarch64
# hwclock
2023-01-17 09:04:58.845411-07:00

Patch:

# uname -mr
6.2.0-rc4-00032-g20165e83052e aarch64
# hwclock
2023-01-17 10:25:38.843788-07:00

Cheers,
Nathan

_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

author maintainer
#5 lore raw
Quoted 76 lines · Nathan Chancellor
Quoted 47 lines · Ard Biesheuvel
Quoted 41 lines · Ard Biesheuvel

Linux on arm64 is now in the same boat as x86, where supporting laptops that were built to run Windows and never tested beyond what is required for the Windows Logo certification need workarounds for all kinds of bizarre behaviors.

On Snapdragon laptops, we cannot call SetVirtualAddressMap() from the stub, because the firmware will crash while trying to access memory via the virtual addresses being installed, which is explicitly unsupported by the EFI spec.

However, not calling SetVirtualAddressMap() results in other problems:
on Ampere Altra, it causes SetTime() to crash. On Surface and Flex5g Windows-on-ARM laptops, it causes ResetSystem() to crash.

So let's try to work around this while not making too much of a mess.

First of all, install a 1:1 mapping instead of avoiding SetVaMap() altogether - from the EFI spec pov, this should amount to the same thing.

Then, given that we already use a SMBIOS based hack for Altra to force the use of SetVirtualAddressMap(), let's check for Surface systems in the same way.

Please test, and please report the SMBIOS type 1 family field for which this workaround is needed.

Also, note that these changes will not make a difference if the EFI_RT_PROPERTIES_TABLE lists SetVirtualAddressMap() as not implemented.

Nathan, I would appreciate it if you could give this a spin on your Altra box (only patch #1 should make a difference), and for good measure, double check that hwclock still works as it should.

Cc Johan Hovold <[email protected]>
Cc Maximilian Luz <[email protected]>
Cc Nathan Chancellor <[email protected]>
Cc Steev Klimaszewski <[email protected]>
Cc Shawn Guo <[email protected]>
Quoted 4 lines

Ard Biesheuvel (2):
arm64: efi: Prefer a flat virtual mapping of the runtime services
arm64: efi: Force use of SetVirtualAddressMap() on MS Surface

Quoted 6 lines

Bah this does not even work on Yoga C630, so this is not going to help us.

If we want ResetSystem() on these machines, we'll have to retain other memory ranges and map the in the EFI runtime map. Yuck.

Nathan - still interested in whether patch #1 works on Altra,

I applied patch 1 on top of commit 6e50979a9c87 ("Merge tag 'mm-hotfixes-stable-2023-01-16-15-23' of
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm") in Linus' tree and everything still appears to be okay with hwclock. If there is any more specific testing that I should do, please let me know. Feel free to add

Tested-by Nathan Chancellor <[email protected]>

to patch 1 in future revisions, and I am happy to test anything else that you might need in this series or future ones.

Mainline:

# uname -mr
6.2.0-rc4-00031-g6e50979a9c87 aarch64
# hwclock
2023-01-17 09:04:58.845411-07:00
Quoted 8 lines

Patch:

# uname -mr
6.2.0-rc4-00032-g20165e83052e aarch64
# hwclock
2023-01-17 10:25:38.843788-07:00

Thanks Nathan,

Forgot to mention, though: it is SetTime() not GetTime() that is problematic on this platform. Could you please double check whether setting the RTC using hwclock works too?

_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

#6 lore raw
Quoted 86 lines · Ard Biesheuvel
Quoted 76 lines · Nathan Chancellor
Quoted 47 lines · Ard Biesheuvel
Quoted 41 lines · Ard Biesheuvel

Linux on arm64 is now in the same boat as x86, where supporting laptops that were built to run Windows and never tested beyond what is required for the Windows Logo certification need workarounds for all kinds of bizarre behaviors.

On Snapdragon laptops, we cannot call SetVirtualAddressMap() from the stub, because the firmware will crash while trying to access memory via the virtual addresses being installed, which is explicitly unsupported by the EFI spec.

However, not calling SetVirtualAddressMap() results in other problems:
on Ampere Altra, it causes SetTime() to crash. On Surface and Flex5g Windows-on-ARM laptops, it causes ResetSystem() to crash.

So let's try to work around this while not making too much of a mess.

First of all, install a 1:1 mapping instead of avoiding SetVaMap() altogether - from the EFI spec pov, this should amount to the same thing.

Then, given that we already use a SMBIOS based hack for Altra to force the use of SetVirtualAddressMap(), let's check for Surface systems in the same way.

Please test, and please report the SMBIOS type 1 family field for which this workaround is needed.

Also, note that these changes will not make a difference if the EFI_RT_PROPERTIES_TABLE lists SetVirtualAddressMap() as not implemented.

Nathan, I would appreciate it if you could give this a spin on your Altra box (only patch #1 should make a difference), and for good measure, double check that hwclock still works as it should.

Cc Johan Hovold <[email protected]>
Cc Maximilian Luz <[email protected]>
Cc Nathan Chancellor <[email protected]>
Cc Steev Klimaszewski <[email protected]>
Cc Shawn Guo <[email protected]>
Quoted 4 lines

Ard Biesheuvel (2):
arm64: efi: Prefer a flat virtual mapping of the runtime services
arm64: efi: Force use of SetVirtualAddressMap() on MS Surface

Quoted 6 lines

Bah this does not even work on Yoga C630, so this is not going to help us.

If we want ResetSystem() on these machines, we'll have to retain other memory ranges and map the in the EFI runtime map. Yuck.

Nathan - still interested in whether patch #1 works on Altra,

I applied patch 1 on top of commit 6e50979a9c87 ("Merge tag 'mm-hotfixes-stable-2023-01-16-15-23' of
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm") in Linus' tree and everything still appears to be okay with hwclock. If there is any more specific testing that I should do, please let me know. Feel free to add

Tested-by Nathan Chancellor <[email protected]>

to patch 1 in future revisions, and I am happy to test anything else that you might need in this series or future ones.

Mainline:

# uname -mr
6.2.0-rc4-00031-g6e50979a9c87 aarch64
# hwclock
2023-01-17 09:04:58.845411-07:00
Quoted 8 lines

Patch:

# uname -mr
6.2.0-rc4-00032-g20165e83052e aarch64
# hwclock
2023-01-17 10:25:38.843788-07:00
Quoted 5 lines

Thanks Nathan,

Forgot to mention, though: it is SetTime() not GetTime() that is problematic on this platform. Could you please double check whether setting the RTC using hwclock works too?

Ah, okay, makes sense! As far as I can tell, that works too.

Mainline:

# uname -mr
6.2.0-rc4-00031-g6e50979a9c87 aarch64
# hwclock --systohc
# echo $status
0

Patch:

# uname -mr
6.2.0-rc4-00032-g20165e83052e aarch64
# hwclock --systohc
# echo $status
0

Cheers,
Nathan

author maintainer
#7 lore raw
Quoted 108 lines · Nathan Chancellor
Quoted 86 lines · Ard Biesheuvel
Quoted 76 lines · Nathan Chancellor
Quoted 47 lines · Ard Biesheuvel
Quoted 41 lines · Ard Biesheuvel

Linux on arm64 is now in the same boat as x86, where supporting laptops that were built to run Windows and never tested beyond what is required for the Windows Logo certification need workarounds for all kinds of bizarre behaviors.

On Snapdragon laptops, we cannot call SetVirtualAddressMap() from the stub, because the firmware will crash while trying to access memory via the virtual addresses being installed, which is explicitly unsupported by the EFI spec.

However, not calling SetVirtualAddressMap() results in other problems:
on Ampere Altra, it causes SetTime() to crash. On Surface and Flex5g Windows-on-ARM laptops, it causes ResetSystem() to crash.

So let's try to work around this while not making too much of a mess.

First of all, install a 1:1 mapping instead of avoiding SetVaMap() altogether - from the EFI spec pov, this should amount to the same thing.

Then, given that we already use a SMBIOS based hack for Altra to force the use of SetVirtualAddressMap(), let's check for Surface systems in the same way.

Please test, and please report the SMBIOS type 1 family field for which this workaround is needed.

Also, note that these changes will not make a difference if the EFI_RT_PROPERTIES_TABLE lists SetVirtualAddressMap() as not implemented.

Nathan, I would appreciate it if you could give this a spin on your Altra box (only patch #1 should make a difference), and for good measure, double check that hwclock still works as it should.

Cc Johan Hovold <[email protected]>
Cc Maximilian Luz <[email protected]>
Cc Nathan Chancellor <[email protected]>
Cc Steev Klimaszewski <[email protected]>
Cc Shawn Guo <[email protected]>
Quoted 4 lines

Ard Biesheuvel (2):
arm64: efi: Prefer a flat virtual mapping of the runtime services
arm64: efi: Force use of SetVirtualAddressMap() on MS Surface

Quoted 6 lines

Bah this does not even work on Yoga C630, so this is not going to help us.

If we want ResetSystem() on these machines, we'll have to retain other memory ranges and map the in the EFI runtime map. Yuck.

Nathan - still interested in whether patch #1 works on Altra,

I applied patch 1 on top of commit 6e50979a9c87 ("Merge tag 'mm-hotfixes-stable-2023-01-16-15-23' of
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm") in Linus' tree and everything still appears to be okay with hwclock. If there is any more specific testing that I should do, please let me know. Feel free to add

Tested-by Nathan Chancellor <[email protected]>

to patch 1 in future revisions, and I am happy to test anything else that you might need in this series or future ones.

Mainline:

# uname -mr
6.2.0-rc4-00031-g6e50979a9c87 aarch64
# hwclock
2023-01-17 09:04:58.845411-07:00
Quoted 8 lines

Patch:

# uname -mr
6.2.0-rc4-00032-g20165e83052e aarch64
# hwclock
2023-01-17 10:25:38.843788-07:00
Quoted 5 lines

Thanks Nathan,

Forgot to mention, though: it is SetTime() not GetTime() that is problematic on this platform. Could you please double check whether setting the RTC using hwclock works too?

Ah, okay, makes sense! As far as I can tell, that works too.

Mainline:

# uname -mr
6.2.0-rc4-00031-g6e50979a9c87 aarch64
# hwclock --systohc
# echo $status
0

Patch:

Quoted 8 lines
# uname -mr
6.2.0-rc4-00032-g20165e83052e aarch64
# hwclock --systohc
# echo $status
0

Thanks again!

#8 lore raw
Quoted 89 lines · Ard Biesheuvel
Quoted 88 lines · Nathan Chancellor
Quoted 86 lines · Ard Biesheuvel
Quoted 84 lines · Nathan Chancellor
Quoted 47 lines · Ard Biesheuvel
Quoted 41 lines · Ard Biesheuvel

Linux on arm64 is now in the same boat as x86, where supporting laptops that were built to run Windows and never tested beyond what is required for the Windows Logo certification need workarounds for all kinds of bizarre behaviors.

On Snapdragon laptops, we cannot call SetVirtualAddressMap() from the stub, because the firmware will crash while trying to access memory via the virtual addresses being installed, which is explicitly unsupported by the EFI spec.

However, not calling SetVirtualAddressMap() results in other problems:
on Ampere Altra, it causes SetTime() to crash. On Surface and Flex5g Windows-on-ARM laptops, it causes ResetSystem() to crash.

So let's try to work around this while not making too much of a mess.

First of all, install a 1:1 mapping instead of avoiding SetVaMap() altogether - from the EFI spec pov, this should amount to the same thing.

Then, given that we already use a SMBIOS based hack for Altra to force the use of SetVirtualAddressMap(), let's check for Surface systems in the same way.

Please test, and please report the SMBIOS type 1 family field for which this workaround is needed.

Also, note that these changes will not make a difference if the EFI_RT_PROPERTIES_TABLE lists SetVirtualAddressMap() as not implemented.

Nathan, I would appreciate it if you could give this a spin on your Altra box (only patch #1 should make a difference), and for good measure, double check that hwclock still works as it should.

Cc Johan Hovold <[email protected]>
Cc Maximilian Luz <[email protected]>
Cc Nathan Chancellor <[email protected]>
Cc Steev Klimaszewski <[email protected]>
Cc Shawn Guo <[email protected]>
Quoted 4 lines

Ard Biesheuvel (2):
arm64: efi: Prefer a flat virtual mapping of the runtime services
arm64: efi: Force use of SetVirtualAddressMap() on MS Surface

Quoted 6 lines

Bah this does not even work on Yoga C630, so this is not going to help us.

If we want ResetSystem() on these machines, we'll have to retain other memory ranges and map the in the EFI runtime map. Yuck.

Nathan - still interested in whether patch #1 works on Altra,

I applied patch 1 on top of commit 6e50979a9c87 ("Merge tag 'mm-hotfixes-stable-2023-01-16-15-23' of
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm") in Linus' tree and everything still appears to be okay with hwclock. If there is any more specific testing that I should do, please let me know. Feel free to add

Tested-by Nathan Chancellor <[email protected]>

to patch 1 in future revisions, and I am happy to test anything else that you might need in this series or future ones.

Mainline:

# uname -mr
6.2.0-rc4-00031-g6e50979a9c87 aarch64
# hwclock
2023-01-17 09:04:58.845411-07:00

Patch:

# uname -mr
6.2.0-rc4-00032-g20165e83052e aarch64
# hwclock
2023-01-17 10:25:38.843788-07:00
Quoted 5 lines
Quoted 5 lines
Quoted 5 lines

Thanks Nathan,

Forgot to mention, though: it is SetTime() not GetTime() that is problematic on this platform. Could you please double check whether setting the RTC using hwclock works too?

The other runtime service that triggers this is SetVariable, which I have been testing like this. The tests still pass on systems with the affected firmware with the SMBIOS string mitigation in place and this flat va mapping applied.

#!/bin/sh

function set_timeout() {
	TO=$1

	re='^[0-9]$'
	if ! [[ "$TO" =~ $re ]]; then
		echo "Timeout must be 0-9"
		exit 1
	fi

	efibootmgr -t $TO > /dev/null
	efivar -n 8be4df61-93ca-11d2-aa0d-00e098032b8c-Timeout | grep -q "00000000  0$TO 00"
	if [ $? -ne 0 ]; then
		echo "ERROR: timeout $TO not reflected in efivar"
		exit 1
	fi
	echo "SUCCESS: timeout $TO reflected in efivar"
	return 0
}

set_timeout 4
set_timeout 5
exit 0

Thanks,

Darren

Quoted 25 lines
Quoted 15 lines

Ah, okay, makes sense! As far as I can tell, that works too.

Mainline:

# uname -mr
6.2.0-rc4-00031-g6e50979a9c87 aarch64
# hwclock --systohc
# echo $status
0

Patch:

Quoted 8 lines
# uname -mr
6.2.0-rc4-00032-g20165e83052e aarch64
# hwclock --systohc
# echo $status
0

Thanks again!

Signature · 2 lines
Darren Hart
Ampere Computing / OS and Kernel