Re: [GIT PULL] EFI urgent fixes

From: Ard Biesheuvel
Date: Wed Feb 18 2015 - 11:36:29 EST



> On 18 feb. 2015, at 13:43, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
>
> * Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> wrote:
>
>> Folks, please pull the following fixes. The revert addresses a
>> regression that Ard hit when booting Qemu and Xen, and the other patch
>> ensures that we don't triple fault when receiving an NMI or MCE during
>> an EFI mixed mode call, which may happen, for instance, when running
>> perf.
>>
>> The pull is against tip/x86/efi because tip/x86/urgent doesn't contain
>> commit d1a8d66b9177 ("efi/libstub: Call get_memory_map() to obtain map
>> and desc sizes") needed for the revert.
>>
>> If you'd prefer for me to resend this after the merge window closes,
>> just let me know.
>>
>> The following changes since commit 3c01b74e818a7a3b2ee9b0d584cca0bc154a031c:
>>
>> Merge tag 'efi-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi into x86/efi (2015-01-29 19:16:40 +0100)
>>
>> are available in the git repository at:
>>
>>
>> git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi.git tags/efi-urgent
>>
>> for you to fetch changes up to 43a9f69692b232d1c64c913a27507eb14a1c47fd:
>>
>> Revert "efi/libstub: Call get_memory_map() to obtain map and desc sizes" (2015-02-18 11:38:13 +0000)
>>
>> ----------------------------------------------------------------
>> * Leave a valid 64-bit IDT installed during runtime EFI mixed mode
>> calls to avoid triple faults if an NMI/MCE is received.
>>
>> * Revert Ard's change to the libstub get_memory_map() that went into
>> the v3.20 merge window because it causes boot regressions on Qemu and
>> Xen.
>>
>> ----------------------------------------------------------------
>> Matt Fleming (2):
>> x86/efi: Avoid triple faults during EFI mixed mode calls
>> Revert "efi/libstub: Call get_memory_map() to obtain map and desc sizes"
>>
>> arch/x86/boot/compressed/Makefile | 1 +
>> arch/x86/boot/compressed/efi_stub_64.S | 25 ----
>> arch/x86/boot/compressed/efi_thunk_64.S | 196 +++++++++++++++++++++++++
>> arch/x86/platform/efi/efi_stub_64.S | 161 --------------------
>> arch/x86/platform/efi/efi_thunk_64.S | 121 ++++++++++++---
>> drivers/firmware/efi/libstub/efi-stub-helper.c | 16 +-
>> 6 files changed, 307 insertions(+), 213 deletions(-)
>> create mode 100644 arch/x86/boot/compressed/efi_thunk_64.S
>
> Pulled, thanks Matt!
>
> Btw., I find the revert a bit sad: in most cases breaking
> virtualized environments isn't a regression really, it's
> _them_ who couple to the kernel in an incestuous way that
> causes the problem: fixes should come from them ...
>

It potentially breaks physical environments as well, it is just that i spotted it while testing virt ports of Tianocore. And frankly, the patch wasn't entirely correct to begin with

Regards,
Ard.

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