| commit | f14c05f14493f8960559172b4653f33e26357703 | [log] [tgz] |
|---|---|---|
| author | Furquan Shaikh <furquan@google.com> | Mon Mar 08 22:08:42 2021 -0800 |
| committer | Furquan Shaikh <furquan@google.com> | Fri Mar 12 17:33:01 2021 +0000 |
| tree | c0c1ab2091b3068fded3a5652a0d488c1b06af1e | |
| parent | 105d91e11476c8889fc7c5f0048c325fef3288fd [diff] |
cpu/intel/microcode: Fix caching logic in intel_microcode_find CB:49896 added support in `intel_microcode_find()` to cache the found microcode for faster subsequent accesses. This works okay when the function succeeds in finding the microcode on BSP. However, if for any reason, `cpu_microcode_blob.bin` does not contain a valid microcode for the given processor, then the logic ends up attempting to find microcode again and again every time it is called (because `ucode_updates` is set to NULL on failed find, thus retriggering the whole find sequence every time). This leads to a weird race condition when multiple APs are running in parallel and executing this function. A snippet of the issues observed in the scenario described above: ``` ... microcode: Update skipped, already up-to-date ... Microcode header corrupted! ... ``` 1. AP reports that microcode update is being skipped since the current version matches the version in CBFS (even though there is no matching microcode update in CBFS). 2. AP reports microcode header is corrupted because it thinks that the data size reported in the microcode is larger than the file read from CBFS. Above issues occur because each time an AP calls `intel_microcode_find()`, it might end up seeing some intermittent state of `ucode_updates` and taking incorrect action. This change fixes this race condition by separating the logic for finding microcode into an internal function `find_cbfs_microcode()` and maintaining the caching logic in `intel_microcode_find()` using a boolean flag `microcode_checked`. BUG=b:182232187 TEST=Verified that `intel_microcode_find()` no longer makes repeated attempts to find microcode from CBFS if it failed the first time. Change-Id: I8600c830ba029e5cb9c0d7e0f1af18d87c61ad3a Signed-off-by: Furquan Shaikh <furquan@google.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/51371 Reviewed-by: Patrick Rudolph Reviewed-by: Angel Pons <th3fanbus@gmail.com> Reviewed-by: Aaron Durbin <adurbin@chromium.org> Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
coreboot is a Free Software project aimed at replacing the proprietary BIOS (firmware) found in most computers. coreboot performs a little bit of hardware initialization and then executes additional boot logic, called a payload.
With the separation of hardware initialization and later boot logic, coreboot can scale from specialized applications that run directly firmware, run operating systems in flash, load custom bootloaders, or implement firmware standards, like PC BIOS services or UEFI. This allows for systems to only include the features necessary in the target application, reducing the amount of code and flash space required.
coreboot was formerly known as LinuxBIOS.
After the basic initialization of the hardware has been performed, any desired "payload" can be started by coreboot.
See https://www.coreboot.org/Payloads for a list of supported payloads.
coreboot supports a wide range of chipsets, devices, and mainboards.
For details please consult:
ANY_TOOLCHAIN Kconfig option if you're feeling lucky (no support in this case).Optional:
make menuconfig and make nconfig)Please consult https://www.coreboot.org/Build_HOWTO for details.
If you want to test coreboot without any risks before you really decide to use it on your hardware, you can use the QEMU system emulator to run coreboot virtually in QEMU.
Please see https://www.coreboot.org/QEMU for details.
Further details on the project, a FAQ, many HOWTOs, news, development guidelines and more can be found on the coreboot website:
You can contact us directly on the coreboot mailing list:
https://www.coreboot.org/Mailinglist
The copyright on coreboot is owned by quite a large number of individual developers and companies. Please check the individual source files for details.
coreboot is licensed under the terms of the GNU General Public License (GPL). Some files are licensed under the "GPL (version 2, or any later version)", and some files are licensed under the "GPL, version 2". For some parts, which were derived from other projects, other (GPL-compatible) licenses may apply. Please check the individual source files for details.
This makes the resulting coreboot images licensed under the GPL, version 2.