Messages in this thread | | | Date | Fri, 2 Feb 2024 15:51:12 +0800 | Subject | Re: [PATCH -next v4 2/3] x86/mce: rename MCE_IN_KERNEL_COPYIN to MCE_IN_KERNEL_COPY_MC | From | Tong Tiangen <> |
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在 2024/2/1 22:20, Borislav Petkov 写道: > On Thu, Feb 01, 2024 at 07:37:25PM +0800, Tong Tiangen wrote: >> 在 2024/1/31 15:02, Borislav Petkov 写道: >>> On Thu, Jan 11, 2024 at 09:55:47PM +0800, Tong Tiangen wrote: >>>> Currently, there are some kernel memory copy scenarios is also mc safe >>>> which use copy_mc_to_kernel() or copy_mc_user_highpage(). >>> >>> Both of those end up in copy_mc_enhanced_fast_string() which does >>> EX_TYPE_DEFAULT_MCE_SAFE. >> >> OK, how about this commit msg change? :) >> >> Currently, there are some kernel memory copy scenarios is also mc safe >> which use copy_mc_to_kernel() or copy_mc_user_highpage(), **both of those >> end up in copy_mc_enhanced_fast_string() or copy_mc_fragile() which does >> EX_TYPE_DEFAULT_MCE_SAFE.** >> >> In these scenarios, posion pages need to be isolated too. Therefore, a >> macro similar to MCE_IN_KERNEL_COPYIN is required. For this reason, we >> can rename MCE_IN_KERNEL_COPYIN to MCE_IN_KERNEL_COPY_MC, the new macro >> can be applied to both user-to-kernel mc safe copy and kernel-to-kernel >> mc safe copy. > > Maybe my question wasn't clear: why is that renaming churn needed at > all? What are you "fixing" here? > > What is the problem that you're encountering which needs fixing?
This patch is a prepare patch and the next patch is a fix patch, the complete logic of the two patches is as follows:
The problem i'm encountering: ------------------------------- In the x86 mce processing, error_context() setting macro MCE_IN_KERNEL_COPYIN to identify copy from user(user-to-kernel copy) for fixup_type EX_TYPE_UACCESS.
Then do_machine_check() uses macro MCE_IN_KERNEL_COPYIN to isolate posion page in memory_failure().
Currently, there are some kernel memory copy scenarios is also mc safe which use copy_mc_to_kernel() or copy_mc_user_highpage(), these kernel- to-kernel copy use fixup_type EX_TYPE_DEFAULT_MCE_SAFE. In these scenarios, posion pages need to be isolated too and the current implementation is to actively call memory_failure_queue() when the copy fails.
Calling memory_failure_queue() separately is not a good implementation, call it uniformly in do_machine_check() is more reasonable.
Solution: ---------- A macro similar to MCE_IN_KERNEL_COPYIN is required, so we can rename MCE_IN_KERNEL_COPYIN to MCE_IN_KERNEL_COPY_MC, the new macro can be applied to both user-to-kernel mc safe copy and kernel-to-kernel mc safe copy, in error_context(),we can set MCE_IN_KERNEL_COPY_MC for both fixup_type EX_TYPE_UACCESS and EX_TYPE_DEFAULT_MCE_SAFE.
Do you think it's clear to say so and then we can merge the two patches to make the complete logic clearer in commit msg ?
Many thanks. Tong.
> > Thx. >
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