Re: [PATCH v2 RESEND] x86/asm: Force native_apic_mem_read to use mov

From: Dave Hansen
Date: Fri Nov 17 2023 - 14:23:55 EST


On 11/17/23 10:14, Sidharth Telang wrote:
>> Is this blocked on an item? There seems to be consensus that this
>> patch fixes a bug and is taking the right high-level approach (i.e.,
>> change the guest code to avoid triggering a sequence that isn't
>> supported under CVM exception-based emulation). Without something like
>> this, we weren't able to build the kernel w/ CLANG when it is
>> configured to run under SEV-ES.
>
>> We sent out two versions of the patch. One that does the mov directly
>> [1] and a second that calls readl [2]. Is one of these two patches
>> acceptable? Or do we need to follow up on something?
>>
>> [1] https://lore.kernel.org/lkml/0D6A1E49-F21B-42AA-BBBF-13BFC308BB1E@xxxxxxxxx/T/
>> [2] https://lore.kernel.org/all/20220812183501.3555820-1-acdunlap@xxxxxxxxxx/
>
> Signal-boosting this thread: is this blocked on any item?

Yes, it's blocked on you sending a well-described patch.

You sent out two patches which both received a lot of discussion and
induced a lot of confusion. Can you please take all the knowledge from
this thread and send a third patch that has a proper changelog
incorporating all that knowledge?

Which approach should that patch have? Whatever one is as close to what
native_apic_mem_write() does as possible.