Re: [PATCH v2 RESEND] x86/asm: Force native_apic_mem_read to use mov
From: Peter Gonda
Date: Wed Sep 14 2022 - 07:13:24 EST
On Thu, Sep 8, 2022 at 6:05 PM Adam Dunlap <acdunlap@xxxxxxxxxx> wrote:
>
> Previously, when compiled with clang, native_apic_mem_read gets inlined
> into __xapic_wait_icr_idle and optimized to a testl instruction. When
> run in a VM with SEV-ES enabled, it attempts to emulate this
> instruction, but the emulator does not support it. Instead, use inline
> assembly to force native_apic_mem_read to use the mov instruction which
> is supported by the emulator.
This seems to be an issue with the SEV-ES in guest #VC handler's
"emulator" right?
If that's the case I think this should be fixed in the #VC handler
instead of fixing the code that is failing to be emulated. What if
there are other places where a testl is used and our tests have not
caught them.