Re: [PATCH] KVM: VMX: restore vmx_vmexit alignment

From: Jon Kohler
Date: Wed May 31 2023 - 15:46:29 EST

> On May 31, 2023, at 3:42 PM, Alexey Dobriyan <adobriyan@xxxxxxxxx> wrote:
> On Wed, May 31, 2023 at 11:20:31AM -0700, Sean Christopherson wrote:
>> On Wed, May 31, 2023, Jon Kohler wrote:
>>> Commit 8bd200d23ec4 ("KVM: VMX: Flatten __vmx_vcpu_run()") changed
>>> vmx_vmexit from SYM_FUNC_START to SYM_INNER_LABEL, accidentally
>>> removing 16 byte alignment as SYM_FUNC_START uses SYM_A_ALIGN and
>>> SYM_INNER_LABEL does not. Josh mentioned [1] this was unintentional.
>> Anyone know if this is this stable material, or just nice to have?
> Can this improve vmexit latency? I didn't measure it.

Exit latency *appeared* to be the same before/after, might be a little bit better but
any improvement appeared to be lost in the noise. I didn’t see a regression though,
so thats nice. That puts it in the nice-to-have camp for me.