Re: [PATCH 13/25] KVM: TDX: create/destroy VM structure

Edgecombe, Rick P
2024-08-21T16:52:23Z

On Wed, 2024-08-21 at 08:39 +0300, Tony Lindgren wrote:
> > Hmm, we would have to make SEAMCALLs to spin on that lock, where as mutexes
> > can
> > sleep. I suspect that is where it came from. But we are trying to make the
> > code
> > simple and obviously correct and add optimizations later. This might fit
> > that
> > pattern, especially since it is just used during VM creation and teardown.
>
> For handling the busy retries for SEAMCALL callers, we could just use
> iopoll.h read_poll_timeout(). I think it can handle toggling the resume
> bit while looping, need to test that though. See for example the
> smp_func_do_phymem_cache_wb() for toggling the resume variable.

Nice. It seems worth trying to me.

>
> The overhead of a SEAMCALL may not be that bad in the retry case.