Re: [PATCH 1/4] x86/sgx: Add total number of EPC pages

[Jarkko Sakkinen]

On Fri, Mar 28, 2025 at 08:07:24AM +0000, Reshetova, Elena wrote:
> > Yes but obviously I cannot promise that I'll accept this as it is
> > until I see the final version
> 
> Are you saying you prefer *this version with spinlock* vs. 
> simpler version that utilizes the fact that sgx_nr_free_pages is changed
> into tracking of number of used pages? 

I don't know really what I do prefer.

Maybe +1 version would make sense where you keep with the approach
you've chosen (used pages) and better rationalize why it is mandatory,
and why free pages would be worse?

> 
> > 
> > Also you probably should use mutex given the loop where we cannot
> > temporarily exit the lock (like e.g. in keyrings gc we can).
> 
> Not sure I understand this, could you please elaborate why do I need an
> additional mutex here? Or are you suggesting switching spinlock to mutex? 

In your code example you had a loop inside spinlock, which was based on
a return code of an opcode, i.e. potentially infinite loop.

I'd like to remind you that the hardware I have is NUC7 from 2018 so
you really have to nail how things will work semantically as I can
only think these things only in theoretical level ;-) [1]


> 
> Best Regards,
> Elena.
> 

[1] https://social.kernel.org/notice/AsUbsYH0T4bTcUSdUW

BR, Jarkko