Re: [PATCH] x86: sgx: Don't track poisoned pages for reclaiming

[Huang, Kai]

On 12/02/2025 10:03 am, Jarkko Sakkinen wrote:
> On Tue, Feb 11, 2025 at 08:25:58AM -0800, Dave Hansen wrote:
> > > arch_memory_failure() but stay on sgx_active_page_list.
> > > page->poison is not checked in the reclaimer logic meaning that a page could be
> > > reclaimed and go through ETRACK, EBLOCK and EWB.  This can lead to the
> > > firmware receiving and MCE in one of those operations and going into
> > > "unbreakable shutdown" and triggering a kernel panic on remaining cores.
> >
> > This requires low-level SGX implementation knowledge to fully
> > understand. Both what "ETRACK, EBLOCK and EWB" are in the first place,
> > how they are involved in reclaim and also why EREMOVE doesn't lead to
> > the same fate.
>
> Does it? [I'll dig up Intel SDM to check this]

I just did. :-)

It seems EREMOVE only reads and updates the EPCM entry for the target 
EPC page but won't actually access that EPC page.