Re: [PATCH v3 0/3] x86/sgx: fine grained SGX MCA behavior

From: Kai Huang <kai.huang@intel.com>
To: "Du, Fan" <fan.du@intel.com>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	Jarkko Sakkinen <jarkko@kernel.org>,
	"Li, Zhiquan1" <zhiquan1.li@intel.com>,
	"linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
	"Luck, Tony" <tony.luck@intel.com>,
	"Hansen, Dave" <dave.hansen@intel.com>,
	"Zhang, Cathy" <cathy.zhang@intel.com>
Cc: "Christopherson,, Sean" <seanjc@google.com>
Subject: Re: [PATCH v3 0/3] x86/sgx: fine grained SGX MCA behavior
Date: Mon, 06 Jun 2022 22:40:24 +1200	[thread overview]
Message-ID: <ccfc5dacc80454e35b0f13410abc8606832f7517.camel@intel.com> (raw)
In-Reply-To: <MN0PR11MB6181099B27E37C05659A30B199A19@MN0PR11MB6181.namprd11.prod.outlook.com>

On Fri, 2022-06-03 at 13:15 +1200, Du, Fan wrote:
> > 
> > This applies on top of Cathy's series, right? Why not send one
> > series with all 12 patches included?
> > 
> > It makes reviewing easier, and we are well beyond 5.19 timeline
> > for these features.
> 
> Patches from Zhiquan try to improve SGX MCA handling, actually this is a BUG
> being
> discussed with customer with SGX deployment already - SGX VM instance got
> killed
> in case of SGX application inside VM consumed poison EPC pages. Expected
> behavior:
> SGX application get killed only in such scenario.
> 
> Seamless patchset from Catchy is another standalone feature, the design seems
> still under discussion. Combining those two distinct purpose-built patchset
> together
> looks wired.

Right.  Those are two different features and I don't see why they should be sent
out together.

Btw, please also note Cathy's SGX rebootless recovery may never get accepted:

https://lore.kernel.org/linux-sgx/Yo0xSNt0JKGgOG59@zn.tnic/T/#m4d1a56fc3ed547d200443dab50bed6484e6d2e1d
https://lore.kernel.org/all/20220524185324.28395-1-bp@alien8.de/

> 
> Zhiquan's patchset introduced the SGX_EPC_PAGE_IS_VEPC [1] macro to mark guest
> EPC page, luckily Cathy's patchset also has a prior built macro
> SGX_EPC_PAGE_KVM_GUEST
> with same semantics as a simple standalone patch[2].
> 
> For completeness, how about incorporate Cathy's patch[2](keep original
> authorship)
> into Zhiquan up-coming next version(3 patch from Zhiquan, 1 patch from Cathy)?
> Offline synced with Cathy, she is personally ok. while let's see what others
> think about on
> how to prioritize those two things - bugfix and feature enhancement.

Zhiquan's series only needs one flag: SGX_EPC_PAGE_KVM_GUEST.  It doesn't need 
SGX_EPC_PAGE_VA.  I would suggest to just use SGX_EPC_PAGE_KVM_GUEST (if it is
preferred comparing to SGX_EPC_PAGE_IS_VEPC) in Zhiquan's series.

-- 
Thanks,
-Kai