linux-kernel - Re: [PATCH v19 038/130] KVM: TDX: create/destroy VM structure

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Message-ID: <20240323013642.GE2357401@ls.amr.corp.intel.com>
Date: Fri, 22 Mar 2024 18:36:42 -0700
From: Isaku Yamahata <isaku.yamahata@...el.com>
To: "Huang, Kai" <kai.huang@...el.com>
Cc: "Yamahata, Isaku" <isaku.yamahata@...el.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"isaku.yamahata@...il.com" <isaku.yamahata@...il.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	"Aktas, Erdem" <erdemaktas@...gle.com>,
	Sean Christopherson <seanjc@...gle.com>,
	Sagi Shahar <sagis@...gle.com>, "Chen, Bo2" <chen.bo@...el.com>,
	"Yuan, Hang" <hang.yuan@...el.com>,
	"Zhang, Tina" <tina.zhang@...el.com>,
	Sean Christopherson <sean.j.christopherson@...el.com>,
	isaku.yamahata@...ux.intel.com
Subject: Re: [PATCH v19 038/130] KVM: TDX: create/destroy VM structure

On Fri, Mar 22, 2024 at 02:06:19PM +1300,
"Huang, Kai" <kai.huang@...el.com> wrote:

> Roughly checking the code, you have implemented many things including
> MNG.KEY.CONFIG staff.  It's worth to add some text here to give reviewer a
> rough idea what's going on here.
> 
> > 
> > Before tearing down private page tables, TDX requires some resources of the
> > guest TD to be destroyed (i.e. HKID must have been reclaimed, etc).  Add
> > mmu notifier release callback before tearing down private page tables for
> > it. >
> > Add vm_free() of kvm_x86_ops hook at the end of kvm_arch_destroy_vm()
> > because some per-VM TDX resources, e.g. TDR, need to be freed after other
> > TDX resources, e.g. HKID, were freed.
> 
> I think we should split the "adding callbacks' part out, given you have ...
> 
> 	9 files changed, 520 insertions(+), 8 deletions(-)
> 
> ... in this patch.
> 
> IMHO, >500 LOC change normally means there are too many things in this
> patch, thus hard to review, and we should split.
> 
> I think perhaps we can split this big patch to smaller pieces based on the
> steps, like we did for the init_tdx_module() function in the TDX host
> patchset??
> 
> (But I would like to hear from others too.)

Ok, how about those steps
- tdr allocation/free
- allocate+configure/release HKID
- phyemme cache wb
- tdcs allocation/free
- clearing page

520/5 = 104.  Want more steps?


> > +	if (WARN_ON_ONCE(err))
> > +		pr_tdx_error(TDH_PHYMEM_CACHE_WB, err, NULL);
> > +}
> 
> [snip]
> 
> I am stopping here, because I need to take a break.
> 
> Again I think we should split this patch, there are just too many things to
> review here.

Thank you so much for the review. Let me try to break this patch.
-- 
Isaku Yamahata <isaku.yamahata@...el.com>