linux-kernel - Re: [PATCH 10/16] KVM: x86/tdp_mmu: Support TDX private mapping for TDP MMU

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Message-ID: <35b63d56fe6ebd98c61b7c7ca1680da91c28a4d0.camel@intel.com>
Date: Thu, 23 May 2024 18:27:49 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "Yamahata, Isaku" <isaku.yamahata@...el.com>
CC: "isaku.yamahata@...il.com" <isaku.yamahata@...il.com>, "seanjc@...gle.com"
	<seanjc@...gle.com>, "Huang, Kai" <kai.huang@...el.com>, "sagis@...gle.com"
	<sagis@...gle.com>, "isaku.yamahata@...ux.intel.com"
	<isaku.yamahata@...ux.intel.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Zhao, Yan Y" <yan.y.zhao@...el.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>, "pbonzini@...hat.com"
	<pbonzini@...hat.com>, "dmatlack@...gle.com" <dmatlack@...gle.com>, "Aktas,
 Erdem" <erdemaktas@...gle.com>
Subject: Re: [PATCH 10/16] KVM: x86/tdp_mmu: Support TDX private mapping for
 TDP MMU

On Wed, 2024-05-22 at 17:01 -0700, Isaku Yamahata wrote:
> Ok, Let's include the patch.

We were discussing offline, that actually the existing behavior of
kvm_mmu_max_gfn() can be improved for normal VMs. It would be more proper to
trigger it off of the GFN range supported by EPT level, than the host MAXPA. 

Today I was thinking, to fix this would need somthing like an x86_ops.max_gfn(),
so it could get at VMX stuff (usage of 4/5 level EPT). If that exists we might
as well just call it directly in kvm_mmu_max_gfn().

Then for TDX we could just provide a TDX implementation, rather than stash the
GFN on the kvm struct? Instead it could use gpaw stashed on struct kvm_tdx. The
op would still need to be take a struct kvm.

What do you think of that alternative?