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Message-ID: <0d18e8aa-93ac-ea3e-37ee-d104d681459d@redhat.com>
Date:   Tue, 5 Apr 2022 16:02:08 +0200
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Subject: Re: [RFC PATCH v5 033/104] KVM: x86: Add infrastructure for stolen
 GPA bits
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To:     Isaku Yamahata <isaku.yamahata@gmail.com>,
        Kai Huang <kai.huang@intel.com>
Cc:     isaku.yamahata@intel.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, Jim Mattson <jmattson@google.com>,
        erdemaktas@google.com, Connor Kuehl <ckuehl@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Chao Peng <chao.p.peng@linux.intel.com>
References: <cover.1646422845.git.isaku.yamahata@intel.com>
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 <2b8038c17b85658a054191b362840240bd66e46b.camel@intel.com>
 <20220401023426.GF2084469@ls.amr.corp.intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <20220401023426.GF2084469@ls.amr.corp.intel.com>
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On 4/1/22 04:34, Isaku Yamahata wrote:
> Sure, this patch heavily changed from the original patch Now.  One suggestion
> is that private/shared is characteristic to kvm page fault, not gpa/gfn.
> It's TDX specific.
> 
> - Add a helper function to check if KVM MMU is TD or VM. Right now
>    kvm_gfn_stolen_mask() is used.  Probably kvm_mmu_has_private_bit().
>    (any better name?)

I think use of kvm_gfn_stolen_mask() should be minimized anyway.  I 
would rename it to to kvm_{gfn,gpa}_private_mask and not return bool.

> - Let's keep address conversion functions: address => unalias/shared/private

unalias is the same as private.  It doesn't seem to have a lot of uses. 
  I would just inline "x & ~gfn_private_mask", or "x & 
~kvm_gfn_private_mask(kvm)"; or the same with gpa of course.

The shared and private conversion functions should remain.

> - Add struct kvm_page_fault.is_private
>    see how kvm_is_private_{gpa, gfn}() can be removed (or reduced).

Agreed.

Paolo