linux-kernel - Re: [PATCH v18 061/121] KVM: TDX: MTRR: implement get_mt

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Message-ID: <20240226192224.GQ177224@ls.amr.corp.intel.com>
Date: Mon, 26 Feb 2024 11:22:24 -0800
From: Isaku Yamahata <isaku.yamahata@...ux.intel.com>
To: Binbin Wu <binbin.wu@...ux.intel.com>
Cc: isaku.yamahata@...el.com, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, isaku.yamahata@...il.com,
	Paolo Bonzini <pbonzini@...hat.com>, erdemaktas@...gle.com,
	Sean Christopherson <seanjc@...gle.com>,
	Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>,
	chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com,
	isaku.yamahata@...ux.intel.com
Subject: Re: [PATCH v18 061/121] KVM: TDX: MTRR: implement get_mt_mask() for
 TDX

On Mon, Feb 19, 2024 at 01:20:58PM +0800,
Binbin Wu <binbin.wu@...ux.intel.com> wrote:

> 
> 
> On 1/23/2024 7:53 AM, isaku.yamahata@...el.com wrote:
> > From: Isaku Yamahata <isaku.yamahata@...el.com>
> > 
> > Because TDX virtualize cpuid[0x1].EDX[MTRR: bit 12] to fixed 1, guest TD
> > thinks MTRR is supported.  Although TDX supports only WB for private GPA,
> > it's desirable to support MTRR for shared GPA.  As guest access to MTRR
> > MSRs causes #VE and KVM/x86 tracks the values of MTRR MSRs, the remining
> 
> s/remining/remaining
> 
> > part is to implement get_mt_mask method for TDX for shared GPA.
> > 
> > Pass around shared bit from kvm fault handler to get_mt_mask method so that
> > it can determine if the gfn is shared or private.  Implement get_mt_mask()
> > following vmx case for shared GPA and return WB for private GPA.
> 
> But the shared bit is not consumed in get_mt_mask()?

This paragraph became stale. I eliminated this paragraph.
-- 
Isaku Yamahata <isaku.yamahata@...ux.intel.com>