linux-kernel - Re: [PATCH v19 060/130] KVM: x86/tdp_mmu: Apply mmu notifier callback to only shared GPA

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Date: Thu, 28 Mar 2024 13:55:17 -0700
From: Isaku Yamahata <isaku.yamahata@...el.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 v19 060/130] KVM: x86/tdp_mmu: Apply mmu notifier
 callback to only shared GPA

On Thu, Mar 28, 2024 at 04:29:50PM +0800,
Binbin Wu <binbin.wu@...ux.intel.com> wrote:

> 
> 
> On 2/26/2024 4:26 PM, isaku.yamahata@...el.com wrote:
> > From: Isaku Yamahata <isaku.yamahata@...el.com>
> > 
> > The private GPAs that typically guest memfd backs aren't subject to MMU
> > notifier because it isn't mapped into virtual address of user process.
> > kvm_tdp_mmu_handle_gfn() handles the callback of the MMU notifier,
> > clear_flush_young(), clear_young(), test_young()() and change_pte().  Make
>                                                    ^
>                                                    an extra "()"

Will fix it. Thanks.

> > kvm_tdp_mmu_handle_gfn() aware of private mapping and skip private mapping.
> > 
> > Even with AS_UNMOVABLE set, those mmu notifier are called.  For example,
> > ksmd triggers change_pte().
> 
> The description about the "AS_UNMOVABLE", you are refering to shared memory,
> right?
> Then, it seems not related to the change of this patch.

Ok, will remove this sentence.
-- 
Isaku Yamahata <isaku.yamahata@...el.com>