linux-kernel - Re: [PATCH v18 053/121] KVM: x86/mmu: TDX: Do not enable page track for TD guest

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Date: Sun, 4 Feb 2024 16:46:35 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: isaku.yamahata@...el.com
Cc: 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,
 Yan Zhao <yan.y.zhao@...el.com>, Yuan Yao <yuan.yao@...ux.intel.com>
Subject: Re: [PATCH v18 053/121] KVM: x86/mmu: TDX: Do not enable page track
 for TD guest



On 1/23/2024 7:53 AM, isaku.yamahata@...el.com wrote:
> From: Yan Zhao <yan.y.zhao@...el.com>
>
> TDX does not support write protection and hence page track.
> Though !tdp_enabled and kvm_shadow_root_allocated(kvm) are always false
> for TD guest, should also return false when external write tracking is
> enabled.

Nit:
The preferred shortlog prefix format is "KVM: <topic>:", remove "TDX" from
the shortlog?
"KVM: x86/mmu: Do not enable page track for TD guest" should be OK.

Reviewed-by: Binbin Wu <binbin.wu@...ux.intel.com>

>
> Cc: Yuan Yao <yuan.yao@...ux.intel.com>
> Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
> ---
>   arch/x86/kvm/mmu/page_track.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
> index c87da11f3a04..ce698ab213c1 100644
> --- a/arch/x86/kvm/mmu/page_track.c
> +++ b/arch/x86/kvm/mmu/page_track.c
> @@ -22,6 +22,9 @@
>   
>   bool kvm_page_track_write_tracking_enabled(struct kvm *kvm)
>   {
> +	if (kvm->arch.vm_type == KVM_X86_TDX_VM)
> +		return false;
> +
>   	return IS_ENABLED(CONFIG_KVM_EXTERNAL_WRITE_TRACKING) ||
>   	       !tdp_enabled || kvm_shadow_root_allocated(kvm);
>   }