linux-kernel - Re: [PATCH v8 035/103] KVM: x86/mmu: Allow per-VM override of the TDP max page level

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Date:   Thu, 1 Sep 2022 14:07:00 +0800
From:   Yuan Yao <yuan.yao@...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>
Subject: Re: [PATCH v8 035/103] KVM: x86/mmu: Allow per-VM override of the
 TDP max page level

On Sun, Aug 07, 2022 at 03:01:20PM -0700, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
>
> TDX requires special handling to support large private page.  For
> simplicity, only support 4K page for TD guest for now.  Add per-VM maximum
> page level support to support different maximum page sizes for TD guest and
> conventional VMX guest.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>

Reviewed-by: Yuan Yao <yuan.yao@...el.com>

> ---
>  arch/x86/include/asm/kvm_host.h | 1 +
>  arch/x86/kvm/mmu/mmu.c          | 1 +
>  arch/x86/kvm/mmu/mmu_internal.h | 2 +-
>  3 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 3c4051d4512b..e07294fc2219 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1142,6 +1142,7 @@ struct kvm_arch {
>  	unsigned long n_requested_mmu_pages;
>  	unsigned long n_max_mmu_pages;
>  	unsigned int indirect_shadow_pages;
> +	int tdp_max_page_level;
>  	u8 mmu_valid_gen;
>  	struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES];
>  	struct list_head active_mmu_pages;
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 1f7f61e04b94..0e5a6dcc4966 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -6063,6 +6063,7 @@ int kvm_mmu_init_vm(struct kvm *kvm)
>  	kvm->arch.split_desc_cache.kmem_cache = pte_list_desc_cache;
>  	kvm->arch.split_desc_cache.gfp_zero = __GFP_ZERO;
>
> +	kvm->arch.tdp_max_page_level = KVM_MAX_HUGEPAGE_LEVEL;
>  	return 0;
>  }
>
> diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
> index 582def531d4d..e1b2e84c16b5 100644
> --- a/arch/x86/kvm/mmu/mmu_internal.h
> +++ b/arch/x86/kvm/mmu/mmu_internal.h
> @@ -272,7 +272,7 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
>  		.nx_huge_page_workaround_enabled =
>  			is_nx_huge_page_enabled(vcpu->kvm),
>
> -		.max_level = KVM_MAX_HUGEPAGE_LEVEL,
> +		.max_level = vcpu->kvm->arch.tdp_max_page_level,
>  		.req_level = PG_LEVEL_4K,
>  		.goal_level = PG_LEVEL_4K,
>  	};
> --
> 2.25.1
>