Re: [PATCH 1/8] KVM: x86/mmu: Refactor is_tdp_mmu_root()

From: Ben Gardon <bgardon@google.com>
To: David Matlack <dmatlack@google.com>
Cc: kvm <kvm@vger.kernel.org>, Joerg Roedel <joro@8bytes.org>,
	Jim Mattson <jmattson@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Junaid Shahid <junaids@google.com>,
	Andrew Jones <drjones@redhat.com>
Subject: Re: [PATCH 1/8] KVM: x86/mmu: Refactor is_tdp_mmu_root()
Date: Mon, 14 Jun 2021 10:56:25 -0700	[thread overview]
Message-ID: <CANgfPd86b95ZCOFs89eqbcvmkiNz08WT+yuWdR-jZ-YjSeWArA@mail.gmail.com> (raw)
In-Reply-To: <20210611235701.3941724-2-dmatlack@google.com>

On Fri, Jun 11, 2021 at 4:57 PM David Matlack <dmatlack@google.com> wrote:
>
> Refactor is_tdp_mmu_root() into is_vcpu_using_tdp_mmu() to reduce
> duplicated code at call sites and make the code more readable.
>
> Signed-off-by: David Matlack <dmatlack@google.com>

Nice cleanup!

Reviewed-by: Ben Gardon <bgardon@google.com>

> ---
>  arch/x86/kvm/mmu/mmu.c     | 10 +++++-----
>  arch/x86/kvm/mmu/tdp_mmu.c |  2 +-
>  arch/x86/kvm/mmu/tdp_mmu.h |  8 +++++---
>  3 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 0144c40d09c7..eccd889d20a5 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -3545,7 +3545,7 @@ static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep)
>                 return reserved;
>         }
>
> -       if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa))
> +       if (is_vcpu_using_tdp_mmu(vcpu))
>                 leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, &root);
>         else
>                 leaf = get_walk(vcpu, addr, sptes, &root);
> @@ -3729,7 +3729,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
>         if (page_fault_handle_page_track(vcpu, error_code, gfn))
>                 return RET_PF_EMULATE;
>
> -       if (!is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) {
> +       if (!is_vcpu_using_tdp_mmu(vcpu)) {
>                 r = fast_page_fault(vcpu, gpa, error_code);
>                 if (r != RET_PF_INVALID)
>                         return r;
> @@ -3751,7 +3751,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
>
>         r = RET_PF_RETRY;
>
> -       if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa))
> +       if (is_vcpu_using_tdp_mmu(vcpu))
>                 read_lock(&vcpu->kvm->mmu_lock);
>         else
>                 write_lock(&vcpu->kvm->mmu_lock);
> @@ -3762,7 +3762,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
>         if (r)
>                 goto out_unlock;
>
> -       if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa))
> +       if (is_vcpu_using_tdp_mmu(vcpu))
>                 r = kvm_tdp_mmu_map(vcpu, gpa, error_code, map_writable, max_level,
>                                     pfn, prefault);
>         else
> @@ -3770,7 +3770,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
>                                  prefault, is_tdp);
>
>  out_unlock:
> -       if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa))
> +       if (is_vcpu_using_tdp_mmu(vcpu))
>                 read_unlock(&vcpu->kvm->mmu_lock);
>         else
>                 write_unlock(&vcpu->kvm->mmu_lock);
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 237317b1eddd..f4cc79dabeae 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -979,7 +979,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
>
>         if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)))
>                 return RET_PF_RETRY;
> -       if (WARN_ON(!is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)))
> +       if (WARN_ON(!is_vcpu_using_tdp_mmu(vcpu)))
>                 return RET_PF_RETRY;
>
>         level = kvm_mmu_hugepage_adjust(vcpu, gfn, max_level, &pfn,
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
> index 5fdf63090451..c8cf12809fcf 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.h
> +++ b/arch/x86/kvm/mmu/tdp_mmu.h
> @@ -91,16 +91,18 @@ static inline bool is_tdp_mmu_enabled(struct kvm *kvm) { return false; }
>  static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return false; }
>  #endif
>
> -static inline bool is_tdp_mmu_root(struct kvm *kvm, hpa_t hpa)
> +static inline bool is_vcpu_using_tdp_mmu(struct kvm_vcpu *vcpu)
>  {
> +       struct kvm *kvm = vcpu->kvm;
>         struct kvm_mmu_page *sp;
> +       hpa_t root_hpa = vcpu->arch.mmu->root_hpa;
>
>         if (!is_tdp_mmu_enabled(kvm))
>                 return false;
> -       if (WARN_ON(!VALID_PAGE(hpa)))
> +       if (WARN_ON(!VALID_PAGE(root_hpa)))
>                 return false;
>
> -       sp = to_shadow_page(hpa);
> +       sp = to_shadow_page(root_hpa);
>         if (WARN_ON(!sp))
>                 return false;
>
> --
> 2.32.0.272.g935e593368-goog
>