linux-kernel - Re: [PATCH v3 05/18] KVM: arm64: Pass walk flags to kvm_pgtable_stage2

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Message-ID: <CA+EHjTzfqR8=g=VzazL3__TyGpJJtPCoG20sJeUnY+d0b6NSBA@mail.gmail.com>
Date: Tue, 17 Dec 2024 08:47:24 +0000
From: Fuad Tabba <tabba@...gle.com>
To: Quentin Perret <qperret@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Vincent Donnefort <vdonnefort@...gle.com>, 
	Sebastian Ene <sebastianene@...gle.com>, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 05/18] KVM: arm64: Pass walk flags to kvm_pgtable_stage2_mkyoung

On Mon, 16 Dec 2024 at 17:58, Quentin Perret <qperret@...gle.com> wrote:
>
> kvm_pgtable_stage2_mkyoung currently assumes that it is being called
> from a 'shared' walker, which will not be true once called from pKVM.
> To allow for the re-use of that function, make the walk flags one of
> its parameters.
>
> Signed-off-by: Quentin Perret <qperret@...gle.com>

Reviewed-by: Fuad Tabba <tabba@...gle.com>

Cheers,
/fuad

> ---
>  arch/arm64/include/asm/kvm_pgtable.h | 4 +++-
>  arch/arm64/kvm/hyp/pgtable.c         | 7 +++----
>  arch/arm64/kvm/mmu.c                 | 3 ++-
>  3 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index aab04097b505..38b7ec1c8614 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -669,13 +669,15 @@ int kvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size);
>   * kvm_pgtable_stage2_mkyoung() - Set the access flag in a page-table entry.
>   * @pgt:       Page-table structure initialised by kvm_pgtable_stage2_init*().
>   * @addr:      Intermediate physical address to identify the page-table entry.
> + * @flags:     Flags to control the page-table walk (ex. a shared walk)
>   *
>   * The offset of @addr within a page is ignored.
>   *
>   * If there is a valid, leaf page-table entry used to translate @addr, then
>   * set the access flag in that entry.
>   */
> -void kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr);
> +void kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr,
> +                               enum kvm_pgtable_walk_flags flags);
>
>  /**
>   * kvm_pgtable_stage2_test_clear_young() - Test and optionally clear the access
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 40bd55966540..0470aedb4bf4 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -1245,14 +1245,13 @@ int kvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
>                                         NULL, NULL, 0);
>  }
>
> -void kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)
> +void kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr,
> +                               enum kvm_pgtable_walk_flags flags)
>  {
>         int ret;
>
>         ret = stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
> -                                      NULL, NULL,
> -                                      KVM_PGTABLE_WALK_HANDLE_FAULT |
> -                                      KVM_PGTABLE_WALK_SHARED);
> +                                      NULL, NULL, flags);
>         if (!ret)
>                 dsb(ishst);
>  }
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index c9d46ad57e52..a2339b76c826 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1718,13 +1718,14 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>  /* Resolve the access fault by making the page young again. */
>  static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
>  {
> +       enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_HANDLE_FAULT | KVM_PGTABLE_WALK_SHARED;
>         struct kvm_s2_mmu *mmu;
>
>         trace_kvm_access_fault(fault_ipa);
>
>         read_lock(&vcpu->kvm->mmu_lock);
>         mmu = vcpu->arch.hw_mmu;
> -       kvm_pgtable_stage2_mkyoung(mmu->pgt, fault_ipa);
> +       kvm_pgtable_stage2_mkyoung(mmu->pgt, fault_ipa, flags);
>         read_unlock(&vcpu->kvm->mmu_lock);
>  }
>
> --
> 2.47.1.613.gc27f4b7a9f-goog
>