linux-kernel - Re: [PATCH v3 06/18] KVM: arm64: Pass walk flags to kvm_pgtable_stage2_relax

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Message-ID: <CA+EHjTyf+yjBsQ5zGs+PZJGUJSSftyEepo6A7YmgMnf8cTMH1w@mail.gmail.com>
Date: Tue, 17 Dec 2024 08:47:35 +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 06/18] KVM: arm64: Pass walk flags to kvm_pgtable_stage2_relax_perms

On Mon, 16 Dec 2024 at 17:58, Quentin Perret <qperret@...gle.com> wrote:
>
> kvm_pgtable_stage2_relax_perms 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         | 6 ++----
>  arch/arm64/kvm/mmu.c                 | 7 +++----
>  3 files changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index 38b7ec1c8614..c2f4149283ef 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -707,6 +707,7 @@ bool kvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr,
>   * @pgt:       Page-table structure initialised by kvm_pgtable_stage2_init*().
>   * @addr:      Intermediate physical address to identify the page-table entry.
>   * @prot:      Additional permissions to grant for the mapping.
> + * @flags:     Flags to control the page-table walk (ex. a shared walk)
>   *
>   * The offset of @addr within a page is ignored.
>   *
> @@ -719,7 +720,8 @@ bool kvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr,
>   * Return: 0 on success, negative error code on failure.
>   */
>  int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr,
> -                                  enum kvm_pgtable_prot prot);
> +                                  enum kvm_pgtable_prot prot,
> +                                  enum kvm_pgtable_walk_flags flags);
>
>  /**
>   * kvm_pgtable_stage2_flush_range() - Clean and invalidate data cache to Point
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 0470aedb4bf4..b7a3b5363235 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -1307,7 +1307,7 @@ bool kvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr,
>  }
>
>  int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr,
> -                                  enum kvm_pgtable_prot prot)
> +                                  enum kvm_pgtable_prot prot, enum kvm_pgtable_walk_flags flags)
>  {
>         int ret;
>         s8 level;
> @@ -1325,9 +1325,7 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr,
>         if (prot & KVM_PGTABLE_PROT_X)
>                 clr |= KVM_PTE_LEAF_ATTR_HI_S2_XN;
>
> -       ret = stage2_update_leaf_attrs(pgt, addr, 1, set, clr, NULL, &level,
> -                                      KVM_PGTABLE_WALK_HANDLE_FAULT |
> -                                      KVM_PGTABLE_WALK_SHARED);
> +       ret = stage2_update_leaf_attrs(pgt, addr, 1, set, clr, NULL, &level, flags);
>         if (!ret || ret == -EAGAIN)
>                 kvm_call_hyp(__kvm_tlb_flush_vmid_ipa_nsh, pgt->mmu, addr, level);
>         return ret;
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index a2339b76c826..641e4fec1659 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1452,6 +1452,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>         enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
>         struct kvm_pgtable *pgt;
>         struct page *page;
> +       enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_HANDLE_FAULT | KVM_PGTABLE_WALK_SHARED;
>
>         if (fault_is_perm)
>                 fault_granule = kvm_vcpu_trap_get_perm_fault_granule(vcpu);
> @@ -1695,13 +1696,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>                  * PTE, which will be preserved.
>                  */
>                 prot &= ~KVM_NV_GUEST_MAP_SZ;
> -               ret = kvm_pgtable_stage2_relax_perms(pgt, fault_ipa, prot);
> +               ret = kvm_pgtable_stage2_relax_perms(pgt, fault_ipa, prot, flags);
>         } else {
>                 ret = kvm_pgtable_stage2_map(pgt, fault_ipa, vma_pagesize,
>                                              __pfn_to_phys(pfn), prot,
> -                                            memcache,
> -                                            KVM_PGTABLE_WALK_HANDLE_FAULT |
> -                                            KVM_PGTABLE_WALK_SHARED);
> +                                            memcache, flags);
>         }
>
>  out_unlock:
> --
> 2.47.1.613.gc27f4b7a9f-goog
>