diff mbox series

[v3,16/21] KVM: arm64: Enable retrieving protections attributes of PTEs

Message ID 20210729132818.4091769-17-qperret@google.com (mailing list archive)
State New, archived
Headers show
Series Track shared pages at EL2 in protected mode | expand

Commit Message

Quentin Perret July 29, 2021, 1:28 p.m. UTC 
Introduce helper functions in the KVM stage-2 and stage-1 page-table
manipulation library allowing to retrieve the enum kvm_pgtable_prot of a
PTE. This will be useful to implement custom walkers outside of
pgtable.c.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_pgtable.h | 20 +++++++++++++++
 arch/arm64/kvm/hyp/pgtable.c         | 37 ++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

Comments

Fuad Tabba Aug. 2, 2021, 2:52 p.m. UTC | #1 
Hi Quentin,

On Thu, Jul 29, 2021 at 3:29 PM Quentin Perret <qperret@google.com> wrote:
>
> Introduce helper functions in the KVM stage-2 and stage-1 page-table
> manipulation library allowing to retrieve the enum kvm_pgtable_prot of a
> PTE. This will be useful to implement custom walkers outside of
> pgtable.c.
>
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/kvm_pgtable.h | 20 +++++++++++++++
>  arch/arm64/kvm/hyp/pgtable.c         | 37 ++++++++++++++++++++++++++++
>  2 files changed, 57 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index d5ca9b6ce241..7ff9f52239ba 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -505,4 +505,24 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
>   */
>  int kvm_pgtable_get_leaf(struct kvm_pgtable *pgt, u64 addr,
>                          kvm_pte_t *ptep, u32 *level);
> +
> +/**
> + * kvm_pgtable_stage2_pte_prot() - Retrieve the protection attributes of a
> + *                                stage-2 Page-Table Entry.
> + * @pte:       Page-table entry
> + *
> + * Return: protection attributes of the page-table entry in the enum
> + *        kvm_pgtable_prot format.
> + */
> +enum kvm_pgtable_prot kvm_pgtable_stage2_pte_prot(kvm_pte_t pte);
> +
> +/**
> + * kvm_pgtable_hyp_pte_prot() - Retrieve the protection attributes of a stage-1
> + *                             Page-Table Entry.
> + * @pte:       Page-table entry
> + *
> + * Return: protection attributes of the page-table entry in the enum
> + *        kvm_pgtable_prot format.
> + */
> +enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte);
>  #endif /* __ARM64_KVM_PGTABLE_H__ */
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 1915489bb127..a6eda8f23cb6 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -363,6 +363,26 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep)
>         return 0;
>  }
>
> +enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte)
> +{
> +       enum kvm_pgtable_prot prot = pte & KVM_PTE_LEAF_ATTR_HI_SW;
> +       u32 ap;
> +
> +       if (!kvm_pte_valid(pte))
> +               return prot;
> +
> +       if (!(pte & KVM_PTE_LEAF_ATTR_HI_S1_XN))
> +               prot |= KVM_PGTABLE_PROT_X;
> +
> +       ap = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S1_AP, pte);
> +       if (ap == KVM_PTE_LEAF_ATTR_LO_S1_AP_RO)
> +               prot |= KVM_PGTABLE_PROT_R;
> +       else if (ap == KVM_PTE_LEAF_ATTR_LO_S1_AP_RW)
> +               prot |= KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W;

nit: why not use the freshly minted KVM_PGTABLE_PROT_RW?

Thanks,
/fuad


> +
> +       return prot;
> +}
> +
>  static bool hyp_pte_needs_update(kvm_pte_t old, kvm_pte_t new)
>  {
>         /*
> @@ -565,6 +585,23 @@ static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot p
>         return 0;
>  }
>
> +enum kvm_pgtable_prot kvm_pgtable_stage2_pte_prot(kvm_pte_t pte)
> +{
> +       enum kvm_pgtable_prot prot = pte & KVM_PTE_LEAF_ATTR_HI_SW;
> +
> +       if (!kvm_pte_valid(pte))
> +               return prot;
> +
> +       if (pte & KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R)
> +               prot |= KVM_PGTABLE_PROT_R;
> +       if (pte & KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W)
> +               prot |= KVM_PGTABLE_PROT_W;
> +       if (!(pte & KVM_PTE_LEAF_ATTR_HI_S2_XN))
> +               prot |= KVM_PGTABLE_PROT_X;
> +
> +       return prot;
> +}
> +
>  static bool stage2_pte_needs_update(kvm_pte_t old, kvm_pte_t new)
>  {
>         if (!kvm_pte_valid(old) || !kvm_pte_valid(new))
> --
> 2.32.0.432.gabb21c7263-goog
>
Quentin Perret Aug. 3, 2021, 10:24 a.m. UTC | #2 
On Monday 02 Aug 2021 at 16:52:49 (+0200), Fuad Tabba wrote:
> Hi Quentin,
> 
> On Thu, Jul 29, 2021 at 3:29 PM Quentin Perret <qperret@google.com> wrote:
> >
> > Introduce helper functions in the KVM stage-2 and stage-1 page-table
> > manipulation library allowing to retrieve the enum kvm_pgtable_prot of a
> > PTE. This will be useful to implement custom walkers outside of
> > pgtable.c.
> >
> > Signed-off-by: Quentin Perret <qperret@google.com>
> > ---
> >  arch/arm64/include/asm/kvm_pgtable.h | 20 +++++++++++++++
> >  arch/arm64/kvm/hyp/pgtable.c         | 37 ++++++++++++++++++++++++++++
> >  2 files changed, 57 insertions(+)
> >
> > diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> > index d5ca9b6ce241..7ff9f52239ba 100644
> > --- a/arch/arm64/include/asm/kvm_pgtable.h
> > +++ b/arch/arm64/include/asm/kvm_pgtable.h
> > @@ -505,4 +505,24 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
> >   */
> >  int kvm_pgtable_get_leaf(struct kvm_pgtable *pgt, u64 addr,
> >                          kvm_pte_t *ptep, u32 *level);
> > +
> > +/**
> > + * kvm_pgtable_stage2_pte_prot() - Retrieve the protection attributes of a
> > + *                                stage-2 Page-Table Entry.
> > + * @pte:       Page-table entry
> > + *
> > + * Return: protection attributes of the page-table entry in the enum
> > + *        kvm_pgtable_prot format.
> > + */
> > +enum kvm_pgtable_prot kvm_pgtable_stage2_pte_prot(kvm_pte_t pte);
> > +
> > +/**
> > + * kvm_pgtable_hyp_pte_prot() - Retrieve the protection attributes of a stage-1
> > + *                             Page-Table Entry.
> > + * @pte:       Page-table entry
> > + *
> > + * Return: protection attributes of the page-table entry in the enum
> > + *        kvm_pgtable_prot format.
> > + */
> > +enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte);
> >  #endif /* __ARM64_KVM_PGTABLE_H__ */
> > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> > index 1915489bb127..a6eda8f23cb6 100644
> > --- a/arch/arm64/kvm/hyp/pgtable.c
> > +++ b/arch/arm64/kvm/hyp/pgtable.c
> > @@ -363,6 +363,26 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep)
> >         return 0;
> >  }
> >
> > +enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte)
> > +{
> > +       enum kvm_pgtable_prot prot = pte & KVM_PTE_LEAF_ATTR_HI_SW;
> > +       u32 ap;
> > +
> > +       if (!kvm_pte_valid(pte))
> > +               return prot;
> > +
> > +       if (!(pte & KVM_PTE_LEAF_ATTR_HI_S1_XN))
> > +               prot |= KVM_PGTABLE_PROT_X;
> > +
> > +       ap = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S1_AP, pte);
> > +       if (ap == KVM_PTE_LEAF_ATTR_LO_S1_AP_RO)
> > +               prot |= KVM_PGTABLE_PROT_R;
> > +       else if (ap == KVM_PTE_LEAF_ATTR_LO_S1_AP_RW)
> > +               prot |= KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W;
> 
> nit: why not use the freshly minted KVM_PGTABLE_PROT_RW?

No good reason, I'll fix that up, thanks!
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index d5ca9b6ce241..7ff9f52239ba 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -505,4 +505,24 @@  int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
  */
 int kvm_pgtable_get_leaf(struct kvm_pgtable *pgt, u64 addr,
 			 kvm_pte_t *ptep, u32 *level);
+
+/**
+ * kvm_pgtable_stage2_pte_prot() - Retrieve the protection attributes of a
+ *				   stage-2 Page-Table Entry.
+ * @pte:	Page-table entry
+ *
+ * Return: protection attributes of the page-table entry in the enum
+ *	   kvm_pgtable_prot format.
+ */
+enum kvm_pgtable_prot kvm_pgtable_stage2_pte_prot(kvm_pte_t pte);
+
+/**
+ * kvm_pgtable_hyp_pte_prot() - Retrieve the protection attributes of a stage-1
+ *				Page-Table Entry.
+ * @pte:	Page-table entry
+ *
+ * Return: protection attributes of the page-table entry in the enum
+ *	   kvm_pgtable_prot format.
+ */
+enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte);
 #endif	/* __ARM64_KVM_PGTABLE_H__ */
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 1915489bb127..a6eda8f23cb6 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -363,6 +363,26 @@  static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep)
 	return 0;
 }
 
+enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte)
+{
+	enum kvm_pgtable_prot prot = pte & KVM_PTE_LEAF_ATTR_HI_SW;
+	u32 ap;
+
+	if (!kvm_pte_valid(pte))
+		return prot;
+
+	if (!(pte & KVM_PTE_LEAF_ATTR_HI_S1_XN))
+		prot |= KVM_PGTABLE_PROT_X;
+
+	ap = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S1_AP, pte);
+	if (ap == KVM_PTE_LEAF_ATTR_LO_S1_AP_RO)
+		prot |= KVM_PGTABLE_PROT_R;
+	else if (ap == KVM_PTE_LEAF_ATTR_LO_S1_AP_RW)
+		prot |= KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W;
+
+	return prot;
+}
+
 static bool hyp_pte_needs_update(kvm_pte_t old, kvm_pte_t new)
 {
 	/*
@@ -565,6 +585,23 @@  static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot p
 	return 0;
 }
 
+enum kvm_pgtable_prot kvm_pgtable_stage2_pte_prot(kvm_pte_t pte)
+{
+	enum kvm_pgtable_prot prot = pte & KVM_PTE_LEAF_ATTR_HI_SW;
+
+	if (!kvm_pte_valid(pte))
+		return prot;
+
+	if (pte & KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R)
+		prot |= KVM_PGTABLE_PROT_R;
+	if (pte & KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W)
+		prot |= KVM_PGTABLE_PROT_W;
+	if (!(pte & KVM_PTE_LEAF_ATTR_HI_S2_XN))
+		prot |= KVM_PGTABLE_PROT_X;
+
+	return prot;
+}
+
 static bool stage2_pte_needs_update(kvm_pte_t old, kvm_pte_t new)
 {
 	if (!kvm_pte_valid(old) || !kvm_pte_valid(new))