Commit 9024b3d0 authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: Enable retrieving protections attributes of PTEs 



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: default avatarQuentin Perret <qperret@google.com>
Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-17-qperret@google.com
parent e009dce1

arch/arm64/include/asm/kvm_pgtable.h

+20 −0
Original line number Diff line number Diff line
@@ -507,4 +507,24 @@ 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__ */

arch/arm64/kvm/hyp/pgtable.c

+37 −0
Original line number Diff line number Diff line
@@ -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_RW;



	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))