Commit e0e5a07f authored by Will Deacon's avatar Will Deacon Committed by Marc Zyngier
Browse files

KVM: arm64: Add support for stage-2 page-aging in generic page-table 



Add stage-2 mkyoung(), mkold() and is_young() operations to the generic
page-table code.

Signed-off-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-11-will@kernel.org
parent 52bae936

arch/arm64/include/asm/kvm_pgtable.h

+44 −0
Original line number Diff line number Diff line
@@ -186,6 +186,50 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size, 
 */

int kvm_pgtable_stage2_unmap(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.

 *

 * 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.

 *

 * Return: The old page-table entry prior to setting the flag, 0 on failure.

 */

kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr);



/**

 * kvm_pgtable_stage2_mkold() - Clear 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.

 *

 * The offset of @addr within a page is ignored.

 *

 * If there is a valid, leaf page-table entry used to translate @addr, then

 * clear the access flag in that entry.

 *

 * Note that it is the caller's responsibility to invalidate the TLB after

 * calling this function to ensure that the updated permissions are visible

 * to the CPUs.

 *

 * Return: The old page-table entry prior to clearing the flag, 0 on failure.

 */

kvm_pte_t kvm_pgtable_stage2_mkold(struct kvm_pgtable *pgt, u64 addr);



/**

 * kvm_pgtable_stage2_is_young() - Test whether a page-table entry has the

 *				   access flag set.

 * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().

 * @addr:	Intermediate physical address to identify the page-table entry.

 *

 * The offset of @addr within a page is ignored.

 *

 * Return: True if the page-table entry has the access flag set, false otherwise.

 */

bool kvm_pgtable_stage2_is_young(struct kvm_pgtable *pgt, u64 addr);



/**

 * kvm_pgtable_walk() - Walk a page-table.

 * @pgt:	Page-table structure initialised by kvm_pgtable_*_init().

arch/arm64/kvm/hyp/pgtable.c

+86 −0
Original line number Diff line number Diff line
@@ -690,6 +690,92 @@ int kvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size) 
	return kvm_pgtable_walk(pgt, addr, size, &walker);

}



struct stage2_attr_data {

	kvm_pte_t	attr_set;

	kvm_pte_t	attr_clr;

	kvm_pte_t	pte;

};



static int stage2_attr_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,

			      enum kvm_pgtable_walk_flags flag,

			      void * const arg)

{

	kvm_pte_t pte = *ptep;

	struct stage2_attr_data *data = arg;



	if (!kvm_pte_valid(pte))

		return 0;



	data->pte = pte;

	pte &= ~data->attr_clr;

	pte |= data->attr_set;



	/*

	 * We may race with the CPU trying to set the access flag here,

	 * but worst-case the access flag update gets lost and will be

	 * set on the next access instead.

	 */

	if (data->pte != pte)

		WRITE_ONCE(*ptep, pte);



	return 0;

}



static int stage2_update_leaf_attrs(struct kvm_pgtable *pgt, u64 addr,

				    u64 size, kvm_pte_t attr_set,

				    kvm_pte_t attr_clr, kvm_pte_t *orig_pte)

{

	int ret;

	kvm_pte_t attr_mask = KVM_PTE_LEAF_ATTR_LO | KVM_PTE_LEAF_ATTR_HI;

	struct stage2_attr_data data = {

		.attr_set	= attr_set & attr_mask,

		.attr_clr	= attr_clr & attr_mask,

	};

	struct kvm_pgtable_walker walker = {

		.cb		= stage2_attr_walker,

		.arg		= &data,

		.flags		= KVM_PGTABLE_WALK_LEAF,

	};



	ret = kvm_pgtable_walk(pgt, addr, size, &walker);

	if (ret)

		return ret;



	if (orig_pte)

		*orig_pte = data.pte;

	return 0;

}



kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)

{

	kvm_pte_t pte = 0;

	stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,

				 &pte);

	dsb(ishst);

	return pte;

}



kvm_pte_t kvm_pgtable_stage2_mkold(struct kvm_pgtable *pgt, u64 addr)

{

	kvm_pte_t pte = 0;

	stage2_update_leaf_attrs(pgt, addr, 1, 0, KVM_PTE_LEAF_ATTR_LO_S2_AF,

				 &pte);

	/*

	 * "But where's the TLBI?!", you scream.

	 * "Over in the core code", I sigh.

	 *

	 * See the '->clear_flush_young()' callback on the KVM mmu notifier.

	 */

	return pte;

}



bool kvm_pgtable_stage2_is_young(struct kvm_pgtable *pgt, u64 addr)

{

	kvm_pte_t pte = 0;

	stage2_update_leaf_attrs(pgt, addr, 1, 0, 0, &pte);

	return pte & KVM_PTE_LEAF_ATTR_LO_S2_AF;

}



int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm)

{

	size_t pgd_sz;