Commit 82bb0244 authored by Will Deacon's avatar Will Deacon Committed by Marc Zyngier
Browse files

KVM: arm64: Implement kvm_pgtable_hyp_unmap() at EL2 



Implement kvm_pgtable_hyp_unmap() which can be used to remove hypervisor
stage-1 mappings at EL2.

Signed-off-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211215161232.1480836-6-qperret@google.com
parent 34ec7cbf

arch/arm64/include/asm/kvm_pgtable.h

+21 −0
Original line number Diff line number Diff line
@@ -251,6 +251,27 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt); 
int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,

			enum kvm_pgtable_prot prot);



/**

 * kvm_pgtable_hyp_unmap() - Remove a mapping from a hypervisor stage-1 page-table.

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

 * @addr:	Virtual address from which to remove the mapping.

 * @size:	Size of the mapping.

 *

 * The offset of @addr within a page is ignored, @size is rounded-up to

 * the next page boundary and @phys is rounded-down to the previous page

 * boundary.

 *

 * TLB invalidation is performed for each page-table entry cleared during the

 * unmapping operation and the reference count for the page-table page

 * containing the cleared entry is decremented, with unreferenced pages being

 * freed. The unmapping operation will stop early if it encounters either an

 * invalid page-table entry or a valid block mapping which maps beyond the range

 * being unmapped.

 *

 * Return: Number of bytes unmapped, which may be 0.

 */

u64 kvm_pgtable_hyp_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size);



/**

 * kvm_get_vtcr() - Helper to construct VTCR_EL2

 * @mmfr0:	Sanitized value of SYS_ID_AA64MMFR0_EL1 register.

arch/arm64/kvm/hyp/pgtable.c

+63 −0
Original line number Diff line number Diff line
@@ -451,6 +451,69 @@ int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys, 
	return ret;

}



struct hyp_unmap_data {

	u64				unmapped;

	struct kvm_pgtable_mm_ops	*mm_ops;

};



static int hyp_unmap_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, *childp = NULL;

	u64 granule = kvm_granule_size(level);

	struct hyp_unmap_data *data = arg;

	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;



	if (!kvm_pte_valid(pte))

		return -EINVAL;



	if (kvm_pte_table(pte, level)) {

		childp = kvm_pte_follow(pte, mm_ops);



		if (mm_ops->page_count(childp) != 1)

			return 0;



		kvm_clear_pte(ptep);

		dsb(ishst);

		__tlbi_level(vae2is, __TLBI_VADDR(addr, 0), level);

	} else {

		if (end - addr < granule)

			return -EINVAL;



		kvm_clear_pte(ptep);

		dsb(ishst);

		__tlbi_level(vale2is, __TLBI_VADDR(addr, 0), level);

		data->unmapped += granule;

	}



	dsb(ish);

	isb();

	mm_ops->put_page(ptep);



	if (childp)

		mm_ops->put_page(childp);



	return 0;

}



u64 kvm_pgtable_hyp_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)

{

	struct hyp_unmap_data unmap_data = {

		.mm_ops	= pgt->mm_ops,

	};

	struct kvm_pgtable_walker walker = {

		.cb	= hyp_unmap_walker,

		.arg	= &unmap_data,

		.flags	= KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST,

	};



	if (!pgt->mm_ops->page_count)

		return 0;



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

	return unmap_data.unmapped;

}



int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits,

			 struct kvm_pgtable_mm_ops *mm_ops)

{