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KVM: arm64: Implement kvm_pgtable_hyp_unmap() at EL2

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

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211215161232.1480836-6-qperret@google.com
This commit is contained in:
Will Deacon 2021-12-15 16:12:22 +00:00 committed by Marc Zyngier
parent 34ec7cbf1e
commit 82bb02445d
2 changed files with 84 additions and 0 deletions
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21
arch/arm64/include/asm/kvm_pgtable.h
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@ -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.

63
arch/arm64/kvm/hyp/pgtable.c
View File

@ -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)
{