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

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
......@@ -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().
......
......@@ -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;
......
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