Commit 83844a23 authored by Oliver Upton's avatar Oliver Upton Committed by Marc Zyngier
Browse files

KVM: arm64: Stash observed pte value in visitor context 



Rather than reading the ptep all over the shop, read the ptep once from
__kvm_pgtable_visit() and stick it in the visitor context. Reread the
ptep after visiting a leaf in case the callback installed a new table
underneath.

No functional change intended.

Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
Reviewed-by: default avatarBen Gardon <bgardon@google.com>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221107215644.1895162-3-oliver.upton@linux.dev
parent dfc7a776

arch/arm64/include/asm/kvm_pgtable.h

+1 −0
Original line number Diff line number Diff line
@@ -201,6 +201,7 @@ enum kvm_pgtable_walk_flags { 


struct kvm_pgtable_visit_ctx {

	kvm_pte_t				*ptep;

	kvm_pte_t				old;

	void					*arg;

	u64					addr;

	u64					end;

arch/arm64/kvm/hyp/nvhe/mem_protect.c

+2 −3
Original line number Diff line number Diff line
@@ -421,12 +421,11 @@ static int __check_page_state_visitor(const struct kvm_pgtable_visit_ctx *ctx, 
				      enum kvm_pgtable_walk_flags visit)

{

	struct check_walk_data *d = ctx->arg;

	kvm_pte_t pte = *ctx->ptep;



	if (kvm_pte_valid(pte) && !addr_is_memory(kvm_pte_to_phys(pte)))

	if (kvm_pte_valid(ctx->old) && !addr_is_memory(kvm_pte_to_phys(ctx->old)))

		return -EINVAL;



	return d->get_page_state(pte) == d->desired ? 0 : -EPERM;

	return d->get_page_state(ctx->old) == d->desired ? 0 : -EPERM;

}



static int check_page_state_range(struct kvm_pgtable *pgt, u64 addr, u64 size,

arch/arm64/kvm/hyp/nvhe/setup.c

+3 −4
Original line number Diff line number Diff line
@@ -192,10 +192,9 @@ static int finalize_host_mappings_walker(const struct kvm_pgtable_visit_ctx *ctx 
	struct kvm_pgtable_mm_ops *mm_ops = ctx->arg;

	enum kvm_pgtable_prot prot;

	enum pkvm_page_state state;

	kvm_pte_t pte = *ctx->ptep;

	phys_addr_t phys;



	if (!kvm_pte_valid(pte))

	if (!kvm_pte_valid(ctx->old))

		return 0;



	/*
@@ -210,7 +209,7 @@ static int finalize_host_mappings_walker(const struct kvm_pgtable_visit_ctx *ctx 
	if (ctx->level != (KVM_PGTABLE_MAX_LEVELS - 1))

		return -EINVAL;



	phys = kvm_pte_to_phys(pte);

	phys = kvm_pte_to_phys(ctx->old);

	if (!addr_is_memory(phys))

		return -EINVAL;
@@ -218,7 +217,7 @@ static int finalize_host_mappings_walker(const struct kvm_pgtable_visit_ctx *ctx 
	 * Adjust the host stage-2 mappings to match the ownership attributes

	 * configured in the hypervisor stage-1.

	 */

	state = pkvm_getstate(kvm_pgtable_hyp_pte_prot(pte));

	state = pkvm_getstate(kvm_pgtable_hyp_pte_prot(ctx->old));

	switch (state) {

	case PKVM_PAGE_OWNED:

		return host_stage2_set_owner_locked(phys, PAGE_SIZE, pkvm_hyp_id);

arch/arm64/kvm/hyp/pgtable.c

+42 −44
Original line number Diff line number Diff line
@@ -189,6 +189,7 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data, 
	enum kvm_pgtable_walk_flags flags = data->walker->flags;

	struct kvm_pgtable_visit_ctx ctx = {

		.ptep	= ptep,

		.old	= READ_ONCE(*ptep),

		.arg	= data->walker->arg,

		.addr	= data->addr,

		.end	= data->end,
@@ -196,16 +197,16 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data, 
		.flags	= flags,

	};

	int ret = 0;

	kvm_pte_t *childp, pte = *ptep;

	bool table = kvm_pte_table(pte, level);

	kvm_pte_t *childp;

	bool table = kvm_pte_table(ctx.old, level);



	if (table && (ctx.flags & KVM_PGTABLE_WALK_TABLE_PRE))

		ret = kvm_pgtable_visitor_cb(data, &ctx, KVM_PGTABLE_WALK_TABLE_PRE);



	if (!table && (ctx.flags & KVM_PGTABLE_WALK_LEAF)) {

		ret = kvm_pgtable_visitor_cb(data, &ctx, KVM_PGTABLE_WALK_LEAF);

		pte = *ptep;

		table = kvm_pte_table(pte, level);

		ctx.old = READ_ONCE(*ptep);

		table = kvm_pte_table(ctx.old, level);

	}



	if (ret)
@@ -217,7 +218,7 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data, 
		goto out;

	}



	childp = kvm_pte_follow(pte, data->pgt->mm_ops);

	childp = kvm_pte_follow(ctx.old, data->pgt->mm_ops);

	ret = __kvm_pgtable_walk(data, childp, level + 1);

	if (ret)

		goto out;
@@ -299,7 +300,7 @@ static int leaf_walker(const struct kvm_pgtable_visit_ctx *ctx, 
{

	struct leaf_walk_data *data = ctx->arg;



	data->pte   = *ctx->ptep;

	data->pte   = ctx->old;

	data->level = ctx->level;



	return 0;
@@ -388,7 +389,7 @@ enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte) 
static bool hyp_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx,

				    struct hyp_map_data *data)

{

	kvm_pte_t new, old = *ctx->ptep;

	kvm_pte_t new;

	u64 granule = kvm_granule_size(ctx->level), phys = data->phys;



	if (!kvm_block_mapping_supported(ctx, phys))
@@ -396,11 +397,11 @@ static bool hyp_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx, 


	data->phys += granule;

	new = kvm_init_valid_leaf_pte(phys, data->attr, ctx->level);

	if (old == new)

	if (ctx->old == new)

		return true;

	if (!kvm_pte_valid(old))

	if (!kvm_pte_valid(ctx->old))

		data->mm_ops->get_page(ctx->ptep);

	else if (WARN_ON((old ^ new) & ~KVM_PTE_LEAF_ATTR_HI_SW))

	else if (WARN_ON((ctx->old ^ new) & ~KVM_PTE_LEAF_ATTR_HI_SW))

		return false;



	smp_store_release(ctx->ptep, new);
@@ -461,16 +462,16 @@ struct hyp_unmap_data { 
static int hyp_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx,

			    enum kvm_pgtable_walk_flags visit)

{

	kvm_pte_t pte = *ctx->ptep, *childp = NULL;

	kvm_pte_t *childp = NULL;

	u64 granule = kvm_granule_size(ctx->level);

	struct hyp_unmap_data *data = ctx->arg;

	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;



	if (!kvm_pte_valid(pte))

	if (!kvm_pte_valid(ctx->old))

		return -EINVAL;



	if (kvm_pte_table(pte, ctx->level)) {

		childp = kvm_pte_follow(pte, mm_ops);

	if (kvm_pte_table(ctx->old, ctx->level)) {

		childp = kvm_pte_follow(ctx->old, mm_ops);



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

			return 0;
@@ -538,15 +539,14 @@ static int hyp_free_walker(const struct kvm_pgtable_visit_ctx *ctx, 
			   enum kvm_pgtable_walk_flags visit)

{

	struct kvm_pgtable_mm_ops *mm_ops = ctx->arg;

	kvm_pte_t pte = *ctx->ptep;



	if (!kvm_pte_valid(pte))

	if (!kvm_pte_valid(ctx->old))

		return 0;



	mm_ops->put_page(ctx->ptep);



	if (kvm_pte_table(pte, ctx->level))

		mm_ops->put_page(kvm_pte_follow(pte, mm_ops));

	if (kvm_pte_table(ctx->old, ctx->level))

		mm_ops->put_page(kvm_pte_follow(ctx->old, mm_ops));



	return 0;

}
@@ -691,7 +691,7 @@ static void stage2_put_pte(const struct kvm_pgtable_visit_ctx *ctx, struct kvm_s 
	 * Clear the existing PTE, and perform break-before-make with

	 * TLB maintenance if it was valid.

	 */

	if (kvm_pte_valid(*ctx->ptep)) {

	if (kvm_pte_valid(ctx->old)) {

		kvm_clear_pte(ctx->ptep);

		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, ctx->addr, ctx->level);

	}
@@ -722,7 +722,7 @@ static bool stage2_leaf_mapping_allowed(const struct kvm_pgtable_visit_ctx *ctx, 
static int stage2_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx,

				      struct stage2_map_data *data)

{

	kvm_pte_t new, old = *ctx->ptep;

	kvm_pte_t new;

	u64 granule = kvm_granule_size(ctx->level), phys = data->phys;

	struct kvm_pgtable *pgt = data->mmu->pgt;

	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
@@ -735,14 +735,14 @@ static int stage2_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx, 
	else

		new = kvm_init_invalid_leaf_owner(data->owner_id);



	if (stage2_pte_is_counted(old)) {

	if (stage2_pte_is_counted(ctx->old)) {

		/*

		 * Skip updating the PTE if we are trying to recreate the exact

		 * same mapping or only change the access permissions. Instead,

		 * the vCPU will exit one more time from guest if still needed

		 * and then go through the path of relaxing permissions.

		 */

		if (!stage2_pte_needs_update(old, new))

		if (!stage2_pte_needs_update(ctx->old, new))

			return -EAGAIN;



		stage2_put_pte(ctx, data->mmu, mm_ops);
@@ -773,7 +773,7 @@ static int stage2_map_walk_table_pre(const struct kvm_pgtable_visit_ctx *ctx, 
	if (!stage2_leaf_mapping_allowed(ctx, data))

		return 0;



	data->childp = kvm_pte_follow(*ctx->ptep, data->mm_ops);

	data->childp = kvm_pte_follow(ctx->old, data->mm_ops);

	kvm_clear_pte(ctx->ptep);



	/*
@@ -790,11 +790,11 @@ static int stage2_map_walk_leaf(const struct kvm_pgtable_visit_ctx *ctx, 
				struct stage2_map_data *data)

{

	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;

	kvm_pte_t *childp, pte = *ctx->ptep;

	kvm_pte_t *childp;

	int ret;



	if (data->anchor) {

		if (stage2_pte_is_counted(pte))

		if (stage2_pte_is_counted(ctx->old))

			mm_ops->put_page(ctx->ptep);



		return 0;
@@ -819,7 +819,7 @@ static int stage2_map_walk_leaf(const struct kvm_pgtable_visit_ctx *ctx, 
	 * a table. Accesses beyond 'end' that fall within the new table

	 * will be mapped lazily.

	 */

	if (stage2_pte_is_counted(pte))

	if (stage2_pte_is_counted(ctx->old))

		stage2_put_pte(ctx, data->mmu, mm_ops);



	kvm_set_table_pte(ctx->ptep, childp, mm_ops);
@@ -844,7 +844,7 @@ static int stage2_map_walk_table_post(const struct kvm_pgtable_visit_ctx *ctx, 
		data->childp = NULL;

		ret = stage2_map_walk_leaf(ctx, data);

	} else {

		childp = kvm_pte_follow(*ctx->ptep, mm_ops);

		childp = kvm_pte_follow(ctx->old, mm_ops);

	}



	mm_ops->put_page(childp);
@@ -954,23 +954,23 @@ static int stage2_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx, 
	struct kvm_pgtable *pgt = ctx->arg;

	struct kvm_s2_mmu *mmu = pgt->mmu;

	struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;

	kvm_pte_t pte = *ctx->ptep, *childp = NULL;

	kvm_pte_t *childp = NULL;

	bool need_flush = false;



	if (!kvm_pte_valid(pte)) {

		if (stage2_pte_is_counted(pte)) {

	if (!kvm_pte_valid(ctx->old)) {

		if (stage2_pte_is_counted(ctx->old)) {

			kvm_clear_pte(ctx->ptep);

			mm_ops->put_page(ctx->ptep);

		}

		return 0;

	}



	if (kvm_pte_table(pte, ctx->level)) {

		childp = kvm_pte_follow(pte, mm_ops);

	if (kvm_pte_table(ctx->old, ctx->level)) {

		childp = kvm_pte_follow(ctx->old, mm_ops);



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

			return 0;

	} else if (stage2_pte_cacheable(pgt, pte)) {

	} else if (stage2_pte_cacheable(pgt, ctx->old)) {

		need_flush = !stage2_has_fwb(pgt);

	}
@@ -982,7 +982,7 @@ static int stage2_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx, 
	stage2_put_pte(ctx, mmu, mm_ops);



	if (need_flush && mm_ops->dcache_clean_inval_poc)

		mm_ops->dcache_clean_inval_poc(kvm_pte_follow(pte, mm_ops),

		mm_ops->dcache_clean_inval_poc(kvm_pte_follow(ctx->old, mm_ops),

					       kvm_granule_size(ctx->level));



	if (childp)
@@ -1013,11 +1013,11 @@ struct stage2_attr_data { 
static int stage2_attr_walker(const struct kvm_pgtable_visit_ctx *ctx,

			      enum kvm_pgtable_walk_flags visit)

{

	kvm_pte_t pte = *ctx->ptep;

	kvm_pte_t pte = ctx->old;

	struct stage2_attr_data *data = ctx->arg;

	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;



	if (!kvm_pte_valid(pte))

	if (!kvm_pte_valid(ctx->old))

		return 0;



	data->level = ctx->level;
@@ -1036,7 +1036,7 @@ static int stage2_attr_walker(const struct kvm_pgtable_visit_ctx *ctx, 
		 * stage-2 PTE if we are going to add executable permission.

		 */

		if (mm_ops->icache_inval_pou &&

		    stage2_pte_executable(pte) && !stage2_pte_executable(*ctx->ptep))

		    stage2_pte_executable(pte) && !stage2_pte_executable(ctx->old))

			mm_ops->icache_inval_pou(kvm_pte_follow(pte, mm_ops),

						  kvm_granule_size(ctx->level));

		WRITE_ONCE(*ctx->ptep, pte);
@@ -1142,13 +1142,12 @@ static int stage2_flush_walker(const struct kvm_pgtable_visit_ctx *ctx, 
{

	struct kvm_pgtable *pgt = ctx->arg;

	struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;

	kvm_pte_t pte = *ctx->ptep;



	if (!kvm_pte_valid(pte) || !stage2_pte_cacheable(pgt, pte))

	if (!kvm_pte_valid(ctx->old) || !stage2_pte_cacheable(pgt, ctx->old))

		return 0;



	if (mm_ops->dcache_clean_inval_poc)

		mm_ops->dcache_clean_inval_poc(kvm_pte_follow(pte, mm_ops),

		mm_ops->dcache_clean_inval_poc(kvm_pte_follow(ctx->old, mm_ops),

					       kvm_granule_size(ctx->level));

	return 0;

}
@@ -1200,15 +1199,14 @@ static int stage2_free_walker(const struct kvm_pgtable_visit_ctx *ctx, 
			      enum kvm_pgtable_walk_flags visit)

{

	struct kvm_pgtable_mm_ops *mm_ops = ctx->arg;

	kvm_pte_t pte = *ctx->ptep;



	if (!stage2_pte_is_counted(pte))

	if (!stage2_pte_is_counted(ctx->old))

		return 0;



	mm_ops->put_page(ctx->ptep);



	if (kvm_pte_table(pte, ctx->level))

		mm_ops->put_page(kvm_pte_follow(pte, mm_ops));

	if (kvm_pte_table(ctx->old, ctx->level))

		mm_ops->put_page(kvm_pte_follow(ctx->old, mm_ops));



	return 0;

}