[PATCH 1/5] KVM: x86/mmu: Fix wrong gfn range of tlb flushing in validate_direct_spte()

[PATCH 1/5] KVM: x86/mmu: Fix wrong gfn range of tlb flushing in validate_direct_spte()

[Hou Wenlong]

The spte pointing to the children SP is dropped, so the whole gfn range
covered by the children SP should be flushed.

Fixes: c3134ce240eed ("KVM: Replace old tlb flush function with new one to flush a specified range.")
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
 arch/x86/kvm/mmu/mmu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 79c6a821ea0d..b8a1f5b46b9d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2333,7 +2333,8 @@ static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 			return;
 
 		drop_parent_pte(child, sptep);
-		kvm_flush_remote_tlbs_with_address(vcpu->kvm, child->gfn, 1);
+		kvm_flush_remote_tlbs_with_address(vcpu->kvm, child->gfn,
+				KVM_PAGES_PER_HPAGE(child->role.level + 1));
 	}
 }
 
-- 
2.31.1

[PATCH 2/5] KVM: x86/mmu: Fix wrong gfn range of tlb flushing in kvm_set_pte_rmapp()

[Hou Wenlong]

When the spte of hupe page is dropped in kvm_set_pte_rmapp(),
the whole gfn range covered by the spte should be flushed.
However, rmap_walk_init_level() doesn't align down the gfn
for new level like tdp iterator does, then the gfn used in
kvm_set_pte_rmapp() is not the base gfn of huge page. And
the size of gfn range is wrong too for huge page. Since
the base gfn of huge page is more meaningful during the
rmap walking, so align down the gfn for new level and use
the correct size of huge page for tlb flushing in
kvm_set_pte_rmapp().

Fixes: c3134ce240eed ("KVM: Replace old tlb flush function with new one to flush a specified range.")
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
 arch/x86/kvm/mmu/mmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b8a1f5b46b9d..37bfc88ea212 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1427,7 +1427,7 @@ static bool kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 	}
 
 	if (need_flush && kvm_available_flush_tlb_with_range()) {
-		kvm_flush_remote_tlbs_with_address(kvm, gfn, 1);
+		kvm_flush_remote_tlbs_with_address(kvm, gfn, KVM_PAGES_PER_HPAGE(level));
 		return false;
 	}
 
@@ -1455,7 +1455,7 @@ static void
 rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level)
 {
 	iterator->level = level;
-	iterator->gfn = iterator->start_gfn;
+	iterator->gfn = iterator->start_gfn & -KVM_PAGES_PER_HPAGE(level);
 	iterator->rmap = gfn_to_rmap(iterator->gfn, level, iterator->slot);
 	iterator->end_rmap = gfn_to_rmap(iterator->end_gfn, level, iterator->slot);
 }
-- 
2.31.1

Re: [PATCH 2/5] KVM: x86/mmu: Fix wrong gfn range of tlb flushing in kvm_set_pte_rmapp()

[Sean Christopherson]

On Fri, Jun 24, 2022, Hou Wenlong wrote:
> When the spte of hupe page is dropped in kvm_set_pte_rmapp(),
> the whole gfn range covered by the spte should be flushed.
> However, rmap_walk_init_level() doesn't align down the gfn
> for new level like tdp iterator does, then the gfn used in
> kvm_set_pte_rmapp() is not the base gfn of huge page. And
> the size of gfn range is wrong too for huge page. Since
> the base gfn of huge page is more meaningful during the
> rmap walking, so align down the gfn for new level and use
> the correct size of huge page for tlb flushing in
> kvm_set_pte_rmapp().

It's also worth noting that kvm_set_pte_rmapp() is the other user of the rmap
iterators that consumes @gfn, i.e. modifying iterator->gfn is safe-ish.

> Fixes: c3134ce240eed ("KVM: Replace old tlb flush function with new one to flush a specified range.")
> Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
> ---
>  arch/x86/kvm/mmu/mmu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index b8a1f5b46b9d..37bfc88ea212 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1427,7 +1427,7 @@ static bool kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
>  	}
>  
>  	if (need_flush && kvm_available_flush_tlb_with_range()) {
> -		kvm_flush_remote_tlbs_with_address(kvm, gfn, 1);
> +		kvm_flush_remote_tlbs_with_address(kvm, gfn, KVM_PAGES_PER_HPAGE(level));
>  		return false;
>  	}
>  
> @@ -1455,7 +1455,7 @@ static void
>  rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level)
>  {
>  	iterator->level = level;
> -	iterator->gfn = iterator->start_gfn;
> +	iterator->gfn = iterator->start_gfn & -KVM_PAGES_PER_HPAGE(level);

Hrm, arguably this be done on start_gfn in slot_rmap_walk_init().  Having iter->gfn
be less than iter->start_gfn will be odd.

>  	iterator->rmap = gfn_to_rmap(iterator->gfn, level, iterator->slot);
>  	iterator->end_rmap = gfn_to_rmap(iterator->end_gfn, level, iterator->slot);
>  }
> -- 
> 2.31.1
> 

[PATCH 3/5] KVM: x86/mmu: Reduce gfn range of tlb flushing in tdp_mmu_map_handle_target_level()

[Hou Wenlong]

Since the children SP is zapped, the gfn range of tlb flushing should be
the range covered by children SP not parent SP. Replace sp->gfn which is
the base gfn of parent SP with iter->gfn and use the correct size of
gfn range for children SP to reduce tlb flushing range.

Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index f3a430d64975..85838ae169b8 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1075,8 +1075,8 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
 		return RET_PF_RETRY;
 	else if (is_shadow_present_pte(iter->old_spte) &&
 		 !is_last_spte(iter->old_spte, iter->level))
-		kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
-						   KVM_PAGES_PER_HPAGE(iter->level + 1));
+		kvm_flush_remote_tlbs_with_address(vcpu->kvm, iter->gfn,
+						   KVM_PAGES_PER_HPAGE(iter->level));
 
 	/*
 	 * If the page fault was caused by a write but the page is write
-- 
2.31.1

[PATCH 4/5] KVM: x86/mmu: Fix wrong start gfn of tlb flushing with range

[Hou Wenlong]

When a spte is dropped, the start gfn of tlb flushing should
be the gfn of spte not the base gfn of SP which contains the
spte.

Fixes: c3134ce240eed ("KVM: Replace old tlb flush function with new one to flush a specified range.")
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
 arch/x86/kvm/mmu/mmu.c         | 8 +++++---
 arch/x86/kvm/mmu/paging_tmpl.h | 3 ++-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 37bfc88ea212..577b85860891 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1145,7 +1145,8 @@ static void drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush)
 	drop_spte(kvm, sptep);
 
 	if (flush)
-		kvm_flush_remote_tlbs_with_address(kvm, sp->gfn,
+		kvm_flush_remote_tlbs_with_address(kvm,
+			kvm_mmu_page_get_gfn(sp, sptep - sp->spt),
 			KVM_PAGES_PER_HPAGE(sp->role.level));
 }
 
@@ -1596,7 +1597,7 @@ static void __rmap_add(struct kvm *kvm,
 	if (rmap_count > RMAP_RECYCLE_THRESHOLD) {
 		kvm_unmap_rmapp(kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
 		kvm_flush_remote_tlbs_with_address(
-				kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
+				kvm, gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
 	}
 }
 
@@ -6397,7 +6398,8 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
 			pte_list_remove(kvm, rmap_head, sptep);
 
 			if (kvm_available_flush_tlb_with_range())
-				kvm_flush_remote_tlbs_with_address(kvm, sp->gfn,
+				kvm_flush_remote_tlbs_with_address(kvm,
+					kvm_mmu_page_get_gfn(sp, sptep - sp->spt),
 					KVM_PAGES_PER_HPAGE(sp->role.level));
 			else
 				need_tlb_flush = 1;
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 2448fa8d8438..fa78ee0caffd 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -938,7 +938,8 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root_hpa)
 			mmu_page_zap_pte(vcpu->kvm, sp, sptep, NULL);
 			if (is_shadow_present_pte(old_spte))
 				kvm_flush_remote_tlbs_with_address(vcpu->kvm,
-					sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
+					kvm_mmu_page_get_gfn(sp, sptep - sp->spt),
+					KVM_PAGES_PER_HPAGE(sp->role.level));
 
 			if (!rmap_can_add(vcpu))
 				break;
-- 
2.31.1

[PATCH 5/5] KVM: x86/mmu: Use 1 as the size of gfn range for tlb flushing in FNAME(invlpg)()

[Hou Wenlong]

Only SP with PG_LEVLE_4K level could be unsync, so the size of gfn range
must be 1.

Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
 arch/x86/kvm/mmu/paging_tmpl.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index fa78ee0caffd..fc6d8dcff019 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -938,8 +938,7 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root_hpa)
 			mmu_page_zap_pte(vcpu->kvm, sp, sptep, NULL);
 			if (is_shadow_present_pte(old_spte))
 				kvm_flush_remote_tlbs_with_address(vcpu->kvm,
-					kvm_mmu_page_get_gfn(sp, sptep - sp->spt),
-					KVM_PAGES_PER_HPAGE(sp->role.level));
+					kvm_mmu_page_get_gfn(sp, sptep - sp->spt), 1);
 
 			if (!rmap_can_add(vcpu))
 				break;
-- 
2.31.1