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From: Quentin Perret <qperret@google.com>
To: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	 Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	 Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Fuad Tabba <tabba@google.com>,
	David Brazdil <dbrazdil@google.com>
Cc: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu,  linux-kernel@vger.kernel.org,
	kernel-team@android.com
Subject: [PATCH 07/16] KVM: arm64: Refcount hyp stage-1 pgtable pages
Date: Wed, 13 Oct 2021 16:58:22 +0100	[thread overview]
Message-ID: <20211013155831.943476-8-qperret@google.com> (raw)
In-Reply-To: <20211013155831.943476-1-qperret@google.com>

To prepare the ground for allowing hyp stage-1 mappings to be removed at
run-time, update the KVM page-table code to maintain a correct refcount
using the ->{get,put}_page() function callbacks.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index f8ceebe4982e..768a58835153 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -408,8 +408,10 @@ static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 		return false;
 
 	new = kvm_init_valid_leaf_pte(phys, data->attr, level);
-	if (hyp_pte_needs_update(old, new))
+	if (hyp_pte_needs_update(old, new)) {
 		smp_store_release(ptep, new);
+		data->mm_ops->get_page(ptep);
+	}
 
 	data->phys += granule;
 	return true;
@@ -433,6 +435,7 @@ static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 		return -ENOMEM;
 
 	kvm_set_table_pte(ptep, childp, mm_ops);
+	mm_ops->get_page(ptep);
 	return 0;
 }
 
@@ -482,8 +485,16 @@ static int hyp_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			   enum kvm_pgtable_walk_flags flag, void * const arg)
 {
 	struct kvm_pgtable_mm_ops *mm_ops = arg;
+	kvm_pte_t pte = *ptep;
+
+	if (!kvm_pte_valid(pte))
+		return 0;
+
+	mm_ops->put_page(ptep);
+
+	if (kvm_pte_table(pte, level))
+		mm_ops->put_page(kvm_pte_follow(pte, mm_ops));
 
-	mm_ops->put_page((void *)kvm_pte_follow(*ptep, mm_ops));
 	return 0;
 }
 
@@ -491,7 +502,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
 {
 	struct kvm_pgtable_walker walker = {
 		.cb	= hyp_free_walker,
-		.flags	= KVM_PGTABLE_WALK_TABLE_POST,
+		.flags	= KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST,
 		.arg	= pgt->mm_ops,
 	};
 
-- 
2.33.0.882.g93a45727a2-goog


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  parent reply	other threads:[~2021-10-13 16:03 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-13 15:58 [PATCH 00/16] KVM: arm64: Implement unshare hypercall for pkvm Quentin Perret
2021-10-13 15:58 ` [PATCH 01/16] KVM: arm64: Introduce do_share() helper for memory sharing between components Quentin Perret
2021-10-15 15:11   ` Andrew Walbran
2021-10-19 10:37     ` Quentin Perret
2021-10-13 15:58 ` [PATCH 02/16] KVM: arm64: Implement __pkvm_host_share_hyp() using do_share() Quentin Perret
2021-10-13 15:58 ` [PATCH 03/16] KVM: arm64: Avoid remapping the SVE state in the hyp stage-1 Quentin Perret
2021-10-16 11:04   ` Marc Zyngier
2021-10-18 10:36     ` Quentin Perret
2021-10-13 15:58 ` [PATCH 04/16] KVM: arm64: Introduce kvm_share_hyp() Quentin Perret
2021-10-17 10:41   ` Marc Zyngier
2021-10-18 10:51     ` Quentin Perret
2021-10-13 15:58 ` [PATCH 05/16] KVM: arm64: Accept page ranges in pkvm share hypercall Quentin Perret
2021-10-13 15:58 ` [PATCH 06/16] KVM: arm64: Provide {get,put}_page() stubs for early hyp allocator Quentin Perret
2021-10-13 15:58 ` Quentin Perret [this message]
2021-10-13 15:58 ` [PATCH 08/16] KVM: arm64: Fixup hyp stage-1 refcount Quentin Perret
2021-10-13 15:58 ` [PATCH 09/16] KVM: arm64: Hook up ->page_count() for hypervisor stage-1 page-table Quentin Perret
2021-10-13 15:58 ` [PATCH 10/16] KVM: arm64: Implement kvm_pgtable_hyp_unmap() at EL2 Quentin Perret
2021-10-13 15:58 ` [PATCH 11/16] KVM: arm64: Back hyp_vmemmap for all of memory Quentin Perret
2021-10-13 15:58 ` [PATCH 12/16] KVM: arm64: Move hyp refcount helpers to header files Quentin Perret
2021-10-13 15:58 ` [PATCH 13/16] KVM: arm64: Move double-sharing logic into hyp-specific function Quentin Perret
2021-10-13 15:58 ` [PATCH 14/16] KVM: arm64: Refcount shared pages at EL2 Quentin Perret
2021-10-13 15:58 ` [PATCH 15/16] KVM: arm64: pkvm: Introduce an unshare hypercall Quentin Perret
2021-10-13 15:58 ` [PATCH 16/16] KVM: arm64: pkvm: Unshare guest structs during teardown Quentin Perret
2021-10-16 12:25   ` Marc Zyngier
2021-10-18 10:32     ` Quentin Perret
2021-10-18 14:03       ` Quentin Perret
2021-10-18 17:12         ` Marc Zyngier
2021-10-19  9:40           ` Quentin Perret

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