Subject: [PATCH v2 13/22] KVM: arm64: Add support for stage-2 write-protect in generic page-table

From: Will Deacon <[email-masked]>
Date: Tue, 18 Aug 2020 14:28:09 +0100

From: Quentin Perret <[email-masked]>

Add a stage-2 wrprotect() operation to the generic page-table code.

Cc: Marc Zyngier <[email-masked]>
Signed-off-by: Quentin Perret <[email-masked]>
Signed-off-by: Will Deacon <[email-masked]>
---
 arch/arm64/include/asm/kvm_pgtable.h | 15 +++++++++++++++
 arch/arm64/kvm/hyp/pgtable.c         |  6 ++++++
 2 files changed, 21 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index ae56534f87a0..0c96b78d791d 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -173,6 +173,21 @@ 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_wrprotect() - Write-protect guest stage-2 address range
+ *                                  without TLB invalidation.
+ * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
+ * @addr:	Intermediate physical address from which to write-protect,
+ * @size:	Size of the range.
+ *
+ * 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: 0 on success, negative error code on failure.
+ */
+int kvm_pgtable_stage2_wrprotect(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().
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 30713eb773e0..c218651f8eba 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -726,6 +726,12 @@ static int stage2_update_leaf_attrs(struct kvm_pgtable *pgt, u64 addr,
 	return 0;
 }
 
+int kvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
+{
+	return stage2_update_leaf_attrs(pgt, addr, size, 0,
+					KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W, NULL);
+}
+
 kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)
 {
 	kvm_pte_t pte = 0;
-- 
2.28.0.220.ged08abb693-goog

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