[PATCH v3 12/21] KVM: arm64: Add support for stage-2 write-protect in generic page-table

Will Deacon
2020-08-25T09:44:29Z

From: Quentin Perret <qperret@google.com>

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

Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
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;
--
2.28.0.297.g1956fa8f8d-goog