[PATCH v4 02/17] KVM: arm64: Add pkvm_remove_mappings

[Vincent Donnefort]

Add the counterpart to pkvm_create_mappings(), allowing previously
mapped ranges to be removed. This will be useful for the upcoming pKVM
heap allocator to manage its private mappings.

Reviewed-by: Fuad Tabba <fuad.tabba at linux.dev>
Tested-by: Fuad Tabba <fuad.tabba at linux.dev>
Signed-off-by: Vincent Donnefort <vdonnefort at google.com>

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mm.h b/arch/arm64/kvm/hyp/include/nvhe/mm.h
index 85f1e3c711d9..00cadd13ee5d 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mm.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mm.h
@@ -25,6 +25,7 @@ int hyp_back_vmemmap(phys_addr_t back);
 int pkvm_cpu_set_vector(enum arm64_hyp_spectre_vector slot);
 int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot);
 int pkvm_create_mappings_locked(void *from, void *to, enum kvm_pgtable_prot prot);
+void pkvm_remove_mappings(void *from, void *to);
 int __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
 				  enum kvm_pgtable_prot prot,
 				  unsigned long *haddr);
diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c
index 755630c0d15e..9ab7f613fa36 100644
--- a/arch/arm64/kvm/hyp/nvhe/mm.c
+++ b/arch/arm64/kvm/hyp/nvhe/mm.c
@@ -164,6 +164,24 @@ int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
 	return ret;
 }
 
+/**
+ * pkvm_remove_mappings - Remove mappings from the hypervisor page-table
+ * @from:	The starting virtual address of the range to remove
+ * @to:		The ending virtual address of the range to remove
+ */
+void pkvm_remove_mappings(void *from, void *to)
+{
+	u64 size;
+
+	WARN_ON(from > to);
+	to = PTR_ALIGN(to, PAGE_SIZE);
+	from = PTR_ALIGN_DOWN(from, PAGE_SIZE);
+	size = (u64)to - (u64)from;
+
+	guard(hyp_spinlock)(&pkvm_pgd_lock);
+	WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, (u64)from, size) != size);
+}
+
 int hyp_back_vmemmap(phys_addr_t back)
 {
 	unsigned long i, start, size, end = 0;
-- 
2.55.0.508.g3f0d502094-goog