xen/riscv: add destroy_xen_mappings() to remove mappings in Xen page tables

Introduce the destroy_xen_mappings() function, which removes page
mappings in Xen's page tables between a start address s and an end
address e.
The function ensures that both s and e are page-aligned
and verifies that the start address is less than or equal to the end
address before calling pt_update() to invalidate the mappings.
The pt_update() function is called with INVALID_MFN and PTE_VALID=0
in the flags, which tell pt_update() to remove mapping. No additional
ASSERT() is required to check these arguments, as they are hardcoded in
the call to pt_update() within destroy_xen_mappings().

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/riscv/mm.c b/xen/arch/riscv/mm.c
index 9359dc7f335d83dd7bbe96e5b113e7e40d631317..f2bf279bacfcbedd50e031aae4837d9a7401e4f9 100644 (file)
--- a/xen/arch/riscv/mm.c
+++ b/xen/arch/riscv/mm.c
@@ -360,12 +360,6 @@ int xenmem_add_to_physmap_one(struct domain *d, unsigned int space,
     return 0;
 }
 
-int destroy_xen_mappings(unsigned long s, unsigned long e)
-{
-    BUG_ON("unimplemented");
-    return -1;
-}
-
 void share_xen_page_with_guest(struct page_info *page, struct domain *d,
                                enum XENSHARE_flags flags)
 {

diff --git a/xen/arch/riscv/pt.c b/xen/arch/riscv/pt.c
index d62aceb36c1e434641c598c1417ca8da451fdf57..798483aa3b0c32b86a4aa8bdd7a3afe4d71357ef 100644 (file)
--- a/xen/arch/riscv/pt.c
+++ b/xen/arch/riscv/pt.c
@@ -421,6 +421,14 @@ int map_pages_to_xen(unsigned long virt,
     return pt_update(virt, mfn, nr_mfns, flags);
 }
 
+int destroy_xen_mappings(unsigned long s, unsigned long e)
+{
+    ASSERT(IS_ALIGNED(s, PAGE_SIZE));
+    ASSERT(IS_ALIGNED(e, PAGE_SIZE));
+
+    return s < e ? pt_update(s, INVALID_MFN, PFN_DOWN(e - s), 0) : -EINVAL;
+}
+
 int __init populate_pt_range(unsigned long virt, unsigned long nr_mfns)
 {
     return pt_update(virt, INVALID_MFN, nr_mfns, PTE_POPULATE);