x86/xen: map foreign pfns for autotranslated guests

When running as a dom0 in PVH mode, foreign pfns that are accessed
must be added to our p2m which is managed by xen. This is done via
XENMEM_add_to_physmap_range hypercall. This is needed for toolstack
building guests and mapping guest memory, xentrace mapping xen pages,
etc.

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

1 files changed, 118 insertions, 3 deletions

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index d91602424b39..6f6e15d28466 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2510,6 +2510,95 @@ void __init xen_hvm_init_mmu_ops(void)
 }
 #endif
 
+#ifdef CONFIG_XEN_PVH
+/*
+ * Map foreign gfn (fgfn), to local pfn (lpfn). This for the user
+ * space creating new guest on pvh dom0 and needing to map domU pages.
+ */
+static int xlate_add_to_p2m(unsigned long lpfn, unsigned long fgfn,
+                            unsigned int domid)
+{
+        int rc, err = 0;
+        xen_pfn_t gpfn = lpfn;
+        xen_ulong_t idx = fgfn;
+
+        struct xen_add_to_physmap_range xatp = {
+                .domid = DOMID_SELF,
+                .foreign_domid = domid,
+                .size = 1,
+                .space = XENMAPSPACE_gmfn_foreign,
+        };
+        set_xen_guest_handle(xatp.idxs, &idx);
+        set_xen_guest_handle(xatp.gpfns, &gpfn);
+        set_xen_guest_handle(xatp.errs, &err);
+
+        rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap_range, &xatp);
+        if (rc < 0)
+                return rc;
+        return err;
+}
+
+static int xlate_remove_from_p2m(unsigned long spfn, int count)
+{
+        struct xen_remove_from_physmap xrp;
+        int i, rc;
+
+        for (i = 0; i < count; i++) {
+                xrp.domid = DOMID_SELF;
+                xrp.gpfn = spfn+i;
+                rc = HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrp);
+                if (rc)
+                        break;
+        }
+        return rc;
+}
+
+struct xlate_remap_data {
+        unsigned long fgfn; /* foreign domain's gfn */
+        pgprot_t prot;
+        domid_t  domid;
+        int index;
+        struct page **pages;
+};
+
+static int xlate_map_pte_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
+                            void *data)
+{
+        int rc;
+        struct xlate_remap_data *remap = data;
+        unsigned long pfn = page_to_pfn(remap->pages[remap->index++]);
+        pte_t pteval = pte_mkspecial(pfn_pte(pfn, remap->prot));
+
+        rc = xlate_add_to_p2m(pfn, remap->fgfn, remap->domid);
+        if (rc)
+                return rc;
+        native_set_pte(ptep, pteval);
+
+        return 0;
+}
+
+static int xlate_remap_gfn_range(struct vm_area_struct *vma,
+                                 unsigned long addr, unsigned long mfn,
+                                 int nr, pgprot_t prot, unsigned domid,
+                                 struct page **pages)
+{
+        int err;
+        struct xlate_remap_data pvhdata;
+
+        BUG_ON(!pages);
+
+        pvhdata.fgfn = mfn;
+        pvhdata.prot = prot;
+        pvhdata.domid = domid;
+        pvhdata.index = 0;
+        pvhdata.pages = pages;
+        err = apply_to_page_range(vma->vm_mm, addr, nr << PAGE_SHIFT,
+                                  xlate_map_pte_fn, &pvhdata);
+        flush_tlb_all();
+        return err;
+}
+#endif
+
 #define REMAP_BATCH_SIZE 16
 
 struct remap_data {
@@ -2544,11 +2633,18 @@ int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
         unsigned long range;
         int err = 0;
 
-        if (xen_feature(XENFEAT_auto_translated_physmap))
-                return -EINVAL;
-
         BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO)));
 
+        if (xen_feature(XENFEAT_auto_translated_physmap)) {
+#ifdef CONFIG_XEN_PVH
+                /* We need to update the local page tables and the xen HAP */
+                return xlate_remap_gfn_range(vma, addr, mfn, nr, prot,
+                                             domid, pages);
+#else
+                return -EINVAL;
+#endif
+        }
+
         rmd.mfn = mfn;
         rmd.prot = prot;
 
@@ -2586,6 +2682,25 @@ int xen_unmap_domain_mfn_range(struct vm_area_struct *vma,
         if (!pages || !xen_feature(XENFEAT_auto_translated_physmap))
                 return 0;
 
+#ifdef CONFIG_XEN_PVH
+        while (numpgs--) {
+                /*
+                 * The mmu has already cleaned up the process mmu
+                 * resources at this point (lookup_address will return
+                 * NULL).
+                 */
+                unsigned long pfn = page_to_pfn(pages[numpgs]);
+
+                xlate_remove_from_p2m(pfn, 1);
+        }
+        /*
+         * We don't need to flush tlbs because as part of
+         * xlate_remove_from_p2m, the hypervisor will do tlb flushes
+         * after removing the p2m entries from the EPT/NPT
+         */
+        return 0;
+#else
         return -EINVAL;
+#endif
 }
 EXPORT_SYMBOL_GPL(xen_unmap_domain_mfn_range);