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 d916024..6f6e15d 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);