xen: unify foreign GFN map/unmap for auto-xlated physmap guests

Auto-translated physmap guests (arm, arm64 and x86 PVHVM/PVH) map and
unmap foreign GFNs using the same method (updating the physmap).
Unify the two arm and x86 implementations into one commont one.

Note that on arm and arm64, the correct error code will be returned
(instead of always -EFAULT) and map/unmap failure warnings are no
longer printed.  These changes are required if the foreign domain is
paging (-ENOENT failures are expected and must be propagated up to the
caller).

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

3 files changed, 140 insertions, 0 deletions

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index b812462083fc..afc39ca5cc4f 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -253,4 +253,10 @@ config XEN_EFI
         def_bool y
         depends on X86_64 && EFI
 
+config XEN_AUTO_XLATE
+        def_bool y
+        depends on ARM || ARM64 || XEN_PVHVM
+        help
+          Support for auto-translated physmap guests.
+
 endmenu
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 2ccd3592d41f..40edd1cbb60d 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_XEN_ACPI_HOTPLUG_CPU)	+= xen-acpi-cpuhotplug.o
 obj-$(CONFIG_XEN_ACPI_PROCESSOR)        += xen-acpi-processor.o
 obj-$(CONFIG_XEN_EFI)                   += efi.o
 obj-$(CONFIG_XEN_SCSI_BACKEND)          += xen-scsiback.o
+obj-$(CONFIG_XEN_AUTO_XLATE)            += xlate_mmu.o
 xen-evtchn-y                            := evtchn.o
 xen-gntdev-y                            := gntdev.o
 xen-gntalloc-y                          := gntalloc.o
diff --git a/drivers/xen/xlate_mmu.c b/drivers/xen/xlate_mmu.c
new file mode 100644
index 000000000000..7724d90fc697
--- /dev/null
+++ b/drivers/xen/xlate_mmu.c
@@ -0,0 +1,133 @@
+/*
+ * MMU operations common to all auto-translated physmap guests.
+ *
+ * Copyright (C) 2015 Citrix Systems R&D Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+#include <linux/kernel.h>
+#include <linux/mm.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/xen/hypervisor.h>
+
+#include <xen/xen.h>
+#include <xen/page.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/memory.h>
+
+/* map fgmfn of domid to lpfn in the current domain */
+static int map_foreign_page(unsigned long lpfn, unsigned long fgmfn,
+                            unsigned int domid)
+{
+        int rc;
+        struct xen_add_to_physmap_range xatp = {
+                .domid = DOMID_SELF,
+                .foreign_domid = domid,
+                .size = 1,
+                .space = XENMAPSPACE_gmfn_foreign,
+        };
+        xen_ulong_t idx = fgmfn;
+        xen_pfn_t gpfn = lpfn;
+        int err = 0;
+
+        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);
+        return rc < 0 ? rc : err;
+}
+
+struct remap_data {
+        xen_pfn_t fgmfn; /* foreign domain's gmfn */
+        pgprot_t prot;
+        domid_t  domid;
+        struct vm_area_struct *vma;
+        int index;
+        struct page **pages;
+        struct xen_remap_mfn_info *info;
+};
+
+static int remap_pte_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
+                        void *data)
+{
+        struct remap_data *info = data;
+        struct page *page = info->pages[info->index++];
+        unsigned long pfn = page_to_pfn(page);
+        pte_t pte = pte_mkspecial(pfn_pte(pfn, info->prot));
+        int rc;
+
+        rc = map_foreign_page(pfn, info->fgmfn, info->domid);
+        if (rc < 0)
+                return rc;
+        set_pte_at(info->vma->vm_mm, addr, ptep, pte);
+
+        return 0;
+}
+
+int xen_xlate_remap_gfn_range(struct vm_area_struct *vma,
+                              unsigned long addr,
+                              xen_pfn_t gfn, int nr,
+                              pgprot_t prot, unsigned domid,
+                              struct page **pages)
+{
+        int err;
+        struct remap_data data;
+
+        /* TBD: Batching, current sole caller only does page at a time */
+        if (nr > 1)
+                return -EINVAL;
+
+        data.fgmfn = gfn;
+        data.prot = prot;
+        data.domid = domid;
+        data.vma = vma;
+        data.index = 0;
+        data.pages = pages;
+        err = apply_to_page_range(vma->vm_mm, addr, nr << PAGE_SHIFT,
+                                  remap_pte_fn, &data);
+        return err;
+}
+EXPORT_SYMBOL_GPL(xen_xlate_remap_gfn_range);
+
+int xen_xlate_unmap_gfn_range(struct vm_area_struct *vma,
+                              int nr, struct page **pages)
+{
+        int i;
+
+        for (i = 0; i < nr; i++) {
+                struct xen_remove_from_physmap xrp;
+                unsigned long pfn;
+
+                pfn = page_to_pfn(pages[i]);
+
+                xrp.domid = DOMID_SELF;
+                xrp.gpfn = pfn;
+                (void)HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrp);
+        }
+        return 0;
+}
+EXPORT_SYMBOL_GPL(xen_xlate_unmap_gfn_range);