[Xen-devel] [PATCH v2 2/5] xen: Provide XEN_DMOP_add_to_physmap

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

Provide XEN_DMOP_add_to_physmap, a limited version of
XENMEM_add_to_physmap to allow a deprivileged QEMU to move VRAM when a
guest programs its BAR. It is equivalent to XENMEM_add_to_physmap with
space == XENMAPSPACE_gmfn_range.

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---

Changed in v2:
* Make it operate on a range.

 xen/arch/x86/hvm/dm.c          | 31 +++++++++++++++++++++++++++++++
 xen/include/public/hvm/dm_op.h | 17 +++++++++++++++++
 xen/include/xlat.lst           |  1 +
 3 files changed, 49 insertions(+)

diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
index 32ade95..0027567 100644
--- a/xen/arch/x86/hvm/dm.c
+++ b/xen/arch/x86/hvm/dm.c
@@ -640,6 +640,36 @@ static int dm_op(const struct dmop_args *op_args)
         break;
     }
 
+    case XEN_DMOP_add_to_physmap:
+    {
+        struct xen_dm_op_add_to_physmap *data =
+            &op.u.add_to_physmap;
+        struct xen_add_to_physmap xatp = {
+            .domid = op_args->domid,
+            .size = data->size,
+            .space = XENMAPSPACE_gmfn_range,
+            .idx = data->idx,
+            .gpfn = data->gpfn,
+        };
+
+        if ( data->pad0 || data->pad1 )
+        {
+            rc = -EINVAL;
+            break;
+        }
+
+        rc = xenmem_add_to_physmap(d, &xatp, 0);
+        if ( rc > 0 )
+        {
+            data->size -= rc;
+            data->idx += rc;
+            data->gpfn += rc;
+            const_op = false;
+            rc = -ERESTART;
+        }
+        break;
+    }
+
     default:
         rc = -EOPNOTSUPP;
         break;
@@ -669,6 +699,7 @@ CHECK_dm_op_set_mem_type;
 CHECK_dm_op_inject_event;
 CHECK_dm_op_inject_msi;
 CHECK_dm_op_remote_shutdown;
+CHECK_dm_op_add_to_physmap;
 
 int compat_dm_op(domid_t domid,
                  unsigned int nr_bufs,
diff --git a/xen/include/public/hvm/dm_op.h b/xen/include/public/hvm/dm_op.h
index e173085..f685110 100644
--- a/xen/include/public/hvm/dm_op.h
+++ b/xen/include/public/hvm/dm_op.h
@@ -368,6 +368,22 @@ struct xen_dm_op_remote_shutdown {
                            /* (Other reason values are not blocked) */
 };
 
+/*
+ * XEN_DMOP_add_to_physmap : Sets the GPFNs at which a page range appears in
+ *                           the specified guest's pseudophysical address
+ *                           space. Identical to XENMEM_add_to_physmap with
+ *                           space == XENMAPSPACE_gmfn_range.
+ */
+#define XEN_DMOP_add_to_physmap 17
+
+struct xen_dm_op_add_to_physmap {
+    uint16_t size;         /* Number of GMFNs to process. */
+    uint16_t pad0;
+    uint32_t pad1;
+    uint64_aligned_t idx;  /* Index into GMFN space. */
+    uint64_aligned_t gpfn; /* Starting GPFN where the GMFNs should appear. */
+};
+
 struct xen_dm_op {
     uint32_t op;
     uint32_t pad;
@@ -389,6 +405,7 @@ struct xen_dm_op {
         struct xen_dm_op_map_mem_type_to_ioreq_server
                 map_mem_type_to_ioreq_server;
         struct xen_dm_op_remote_shutdown remote_shutdown;
+        struct xen_dm_op_add_to_physmap add_to_physmap;
     } u;
 };
 
diff --git a/xen/include/xlat.lst b/xen/include/xlat.lst
index 4346cbe..d40bac6 100644
--- a/xen/include/xlat.lst
+++ b/xen/include/xlat.lst
@@ -57,6 +57,7 @@
 ?      grant_entry_v2                  grant_table.h
 ?      gnttab_swap_grant_ref           grant_table.h
 !      dm_op_buf                       hvm/dm_op.h
+?      dm_op_add_to_physmap            hvm/dm_op.h
 ?      dm_op_create_ioreq_server       hvm/dm_op.h
 ?      dm_op_destroy_ioreq_server      hvm/dm_op.h
 ?      dm_op_get_ioreq_server_info     hvm/dm_op.h
-- 
2.9.5


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