[RFC PATCH 1/2] xen: introduce arch_iommu_grant_(un)map_page

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

From: Julien Grall <julien.grall@citrix.com>

From: Julien Grall <julien.grall@citrix.com>

Introduce two arch specific iommu grant mapping and unmapping functions,
they are called from __gnttab_map_grant_ref and __gnttab_unmap_common.

The x86 implementation simply calls iommu_(un)map_page.
The ARM implementation is based on arm_smmu_(un)map_page.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
 xen/common/grant_table.c            |   10 +++----
 xen/drivers/passthrough/arm/iommu.c |   49 +++++++++++++++++++++++++++++++++++
 xen/drivers/passthrough/arm/smmu.c  |   42 ------------------------------
 xen/drivers/passthrough/x86/iommu.c |   11 ++++++++
 xen/include/xen/iommu.h             |    4 +++
 5 files changed, 69 insertions(+), 47 deletions(-)

diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 464007e..6ea1c2f 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -738,13 +738,13 @@ __gnttab_map_grant_ref(
              !(old_pin & (GNTPIN_hstw_mask|GNTPIN_devw_mask)) )
         {
             if ( wrc == 0 )
-                err = iommu_map_page(ld, frame, frame,
-                                     IOMMUF_readable|IOMMUF_writable);
+                err = arch_iommu_grant_map_page(ld, frame,
+                                                IOMMUF_readable|IOMMUF_writable);
         }
         else if ( act_pin && !old_pin )
         {
             if ( (wrc + rdc) == 0 )
-                err = iommu_map_page(ld, frame, frame, IOMMUF_readable);
+                err = arch_iommu_grant_map_page(ld, frame, IOMMUF_readable);
         }
         if ( err )
         {
@@ -941,9 +941,9 @@ __gnttab_unmap_common(
         int err = 0;
         mapcount(lgt, rd, op->frame, &wrc, &rdc);
         if ( (wrc + rdc) == 0 )
-            err = iommu_unmap_page(ld, op->frame);
+            err = arch_iommu_grant_unmap_page(ld, op->frame);
         else if ( wrc == 0 )
-            err = iommu_map_page(ld, op->frame, op->frame, IOMMUF_readable);
+            err = arch_iommu_grant_map_page(ld, op->frame, IOMMUF_readable);
         if ( err )
         {
             rc = GNTST_general_error;
diff --git a/xen/drivers/passthrough/arm/iommu.c b/xen/drivers/passthrough/arm/iommu.c
index 3007b99..6460b7e 100644
--- a/xen/drivers/passthrough/arm/iommu.c
+++ b/xen/drivers/passthrough/arm/iommu.c
@@ -18,6 +18,8 @@
 #include <xen/lib.h>
 #include <xen/iommu.h>
 #include <xen/device_tree.h>
+#include <xen/sched.h>
+#include <asm/p2m.h>
 #include <asm/device.h>
 
 static const struct iommu_ops *iommu_ops;
@@ -68,3 +70,50 @@ void arch_iommu_domain_destroy(struct domain *d)
 {
     iommu_dt_domain_destroy(d);
 }
+
+int arch_iommu_grant_map_page(struct domain *d, unsigned long frame,
+                              unsigned flags)
+{
+    p2m_type_t t;
+
+    /* Grant mappings can be used for DMA requests. The dev_bus_addr returned by
+     * the hypercall is the MFN (not the IPA). For device protected by
+     * an IOMMU, Xen needs to add a 1:1 mapping in the domain p2m to
+     * allow DMA request to work.
+     * This is only valid when the domain is directed mapped.
+     */
+    BUG_ON(!is_domain_direct_mapped(d));
+
+    /* We only support readable and writable flags */
+    if ( !(flags & (IOMMUF_readable | IOMMUF_writable)) )
+        return -EINVAL;
+
+    t = (flags & IOMMUF_writable) ? p2m_iommu_map_rw : p2m_iommu_map_ro;
+
+    /* The function guest_physmap_add_entry replaces the current mapping
+     * if there is already one...
+     */
+    return guest_physmap_add_entry(d, frame, frame, 0, t);
+}
+
+int arch_iommu_grant_unmap_page(struct domain *d, unsigned long frame)
+{
+    /* This function should only be used by gnttab code when the domain
+     * is direct mapped
+     */
+    if ( !is_domain_direct_mapped(d) )
+        return -EINVAL;
+
+    guest_physmap_remove_page(d, frame, frame, 0);
+
+    return 0;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/drivers/passthrough/arm/smmu.c b/xen/drivers/passthrough/arm/smmu.c
index f4eb2a2..21b4572 100644
--- a/xen/drivers/passthrough/arm/smmu.c
+++ b/xen/drivers/passthrough/arm/smmu.c
@@ -1536,46 +1536,6 @@ static void arm_smmu_iommu_domain_teardown(struct domain *d)
     xfree(smmu_domain);
 }
 
-static int arm_smmu_map_page(struct domain *d, unsigned long gfn,
-                             unsigned long mfn, unsigned int flags)
-{
-    p2m_type_t t;
-
-    /* Grant mappings can be used for DMA requests. The dev_bus_addr returned by
-     * the hypercall is the MFN (not the IPA). For device protected by
-     * an IOMMU, Xen needs to add a 1:1 mapping in the domain p2m to
-     * allow DMA request to work.
-     * This is only valid when the domain is directed mapped. Hence this
-     * function should only be used by gnttab code with gfn == mfn.
-     */
-    BUG_ON(!is_domain_direct_mapped(d));
-    BUG_ON(mfn != gfn);
-
-    /* We only support readable and writable flags */
-    if ( !(flags & (IOMMUF_readable | IOMMUF_writable)) )
-        return -EINVAL;
-
-    t = (flags & IOMMUF_writable) ? p2m_iommu_map_rw : p2m_iommu_map_ro;
-
-    /* The function guest_physmap_add_entry replaces the current mapping
-     * if there is already one...
-     */
-    return guest_physmap_add_entry(d, gfn, mfn, 0, t);
-}
-
-static int arm_smmu_unmap_page(struct domain *d, unsigned long gfn)
-{
-    /* This function should only be used by gnttab code when the domain
-     * is direct mapped
-     */
-    if ( !is_domain_direct_mapped(d) )
-        return -EINVAL;
-
-    guest_physmap_remove_page(d, gfn, gfn, 0);
-
-    return 0;
-}
-
 static const struct iommu_ops arm_smmu_iommu_ops = {
     .init = arm_smmu_iommu_domain_init,
     .hwdom_init = arm_smmu_iommu_hwdom_init,
@@ -1584,8 +1544,6 @@ static const struct iommu_ops arm_smmu_iommu_ops = {
     .iotlb_flush_all = arm_smmu_iotlb_flush_all,
     .assign_dt_device = arm_smmu_attach_dev,
     .reassign_dt_device = arm_smmu_reassign_dt_dev,
-    .map_page = arm_smmu_map_page,
-    .unmap_page = arm_smmu_unmap_page,
 };
 
 static int __init smmu_init(struct dt_device_node *dev,
diff --git a/xen/drivers/passthrough/x86/iommu.c b/xen/drivers/passthrough/x86/iommu.c
index ce0ca5a..a88626a 100644
--- a/xen/drivers/passthrough/x86/iommu.c
+++ b/xen/drivers/passthrough/x86/iommu.c
@@ -135,6 +135,17 @@ void arch_iommu_domain_destroy(struct domain *d)
     }
 }
 
+int arch_iommu_grant_map_page(struct domain *d, unsigned long frame,
+                              unsigned flags)
+{
+    return iommu_map_page(d, frame, frame, flags);
+}
+
+int arch_iommu_grant_unmap_page(struct domain *d, unsigned long frame)
+{
+    return iommu_unmap_page(d, frame);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 8eb764a..0dd6987 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -76,6 +76,10 @@ int iommu_map_page(struct domain *d, unsigned long gfn, unsigned long mfn,
                    unsigned int flags);
 int iommu_unmap_page(struct domain *d, unsigned long gfn);
 
+int arch_iommu_grant_map_page(struct domain *d, unsigned long frame,
+                              unsigned flags);
+int arch_iommu_grant_unmap_page(struct domain *d, unsigned long frame);
+
 enum iommu_feature
 {
     IOMMU_FEAT_COHERENT_WALK,
-- 
1.7.10.4