[PATCH v2] vpci: add permission checks to map_range()

[Roger Pau Monne]

Just like it's done for the XEN_DOMCTL_memory_mapping hypercall, add
the permissions checks to vPCI map_range(), which is used to map the
BARs into the domain p2m.

Adding those checks requires that for x86 PVH hardware domain builder
the permissions are set before initializing the IOMMU, or else
attempts to initialize vPCI done as part of IOMMU device setup will
fail due to missing permissions to create the BAR mappings.

While moving the call to dom0_setup_permissions() convert the panic()
used for error handling to a printk, the caller will already panic if
required.

Fixes: 9c244fdef7e7 ('vpci: add header handlers')
Signed-off-by: Roger Pau Monné <roger....@citrix.com>
---
Changes since v1:
 - Fix printk calls.
 - Expand commit message.
---
I'm unsure whether on ARM MMIO permissions are properly set for the
hardware domain, but I don't have a system to test with.
---
 xen/arch/x86/hvm/dom0_build.c | 21 ++++++++++++++-------
 xen/drivers/vpci/header.c     | 20 ++++++++++++++++++++
 2 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
index a7ae9c3b046e..bc0e290db612 100644
--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -715,13 +715,6 @@ static int __init pvh_setup_cpus(struct domain *d, paddr_t 
entry,
         return rc;
     }
 
-    rc = dom0_setup_permissions(d);
-    if ( rc )
-    {
-        panic("Unable to setup Dom0 permissions: %d\n", rc);
-        return rc;
-    }
-
     update_domain_wallclock_time(d);
 
     v->is_initialised = 1;
@@ -1184,6 +1177,20 @@ int __init dom0_construct_pvh(struct domain *d, const 
module_t *image,
 
     printk(XENLOG_INFO "*** Building a PVH Dom%d ***\n", d->domain_id);
 
+    if ( is_hardware_domain(d) )
+    {
+        /*
+         * Setup permissions early so that calls to add MMIO regions to the
+         * p2m as part of vPCI setup don't fail due to permission checks.
+         */
+        rc = dom0_setup_permissions(d);
+        if ( rc )
+        {
+            printk("%pd unable to setup permissions: %d\n", d, rc);
+            return rc;
+        }
+    }
+
     /*
      * NB: MMCFG initialization needs to be performed before iommu
      * initialization so the iommu code can fetch the MMCFG regions used by the
diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
index b41556d00746..60f7049e3498 100644
--- a/xen/drivers/vpci/header.c
+++ b/xen/drivers/vpci/header.c
@@ -17,10 +17,13 @@
  * License along with this program; If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <xen/iocap.h>
 #include <xen/sched.h>
 #include <xen/softirq.h>
 #include <xen/vpci.h>
 
+#include <xsm/xsm.h>
+
 #include <asm/event.h>
 #include <asm/p2m.h>
 
@@ -43,6 +46,23 @@ static int cf_check map_range(
     {
         unsigned long size = e - s + 1;
 
+        if ( !iomem_access_permitted(map->d, s, e) )
+        {
+            printk(XENLOG_G_WARNING
+                   "%pd denied access to MMIO range [%#lx, %#lx]\n",
+                   map->d, s, e);
+            return -EPERM;
+        }
+
+        rc = xsm_iomem_mapping(XSM_HOOK, map->d, s, e, map->map);
+        if ( rc )
+        {
+            printk(XENLOG_G_WARNING
+                   "%pd XSM denied access to MMIO range [%#lx, %#lx]: %d\n",
+                   map->d, s, e, rc);
+            return rc;
+        }
+
         /*
          * ARM TODOs:
          * - On ARM whether the memory is prefetchable or not should be passed
-- 
2.41.0