[RFC PATCH v2 1/3] arch, arm: allow dom0 access to I/O memory of mapped devices

[Arianna Avanzini <avanzini.arianna@gmail.com>]

Currently, dom0 is not allowed access to the I/O memory ranges
used to access devices exposed to it. This commit attempts
to give it access to those memory ranges during domain build
by adding the ranges to dom0's iomem_caps.

Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Cc: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Paolo Valente <paolo.valente@unimore.it>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Julien Grall <julien.grall@citrix.com>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Eric Trudeau <etrudeau@broadcom.com>
Cc: Viktor Kleinik <viktor.kleinik@globallogic.com>
---
 xen/arch/arm/domain_build.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 5ca2f15..0b283d8 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -11,6 +11,7 @@
 #include <xen/device_tree.h>
 #include <xen/libfdt/libfdt.h>
 #include <xen/guest_access.h>
+#include <xen/iocap.h>
 #include <asm/setup.h>
 #include <asm/platform.h>
 #include <asm/psci.h>
@@ -733,6 +734,15 @@ static int map_device(struct domain *d, const struct dt_device_node *dev)
         DPRINT("addr %u = 0x%"PRIx64" - 0x%"PRIx64"\n",
                i, addr, addr + size - 1);
 
+        res = iomem_permit_access(d, paddr_to_pfn(addr & PAGE_MASK),
+                                  paddr_to_pfn(PAGE_ALIGN(addr + size - 1)));
+        if ( res )
+        {
+            printk(XENLOG_ERR "Unable to permit to dom0 access to"
+                   " 0x%"PRIx64" - 0x%"PRIx64"\n",
+                   addr & PAGE_MASK, PAGE_ALIGN(addr + size) - 1);
+            return res;
+        }
         res = map_mmio_regions(d, addr & PAGE_MASK,
                                PAGE_ALIGN(addr + size) - 1,
                                addr & PAGE_MASK);
-- 
1.9.0