[Xen-devel] [PATCH v7 01/10] arch/arm: domain build: let dom0 access I/O memory of mapped devices

[Arianna Avanzini <avanzini.arianna@xxxxxxxxx>]

Currently, dom0 is allowed access to the I/O memory ranges used
to access devices exposed to it, but it doesn't have those
ranges in its iomem_caps. This commit attempts to implement the
correct bookkeeping in the generic function which actually maps
a device's I/O memory to the domain, adding the ranges to the
domain's iomem_caps.

NOTE: This commit suffers from the following limitations;
      . with this patch, I/O memory ranges pertaining disabled
        devices are not mapped;
      . the "iomem" option could be used to map memory ranges that
        are not described in the device tree.
      In both these cases, this patch does not allow the domain
      the privileges needed to map the needed I/O memory ranges
      afterwards.

Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
Acked-by: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
Cc: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
Cc: Paolo Valente <paolo.valente@xxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Jan Beulich <JBeulich@xxxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Eric Trudeau <etrudeau@xxxxxxxxxxxx>
Cc: Viktor Kleinik <viktor.kleinik@xxxxxxxxxxxxxxx>

---

    v7:
        - Add limitations to commit description.

    v4:
        - Hopefully improve commit description.

    v3:
        - Print the domain id in the error message instead of always
          printing "dom0".
        - Fix commit description.

---
 xen/arch/arm/domain_build.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 187e071..1802b6e 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>
@@ -740,6 +741,16 @@ 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 dom%d access to"
+                   " 0x%"PRIx64" - 0x%"PRIx64"\n",
+                   d->domain_id,
+                   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);
-- 
1.9.2


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