[RFC PATCH 2/3] arch, arm32: add the XEN_DOMCTL_memory_mapping hypercall

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

This commit introduces a first attempt of implementation of the
XEN_DOMCTL_memory_mapping hypercall for arm32. The following
warnings must be taken into consideration:
. currently, the hypercall simply performs an 1:1 mapping of I/O
  memory ranges (mfn == gfn);
. the range of I/O memory addresses is mapped all at once with
  map_mmio_regions();
. the hypercall takes for granted that any I/O memory range can
  be mapped to a domU if the current domain is dom0.

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: Eric Trudeau <etrudeau@broadcom.com>
Cc: Viktor Kleinik <viktor.kleinik@globallogic.com>
---
 xen/arch/arm/arm32/domctl.c | 74 +++++++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/p2m.c          |  9 ++++++
 xen/include/asm-arm/p2m.h   |  2 ++
 3 files changed, 85 insertions(+)

diff --git a/xen/arch/arm/arm32/domctl.c b/xen/arch/arm/arm32/domctl.c
index c2ca4d3..67cf734 100644
--- a/xen/arch/arm/arm32/domctl.c
+++ b/xen/arch/arm/arm32/domctl.c
@@ -10,8 +10,11 @@
 #include <xen/errno.h>
 #include <xen/sched.h>
 #include <xen/hypercall.h>
+#include <xen/iocap.h>
 #include <public/domctl.h>
 
+#include "cpu.h"
+
 long subarch_do_domctl(struct xen_domctl *domctl, struct domain *d,
                XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
 {
@@ -19,6 +22,77 @@ long subarch_do_domctl(struct xen_domctl *domctl, struct domain *d,
     {
     case XEN_DOMCTL_set_address_size:
         return domctl->u.address_size.size == 32 ? 0 : -EINVAL;
+    case XEN_DOMCTL_memory_mapping:
+    {
+        unsigned long gfn = domctl->u.memory_mapping.first_gfn;
+        unsigned long mfn = domctl->u.memory_mapping.first_mfn;
+        unsigned long nr_mfns = domctl->u.memory_mapping.nr_mfns;
+        int add = domctl->u.memory_mapping.add_mapping;
+        long int ret;
+
+        ret = -EINVAL;
+        if ( (mfn + nr_mfns - 1) < mfn || /* wrap? */
+            ((mfn | (mfn + nr_mfns - 1)) >> (paddr_bits - PAGE_SHIFT)) ||
+            (gfn + nr_mfns - 1) < gfn ) /* wrap? */
+            return ret;
+
+        ret = -EPERM;
+	/*
+	 * NOTE: dom0 seems to have empty iomem_caps but to be however able to
+	 *       access I/O memory ranges. The following check takes for granted
+	 *       that any iomem range can be mapped to a domU if the current
+	 *       domain is dom0.
+	 */
+        if ( current->domain->domain_id != 0 &&
+             !iomem_access_permitted(current->domain, mfn, mfn + nr_mfns - 1) )
+            return ret;
+
+        ret = xsm_iomem_mapping(XSM_HOOK, d, mfn, mfn + nr_mfns - 1, add);
+        if ( ret )
+            return ret;
+
+        if ( add )
+        {
+            printk(XENLOG_G_INFO
+                   "memory_map:add: dom%d gfn=%lx mfn=%lx nr=%lx\n",
+                   d->domain_id, gfn, mfn, nr_mfns);
+            ret = iomem_permit_access(d, mfn, mfn + nr_mfns - 1);
+            if ( !ret )
+            {
+                /* 1:1 iomem mapping (gfn == mfn) */
+                ret = map_mmio_regions(d, gfn, gfn + nr_mfns - 1, mfn);
+                if ( ret )
+                {
+                    printk(XENLOG_G_WARNING
+                           "memory_map:fail: dom%d gfn=%lx mfn=%lx\n",
+                           d->domain_id, gfn, mfn);
+                    if ( iomem_deny_access(d, mfn, mfn + nr_mfns - 1) &&
+                         is_hardware_domain(current->domain) )
+                        printk(XENLOG_ERR
+                               "memory_map: failed to deny dom%d access "
+                               "to [%lx,%lx]\n",
+                               d->domain_id, mfn, mfn + nr_mfns - 1);
+                }
+            }
+        }
+	else
+        {
+            printk(XENLOG_G_INFO
+                   "memory_map:remove: dom%d gfn=%lx mfn=%lx nr=%lx\n",
+                   d->domain_id, gfn, mfn, nr_mfns);
+
+            add = unmap_mmio_regions(d, gfn, gfn + nr_mfns - 1, mfn);
+            ret = iomem_deny_access(d, mfn, mfn + nr_mfns - 1);
+            if ( ret && add )
+                ret = -EIO;
+            if ( ret && is_hardware_domain(current->domain) )
+                printk(XENLOG_ERR
+                       "memory_map: error %ld %s dom%d access to [%lx,%lx]\n",
+                       ret, add ? "removing" : "denying", d->domain_id,
+                       mfn, mfn + nr_mfns - 1);
+	}
+        return ret;
+    }
     default:
         return -ENOSYS;
     }
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index d00c882..710f74e 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -461,6 +461,15 @@ int map_mmio_regions(struct domain *d,
                              maddr, MATTR_DEV, p2m_mmio_direct);
 }
 
+int unmap_mmio_regions(struct domain *d,
+                       paddr_t start_gaddr,
+                       paddr_t end_gaddr,
+                       paddr_t maddr)
+{
+    return apply_p2m_changes(d, REMOVE, start_gaddr, end_gaddr,
+                             maddr, MATTR_DEV, p2m_mmio_direct);
+}
+
 int guest_physmap_add_entry(struct domain *d,
                             unsigned long gpfn,
                             unsigned long mfn,
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index 3b39c45..907ce4a 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -88,6 +88,8 @@ int p2m_populate_ram(struct domain *d, paddr_t start, paddr_t end);
  * address maddr. */
 int map_mmio_regions(struct domain *d, paddr_t start_gaddr,
                      paddr_t end_gaddr, paddr_t maddr);
+int unmap_mmio_regions(struct domain *d, paddr_t start_gaddr,
+                       paddr_t end_gaddr, paddr_t maddr);
 
 int guest_physmap_add_entry(struct domain *d,
                             unsigned long gfn,
-- 
1.8.5.3