[RFC PATCH v2 2/3] arch, arm: 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 ARM. The range of I/O
memory addresses is mapped all at once with map_mmio_regions().

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/domctl.c     | 69 +++++++++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/p2m.c        |  9 +++++++
 xen/include/asm-arm/p2m.h |  2 ++
 3 files changed, 80 insertions(+)

diff --git a/xen/arch/arm/domctl.c b/xen/arch/arm/domctl.c
index 45974e7..078b165 100644
--- a/xen/arch/arm/domctl.c
+++ b/xen/arch/arm/domctl.c
@@ -10,6 +10,7 @@
 #include <xen/errno.h>
 #include <xen/sched.h>
 #include <xen/hypercall.h>
+#include <xen/iocap.h>
 #include <public/domctl.h>
 
 long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
@@ -30,7 +31,75 @@ long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
 
         return p2m_cache_flush(d, s, e);
     }
+    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;
+        if ( !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 )
+            {
+                ret = map_mmio_regions(d, PAGE_ALIGN(pfn_to_paddr(gfn)),
+                                       PAGE_ALIGN(
+                                           pfn_to_paddr(gfn + nr_mfns)) - 1,
+                                       PAGE_ALIGN(pfn_to_paddr(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, PAGE_ALIGN(pfn_to_paddr(gfn)),
+                                     PAGE_ALIGN(
+                                         pfn_to_paddr(gfn + nr_mfns)) - 1,
+                                     PAGE_ALIGN(pfn_to_paddr(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 subarch_do_domctl(domctl, d, u_domctl);
     }
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,
-- 
1.9.0