[Xen-devel] [PATCH 4/6] xen: Allow hardare domain != dom0

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

This adds a hypervisor command line option "hardware_dom=" which takes a
domain ID.  When the domain with this ID is created, it will be used as
the hardware domain.

This is intended to be used when dom0 is a dedicated stub domain for
domain building, allowing the hardware domain to be de-privileged and
act only as a driver domain.

Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/domain_build.c |  4 +++-
 xen/arch/x86/setup.c        |  3 +++
 xen/common/domctl.c         |  8 ++++++++
 xen/common/rangeset.c       | 26 ++++++++++++++++++++++++++
 xen/include/xen/rangeset.h  |  3 +++
 xen/include/xen/sched.h     |  3 ++-
 6 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index 84ce392..e9de496 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -1149,7 +1149,9 @@ int __init construct_dom0(
         printk(" Xen warning: dom0 kernel broken ELF: %s\n",
                elf_check_broken(&elf));
 
-    iommu_dom0_init(dom0);
+    if( is_hardware_domain(dom0) )
+        iommu_dom0_init(dom0);
+
     return 0;
 
 out:
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 3a4f69c..3480854 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -88,6 +88,9 @@ unsigned long __initdata highmem_start;
 size_param("highmem-start", highmem_start);
 #endif
 
+unsigned int __read_mostly hardware_dom;
+integer_param("hardware_dom", hardware_dom);
+
 cpumask_t __read_mostly cpu_present_map;
 
 unsigned long __read_mostly xen_phys_start;
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index eebeee7..11e6b94 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -472,6 +472,14 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) 
u_domctl)
             break;
         }
 
+        if (d->domain_id == hardware_dom) {
+            printk("Initialising hardware domain %d\n", hardware_dom);
+            rangeset_swap(d->irq_caps, dom0->irq_caps);
+
+            dom0 = d;
+            iommu_dom0_init(dom0);
+        }
+
         ret = 0;
 
         memcpy(d->handle, op->u.createdomain.handle,
diff --git a/xen/common/rangeset.c b/xen/common/rangeset.c
index f09c0c4..cd44634 100644
--- a/xen/common/rangeset.c
+++ b/xen/common/rangeset.c
@@ -438,3 +438,29 @@ void rangeset_domain_printk(
 
     spin_unlock(&d->rangesets_lock);
 }
+
+void rangeset_swap(struct rangeset *a, struct rangeset *b)
+{
+    struct list_head tmp;
+    spin_lock(&a->lock);
+    spin_lock(&b->lock);
+    memcpy(&tmp, &a->range_list, sizeof(tmp));
+    memcpy(&a->range_list, &b->range_list, sizeof(tmp));
+    memcpy(&b->range_list, &tmp, sizeof(tmp));
+    if (a->range_list.next == &b->range_list) {
+        a->range_list.next = &a->range_list;
+        a->range_list.prev = &a->range_list;
+    } else {
+        a->range_list.next->prev = &a->range_list;
+        a->range_list.prev->next = &a->range_list;
+    }
+    if (b->range_list.next == &a->range_list) {
+        b->range_list.next = &b->range_list;
+        b->range_list.prev = &b->range_list;
+    } else {
+        b->range_list.next->prev = &b->range_list;
+        b->range_list.prev->next = &b->range_list;
+    }
+    spin_unlock(&a->lock);
+    spin_unlock(&b->lock);
+}
diff --git a/xen/include/xen/rangeset.h b/xen/include/xen/rangeset.h
index 1e16a6b..805ebde 100644
--- a/xen/include/xen/rangeset.h
+++ b/xen/include/xen/rangeset.h
@@ -73,4 +73,7 @@ void rangeset_printk(
 void rangeset_domain_printk(
     struct domain *d);
 
+/* swap contents */
+void rangeset_swap(struct rangeset *a, struct rangeset *b);
+
 #endif /* __XEN_RANGESET_H__ */
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 3be26ec..6c4237b 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -778,7 +778,8 @@ void watchdog_domain_destroy(struct domain *d);
  *    (that is, this would not be suitable for a driver domain)
  *  - There is never a reason to deny dom0 access to this
  */
-#define is_hardware_domain(_d) ((_d)->domain_id == 0)
+extern unsigned int hardware_dom;
+#define is_hardware_domain(d)  ((d)->domain_id == hardware_dom)
 
 /* This check is for functionality specific to a control domain */
 #define is_control_domain(_d) ((_d)->is_privileged)
-- 
1.8.5.3


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