[RFC XEN PATCH v5 2/5] x86/pvh: Allow (un)map_pirq when dom0 is PVH

[Jiqian Chen <Jiqian.Chen@xxxxxxx>]

If run Xen with PVH dom0 and hvm domU, hvm will map a pirq for
a passthrough device by using gsi, see
xen_pt_realize->xc_physdev_map_pirq and
pci_add_dm_done->xc_physdev_map_pirq. Then xc_physdev_map_pirq
will call into Xen, but in hvm_physdev_op, PHYSDEVOP_map_pirq
is not allowed because currd is PVH dom0 and PVH has no
X86_EMU_USE_PIRQ flag, it will fail at has_pirq check.

So, allow PHYSDEVOP_map_pirq when dom0 is PVH and also allow
PHYSDEVOP_unmap_pirq for the failed path to unmap pirq. And
add a new check to prevent self map when caller has no PIRQ
flag.

Co-developed-by: Huang Rui <ray.huang@xxxxxxx>
Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
---
 xen/arch/x86/hvm/hypercall.c |  2 ++
 xen/arch/x86/physdev.c       | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c
index 6ad5b4d5f11f..493998b42ec5 100644
--- a/xen/arch/x86/hvm/hypercall.c
+++ b/xen/arch/x86/hvm/hypercall.c
@@ -74,6 +74,8 @@ long hvm_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
     {
     case PHYSDEVOP_map_pirq:
     case PHYSDEVOP_unmap_pirq:
+        break;
+
     case PHYSDEVOP_eoi:
     case PHYSDEVOP_irq_status_query:
     case PHYSDEVOP_get_free_pirq:
diff --git a/xen/arch/x86/physdev.c b/xen/arch/x86/physdev.c
index 47c4da0af7e1..7f2422c2a483 100644
--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -303,11 +303,22 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) 
arg)
     case PHYSDEVOP_map_pirq: {
         physdev_map_pirq_t map;
         struct msi_info msi;
+        struct domain *d;
 
         ret = -EFAULT;
         if ( copy_from_guest(&map, arg, 1) != 0 )
             break;
 
+        d = rcu_lock_domain_by_any_id(map.domid);
+        if ( d == NULL )
+            return -ESRCH;
+        if ( !is_pv_domain(d) && !has_pirq(d) )
+        {
+            rcu_unlock_domain(d);
+            return -EOPNOTSUPP;
+        }
+        rcu_unlock_domain(d);
+
         switch ( map.type )
         {
         case MAP_PIRQ_TYPE_MSI_SEG:
@@ -341,11 +352,22 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) 
arg)
 
     case PHYSDEVOP_unmap_pirq: {
         struct physdev_unmap_pirq unmap;
+        struct domain *d;
 
         ret = -EFAULT;
         if ( copy_from_guest(&unmap, arg, 1) != 0 )
             break;
 
+        d = rcu_lock_domain_by_any_id(unmap.domid);
+        if ( d == NULL )
+            return -ESRCH;
+        if ( !is_pv_domain(d) && !has_pirq(d) )
+        {
+            rcu_unlock_domain(d);
+            return -EOPNOTSUPP;
+        }
+        rcu_unlock_domain(d);
+
         ret = physdev_unmap_pirq(unmap.domid, unmap.pirq);
         break;
     }
-- 
2.34.1