[RFC Patch v4 6/9] don't zero out ioreq page and handle the pended I/O after resuming

[Wen Congyang <wency@cn.fujitsu.com>]

I check ioreq->state after suspending the guest, and it can be
STATE_IOREQ_NONE, STATE_IOREQ_READY or STATE_IORESP_READY.
1. If it is STATE_IOREQ_NONE, nothing need to be done.
2. If it is STATE_IOREQ_RESP_READY, we will get the response
   in hvm_wait_for_io() before resuming.
3. If it is STATE_IOREQ_READY, we need to kick the event channel,
   and qemu can handle the request.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: Paul Durrant <paul.durrant@citrix.com>
---
 tools/libxc/xc_domain_restore.c |  4 +---
 xen/arch/x86/hvm/hvm.c          | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index fb4ddfc..efaf3c2 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -2310,9 +2310,7 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
     }
 
     /* These comms pages need to be zeroed at the start of day */
-    if ( xc_clear_domain_page(xch, dom, tailbuf.u.hvm.magicpfns[0]) ||
-         xc_clear_domain_page(xch, dom, tailbuf.u.hvm.magicpfns[1]) ||
-         xc_clear_domain_page(xch, dom, tailbuf.u.hvm.magicpfns[2]) )
+    if ( xc_clear_domain_page(xch, dom, tailbuf.u.hvm.magicpfns[2]) )
     {
         PERROR("error zeroing magic pages");
         goto out;
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index bb45593..c4e8687 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -393,6 +393,33 @@ bool_t hvm_io_pending(struct vcpu *v)
     return 0;
 }
 
+static void hvm_reinject_pended_io(struct vcpu *v)
+{
+    struct domain *d = v->domain;
+    struct hvm_ioreq_server *s;
+
+    list_for_each_entry ( s,
+                          &d->arch.hvm_domain.ioreq_server.list,
+                          list_entry )
+    {
+        struct hvm_ioreq_vcpu *sv;
+
+        list_for_each_entry ( sv,
+                              &s->ioreq_vcpu_list,
+                              list_entry )
+        {
+            if ( sv->vcpu == v )
+            {
+                evtchn_port_t port = sv->ioreq_evtchn;
+                ioreq_t * p = get_ioreq(s, v);
+
+                if ( p->state == STATE_IOREQ_READY )
+                    notify_via_xen_event_channel(d, port);
+            }
+        }
+    }
+}
+
 static bool_t hvm_wait_for_io(struct hvm_ioreq_vcpu *sv, ioreq_t *p)
 {
     /* NB. Optimised for common case (p->state == STATE_IOREQ_NONE). */
@@ -1977,6 +2004,7 @@ static int hvm_load_cpu_ctxt(struct domain *d, hvm_domain_context_t *h)
     /* Auxiliary processors should be woken immediately. */
     v->is_initialised = 1;
     clear_bit(_VPF_down, &v->pause_flags);
+    hvm_reinject_pended_io(v);
     vcpu_wake(v);
 
     return 0;
-- 
1.9.3