[PATCH v2 16/24] hw/xen: handle soft reset for primary console

[David Woodhouse <dwmw2@infradead.org>]

From: David Woodhouse <dwmw@amazon.co.uk>

On soft reset, the prinary console event channel needs to be rebound to
the backend port (in the xen-console driver). We could put that into the
xen-console driver itself, but it's slightly less ugly to keep it within
the KVM/Xen code, by stashing the backend port# on event channel reset
and then rebinding in the primary console reset when it has to recreate
the guest port anyway.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 hw/i386/kvm/xen_evtchn.c          |  9 +++++++++
 hw/i386/kvm/xen_primary_console.c | 29 ++++++++++++++++++++++++++++-
 hw/i386/kvm/xen_primary_console.h |  1 +
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/hw/i386/kvm/xen_evtchn.c b/hw/i386/kvm/xen_evtchn.c
index d72dca6591..ce4da6d37a 100644
--- a/hw/i386/kvm/xen_evtchn.c
+++ b/hw/i386/kvm/xen_evtchn.c
@@ -40,6 +40,7 @@
 #include "xen_evtchn.h"
 #include "xen_overlay.h"
 #include "xen_xenstore.h"
+#include "xen_primary_console.h"
 
 #include "sysemu/kvm.h"
 #include "sysemu/kvm_xen.h"
@@ -1098,6 +1099,7 @@ int xen_evtchn_soft_reset(void)
 {
     XenEvtchnState *s = xen_evtchn_singleton;
     bool flush_kvm_routes;
+    uint16_t con_port = xen_primary_console_get_port();
     int i;
 
     if (!s) {
@@ -1108,6 +1110,13 @@ int xen_evtchn_soft_reset(void)
 
     qemu_mutex_lock(&s->port_lock);
 
+    if (con_port) {
+        XenEvtchnPort *p = &s->port_table[con_port];
+        if (p->type == EVTCHNSTAT_interdomain) {
+            xen_primary_console_set_be_port(p->u.interdomain.port);
+        }
+    }
+
     for (i = 0; i < s->nr_ports; i++) {
         close_port(s, i, &flush_kvm_routes);
     }
diff --git a/hw/i386/kvm/xen_primary_console.c b/hw/i386/kvm/xen_primary_console.c
index 0aa1c16ad6..5e6e085ac7 100644
--- a/hw/i386/kvm/xen_primary_console.c
+++ b/hw/i386/kvm/xen_primary_console.c
@@ -112,6 +112,15 @@ uint16_t xen_primary_console_get_port(void)
     return s->guest_port;
 }
 
+void xen_primary_console_set_be_port(uint16_t port)
+{
+    XenPrimaryConsoleState *s = xen_primary_console_singleton;
+    if (s) {
+        printf("be port set to %d\n", port);
+        s->be_port = port;
+    }
+}
+
 uint64_t xen_primary_console_get_pfn(void)
 {
     XenPrimaryConsoleState *s = xen_primary_console_singleton;
@@ -142,6 +151,20 @@ static void alloc_guest_port(XenPrimaryConsoleState *s)
     }
 }
 
+static void rebind_guest_port(XenPrimaryConsoleState *s)
+{
+    struct evtchn_bind_interdomain inter = {
+        .remote_dom = DOMID_QEMU,
+        .remote_port = s->be_port,
+    };
+
+    if (!xen_evtchn_bind_interdomain_op(&inter)) {
+        s->guest_port = inter.local_port;
+    }
+
+    s->be_port = 0;
+}
+
 int xen_primary_console_reset(void)
 {
     XenPrimaryConsoleState *s = xen_primary_console_singleton;
@@ -154,7 +177,11 @@ int xen_primary_console_reset(void)
         xen_overlay_do_map_page(&s->console_page, gpa);
     }
 
-    alloc_guest_port(s);
+    if (s->be_port) {
+        rebind_guest_port(s);
+    } else {
+        alloc_guest_port(s);
+    }
 
     trace_xen_primary_console_reset(s->guest_port);
 
diff --git a/hw/i386/kvm/xen_primary_console.h b/hw/i386/kvm/xen_primary_console.h
index dd4922f3f4..7e2989ea0d 100644
--- a/hw/i386/kvm/xen_primary_console.h
+++ b/hw/i386/kvm/xen_primary_console.h
@@ -16,6 +16,7 @@ void xen_primary_console_create(void);
 int xen_primary_console_reset(void);
 
 uint16_t xen_primary_console_get_port(void);
+void xen_primary_console_set_be_port(uint16_t port);
 uint64_t xen_primary_console_get_pfn(void);
 void *xen_primary_console_get_map(void);
 
-- 
2.40.1