hw/xen: Implement soft reset for emulated gnttab

This is only part of it; we will also need to get the PV back end drivers
to tear down their own mappings (or do it for them, but they kind of need
to stop using the pointers too).

Some more work on the actual PV back ends and xen-bus code is going to be
needed to really make soft reset and migration fully functional, and this
part is the basis for that.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>

diff --git a/hw/i386/kvm/xen_gnttab.c b/hw/i386/kvm/xen_gnttab.c
index 2bf91d36c049475b81ede5fa9c15984073af3bf1..21c30e36591824af0cab43917305d823eec6e4bb 100644 (file)
--- a/hw/i386/kvm/xen_gnttab.c
+++ b/hw/i386/kvm/xen_gnttab.c
@@ -72,13 +72,11 @@ static void xen_gnttab_realize(DeviceState *dev, Error **errp)
         error_setg(errp, "Xen grant table support is for Xen emulation");
         return;
     }
-    s->nr_frames = 0;
     s->max_frames = kvm_xen_get_gnttab_max_frames();
     memory_region_init_ram(&s->gnt_frames, OBJECT(dev), "xen:grant_table",
                            XEN_PAGE_SIZE * s->max_frames, &error_abort);
     memory_region_set_enabled(&s->gnt_frames, true);
     s->entries.v1 = memory_region_get_ram_ptr(&s->gnt_frames);
-    memset(s->entries.v1, 0, XEN_PAGE_SIZE * s->max_frames);
 
     /* Create individual page-sizes aliases for overlays */
     s->gnt_aliases = (void *)g_new0(MemoryRegion, s->max_frames);
@@ -90,8 +88,11 @@ static void xen_gnttab_realize(DeviceState *dev, Error **errp)
         s->gnt_frame_gpas[i] = INVALID_GPA;
     }
 
+    s->nr_frames = 0;
+    memset(s->entries.v1, 0, XEN_PAGE_SIZE * s->max_frames);
     s->entries.v1[GNTTAB_RESERVED_XENSTORE].flags = GTF_permit_access;
     s->entries.v1[GNTTAB_RESERVED_XENSTORE].frame = XEN_SPECIAL_PFN(XENSTORE);
+
     qemu_mutex_init(&s->gnt_lock);
 
     xen_gnttab_singleton = s;
@@ -523,3 +524,24 @@ static struct gnttab_backend_ops emu_gnttab_backend_ops = {
     .unmap = xen_be_gnttab_unmap,
 };
 
+int xen_gnttab_reset(void)
+{
+    XenGnttabState *s = xen_gnttab_singleton;
+
+    if (!s) {
+        return -ENOTSUP;
+    }
+
+    QEMU_LOCK_GUARD(&s->gnt_lock);
+
+    s->nr_frames = 0;
+
+    memset(s->entries.v1, 0, XEN_PAGE_SIZE * s->max_frames);
+
+    s->entries.v1[GNTTAB_RESERVED_XENSTORE].flags = GTF_permit_access;
+    s->entries.v1[GNTTAB_RESERVED_XENSTORE].frame = XEN_SPECIAL_PFN(XENSTORE);
+
+    memset(s->map_track, 0, s->max_frames * ENTRIES_PER_FRAME_V1);
+
+    return 0;
+}

diff --git a/hw/i386/kvm/xen_gnttab.h b/hw/i386/kvm/xen_gnttab.h
index 3bdbe961914762c0d3109efde6b05c90cba4bf9f..ee215239b00810d74e0d955e1c3b369bc338a38a 100644 (file)
--- a/hw/i386/kvm/xen_gnttab.h
+++ b/hw/i386/kvm/xen_gnttab.h
@@ -13,6 +13,7 @@
 #define QEMU_XEN_GNTTAB_H
 
 void xen_gnttab_create(void);
+int xen_gnttab_reset(void);
 int xen_gnttab_map_page(uint64_t idx, uint64_t gfn);
 
 struct gnttab_set_version;

diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index bad3131d08e12a7e31d5fb07dc1add72a6d35fb2..0bb6c601c948bb30206c89faf1972e58de5cf6d7 100644 (file)
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -1406,6 +1406,11 @@ int kvm_xen_soft_reset(void)
         return err;
     }
 
+    err = xen_gnttab_reset();
+    if (err) {
+        return err;
+    }
+
     err = xen_xenstore_reset();
     if (err) {
         return err;