[Qemu-devel] [RFC 4/7] vhost: update_mem_cb implementation

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <address@hidden>

Add the meat of update_mem_cb;  this is called for each region,
to add a region to our temporary list.
Our temporary list is in order we look to see if this
region can be merged with the current head of list.

Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
 hw/virtio/trace-events |  2 ++
 hw/virtio/vhost.c      | 55 +++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
index 4a493bcd46..92fadec192 100644
--- a/hw/virtio/trace-events
+++ b/hw/virtio/trace-events
@@ -2,6 +2,8 @@
 
 # hw/virtio/vhost.c
 vhost_section(const char *name, int r) "%s:%d"
+vhost_update_mem_cb(const char *name, uint64_t gpa, uint64_t size, uint64_t 
host) "%s: 0x%"PRIx64"+0x%"PRIx64" @ 0x%"PRIx64
+vhost_update_mem_cb_abut(const char *name, uint64_t new_size) "%s: 0x%"PRIx64
 
 # hw/virtio/virtio.c
 virtqueue_alloc_element(void *elem, size_t sz, unsigned in_num, unsigned 
out_num) "elem %p size %zd in_num %u out_num %u"
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index c959a59fb3..7e3c6ae032 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -638,11 +638,64 @@ struct vhost_update_mem_tmp {
 /* Called for each MRS from vhost_update_mem */
 static int vhost_update_mem_cb(MemoryRegionSection *mrs, void *opaque)
 {
+    struct vhost_update_mem_tmp *vtmp = opaque;
+    struct vhost_memory_region *cur_vmr;
+    bool need_add = true;
+    uint64_t mrs_size;
+    uint64_t mrs_gpa;
+    uintptr_t mrs_host;
+
     if (!vhost_section(mrs)) {
         return 0;
     }
+    mrs_size = int128_get64(mrs->size);
+    mrs_gpa  = mrs->offset_within_address_space;
+    mrs_host = (uintptr_t)memory_region_get_ram_ptr(mrs->mr) +
+                         mrs->offset_within_region;
+
+    trace_vhost_update_mem_cb(mrs->mr->name, mrs_gpa, mrs_size,
+                              (uint64_t)mrs_host);
+
+    if (vtmp->nregions) {
+        /* Since we already have at least one region, lets see if
+         * this extends it; since we're scanning in order, we only
+         * have to look at the last one, and the FlatView that calls
+         * us shouldn't have overlaps.
+         */
+        struct vhost_memory_region *prev_vmr = vtmp->regions +
+                                               (vtmp->nregions - 1);
+        uint64_t prev_gpa_start = prev_vmr->guest_phys_addr;
+        uint64_t prev_gpa_end   = range_get_last(prev_gpa_start,
+                                                 prev_vmr->memory_size);
+        uint64_t prev_host_start = prev_vmr->userspace_addr;
+        uint64_t prev_host_end   = range_get_last(prev_host_start,
+                                                  prev_vmr->memory_size);
+
+        if (prev_gpa_end + 1 == mrs_gpa &&
+            prev_host_end + 1 == mrs_host &&
+            (!vtmp->dev->vhost_ops->vhost_backend_can_merge ||
+                vtmp->dev->vhost_ops->vhost_backend_can_merge(vtmp->dev,
+                    mrs_host, mrs_size,
+                    prev_host_start, prev_vmr->memory_size))) {
+            /* The two regions abut */
+            need_add = false;
+            mrs_size = mrs_size + prev_vmr->memory_size;
+            prev_vmr->memory_size = mrs_size;
+            trace_vhost_update_mem_cb_abut(mrs->mr->name, mrs_size);
+        }
+    }
+
+    if (need_add) {
+        vtmp->nregions++;
+        vtmp->regions = g_realloc_n(vtmp->regions, vtmp->nregions,
+                                    sizeof(vtmp->regions[0]));
+        cur_vmr = &vtmp->regions[vtmp->nregions - 1];
+        cur_vmr->guest_phys_addr = mrs_gpa;
+        cur_vmr->memory_size     = mrs_size;
+        cur_vmr->userspace_addr  = mrs_host;
+        cur_vmr->flags_padding = 0;
+    }
 
-    /* TODO */
     return 0;
 }
 
-- 
2.14.3