[PATCH v2 3/7] tools: Refactor console/io.c to avoid using xc_domain_getinfo()

[Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>]

It has 2 avoidable occurences

* Check whether a domain is valid, which can be done faster with
    xc_domain_getinfo_single()
* Domain discovery, which can be done much faster with the sysctl
    interface through xc_domain_getinfolist().

Signed-off-by: Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>
---
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Wei Liu <wl@xxxxxxx>
Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/console/daemon/io.c | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/tools/console/daemon/io.c b/tools/console/daemon/io.c
index 6bfe96715b..c5972cb721 100644
--- a/tools/console/daemon/io.c
+++ b/tools/console/daemon/io.c
@@ -405,13 +405,7 @@ static void buffer_advance(struct buffer *buffer, size_t 
len)
 
 static bool domain_is_valid(int domid)
 {
-       bool ret;
-       xc_dominfo_t info;
-
-       ret = (xc_domain_getinfo(xc, domid, 1, &info) == 1 &&
-              info.domid == domid);
-               
-       return ret;
+       return xc_domain_getinfo_single(xc, domid, NULL) == 0;
 }
 
 static int create_hv_log(void)
@@ -961,24 +955,33 @@ static unsigned enum_pass = 0;
 
 static void enum_domains(void)
 {
-       int domid = 1;
-       xc_dominfo_t dominfo;
+       /**
+        * Memory set aside to query the state of every
+        * domain in the hypervisor in a single hypercall.
+        */
+        static xc_domaininfo_t domaininfo[DOMID_FIRST_RESERVED - 1];
+
+       int ret;
        struct domain *dom;
 
        enum_pass++;
 
-       while (xc_domain_getinfo(xc, domid, 1, &dominfo) == 1) {
-               dom = lookup_domain(dominfo.domid);
-               if (dominfo.dying) {
+       /* Fetch info on every valid domain except for dom0 */
+       ret = xc_domain_getinfolist(xc, 1, DOMID_FIRST_RESERVED - 1, 
domaininfo);
+       if (ret < 0)
+               return;
+
+       for (size_t i = 0; i < ret; i++) {
+               dom = lookup_domain(domaininfo[i].domain);
+               if (domaininfo[i].flags & XEN_DOMINF_dying) {
                        if (dom)
                                shutdown_domain(dom);
                } else {
                        if (dom == NULL)
-                               dom = create_domain(dominfo.domid);
+                               dom = create_domain(domaininfo[i].domain);
                }
                if (dom)
                        dom->last_seen = enum_pass;
-               domid = dominfo.domid + 1;
        }
 }
 
-- 
2.34.1