Re: [PATCH 00 of 25] libxc: Hypercall buffers

[Olaf Hering <olaf@aepfle.de>]

Ian,

is the usage like shown below ok, adding an offset +start to the
initial buffer? 

Olaf

--- xen-unstable.hg-4.1.22313.orig/tools/libxc/xc_domain.c
+++ xen-unstable.hg-4.1.22313/tools/libxc/xc_domain.c
@@ -572,6 +572,55 @@ int xc_domain_get_tsc_info(xc_interface
     return rc;
 }
 
+static int do_xenmem_op_retry(xc_interface *xch, int cmd, struct xen_memory_reservation *reservation, size_t len, unsigned long nr_extents, xen_pfn_t *extent_start)
+{
+    xen_pfn_t *es = extent_start;
+    DECLARE_HYPERCALL_BOUNCE(es, nr_extents * sizeof(*es), XC_HYPERCALL_BUFFER_BOUNCE_BOTH);
+    int err = 0;
+    unsigned long count = nr_extents;
+    unsigned long delay = 0;
+    unsigned long start = 0;
+
+    fprintf(stderr, "%s: %d count %lx\n",__func__,cmd,count);
+
+    if ( xc_hypercall_bounce_pre(xch, es) )
+    {
+        PERROR("Could not bounce memory for XENMEM_* hypercall");
+        return -1;
+    }
+
+    while ( start < nr_extents )
+    {
+        es = extent_start + start;
+        set_xen_guest_handle(reservation->extent_start, es);
+        reservation->nr_extents = count;
+
+        err = do_memory_op(xch, cmd, reservation, len);
+        if ( err == count )
+            break;
+
+        if ( err > count || err < 0 )
+            break;
+
+        if ( delay > 1000 * 1000)
+        {
+            err = start;
+            break;
+        }
+
+        if ( err )
+            delay = 0;
+
+        start += err;
+        count -= err;
+        usleep(delay);
+        delay += 666; /* 1500 iterations, 12 seconds */
+    }
+    fprintf(stderr, "%s: %d err %x count %lx start %lx delay %lu/%lu\n",__func__,cmd,err,count,start,delay,delay/666);
+
+    xc_hypercall_bounce_post(xch, es);
+    return err;
+}
 
 int xc_domain_maximum_gpfn(xc_interface *xch, domid_t domid)
 {
@@ -643,10 +692,7 @@ int xc_domain_decrease_reservation(xc_in
                                    unsigned int extent_order,
                                    xen_pfn_t *extent_start)
 {
-    int err;
-    DECLARE_HYPERCALL_BOUNCE(extent_start, nr_extents * sizeof(*extent_start), XC_HYPERCALL_BUFFER_BOUNCE_BOTH);
     struct xen_memory_reservation reservation = {
-        .nr_extents   = nr_extents,
         .extent_order = extent_order,
         .mem_flags    = 0,
         .domid        = domid
@@ -659,18 +705,7 @@ int xc_domain_decrease_reservation(xc_in
         return -1;
     }
 
-    if ( xc_hypercall_bounce_pre(xch, extent_start) )
-    {
-        PERROR("Could not bounce memory for XENMEM_decrease_reservation hypercall");
-        return -1;
-    }
-    set_xen_guest_handle(reservation.extent_start, extent_start);
-
-    err = do_memory_op(xch, XENMEM_decrease_reservation, &reservation, sizeof(reservation));
-
-    xc_hypercall_bounce_post(xch, extent_start);
-
-    return err;
+    return do_xenmem_op_retry(xch, XENMEM_decrease_reservation, &reservation, sizeof(reservation), nr_extents, extent_start);
 }
 
 int xc_domain_decrease_reservation_exact(xc_interface *xch,
@@ -704,13 +739,20 @@ int xc_domain_add_to_physmap(xc_interfac
                              unsigned long idx,
                              xen_pfn_t gpfn)
 {
+    uint8_t delay = 0;
+    int rc;
     struct xen_add_to_physmap xatp = {
         .domid = domid,
         .space = space,
         .idx = idx,
         .gpfn = gpfn,
     };
-    return do_memory_op(xch, XENMEM_add_to_physmap, &xatp, sizeof(xatp));
+    do {
+        rc = do_memory_op(xch, XENMEM_add_to_physmap, &xatp, sizeof(xatp));
+        if ( rc < 0 && errno == ENOENT )
+            usleep(1000);
+    } while ( rc < 0 && errno == ENOENT && ++delay );
+    return rc;
 }
 
 int xc_domain_populate_physmap(xc_interface *xch,
@@ -720,26 +762,13 @@ int xc_domain_populate_physmap(xc_interf
                                unsigned int mem_flags,
                                xen_pfn_t *extent_start)
 {
-    int err;
-    DECLARE_HYPERCALL_BOUNCE(extent_start, nr_extents * sizeof(*extent_start), XC_HYPERCALL_BUFFER_BOUNCE_BOTH);
     struct xen_memory_reservation reservation = {
-        .nr_extents   = nr_extents,
         .extent_order = extent_order,
         .mem_flags    = mem_flags,
         .domid        = domid
     };
 
-    if ( xc_hypercall_bounce_pre(xch, extent_start) )
-    {
-        PERROR("Could not bounce memory for XENMEM_populate_physmap hypercall");
-        return -1;
-    }
-    set_xen_guest_handle(reservation.extent_start, extent_start);
-
-    err = do_memory_op(xch, XENMEM_populate_physmap, &reservation, sizeof(reservation));
-
-    xc_hypercall_bounce_post(xch, extent_start);
-    return err;
+    return do_xenmem_op_retry(xch, XENMEM_populate_physmap, &reservation, sizeof(reservation), nr_extents, extent_start);
 }
 
 int xc_domain_populate_physmap_exact(xc_interface *xch,
@@ -799,6 +828,7 @@ int xc_domain_memory_exchange_pages(xc_i
     set_xen_guest_handle(exchange.in.extent_start, in_extents);
     set_xen_guest_handle(exchange.out.extent_start, out_extents);
 
+    /* FIXME use do_xenmem_op_retry or some retry loop??? */
     rc = do_memory_op(xch, XENMEM_exchange, &exchange, sizeof(exchange));
 
 out: