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Re: [Xen-devel] [v4][PATCH 3/9] tools:libxc: introduce hypercall for xc_reserved_device_memory_map





On 2014/8/22 18:55, Andrew Cooper wrote:
On 22/08/14 11:09, Tiejun Chen wrote:
We will introduce that hypercall xc_reserved_device_memory_map
to libxc.

Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
  tools/libxc/xc_domain.c | 29 +++++++++++++++++++++++++++++
  tools/libxc/xenctrl.h   |  4 ++++
  2 files changed, 33 insertions(+)

diff --git a/tools/libxc/xc_domain.c b/tools/libxc/xc_domain.c
index c67ac9a..08dc16f 100644
--- a/tools/libxc/xc_domain.c
+++ b/tools/libxc/xc_domain.c
@@ -649,6 +649,35 @@ int xc_domain_set_memory_map(xc_interface *xch,

      return rc;
  }
+
+int xc_reserved_device_memory_map(xc_interface *xch,
+                                  struct xen_reserved_device_memory entries[],
+                                  uint32_t max_entries)
+{
+    int rc;
+    struct xen_reserved_device_memory_map memmap = {
+        .nr_entries = max_entries
+    };
+    DECLARE_HYPERCALL_BOUNCE(entries,
+                             sizeof(struct xen_reserved_device_memory) *
+                             max_entries, XC_HYPERCALL_BUFFER_BOUNCE_OUT);
+
+    if ( xc_hypercall_bounce_pre(xch, entries) )
+        return -1;
+
+    set_xen_guest_handle(memmap.buffer, entries);
+
+    rc = do_memory_op(xch, XENMEM_reserved_device_memory_map,
+                      &memmap, sizeof(memmap));
+
+    xc_hypercall_bounce_post(xch, entries);
+
+    if ( errno == ENOBUFS )
+        return memmap.nr_entries;
+
+    return rc ? -errno : memmap.nr_entries;

So how does the caller distinguish between "xen filled in N entries" and
"xen said you need N entries for all the information" ?

Thanks for your reminder, I will add something to check this point.

I think the caller can compare that number of entries as that input parameter with the return value. If equal, this should be in case of "xen filled in N entries". If not, this is in case of "xen said you need N entries for all the information".

Thanks
Tiejun


~Andrew

+}
+
  int xc_get_machine_memory_map(xc_interface *xch,
                                struct e820entry entries[],
                                uint32_t max_entries)
diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 1c5d0db..1cc7852 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -1270,6 +1270,10 @@ int xc_domain_set_memory_map(xc_interface *xch,
  int xc_get_machine_memory_map(xc_interface *xch,
                                struct e820entry entries[],
                                uint32_t max_entries);
+
+int xc_reserved_device_memory_map(xc_interface *xch,
+                                  struct xen_reserved_device_memory entries[],
+                                  uint32_t max_entries);
  #endif
  int xc_domain_set_time_offset(xc_interface *xch,
                                uint32_t domid,



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