[Xen-devel] [PATCH v4 25/31] xen: allow HVM guests to use XENMEM_memory_map

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Enable this hypercall for HVM guests in order to fetch the e820 memory
map in the absence of an emulated BIOS. The memory map is populated and
notified to Xen in arch_setup_meminit_hvm.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 tools/libxc/xc_dom_x86.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
index b587b12..87bce6e 100644
--- a/tools/libxc/xc_dom_x86.c
+++ b/tools/libxc/xc_dom_x86.c
@@ -1205,6 +1205,7 @@ static int check_mmio_hole(uint64_t start, uint64_t 
memsize,
         return 1;
 }
 
+#define MAX_E820_ENTRIES    128
 static int meminit_hvm(struct xc_dom_image *dom)
 {
     unsigned long i, vmemid, nr_pages = dom->total_pages;
@@ -1225,6 +1226,8 @@ static int meminit_hvm(struct xc_dom_image *dom)
     unsigned int nr_vmemranges, nr_vnodes;
     xc_interface *xch = dom->xch;
     uint32_t domid = dom->guest_domid;
+    struct e820entry entries[MAX_E820_ENTRIES];
+    int e820_index = 0;
 
     if ( nr_pages > target_pages )
         memflags |= XENMEMF_populate_on_demand;
@@ -1275,6 +1278,13 @@ static int meminit_hvm(struct xc_dom_image *dom)
         vnode_to_pnode = dom->vnode_to_pnode;
     }
 
+    /* Add one additional memory range to account for the VGA hole */
+    if ( (nr_vmemranges + (dom->emulation ? 1 : 0)) > MAX_E820_ENTRIES )
+    {
+        DOMPRINTF("Too many memory ranges");
+        goto error_out;
+    }
+
     total_pages = 0;
     p2m_size = 0;
     for ( i = 0; i < nr_vmemranges; i++ )
@@ -1363,9 +1373,13 @@ static int meminit_hvm(struct xc_dom_image *dom)
      * Under 2MB mode, we allocate pages in batches of no more than 8MB to 
      * ensure that we can be preempted and hence dom0 remains responsive.
      */
-    if ( dom->emulation )
+    if ( dom->emulation ) {
         rc = xc_domain_populate_physmap_exact(
             xch, domid, 0xa0, 0, memflags, &dom->p2m_host[0x00]);
+        entries[e820_index].addr = 0;
+        entries[e820_index].size = 0xa0 << PAGE_SHIFT;
+        entries[e820_index++].type = E820_RAM;
+    }
 
     stat_normal_pages = 0;
     for ( vmemid = 0; vmemid < nr_vmemranges; vmemid++ )
@@ -1392,6 +1406,12 @@ static int meminit_hvm(struct xc_dom_image *dom)
         else
             cur_pages = vmemranges[vmemid].start >> PAGE_SHIFT;
 
+        /* Build an e820 map. */
+        entries[e820_index].addr = cur_pages << PAGE_SHIFT;
+        entries[e820_index].size = vmemranges[vmemid].end -
+                                   entries[e820_index].addr;
+        entries[e820_index++].type = E820_RAM;
+
         while ( (rc == 0) && (end_pages > cur_pages) )
         {
             /* Clip count to maximum 1GB extent. */
@@ -1509,6 +1529,13 @@ static int meminit_hvm(struct xc_dom_image *dom)
     DPRINTF("  2MB PAGES: 0x%016lx\n", stat_2mb_pages);
     DPRINTF("  1GB PAGES: 0x%016lx\n", stat_1gb_pages);
 
+    rc = xc_domain_set_memory_map(xch, domid, entries, e820_index);
+    if ( rc != 0 )
+    {
+        DOMPRINTF("unable to set memory map.");
+        goto error_out;
+    }
+
     rc = 0;
     goto out;
  error_out:
-- 
1.9.5 (Apple Git-50.3)


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