[Xen-devel] [PATCH v2] xen: fix setup of PVH Dom0 memory map

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

This patch adds the holes removed by MMIO regions to the end of the
memory map for PVH Dom0, so the guest OS doesn't have to manually
populate this memory.

Also, provide a suitable e820 memory map for PVH Dom0, that matches
the underlying p2m map. This means that PVH guests should always use
XENMEM_memory_map in order to obtain the e820, even when running as
Dom0.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
---
Changes since v1:
 - Fix comparison of start_pfn and nr_pages to use < instead of <=.
 - Use memory pages from d->page_list in order to fill the holes in
   the memory map.
 - Use assigments instead of memcpy to create the Dom0 e820 map.
 - Make sure we are calculating the right size of the e820 entries by
   always rounding up the size.
---
 xen/arch/x86/domain_build.c |  107 +++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 104 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index 38ed9f6..52c6fba 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -327,11 +327,14 @@ static __init void pvh_add_mem_mapping(struct domain *d, 
unsigned long gfn,
  * pvh fixme: The following doesn't map MMIO ranges when they sit above the
  *            highest E820 covered address.
  */
-static __init void pvh_map_all_iomem(struct domain *d)
+static __init void pvh_map_all_iomem(struct domain *d, unsigned long nr_pages)
 {
     unsigned long start_pfn, end_pfn, end = 0, start = 0;
     const struct e820entry *entry;
-    unsigned int i, nump;
+    unsigned long nump, nmap, navail, mfn, nr_holes = 0;
+    unsigned int i;
+    struct page_info *page;
+    int rc;
 
     for ( i = 0, entry = e820.map; i < e820.nr_map; i++, entry++ )
     {
@@ -353,6 +356,9 @@ static __init void pvh_map_all_iomem(struct domain *d)
                 nump = end_pfn - start_pfn;
                 /* Add pages to the mapping */
                 pvh_add_mem_mapping(d, start_pfn, start_pfn, nump);
+                if ( start_pfn < nr_pages )
+                    nr_holes += (end_pfn < nr_pages) ?
+                                    nump : (nr_pages - start_pfn);
             }
             start = end;
         }
@@ -369,6 +375,100 @@ static __init void pvh_map_all_iomem(struct domain *d)
         nump = end_pfn - start_pfn;
         pvh_add_mem_mapping(d, start_pfn, start_pfn, nump);
     }
+
+    /*
+     * Add the memory removed by the holes at the end of the
+     * memory map.
+     */
+    for ( i = 0, entry = e820.map; i < e820.nr_map && nr_holes > 0;
+          i++, entry++ )
+    {
+        if ( entry->type != E820_RAM )
+            continue;
+
+        end_pfn = PFN_UP(entry->addr + entry->size);
+        if ( end_pfn <= nr_pages )
+            continue;
+
+        navail = end_pfn - nr_pages;
+        nmap = navail > nr_holes ? nr_holes : navail;
+        nr_holes -= nmap;
+        start_pfn = PFN_DOWN(entry->addr) < nr_pages ?
+                        nr_pages : PFN_DOWN(entry->addr);
+        /*
+         * Populate this memory region using the pages
+         * previously removed by the MMIO holes.
+         */
+        page_list_for_each ( page, &d->page_list )
+        {
+            mfn = page_to_mfn(page);
+            if ( get_gpfn_from_mfn(mfn) != INVALID_M2P_ENTRY )
+                continue;
+
+            rc = guest_physmap_add_page(d, start_pfn, mfn, 0);
+            if ( rc != 0 )
+                panic("Unable to add gpfn %#lx mfn %#lx to Dom0 physmap",
+                      start_pfn, page_to_mfn(page));
+            start_pfn++;
+            if ( --nmap == 0 )
+                break;
+        }
+        ASSERT(nmap == 0);
+    }
+
+    ASSERT(nr_holes == 0);
+}
+
+static __init void pvh_setup_e820(struct domain *d, unsigned long nr_pages)
+{
+    struct e820entry *entry, *entry_guest;
+    unsigned int i;
+    unsigned long pages, cur_pages = 0;
+
+    /*
+     * Craft the e820 memory map for Dom0 based on the hardware e820 map.
+     */
+    d->arch.e820 = xzalloc_array(struct e820entry, e820.nr_map);
+    if ( !d->arch.e820 )
+        panic("Unable to allocate memory for Dom0 e820 map");
+    entry_guest = d->arch.e820;
+
+    /* Clamp e820 memory map to match the memory assigned to Dom0 */
+    for ( i = 0, entry = e820.map; i < e820.nr_map; i++, entry++ )
+    {
+        if ( entry->type != E820_RAM )
+        {
+            *entry_guest = *entry;
+            goto next;
+        }
+
+        if ( nr_pages == cur_pages )
+        {
+            /*
+             * We already have all the assigned memory,
+             * skip this entry
+             */
+            continue;
+        }
+
+        *entry_guest = *entry;
+        pages = (entry_guest->size + PAGE_SIZE-1) >> PAGE_SHIFT;
+        if ( (cur_pages + pages) > nr_pages )
+        {
+            /* Truncate region */
+            entry_guest->size = (nr_pages - cur_pages) << PAGE_SHIFT;
+            cur_pages = nr_pages;
+        }
+        else
+        {
+            cur_pages += pages;
+        }
+next:
+        d->arch.nr_e820++;
+        entry_guest++;
+    }
+    ASSERT(cur_pages == nr_pages);
+    ASSERT(d->arch.nr_e820 <= e820.nr_map);
 }
 
 static __init void dom0_update_physmap(struct domain *d, unsigned long pfn,
@@ -1391,7 +1491,8 @@ int __init construct_dom0(
         pfn = shared_info_paddr >> PAGE_SHIFT;
         dom0_update_physmap(d, pfn, mfn, 0);
 
-        pvh_map_all_iomem(d);
+        pvh_map_all_iomem(d, nr_pages);
+        pvh_setup_e820(d, nr_pages);
     }
 
     if ( d->domain_id == hardware_domid )
-- 
1.7.7.5 (Apple Git-26)


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