>From 483e55bc13c6ab246251fcd62c59adc7bf169c52 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Tue, 13 Jun 2017 10:56:52 -0400
Subject: [PATCH 3/7] xen-mceinj: Loop around xc_get_pfn_list

Now that the xc_get_pfn_list can return max != num_pfns
we need to take that into account and loop around.

While at it fix the code:
 - Move the memset in the loop.
 - Change the loop conditions to exit if the mfn has been found.
 - Explain why 262144 is used.
 - Add munmap if we failed to allocate the buffer.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 tools/tests/mce-test/tools/xen-mceinj.c | 67 ++++++++++++++++++++++-----------
 1 file changed, 45 insertions(+), 22 deletions(-)

diff --git a/tools/tests/mce-test/tools/xen-mceinj.c b/tools/tests/mce-test/tools/xen-mceinj.c
index 22b4401..9c90235 100644
--- a/tools/tests/mce-test/tools/xen-mceinj.c
+++ b/tools/tests/mce-test/tools/xen-mceinj.c
@@ -264,7 +264,7 @@ static uint64_t guest_mfn(xc_interface *xc_handle,
     unsigned long m2p_mfn0;
     unsigned int guest_width;
     unsigned long version;
-    long max_gpfn,i;
+    unsigned long max_gpfn, i, start_pfn, max, old_v;
     uint64_t mfn = MCE_INVALID_MFN;
 
     if ( domain > DOMID_FIRST_RESERVED )
@@ -284,40 +284,63 @@ static uint64_t guest_mfn(xc_interface *xc_handle,
                             &pt_levels, &guest_width) )
         err(xc_handle, "Failed to get platform information\n");
 
-    /* Get guest's pfn list */
-    pfn_buf = malloc(sizeof(uint64_t) * max_gpfn);
-    if ( !pfn_buf )
-        err(xc_handle, "Failed to alloc pfn buf\n");
-    memset(pfn_buf, 0, sizeof(uint64_t) * max_gpfn);
-
-    ret = xc_get_pfn_list(xc_handle, domain, pfn_buf, 0, max_gpfn, &version);
-    if ( ret < 0 ) {
-        free(pfn_buf);
-        err(xc_handle, "Failed to get pfn list %x\n", ret);
-    }
+    max = 262144 /* 1GB of MFNs. */;
 
     /* Now get the m2p table */
     live_m2p = xc_map_m2p(xc_handle, max_mfn, PROT_READ, &m2p_mfn0);
     if ( !live_m2p )
         err(xc_handle, "Failed to map live M2P table\n");
 
-    /* match the mapping */
-    for ( i = 0; i < max_gpfn; i++ )
+
+    /* Get guest's pfn list */
+    pfn_buf = alloc(sizeof(uint64_t) * max);
+    if ( !pfn_buf )
     {
-        uint64_t tmp;
-        tmp = pfn_buf[i];
+        munmap(live_m2p, M2P_SIZE(max_mfn));
+        err(xc_handle, "Failed to alloc pfn buf\n");
+    }
 
-        if (mfn_valid(tmp) &&  (mfn_to_pfn(tmp) == gpfn))
-        {
-            mfn = tmp;
-            Lprintf("We get the mfn 0x%lx for this injection\n", mfn);
+    start_pfn = 0;
+    old_v = version = 0;
+    do {
+        memset(pfn_buf, 0, sizeof(uint64_t) * max);
+        ret = xc_get_pfn_list(xc_handle, domain, pfn_buf, start_pfn, max, &version);
+        if ( old_v != version ) {
+            Lprintf("P2M changed, refetching.\n");
+            start_pfn = 0;
+            old_v = version;
+            continue;
+        }
+
+        if ( ret < 0 )
             break;
+
+        Lprintf("%ld/%ld .. \n", start_pfn, max_gpfn);
+
+        if ( max != ret )
+            max = ret; /* Update it for the next iteration. */
+
+        start_pfn += ret;
+
+        for ( i = 0; i < ret; i++ )
+        {
+            uint64_t tmp;
+            tmp = pfn_buf[i];
+
+            if (mfn_valid(tmp) && (mfn_to_pfn(tmp) == gpfn))
+            {
+                mfn = tmp;
+                Lprintf("We get the mfn 0x%lx for this injection\n", mfn);
+                break;
+            }
         }
-    }
+    } while ( start_pfn < max_gpfn && (mce == MCE_INVALID_MFN) );
 
     munmap(live_m2p, M2P_SIZE(max_mfn));
-
     free(pfn_buf);
+    if ( ret < 0 )
+        err(xc_handle, "Failed to get pfn list %x\n", ret);
+
     return mfn;
 }
 
-- 
2.9.4