i386/acpi: fix gint overflow in crs_range_compare

When very large regions (32GB sized in our case, PCI pass-through of GPUs)
are compared substraction result does not fit into gint.

As a result crs_replace_with_free_ranges does not get sorted ranges and
incorrectly computes PCI64 free space regions. Which then makes linux
guest complain about device and PCI64 hole intersection and device
becomes unusable.

Fix that by returning exactly fitting ranges.

Also fix indentation of an entire crs_replace_with_free_ranges to make
checkpatch happy.

Cc: qemu-stable@nongnu.org
Signed-off-by: Evgeny Yakovlev <wrfsh@yandex-team.ru>
Message-Id: <1563466463-26012-1-git-send-email-wrfsh@yandex-team.ru>
Signed-off-by: Evgeny Yakovlev <wrfsh@yandex-team.ru>
(cherry picked from commit 21e2acd583126db94f6d881005cd58e835160582)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index ede27ab3c46da1fae1790e3f4de7b48fe7c4fc38..bf59c475befa3e7fa82bc3dc26dfc45102b513df 100644 (file)
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -743,10 +743,16 @@ static void crs_range_set_free(CrsRangeSet *range_set)
 
 static gint crs_range_compare(gconstpointer a, gconstpointer b)
 {
-     CrsRangeEntry *entry_a = *(CrsRangeEntry **)a;
-     CrsRangeEntry *entry_b = *(CrsRangeEntry **)b;
+    CrsRangeEntry *entry_a = *(CrsRangeEntry **)a;
+    CrsRangeEntry *entry_b = *(CrsRangeEntry **)b;
 
-     return (int64_t)entry_a->base - (int64_t)entry_b->base;
+    if (entry_a->base < entry_b->base) {
+        return -1;
+    } else if (entry_a->base > entry_b->base) {
+        return 1;
+    } else {
+        return 0;
+    }
 }
 
 /*