[Qemu-devel] [PATCH] extend limit of physical sections number

[Amos Kong <akong@redhat.com>]

 # qemu -drive file=/disk0,if=none,id=v0,format=qcow2 \
 -device virtio-blk-pci,drive=v0,id=v00,multifunction=on,addr=0x04.0
 ....

Launching guest with more than 32 virtio-blk disks,
qemu will crash, because there are too many BARs.

This patch brings the limit of non-tcg up by a factor
of 8 (32767 / 4096), i.e. 32*8 = 256.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Amos Kong <akong@redhat.com>
---
 exec.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/exec.c b/exec.c
index 5aef833..f639c01 100644
--- a/exec.c
+++ b/exec.c
@@ -763,11 +763,18 @@ void phys_mem_set_alloc(void *(*alloc)(ram_addr_t))
 
 static uint16_t phys_section_add(MemoryRegionSection *section)
 {
-    /* The physical section number is ORed with a page-aligned
-     * pointer to produce the iotlb entries.  Thus it should
-     * never overflow into the page-aligned value.
-     */
-    assert(next_map.sections_nb < TARGET_PAGE_SIZE);
+    if (tcg_enabled()) {
+        /* The physical section number is ORed with a page-aligned
+         * pointer to produce the iotlb entries.  Thus it should
+         * never overflow into the page-aligned value.
+         */
+        assert(next_map.sections_nb < TARGET_PAGE_SIZE);
+    } else {
+        /* For KVM or Xen we can use the full range of the ptr field
+         * in PhysPageEntry.
+         */
+        assert(next_map.sections_nb < SHRT_MAX);
+    }
 
     if (next_map.sections_nb == next_map.sections_nb_alloc) {
         next_map.sections_nb_alloc = MAX(next_map.sections_nb_alloc * 2,
-- 
1.8.3.1