We sometime get kernel panic with some devices on Aarch64
hosts. Alex Williamson suggests it might be broken PCIe
root complex. Add trace event to record the latest I/O
access before crashing. In case, assert our accesses are
aligned.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
Cc: Alex Williamson <alex.williamson@redhat.com>
---
 util/vfio-helpers.c | 8 ++++++++
 util/trace-events   | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index 14a549510fe..1d4efafcaa4 100644
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -227,6 +227,10 @@ static int qemu_vfio_pci_read_config(QEMUVFIOState *s, void *buf,
 {
     int ret;
 
+    trace_qemu_vfio_pci_read_config(buf, ofs, size,
+                                    s->config_region_info.offset,
+                                    s->config_region_info.size);
+    assert(QEMU_IS_ALIGNED(s->config_region_info.offset + ofs, size));
     do {
         ret = pread(s->device, buf, size, s->config_region_info.offset + ofs);
     } while (ret == -1 && errno == EINTR);
@@ -237,6 +241,10 @@ static int qemu_vfio_pci_write_config(QEMUVFIOState *s, void *buf, int size, int
 {
     int ret;
 
+    trace_qemu_vfio_pci_write_config(buf, ofs, size,
+                                     s->config_region_info.offset,
+                                     s->config_region_info.size);
+    assert(QEMU_IS_ALIGNED(s->config_region_info.offset + ofs, size));
     do {
         ret = pwrite(s->device, buf, size, s->config_region_info.offset + ofs);
     } while (ret == -1 && errno == EINTR);
diff --git a/util/trace-events b/util/trace-events
index 24c31803b01..c048f85f828 100644
--- a/util/trace-events
+++ b/util/trace-events
@@ -85,3 +85,5 @@ qemu_vfio_new_mapping(void *s, void *host, size_t size, int index, uint64_t iova
 qemu_vfio_do_mapping(void *s, void *host, size_t size, uint64_t iova) "s %p host %p size 0x%zx iova 0x%"PRIx64
 qemu_vfio_dma_map(void *s, void *host, size_t size, bool temporary, uint64_t *iova) "s %p host %p size 0x%zx temporary %d iova %p"
 qemu_vfio_dma_unmap(void *s, void *host) "s %p host %p"
+qemu_vfio_pci_read_config(void *buf, int ofs, int size, uint64_t region_ofs, uint64_t region_size) "read cfg ptr %p ofs 0x%x size %d (region ofs 0x%"PRIx64" size %"PRId64")"
+qemu_vfio_pci_write_config(void *buf, int ofs, int size, uint64_t region_ofs, uint64_t region_size) "write cfg ptr %p ofs 0x%x size %d (region ofs 0x%"PRIx64" size %"PRId64")"
-- 
2.26.2