[RFC PATCH] vfio/common: Separate vfio-pci ranges

["Cédric Le Goater" <clg@redhat.com>]

From: Joao Martins <joao.m.martins@oracle.com>

QEMU computes the DMA logging ranges for two predefined ranges: 32-bit
and 64-bit. In the OVMF case, when the dynamic MMIO window is enabled,
QEMU includes in the 64-bit range the RAM regions at the lower part
and vfio-pci device RAM regions which are at the top of the address
space. This range contains a large gap and the size can be bigger than
the dirty tracking HW limits of some devices (MLX5 has a 2^42 limit).

To avoid such large ranges, introduce a new PCI range covering the
vfio-pci device RAM regions, this only if the addresses are above 4GB
to avoid breaking potential SeaBIOS guests.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
[ clg: - wrote commit log
       - fixed overlapping 32-bit and PCI ranges when using SeaBIOS ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 hw/vfio/common.c     | 51 +++++++++++++++++++++++++++++++++++++++-----
 hw/vfio/trace-events |  2 +-
 2 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 237101d03844273f653d98b6d053a1ae9c05a247..a5548e3bebf999e6d9cef08bdaf1fbc3b437e5eb 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -27,6 +27,7 @@
 
 #include "hw/vfio/vfio-common.h"
 #include "hw/vfio/vfio.h"
+#include "hw/vfio/pci.h"
 #include "exec/address-spaces.h"
 #include "exec/memory.h"
 #include "exec/ram_addr.h"
@@ -1400,6 +1401,8 @@ typedef struct VFIODirtyRanges {
     hwaddr max32;
     hwaddr min64;
     hwaddr max64;
+    hwaddr minpci;
+    hwaddr maxpci;
 } VFIODirtyRanges;
 
 typedef struct VFIODirtyRangesListener {
@@ -1408,6 +1411,31 @@ typedef struct VFIODirtyRangesListener {
     MemoryListener listener;
 } VFIODirtyRangesListener;
 
+static bool vfio_section_is_vfio_pci(MemoryRegionSection *section,
+                                     VFIOContainer *container)
+{
+    VFIOPCIDevice *pcidev;
+    VFIODevice *vbasedev;
+    VFIOGroup *group;
+    Object *owner;
+
+    owner = memory_region_owner(section->mr);
+
+    QLIST_FOREACH(group, &container->group_list, container_next) {
+        QLIST_FOREACH(vbasedev, &group->device_list, next) {
+            if (vbasedev->type != VFIO_DEVICE_TYPE_PCI) {
+                continue;
+            }
+            pcidev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
+            if (OBJECT(pcidev) == owner) {
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
 static void vfio_dirty_tracking_update(MemoryListener *listener,
                                        MemoryRegionSection *section)
 {
@@ -1434,9 +1462,14 @@ static void vfio_dirty_tracking_update(MemoryListener *listener,
      * would be an IOVATree but that has a much bigger runtime overhead and
      * unnecessary complexity.
      */
-    min = (end <= UINT32_MAX) ? &range->min32 : &range->min64;
-    max = (end <= UINT32_MAX) ? &range->max32 : &range->max64;
-
+    if (vfio_section_is_vfio_pci(section, dirty->container) &&
+        iova >= UINT32_MAX) {
+        min = &range->minpci;
+        max = &range->maxpci;
+    } else {
+        min = (end <= UINT32_MAX) ? &range->min32 : &range->min64;
+        max = (end <= UINT32_MAX) ? &range->max32 : &range->max64;
+    }
     if (*min > iova) {
         *min = iova;
     }
@@ -1461,6 +1494,7 @@ static void vfio_dirty_tracking_init(VFIOContainer *container,
     memset(&dirty, 0, sizeof(dirty));
     dirty.ranges.min32 = UINT32_MAX;
     dirty.ranges.min64 = UINT64_MAX;
+    dirty.ranges.minpci = UINT64_MAX;
     dirty.listener = vfio_dirty_tracking_listener;
     dirty.container = container;
 
@@ -1531,7 +1565,8 @@ vfio_device_feature_dma_logging_start_create(VFIOContainer *container,
      * DMA logging uAPI guarantees to support at least a number of ranges that
      * fits into a single host kernel base page.
      */
-    control->num_ranges = !!tracking->max32 + !!tracking->max64;
+    control->num_ranges = !!tracking->max32 + !!tracking->max64 +
+        !!tracking->maxpci;
     ranges = g_try_new0(struct vfio_device_feature_dma_logging_range,
                         control->num_ranges);
     if (!ranges) {
@@ -1550,11 +1585,17 @@ vfio_device_feature_dma_logging_start_create(VFIOContainer *container,
     if (tracking->max64) {
         ranges->iova = tracking->min64;
         ranges->length = (tracking->max64 - tracking->min64) + 1;
+        ranges++;
+    }
+    if (tracking->maxpci) {
+        ranges->iova = tracking->minpci;
+        ranges->length = (tracking->maxpci - tracking->minpci) + 1;
     }
 
     trace_vfio_device_dirty_tracking_start(control->num_ranges,
                                            tracking->min32, tracking->max32,
-                                           tracking->min64, tracking->max64);
+                                           tracking->min64, tracking->max64,
+                                           tracking->minpci, tracking->maxpci);
 
     return feature;
 }
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index ce61b10827b6a1203a5fe1a87a76d96f25c11345..ab52c6bb7f0c11e51fefef231c108d0c9381547e 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -104,7 +104,7 @@ vfio_known_safe_misalignment(const char *name, uint64_t iova, uint64_t offset_wi
 vfio_listener_region_add_no_dma_map(const char *name, uint64_t iova, uint64_t size, uint64_t page_size) "Region \"%s\" 0x%"PRIx64" size=0x%"PRIx64" is not aligned to 0x%"PRIx64" and cannot be mapped for DMA"
 vfio_listener_region_del(uint64_t start, uint64_t end) "region_del 0x%"PRIx64" - 0x%"PRIx64
 vfio_device_dirty_tracking_update(uint64_t start, uint64_t end, uint64_t min, uint64_t max) "section 0x%"PRIx64" - 0x%"PRIx64" -> update [0x%"PRIx64" - 0x%"PRIx64"]"
-vfio_device_dirty_tracking_start(int nr_ranges, uint64_t min32, uint64_t max32, uint64_t min64, uint64_t max64) "nr_ranges %d 32:[0x%"PRIx64" - 0x%"PRIx64"], 64:[0x%"PRIx64" - 0x%"PRIx64"]"
+vfio_device_dirty_tracking_start(int nr_ranges, uint64_t min32, uint64_t max32, uint64_t min64, uint64_t max64, uint64_t minpci, uint64_t maxpci) "nr_ranges %d 32:[0x%"PRIx64" - 0x%"PRIx64"], 64:[0x%"PRIx64" - 0x%"PRIx64"], pci:[0x%"PRIx64" - 0x%"PRIx64"]"
 vfio_disconnect_container(int fd) "close container->fd=%d"
 vfio_put_group(int fd) "close group->fd=%d"
 vfio_get_device(const char * name, unsigned int flags, unsigned int num_regions, unsigned int num_irqs) "Device %s flags: %u, regions: %u, irqs: %u"
-- 
2.41.0