[Qemu-devel] [PATCH qemu v14 16/18] spapr_iommu, vfio, memory: Notify IOMMU about starting/stopping being used by VFIO

[Alexey Kardashevskiy <aik@ozlabs.ru>]

The sPAPR TCE tables manage 2 copies when VFIO is using an IOMMU -
a guest view of the table and a hardware TCE table. If there is no VFIO
presense in the address space, then just the guest view is used, if
this is the case, it is allocated in the KVM. However since there is no
support yet for VFIO in KVM TCE hypercalls, when we start using VFIO,
we need to move the guest view from KVM to the userspace; and we need
to do this for every IOMMU on a bus with VFIO devices.

This adds vfio_start/vfio_stop callbacks in MemoryRegionIOMMUOps to
notifiy IOMMU about changing environment so it can reallocate the table
to/from KVM or (when available) hook the IOMMU groups with the logical
bus (LIOBN) in the KVM.

This removes explicit spapr_tce_set_need_vfio() call from PCI hotplug
path as the new callbacks do this better - they notify IOMMU at
the exact moment when the configuration is changed, and this also
includes the case of PCI hot unplug.

TODO: split into 2 or 3 patches, per maintainership area.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 hw/ppc/spapr_iommu.c  | 12 ++++++++++++
 hw/ppc/spapr_pci.c    |  6 ------
 hw/vfio/common.c      |  9 +++++++++
 include/exec/memory.h |  4 ++++
 4 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
index 6dc3c45..702075d 100644
--- a/hw/ppc/spapr_iommu.c
+++ b/hw/ppc/spapr_iommu.c
@@ -151,6 +151,16 @@ static uint64_t spapr_tce_get_page_sizes(MemoryRegion *iommu)
     return 1ULL << tcet->page_shift;
 }
 
+static void spapr_tce_vfio_start(MemoryRegion *iommu)
+{
+    spapr_tce_set_need_vfio(container_of(iommu, sPAPRTCETable, iommu), true);
+}
+
+static void spapr_tce_vfio_stop(MemoryRegion *iommu)
+{
+    spapr_tce_set_need_vfio(container_of(iommu, sPAPRTCETable, iommu), false);
+}
+
 static void spapr_tce_table_do_enable(sPAPRTCETable *tcet);
 static void spapr_tce_table_do_disable(sPAPRTCETable *tcet);
 
@@ -211,6 +221,8 @@ static const VMStateDescription vmstate_spapr_tce_table = {
 static MemoryRegionIOMMUOps spapr_iommu_ops = {
     .translate = spapr_tce_translate_iommu,
     .get_page_sizes = spapr_tce_get_page_sizes,
+    .vfio_start = spapr_tce_vfio_start,
+    .vfio_stop = spapr_tce_vfio_stop,
 };
 
 static int spapr_tce_table_realize(DeviceState *dev)
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index bfcafdf..af99a36 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1121,12 +1121,6 @@ static void spapr_phb_add_pci_device(sPAPRDRConnector *drc,
     void *fdt = NULL;
     int fdt_start_offset = 0, fdt_size;
 
-    if (object_dynamic_cast(OBJECT(pdev), "vfio-pci")) {
-        sPAPRTCETable *tcet = spapr_tce_find_by_liobn(phb->dma_liobn);
-
-        spapr_tce_set_need_vfio(tcet, true);
-    }
-
     if (dev->hotplugged) {
         fdt = create_device_tree(&fdt_size);
         fdt_start_offset = spapr_create_pci_child_dt(phb, pdev, fdt, 0);
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index b257655..4e873b7 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -421,6 +421,9 @@ static void vfio_listener_region_add(MemoryListener *listener,
         QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
 
         memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
+        if (section->mr->iommu_ops && section->mr->iommu_ops->vfio_start) {
+            section->mr->iommu_ops->vfio_start(section->mr);
+        }
         memory_region_iommu_replay(giommu->iommu, &giommu->n,
                                    false);
 
@@ -466,6 +469,7 @@ static void vfio_listener_region_del(MemoryListener *listener,
     VFIOContainer *container = container_of(listener, VFIOContainer, listener);
     hwaddr iova, end;
     int ret;
+    MemoryRegion *iommu = NULL;
 
     if (vfio_listener_skipped_section(section)) {
         trace_vfio_listener_region_del_skip(
@@ -487,6 +491,7 @@ static void vfio_listener_region_del(MemoryListener *listener,
         QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
             if (giommu->iommu == section->mr) {
                 memory_region_unregister_iommu_notifier(&giommu->n);
+                iommu = giommu->iommu;
                 QLIST_REMOVE(giommu, giommu_next);
                 g_free(giommu);
                 break;
@@ -519,6 +524,10 @@ static void vfio_listener_region_del(MemoryListener *listener,
                      "0x%"HWADDR_PRIx") = %d (%m)",
                      container, iova, end - iova, ret);
     }
+
+    if (iommu && iommu->iommu_ops && iommu->iommu_ops->vfio_stop) {
+        iommu->iommu_ops->vfio_stop(section->mr);
+    }
 }
 
 static const MemoryListener vfio_memory_listener = {
diff --git a/include/exec/memory.h b/include/exec/memory.h
index eb5ce67..f1de133f 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -152,6 +152,10 @@ struct MemoryRegionIOMMUOps {
     IOMMUTLBEntry (*translate)(MemoryRegion *iommu, hwaddr addr, bool is_write);
     /* Returns supported page sizes */
     uint64_t (*get_page_sizes)(MemoryRegion *iommu);
+    /* Called when VFIO starts using this */
+    void (*vfio_start)(MemoryRegion *iommu);
+    /* Called when VFIO stops using this */
+    void (*vfio_stop)(MemoryRegion *iommu);
 };
 
 typedef struct CoalescedMemoryRange CoalescedMemoryRange;
-- 
2.5.0.rc3