[Qemu-devel] [PATCH qemu v16 17/19] 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
notify 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.

This postpones vfio_stop() till the end of region_del() as
vfio_dma_unmap() has to execute before VFIO support is disabled.

As there can be multiple containers attached to the same PHB/LIOBN,
this adds a wrapper with a use counter for every IOMMU MR and
stores them in a list in the VFIOAddressSpace.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v16:
* added a use counter in VFIOAddressSpace->VFIOIOMMUMR

v15:
* s/need_vfio/vfio-Users/g
---
 hw/ppc/spapr_iommu.c          | 12 ++++++++++++
 hw/ppc/spapr_pci.c            |  6 ------
 hw/vfio/common.c              | 45 ++++++++++++++++++++++++++++++++++++++++++-
 include/exec/memory.h         |  4 ++++
 include/hw/vfio/vfio-common.h |  7 +++++++
 5 files changed, 67 insertions(+), 7 deletions(-)

diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
index c945dba..7af2700 100644
--- a/hw/ppc/spapr_iommu.c
+++ b/hw/ppc/spapr_iommu.c
@@ -155,6 +155,16 @@ 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);
 
@@ -239,6 +249,8 @@ 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 5b9ccff..51e7d56 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1086,12 +1086,6 @@ 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 3f2fb23..03daf88 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -421,6 +421,26 @@ 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) {
+            VFIOIOMMUMR *iommumr;
+            bool found = false;
+
+            QLIST_FOREACH(iommumr, &container->space->iommumrs, iommumr_next) {
+                if (iommumr->iommu == section->mr) {
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                iommumr = g_malloc0(sizeof(*iommumr));
+                iommumr->iommu = section->mr;
+                section->mr->iommu_ops->vfio_start(section->mr);
+                QLIST_INSERT_HEAD(&container->space->iommumrs, iommumr,
+                                  iommumr_next);
+            }
+            ++iommumr->users;
+        }
         memory_region_iommu_replay(giommu->iommu, &giommu->n,
                                    false);
 
@@ -470,6 +490,7 @@ static void vfio_listener_region_del(MemoryListener *listener,
     hwaddr iova, end;
     Int128 llend, llsize;
     int ret;
+    MemoryRegion *iommu = NULL;
 
     if (vfio_listener_skipped_section(section)) {
         trace_vfio_listener_region_del_skip(
@@ -490,13 +511,30 @@ static void vfio_listener_region_del(MemoryListener *listener,
 
         QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
             if (giommu->iommu == section->mr) {
+                VFIOIOMMUMR *iommumr;
+
                 memory_region_unregister_iommu_notifier(&giommu->n);
+
+                QLIST_FOREACH(iommumr, &container->space->iommumrs,
+                              iommumr_next) {
+                    if (iommumr->iommu != section->mr) {
+                        continue;
+                    }
+                    --iommumr->users;
+                    if (iommumr->users) {
+                        break;
+                    }
+                    QLIST_REMOVE(iommumr, iommumr_next);
+                    g_free(iommumr);
+                    iommu = giommu->iommu;
+                    break;
+                }
+
                 QLIST_REMOVE(giommu, giommu_next);
                 g_free(giommu);
                 break;
             }
         }
-
         /*
          * FIXME: We assume the one big unmap below is adequate to
          * remove any individual page mappings in the IOMMU which
@@ -527,6 +565,10 @@ static void vfio_listener_region_del(MemoryListener *listener,
                      "0x%"HWADDR_PRIx") = %d (%m)",
                      container, iova, int128_get64(llsize), ret);
     }
+
+    if (iommu && iommu->iommu_ops && iommu->iommu_ops->vfio_stop) {
+        iommu->iommu_ops->vfio_stop(section->mr);
+    }
 }
 
 static const MemoryListener vfio_memory_listener = {
@@ -787,6 +829,7 @@ static VFIOAddressSpace *vfio_get_address_space(AddressSpace *as)
     space = g_malloc0(sizeof(*space));
     space->as = as;
     QLIST_INIT(&space->containers);
+    QLIST_INIT(&space->iommumrs);
 
     QLIST_INSERT_HEAD(&vfio_address_spaces, space, list);
 
diff --git a/include/exec/memory.h b/include/exec/memory.h
index a3a1703..52d2c70 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -151,6 +151,10 @@ 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;
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 808263b..a9e6e33 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -64,9 +64,16 @@ typedef struct VFIORegion {
 typedef struct VFIOAddressSpace {
     AddressSpace *as;
     QLIST_HEAD(, VFIOContainer) containers;
+    QLIST_HEAD(, VFIOIOMMUMR) iommumrs;
     QLIST_ENTRY(VFIOAddressSpace) list;
 } VFIOAddressSpace;
 
+typedef struct VFIOIOMMUMR {
+    MemoryRegion *iommu;
+    int users;
+    QLIST_ENTRY(VFIOIOMMUMR) iommumr_next;
+} VFIOIOMMUMR;
+
 struct VFIOGroup;
 
 typedef struct VFIOContainer {
-- 
2.5.0.rc3