[Qemu-devel] [PATCH qemu v8 06/14] spapr_iommu: Introduce "enabled" state for TCE table

[Alexey Kardashevskiy]

Currently TCE tables are created once at start and their size never
changes. We are going to change that by introducing a Dynamic DMA windows
support where DMA configuration may change during the guest execution.

This changes spapr_tce_new_table() to create an empty stub object. Only
LIOBN is assigned by the time of creation. It still will be called once
at the owner object (VIO or PHB) creation.

This introduces an "enabled" state for TCE table objects with two
helper functions - spapr_tce_table_enable()/spapr_tce_table_disable().
spapr_tce_table_enable() receives TCE table parameters and allocates
a guest view of the TCE table (in the user space or KVM).
spapr_tce_table_disable() disposes the table.

Follow up patches will disable+enable tables on reset (system reset
or DDW reset).

No visible change in behaviour is expected except the actual table
will be reallocated every reset. We might optimize this later.

The other way to implement this would be dynamically create/remove
the TCE table QOM objects but this would make migration impossible
as migration expects all QOM objects to exist at the receiver
so we have to have TCE table objects created when migration begins.

spapr_tce_table_do_enable() is separated from from spapr_tce_table_enable()
as later it will be called at the sPAPRTCETable post-migration stage when
it has all the properties set after the migration.

Signed-off-by: Alexey Kardashevskiy <address@hidden>
---
Changes:
v8:
* add missing unparent_object() to spapr_tce_table_unrealize() (parenting
is made by memory_region_init_iommu)
* tcet->iommu is alive as long as sPAPRTCETable is,
memory_region_set_size() is used to enable/disable MR

v7:
* s'tmp[64]'tmp[32]' as we need less than 64bytes and more than 16 bytes
and 32 is the closest power-of-two (just looks nices to have power-of-two
values)
* updated commit log about having spapr_tce_table_do_enable() splitted
from spapr_tce_table_enable()

v6:
* got rid of set_props()
---
 hw/ppc/spapr_iommu.c    | 79 +++++++++++++++++++++++++++++++++++--------------
 hw/ppc/spapr_pci.c      | 17 +++++++----
 hw/ppc/spapr_pci_vfio.c | 10 +++----
 hw/ppc/spapr_vio.c      |  9 +++---
 include/hw/ppc/spapr.h  | 11 +++----
 5 files changed, 82 insertions(+), 44 deletions(-)

diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
index 0cf5010..fbca136 100644
--- a/hw/ppc/spapr_iommu.c
+++ b/hw/ppc/spapr_iommu.c
@@ -173,15 +173,9 @@ static int spapr_tce_table_realize(DeviceState *dev)
     sPAPRTCETable *tcet = SPAPR_TCE_TABLE(dev);
 
     tcet->fd = -1;
-    tcet->table = spapr_tce_alloc_table(tcet->liobn,
-                                        tcet->nb_table,
-                                        tcet->page_shift,
-                                        &tcet->fd,
-                                        tcet->vfio_accel);
 
     memory_region_init_iommu(&tcet->iommu, OBJECT(dev), &spapr_iommu_ops,
-                             "iommu-spapr",
-                             (uint64_t)tcet->nb_table << tcet->page_shift);
+                             "iommu-spapr", 0);
 
     QLIST_INSERT_HEAD(&spapr_tce_tables, tcet, list);
 
@@ -191,14 +185,10 @@ static int spapr_tce_table_realize(DeviceState *dev)
     return 0;
 }
 
-sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn,
-                                   uint64_t bus_offset,
-                                   uint32_t page_shift,
-                                   uint32_t nb_table,
-                                   bool vfio_accel)
+sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn)
 {
     sPAPRTCETable *tcet;
-    char tmp[64];
+    char tmp[32];
 
     if (spapr_tce_find_by_liobn(liobn)) {
         fprintf(stderr, "Attempted to create TCE table with duplicate"
@@ -206,16 +196,8 @@ sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, 
uint32_t liobn,
         return NULL;
     }
 
-    if (!nb_table) {
-        return NULL;
-    }
-
     tcet = SPAPR_TCE_TABLE(object_new(TYPE_SPAPR_TCE_TABLE));
     tcet->liobn = liobn;
-    tcet->bus_offset = bus_offset;
-    tcet->page_shift = page_shift;
-    tcet->nb_table = nb_table;
-    tcet->vfio_accel = vfio_accel;
 
     snprintf(tmp, sizeof(tmp), "tce-table-%x", liobn);
     object_property_add_child(OBJECT(owner), tmp, OBJECT(tcet), NULL);
@@ -225,14 +207,65 @@ sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, 
uint32_t liobn,
     return tcet;
 }
 
+static void spapr_tce_table_do_enable(sPAPRTCETable *tcet)
+{
+    if (!tcet->nb_table) {
+        return;
+    }
+
+    tcet->table = spapr_tce_alloc_table(tcet->liobn,
+                                        tcet->nb_table,
+                                        tcet->page_shift,
+                                        &tcet->fd,
+                                        tcet->vfio_accel);
+
+    memory_region_set_size(&tcet->iommu,
+                           (uint64_t)tcet->nb_table << tcet->page_shift);
+
+    tcet->enabled = true;
+}
+
+void spapr_tce_table_enable(sPAPRTCETable *tcet,
+                            uint64_t bus_offset, uint32_t page_shift,
+                            uint32_t nb_table, bool vfio_accel)
+{
+    if (tcet->enabled) {
+        return;
+    }
+
+    tcet->bus_offset = bus_offset;
+    tcet->page_shift = page_shift;
+    tcet->nb_table = nb_table;
+    tcet->vfio_accel = vfio_accel;
+
+    spapr_tce_table_do_enable(tcet);
+}
+
+void spapr_tce_table_disable(sPAPRTCETable *tcet)
+{
+    if (!tcet->enabled) {
+        return;
+    }
+
+    memory_region_set_size(&tcet->iommu, 0);
+
+    spapr_tce_free_table(tcet->table, tcet->fd, tcet->nb_table);
+    tcet->fd = -1;
+    tcet->table = NULL;
+    tcet->enabled = false;
+    tcet->bus_offset = 0;
+    tcet->page_shift = 0;
+    tcet->nb_table = 0;
+    tcet->vfio_accel = false;
+}
+
 static void spapr_tce_table_unrealize(DeviceState *dev, Error **errp)
 {
     sPAPRTCETable *tcet = SPAPR_TCE_TABLE(dev);
 
     QLIST_REMOVE(tcet, list);
 
-    spapr_tce_free_table(tcet->table, tcet->fd, tcet->nb_table);
-    tcet->fd = -1;
+    spapr_tce_table_disable(tcet);
 }
 
 MemoryRegion *spapr_tce_get_iommu(sPAPRTCETable *tcet)
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index bbbb699..d1f29d8 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -758,13 +758,12 @@ static int spapr_phb_dma_init_window(sPAPRPHBState *sphb,
                                      uint64_t window_size)
 {
     uint64_t bus_offset = sphb->dma32_window_start;
-    sPAPRTCETable *tcet;
+    sPAPRTCETable *tcet = spapr_tce_find_by_liobn(liobn);
 
-    tcet = spapr_tce_new_table(DEVICE(sphb), liobn, bus_offset, page_shift,
-                               window_size >> page_shift,
-                               false);
-
-    return tcet ? 0 : -1;
+    spapr_tce_table_enable(tcet, bus_offset, page_shift,
+                           window_size >> page_shift,
+                           false);
+    return 0;
 }
 
 /* Macros to operate with address in OF binding to PCI */
@@ -1301,6 +1300,12 @@ static void spapr_phb_realize(DeviceState *dev, Error 
**errp)
         }
     }
 
+    tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn);
+    if (!tcet) {
+            error_setg(errp, "failed to create TCE table");
+            return;
+    }
+
     info->dma_capabilities_update(sphb);
     info->dma_init_window(sphb, sphb->dma_liobn, SPAPR_TCE_PAGE_SHIFT,
                           sphb->dma32_window_size);
diff --git a/hw/ppc/spapr_pci_vfio.c b/hw/ppc/spapr_pci_vfio.c
index f1dd28c..a5b97d0 100644
--- a/hw/ppc/spapr_pci_vfio.c
+++ b/hw/ppc/spapr_pci_vfio.c
@@ -49,13 +49,13 @@ static int spapr_phb_vfio_dma_init_window(sPAPRPHBState 
*sphb,
                                           uint64_t window_size)
 {
     uint64_t bus_offset = sphb->dma32_window_start;
-    sPAPRTCETable *tcet;
+    sPAPRTCETable *tcet = spapr_tce_find_by_liobn(liobn);
 
-    tcet = spapr_tce_new_table(DEVICE(sphb), liobn, bus_offset, page_shift,
-                               window_size >> page_shift,
-                               true);
+    spapr_tce_table_enable(tcet, bus_offset, page_shift,
+                           window_size >> page_shift,
+                           true);
 
-    return tcet ? 0 : -1;
+    return 0;
 }
 
 static void spapr_phb_vfio_reset(DeviceState *qdev)
diff --git a/hw/ppc/spapr_vio.c b/hw/ppc/spapr_vio.c
index e380b5f..46c5bb0 100644
--- a/hw/ppc/spapr_vio.c
+++ b/hw/ppc/spapr_vio.c
@@ -480,11 +480,10 @@ static void spapr_vio_busdev_realize(DeviceState *qdev, 
Error **errp)
         memory_region_add_subregion_overlap(&dev->mrroot, 0, &dev->mrbypass, 
1);
         address_space_init(&dev->as, &dev->mrroot, qdev->id);
 
-        dev->tcet = spapr_tce_new_table(qdev, liobn,
-                                        0,
-                                        SPAPR_TCE_PAGE_SHIFT,
-                                        pc->rtce_window_size >>
-                                        SPAPR_TCE_PAGE_SHIFT, false);
+        dev->tcet = spapr_tce_new_table(qdev, liobn);
+        spapr_tce_table_enable(dev->tcet, 0, SPAPR_TCE_PAGE_SHIFT,
+                               pc->rtce_window_size >> SPAPR_TCE_PAGE_SHIFT,
+                               false);
         dev->tcet->vdev = dev;
         memory_region_add_subregion_overlap(&dev->mrroot, 0,
                                             spapr_tce_get_iommu(dev->tcet), 2);
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 91a61ab..ed68c95 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -552,6 +552,7 @@ typedef struct sPAPRTCETable sPAPRTCETable;
 
 struct sPAPRTCETable {
     DeviceState parent;
+    bool enabled;
     uint32_t liobn;
     uint32_t nb_table;
     uint64_t bus_offset;
@@ -578,11 +579,11 @@ void spapr_events_init(sPAPRMachineState *sm);
 void spapr_events_fdt_skel(void *fdt, uint32_t epow_irq);
 int spapr_h_cas_compose_response(sPAPRMachineState *sm,
                                  target_ulong addr, target_ulong size);
-sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn,
-                                   uint64_t bus_offset,
-                                   uint32_t page_shift,
-                                   uint32_t nb_table,
-                                   bool vfio_accel);
+sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn);
+void spapr_tce_table_enable(sPAPRTCETable *tcet,
+                            uint64_t bus_offset, uint32_t page_shift,
+                            uint32_t nb_table, bool vfio_accel);
+void spapr_tce_table_disable(sPAPRTCETable *tcet);
 MemoryRegion *spapr_tce_get_iommu(sPAPRTCETable *tcet);
 int spapr_dma_dt(void *fdt, int node_off, const char *propname,
                  uint32_t liobn, uint64_t window, uint32_t size);
-- 
2.4.0.rc3.8.gfb3e7d5