[Qemu-devel] [PATCH qemu v13 04/16] spapr_iommu: Introduce "enabled" state for TCE table

[Alexey Kardashevskiy <aik@ozlabs.ru>]

Currently TCE tables are created once at start and their sizes never
change. 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 zero-size IOMMU
memory region (IOMMU MR). 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, allocates
a guest view of the TCE table (in the user space or KVM) and
sets the correct size on the IOMMU MR.
- spapr_tce_table_disable() disposes the table and resets the IOMMU MR
size.

This changes the PHB reset handler to do the default DMA initialization
instead of spapr_phb_realize(). This does not make differenct now but
later with more than just one DMA window, we will have to remove them all
and create the default one on a system 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 the migration code 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 already has all the properties set after the migration.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 hw/ppc/spapr_iommu.c   | 80 +++++++++++++++++++++++++++++++++++---------------
 hw/ppc/spapr_pci.c     | 21 +++++++++----
 hw/ppc/spapr_vio.c     |  9 +++---
 include/hw/ppc/spapr.h | 10 +++----
 4 files changed, 80 insertions(+), 40 deletions(-)

diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
index 8132f64..e66e128 100644
--- a/hw/ppc/spapr_iommu.c
+++ b/hw/ppc/spapr_iommu.c
@@ -174,15 +174,8 @@ 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->page_shift,
-                                        tcet->nb_table,
-                                        &tcet->fd,
-                                        tcet->need_vfio);
-
     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);
 
@@ -224,14 +217,10 @@ void spapr_tce_set_need_vfio(sPAPRTCETable *tcet, bool need_vfio)
     tcet->table = newtable;
 }
 
-sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn,
-                                   uint64_t bus_offset,
-                                   uint32_t page_shift,
-                                   uint32_t nb_table,
-                                   bool need_vfio)
+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"
@@ -239,16 +228,8 @@ 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->need_vfio = need_vfio;
 
     snprintf(tmp, sizeof(tmp), "tce-table-%x", liobn);
     object_property_add_child(OBJECT(owner), tmp, OBJECT(tcet), NULL);
@@ -258,14 +239,65 @@ 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->page_shift,
+                                        tcet->nb_table,
+                                        &tcet->fd,
+                                        tcet->need_vfio);
+
+    memory_region_set_size(&tcet->iommu,
+                           (uint64_t)tcet->nb_table << tcet->page_shift);
+
+    tcet->enabled = true;
+}
+
+void spapr_tce_table_enable(sPAPRTCETable *tcet,
+                            uint32_t page_shift, uint64_t bus_offset,
+                            uint32_t nb_table, bool need_vfio)
+{
+    if (tcet->enabled) {
+        return;
+    }
+
+    tcet->bus_offset = bus_offset;
+    tcet->page_shift = page_shift;
+    tcet->nb_table = nb_table;
+    tcet->need_vfio = need_vfio;
+
+    spapr_tce_table_do_enable(tcet);
+}
+
+static 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->need_vfio = 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 248f20a..c34a906 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -815,12 +815,13 @@ static int spapr_phb_dma_window_enable(sPAPRPHBState *sphb,
         return -1;
     }
 
-    tcet = spapr_tce_new_table(DEVICE(sphb), liobn, window_addr,
-                               page_shift, nb_table, false);
+    tcet = spapr_tce_find_by_liobn(liobn);
     if (!tcet) {
         return -1;
     }
 
+    spapr_tce_table_enable(tcet, page_shift, window_addr, nb_table, false);
+
     memory_region_add_subregion(&sphb->iommu_root, tcet->bus_offset,
                                 spapr_tce_get_iommu(tcet));
     return 0;
@@ -1251,6 +1252,7 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
     int i;
     PCIBus *bus;
     uint64_t msi_window_size = 4096;
+    sPAPRTCETable *tcet;
 
     if (sphb->index != (uint32_t)-1) {
         hwaddr windows_base;
@@ -1402,11 +1404,18 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
         }
     }
 
+    /* DMA setup */
+    tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn);
+    if (!tcet) {
+        error_report("No default TCE table for %s", sphb->dtbusname);
+        return;
+    }
+
     /* Register default 32bit DMA window */
-    if (spapr_phb_dma_window_enable(sphb, sphb->dma_liobn, SPAPR_TCE_PAGE_SHIFT,
-                                    sphb->dma_win_addr, sphb->dma_win_size)) {
-        error_setg(errp, "Unable to create TCE table for %s", sphb->dtbusname);
-    }
+    spapr_phb_dma_window_enable(sphb, sphb->dma_liobn,
+                                SPAPR_TCE_PAGE_SHIFT,
+                                sphb->dma_win_addr,
+                                sphb->dma_win_size);
 
     sphb->msi = g_hash_table_new_full(g_int_hash, g_int_equal, g_free, g_free);
 }
diff --git a/hw/ppc/spapr_vio.c b/hw/ppc/spapr_vio.c
index 0f61a55..a745884 100644
--- a/hw/ppc/spapr_vio.c
+++ b/hw/ppc/spapr_vio.c
@@ -481,11 +481,10 @@ 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, SPAPR_TCE_PAGE_SHIFT, 0,
+                               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 098d85d..3e6bb84 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -539,6 +539,7 @@ typedef struct sPAPRTCETable sPAPRTCETable;
 
 struct sPAPRTCETable {
     DeviceState parent;
+    bool enabled;
     uint32_t liobn;
     uint32_t nb_table;
     uint64_t bus_offset;
@@ -566,11 +567,10 @@ 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,
                                  bool cpu_update, bool memory_update);
-sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn,
-                                   uint64_t bus_offset,
-                                   uint32_t page_shift,
-                                   uint32_t nb_table,
-                                   bool need_vfio);
+sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn);
+void spapr_tce_table_enable(sPAPRTCETable *tcet,
+                            uint32_t page_shift, uint64_t bus_offset,
+                            uint32_t nb_table, bool vfio_accel);
 void spapr_tce_set_need_vfio(sPAPRTCETable *tcet, bool need_vfio);
 
 MemoryRegion *spapr_tce_get_iommu(sPAPRTCETable *tcet);
-- 
2.5.0.rc3