[Qemu-devel] [PATCH 13/13] pseries: Implement IOMMU and DMA for PAPR PCI devices

[David Gibson]

Currently the pseries machine emulation does not support DMA for emulated
PCI devices, because the PAPR spec always requires a (guest visible,
paravirtualized) IOMMU which was not implemented.  Now that we have
infrastructure for IOMMU emulation, we can correct this and allow PCI DMA
for pseries.

With the existing PAPR IOMMU code used for VIO devices, this is almost
trivial. We use a single DMAContext for each (virtual) PCI host bridge,
which is the usual configuration on real PAPR machines (which often have
_many_ PCI host bridges).

Cc: Alex Graf <ag...@suse.de>

Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
---
 hw/spapr.h     |    1 +
 hw/spapr_pci.c |   15 +++++++++++++++
 hw/spapr_pci.h |    1 +
 3 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/hw/spapr.h b/hw/spapr.h
index 210b868..00b15c8 100644
--- a/hw/spapr.h
+++ b/hw/spapr.h
@@ -328,6 +328,7 @@ typedef struct sPAPRTCE {
 } sPAPRTCE;
 
 #define SPAPR_VIO_BASE_LIOBN    0x00000000
+#define SPAPR_PCI_BASE_LIOBN    0x80000000
 
 void spapr_iommu_init(void);
 DMAContext *spapr_tce_new_dma_context(uint32_t liobn, size_t window_size);
diff --git a/hw/spapr_pci.c b/hw/spapr_pci.c
index 523227b..b53fd40 100644
--- a/hw/spapr_pci.c
+++ b/hw/spapr_pci.c
@@ -201,6 +201,14 @@ static MemoryRegionOps spapr_io_ops = {
 /*
  * PHB PCI device
  */
+static DMAContext *spapr_pci_dma_context_fn(PCIBus *bus, void *opaque,
+                                            int devfn)
+{
+    sPAPRPHBState *phb = opaque;
+
+    return phb->dma;
+}
+
 static int spapr_phb_init(SysBusDevice *s)
 {
     sPAPRPHBState *phb = FROM_SYSBUS(sPAPRPHBState, s);
@@ -208,6 +216,7 @@ static int spapr_phb_init(SysBusDevice *s)
     char namebuf[64];
     int i;
     PCIBus *bus;
+    uint32_t liobn;
 
     sprintf(busname, "pci@%" PRIx64, phb->buid);
 
@@ -248,6 +257,10 @@ static int spapr_phb_init(SysBusDevice *s)
                                                  PCI_DEVFN(0, 0),
                                                  SPAPR_PCI_NUM_LSI);
 
+    liobn = SPAPR_PCI_BASE_LIOBN | (pci_find_domain(bus) << 16);
+    phb->dma = spapr_tce_new_dma_context(liobn, 0x40000000);
+    pci_setup_iommu(bus, spapr_pci_dma_context_fn, phb);
+
     QLIST_INSERT_HEAD(&spapr->phbs, phb, list);
 
     /* Initialize the LSI table */
@@ -400,6 +413,8 @@ int spapr_populate_pci_devices(sPAPRPHBState *phb,
     _FDT(fdt_setprop(fdt, bus_off, "interrupt-map", &interrupt_map,
                      7 * sizeof(interrupt_map[0])));
 
+    spapr_dma_dt(fdt, bus_off, "ibm,dma-window", phb->dma);
+
     return 0;
 }
 
diff --git a/hw/spapr_pci.h b/hw/spapr_pci.h
index b4b8a73..365c75e 100644
--- a/hw/spapr_pci.h
+++ b/hw/spapr_pci.h
@@ -37,6 +37,7 @@ typedef struct sPAPRPHBState {
     MemoryRegion memspace, iospace;
     target_phys_addr_t mem_win_addr, mem_win_size, io_win_addr, io_win_size;
     MemoryRegion memwindow, iowindow;
+    DMAContext *dma;
 
     struct {
         uint32_t dt_irq;
-- 
1.7.9.1