[Qemu-devel] [PATCH 1/4] spapr_pci: Allow PCI host bridge DMA window to be configured

[David Gibson <david@gibson.dropbear.id.au>]

At present the PCI host bridge (PHB) for the pseries machine type has a
fixed DMA window from 0..1GB (in PCI address space) which is mapped to real
memory via the PAPR paravirtualized IOMMU.

For better support of VFIO devices, we're going to want to allow for
different configurations of the DMA window.

Eventually we'll want to allow the guest itself to reconfigure the window
via the PAPR dynamic DMA window interface, but as a preliminary this patch
allows the user to reconfigure the window with new properties on the PHB
device.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
 hw/ppc/spapr_pci.c          | 7 +++++--
 include/hw/pci-host/spapr.h | 3 +--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 617b7f3..cb7c351 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1387,7 +1387,7 @@ static void spapr_phb_finish_realize(sPAPRPHBState *sphb, Error **errp)
     sPAPRTCETable *tcet;
     uint32_t nb_table;
 
-    nb_table = SPAPR_PCI_DMA32_SIZE >> SPAPR_TCE_PAGE_SHIFT;
+    nb_table = sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT;
     tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn,
                                0, SPAPR_TCE_PAGE_SHIFT, nb_table, false);
     if (!tcet) {
@@ -1397,7 +1397,7 @@ static void spapr_phb_finish_realize(sPAPRPHBState *sphb, Error **errp)
     }
 
     /* Register default 32bit DMA window */
-    memory_region_add_subregion(&sphb->iommu_root, 0,
+    memory_region_add_subregion(&sphb->iommu_root, sphb->dma_win_addr,
                                 spapr_tce_get_iommu(tcet));
 }
 
@@ -1430,6 +1430,9 @@ static Property spapr_phb_properties[] = {
                        SPAPR_PCI_IO_WIN_SIZE),
     DEFINE_PROP_BOOL("dynamic-reconfiguration", sPAPRPHBState, dr_enabled,
                      true),
+    /* Default DMA window is 0..1GB */
+    DEFINE_PROP_UINT64("dma_win_addr", sPAPRPHBState, dma_win_addr, 0),
+    DEFINE_PROP_UINT64("dma_win_size", sPAPRPHBState, dma_win_size, 0x40000000),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/include/hw/pci-host/spapr.h b/include/hw/pci-host/spapr.h
index 5322b56..7de5e02 100644
--- a/include/hw/pci-host/spapr.h
+++ b/include/hw/pci-host/spapr.h
@@ -78,6 +78,7 @@ struct sPAPRPHBState {
     MemoryRegion memwindow, iowindow, msiwindow;
 
     uint32_t dma_liobn;
+    hwaddr dma_win_addr, dma_win_size;
     AddressSpace iommu_as;
     MemoryRegion iommu_root;
 
@@ -115,8 +116,6 @@ struct sPAPRPHBVFIOState {
 
 #define SPAPR_PCI_MSI_WINDOW         0x40000000000ULL
 
-#define SPAPR_PCI_DMA32_SIZE         0x40000000
-
 static inline qemu_irq spapr_phb_lsi_qirq(struct sPAPRPHBState *phb, int pin)
 {
     sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
-- 
2.4.3