spapr: Improved placement of PCI host bridges in guest memory map

Currently, the MMIO space for accessing PCI on pseries guests begins at
1 TiB in guest address space.  Each PCI host bridge (PHB) has a 64 GiB
chunk of address space in which it places its outbound PIO and 32-bit and
64-bit MMIO windows.

This scheme as several problems:
  - It limits guest RAM to 1 TiB (though we have a limited fix for this
    now)
  - It limits the total MMIO window to 64 GiB.  This is not always enough
    for some of the large nVidia GPGPU cards
  - Putting all the windows into a single 64 GiB area means that naturally
    aligning things within there will waste more address space.
In addition there was a miscalculation in some of the defaults, which meant
that the MMIO windows for each PHB actually slightly overran the 64 GiB
region for that PHB.  We got away without nasty consequences because
the overrun fit within an unused area at the beginning of the next PHB's
region, but it's not pretty.

This patch implements a new scheme which addresses those problems, and is
also closer to what bare metal hardware and pHyp guests generally use.

Because some guest versions (including most current distro kernels) can't
access PCI MMIO above 64 TiB, we put all the PCI windows between 32 TiB and
64 TiB.  This is broken into 1 TiB chunks.  The first 1 TiB contains the
PIO (64 kiB) and 32-bit MMIO (2 GiB) windows for all of the PHBs.  Each
subsequent TiB chunk contains a naturally aligned 64-bit MMIO window for
one PHB each.

This reduces the number of allowed PHBs (without full manual configuration
of all the windows) from 256 to 31, but this should still be plenty in
practice.

We also change some of the default window sizes for manually configured
PHBs to saner values.

Finally we adjust some tests and libqos so that it correctly uses the new
default locations.  Ideally it would parse the device tree given to the
guest, but that's a more complex problem for another time.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/include/hw/pci-host/spapr.h b/include/hw/pci-host/spapr.h
index 23dfb09d36..b92c1b59f1 100644
--- a/include/hw/pci-host/spapr.h
+++ b/include/hw/pci-host/spapr.h
@@ -84,8 +84,14 @@ struct sPAPRPHBState {
 #define SPAPR_PCI_MEM_WIN_BUS_OFFSET 0x80000000ULL
 #define SPAPR_PCI_MEM32_WIN_SIZE     \
     ((1ULL << 32) - SPAPR_PCI_MEM_WIN_BUS_OFFSET)
+#define SPAPR_PCI_MEM64_WIN_SIZE     0x10000000000ULL /* 1 TiB */
 
-#define SPAPR_PCI_MMIO_WIN_SIZE      0xf80000000
+/* Without manual configuration, all PCI outbound windows will be
+ * within this range */
+#define SPAPR_PCI_BASE               (1ULL << 45) /* 32 TiB */
+#define SPAPR_PCI_LIMIT              (1ULL << 46) /* 64 TiB */
+
+#define SPAPR_PCI_2_7_MMIO_WIN_SIZE  0xf80000000
 #define SPAPR_PCI_IO_WIN_SIZE        0x10000
 
 #define SPAPR_PCI_MSI_WINDOW         0x40000000000ULL