Re: [Qemu-devel] [PATCH 3/4] arm: Add PCIe host bridge in virt machine

[Alexander Graf <agraf@suse.de>]

On 07.01.15 16:52, Claudio Fontana wrote:
> On 06.01.2015 17:03, Alexander Graf wrote:
>> Now that we have a working "generic" PCIe host bridge driver, we can plug
>> it into ARMs virt machine to always have PCIe available to normal ARM VMs.
>>
>> I've successfully managed to expose a Bochs VGA device, XHCI and an e1000
>> into an AArch64 VM with this and they all lived happily ever after.
>>
>> Signed-off-by: Alexander Graf <agraf@suse.de>
>>
>> ---
>>
>> Linux 3.19 only supports the generic PCIe host bridge driver for 32bit ARM
>> systems. If you want to use it with AArch64 guests, please apply the following
>> patch or wait until upstream cleaned up the code properly:
>>
>>   http://csgraf.de/agraf/pci/pci-3.19.patch
>> ---
>>  default-configs/arm-softmmu.mak |  2 +
>>  hw/arm/virt.c                   | 83 ++++++++++++++++++++++++++++++++++++++---
>>  2 files changed, 80 insertions(+), 5 deletions(-)
>>
>> diff --git a/default-configs/arm-softmmu.mak b/default-configs/arm-softmmu.mak
>> index f3513fa..7671ee2 100644
>> --- a/default-configs/arm-softmmu.mak
>> +++ b/default-configs/arm-softmmu.mak
>> @@ -82,6 +82,8 @@ CONFIG_ZYNQ=y
>>  CONFIG_VERSATILE_PCI=y
>>  CONFIG_VERSATILE_I2C=y
>>  
>> +CONFIG_PCI_GENERIC=y
>> +
>>  CONFIG_SDHCI=y
>>  CONFIG_INTEGRATOR_DEBUG=y
>>  
>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>> index 2353440..b7635ac 100644
>> --- a/hw/arm/virt.c
>> +++ b/hw/arm/virt.c
>> @@ -42,6 +42,7 @@
>>  #include "exec/address-spaces.h"
>>  #include "qemu/bitops.h"
>>  #include "qemu/error-report.h"
>> +#include "hw/pci-host/gpex.h"
>>  
>>  #define NUM_VIRTIO_TRANSPORTS 32
>>  
>> @@ -69,6 +70,7 @@ enum {
>>      VIRT_MMIO,
>>      VIRT_RTC,
>>      VIRT_FW_CFG,
>> +    VIRT_PCIE,
>>  };
>>  
>>  typedef struct MemMapEntry {
>> @@ -129,13 +131,14 @@ static const MemMapEntry a15memmap[] = {
>>      [VIRT_FW_CFG] =     { 0x09020000, 0x0000000a },
>>      [VIRT_MMIO] =       { 0x0a000000, 0x00000200 },
>>      /* ...repeating for a total of NUM_VIRTIO_TRANSPORTS, each of that size */
>> -    /* 0x10000000 .. 0x40000000 reserved for PCI */
>> +    [VIRT_PCIE] =       { 0x10000000, 0x30000000 },
>>      [VIRT_MEM] =        { 0x40000000, 30ULL * 1024 * 1024 * 1024 },
>>  };
>>  
>>  static const int a15irqmap[] = {
>>      [VIRT_UART] = 1,
>>      [VIRT_RTC] = 2,
>> +    [VIRT_PCIE] = 3,
>>      [VIRT_MMIO] = 16, /* ...to 16 + NUM_VIRTIO_TRANSPORTS - 1 */
>>  };
>>  
>> @@ -312,7 +315,7 @@ static void fdt_add_cpu_nodes(const VirtBoardInfo *vbi)
>>      }
>>  }
>>  
>> -static void fdt_add_gic_node(const VirtBoardInfo *vbi)
>> +static uint32_t fdt_add_gic_node(const VirtBoardInfo *vbi)
>>  {
>>      uint32_t gic_phandle;
>>  
>> @@ -331,9 +334,11 @@ static void fdt_add_gic_node(const VirtBoardInfo *vbi)
>>                                       2, vbi->memmap[VIRT_GIC_CPU].base,
>>                                       2, vbi->memmap[VIRT_GIC_CPU].size);
>>      qemu_fdt_setprop_cell(vbi->fdt, "/intc", "phandle", gic_phandle);
>> +
>> +    return gic_phandle;
>>  }
>>  
>> -static void create_gic(const VirtBoardInfo *vbi, qemu_irq *pic)
>> +static uint32_t create_gic(const VirtBoardInfo *vbi, qemu_irq *pic)
>>  {
>>      /* We create a standalone GIC v2 */
>>      DeviceState *gicdev;
>> @@ -380,7 +385,7 @@ static void create_gic(const VirtBoardInfo *vbi, qemu_irq *pic)
>>          pic[i] = qdev_get_gpio_in(gicdev, i);
>>      }
>>  
>> -    fdt_add_gic_node(vbi);
>> +    return fdt_add_gic_node(vbi);
>>  }
>>  
>>  static void create_uart(const VirtBoardInfo *vbi, qemu_irq *pic)
>> @@ -556,6 +561,71 @@ static void create_fw_cfg(const VirtBoardInfo *vbi)
>>      g_free(nodename);
>>  }
>>  
>> +static void create_pcie(const VirtBoardInfo *vbi, qemu_irq *pic,
>> +                        uint32_t gic_phandle)
>> +{
>> +    hwaddr base = vbi->memmap[VIRT_PCIE].base;
>> +    hwaddr size = vbi->memmap[VIRT_PCIE].size;
>> +    hwaddr size_ioport = 64 * 1024;
>> +    hwaddr size_ecam = PCIE_MMCFG_SIZE_MIN;
>> +    hwaddr size_mmio = size - size_ecam - size_ioport;
>> +    hwaddr base_mmio = base;
>> +    hwaddr base_ioport = base_mmio + size_mmio;
>> +    hwaddr base_ecam = base_ioport + size_ioport;
>> +    int irq = vbi->irqmap[VIRT_PCIE];
>> +    MemoryRegion *mmio_alias;
>> +    MemoryRegion *mmio_reg;
>> +    DeviceState *dev;
>> +    char *nodename;
>> +
>> +    dev = qdev_create(NULL, TYPE_GPEX_HOST);
>> +
>> +    qdev_prop_set_uint64(dev, "mmio_window_size", size_mmio);
>> +    qdev_init_nofail(dev);
>> +
>> +    sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, base_ecam);
>> +    sysbus_mmio_map(SYS_BUS_DEVICE(dev), 2, base_ioport);
>> +
>> +    /* Map the MMIO window at the same spot in bus and cpu layouts */
>> +    mmio_alias = g_new0(MemoryRegion, 1);
>> +    mmio_reg = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 1);
>> +    memory_region_init_alias(mmio_alias, OBJECT(dev), "pcie-mmio",
>> +                             mmio_reg, base_mmio, size_mmio);
>> +    memory_region_add_subregion(get_system_memory(), base_mmio, mmio_alias);
>> +
>> +    sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, pic[irq]);
>> +
>> +    nodename = g_strdup_printf("/pcie@%" PRIx64, base);
>> +    qemu_fdt_add_subnode(vbi->fdt, nodename);
>> +    qemu_fdt_setprop_string(vbi->fdt, nodename,
>> +                            "compatible", "pci-host-ecam-generic");
> 
> is this the only compatible string we should set here? Is this not legacy pci compatible?
> In other device trees I see this mentioned as compatible = "arm,versatile-pci-hostbridge", "pci" for example,
> would it be sensible to make it a list and include "pci" as well?

I couldn't find anything that defines what an "pci" compatible should
look like. We definitely don't implement the legacy PCI config space
accessor registers.

> 
>> +    qemu_fdt_setprop_string(vbi->fdt, nodename, "device_type", "pci");
>> +    qemu_fdt_setprop_cell(vbi->fdt, nodename, "#address-cells", 3);
>> +    qemu_fdt_setprop_cell(vbi->fdt, nodename, "#size-cells", 2);
>> +    qemu_fdt_setprop_cells(vbi->fdt, nodename, "bus-range", 0, 1);
>> +
>> +    qemu_fdt_setprop_sized_cells(vbi->fdt, nodename, "reg",
>> +                                 2, base_ecam, 2, size_ecam);
>> +    qemu_fdt_setprop_sized_cells(vbi->fdt, nodename, "ranges",
>> +                                 1, 0x01000000, 2, 0,
>> +                                 2, base_ioport, 2, size_ioport,
>> +
>> +                                 1, 0x02000000, 2, base_mmio,
>> +                                 2, base_mmio, 2, size_mmio);
>> +
>> +    qemu_fdt_setprop_cell(vbi->fdt, nodename, "#interrupt-cells", 1);
>> +    qemu_fdt_setprop_cells(vbi->fdt, nodename, "interrupt-map",
>> +                           0, 0, 0, /* device */
>> +                           0,       /* PCI irq */
>> +                           gic_phandle, GIC_FDT_IRQ_TYPE_SPI, irq,
>> +                             GIC_FDT_IRQ_FLAGS_LEVEL_HI /* system irq */);
>> +    qemu_fdt_setprop_cells(vbi->fdt, nodename, "interrupt-map-mask",
>> +                           0, 0, 0, /* device */
>> +                           0        /* PCI irq */);
> 
> Interrupt map does not seem to work for me; incidentally this ends up being the same kind of undocumented blob that Alvise posted in his series.

How exactly is this undocumented? The "mask" is a mask over the first
fields of an interrupt-map row plus an IRQ offset. So the mask above
means "Any device with any function and any IRQ on it, map to device IRQ
0" which maps to vbi->irqmap[VIRT_PCIE] (IRQ 3).

> Can you add a good comment about what the ranges property contains (the 0x01000000, 0x02000000 which I suspect means IO vs MMIO IIRC, but there is no need to be cryptic about it).

You're saying you'd prefer a define?

> How does your interrupt map implementation differ from the patchset posted by Alvise? I ask because that one works for me (tm).

His implementation explicitly listed every PCI slot, while mine actually
makes use of the mask and simply routes everything to a single IRQ line.

The benefit of masking devfn out is that you don't need to worry about
the number of slots you support - and anything performance critical
should go via MSI-X anyway ;).

So what exactly do you test it with? I've successfully received IRQs
with a Linux guest, so I'm slightly puzzled you're running into problems.


Alex