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

[Claudio Fontana]

(added cc: Alvise which I mistakenly assumed was in Cc: already)

On 07.01.2015 22:47, Alexander Graf wrote:
> 
> 
> 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 <address@hidden>
>>>
>>> ---
>>>
>>> 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("/address@hidden" 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.

I see, I assumed this patch would support both CAM and ECAM as configuration 
methods, while now I understand
Alvise's patches support only CAM, while these support only ECAM..
So basically I should look at the compatible string and then choose 
configuration method accordingly.
I wonder if I should deal with the case where the compatible string contains 
both ECAM and CAM.

>>
>>> +    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).

(see my answer to Peter below in thread)

this is a bit different to what Alvise's series is doing I think (see later).

> 
>> 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?

Yes that would be helpful :)

> 
>> 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 ;).

The benefit for me (but for me only probably..) is that with one IRQ per slot I 
didn't have to implement shared irqs and msi / msi-x in the guest yet. But that 
should be done eventually 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.

Of course, I am just implementing PCI guest support for OSv/AArch64.
Works with the legacy pci support using Alvise's series to do virtio-pci with 
block, net, rng etc,
but I am now considering going for PCIE support directly although that means 
more implementation work for me.

> 
> 
> Alex
> 

Ciao & thanks,

Claudio