Re: [Qemu-devel] [PATCH] pci-testdev: add optional memory bar

[Laszlo Ersek]

On 09/27/18 14:10, Gerd Hoffmann wrote:
> Add memory bar to pci-testdev.  Size is configurable using the membar
> property.  Setting the size to zero (default) turns it off.  Can be used
> to check whenever guests handle large pci bars correctly.
> 
> Signed-off-by: Gerd Hoffmann <address@hidden>
> ---
>  docs/specs/pci-testdev.txt | 13 +++++++++----
>  hw/misc/pci-testdev.c      | 18 ++++++++++++++++++
>  2 files changed, 27 insertions(+), 4 deletions(-)
> 
> diff --git a/docs/specs/pci-testdev.txt b/docs/specs/pci-testdev.txt
> index 128ae222ef..6b8ace1c55 100644
> --- a/docs/specs/pci-testdev.txt
> +++ b/docs/specs/pci-testdev.txt
> @@ -1,11 +1,11 @@
>  pci-test is a device used for testing low level IO
>  
> -device implements up to two BARs: BAR0 and BAR1.
> -Each BAR can be memory or IO. Guests must detect
> +device implements up to three BARs: BAR0, BAR1 and BAR2.
> +BAR 0+1 can be memory or IO. Guests must detect
>  BAR type and act accordingly.

I suggest "Each of BAR 0+1", or "BAR 0+1 can be memory or IO
(independently of each other)".

Then we should say "must detect BAR types" (plural) as well.

>  
> -Each BAR size is up to 4K bytes.
> -Each BAR starts with the following header:
> +BAR 0+1 size is up to 4K bytes.

I suggest "BAR 0+1 size is up to 4K bytes each".

> +BAR 0+1 starts with the following header:
>  
>  typedef struct PCITestDevHdr {
>      uint8_t test;  <- write-only, starts a given test number
> @@ -24,3 +24,8 @@ All registers are little endian.
>  device is expected to always implement tests 0 to N on each BAR, and to add 
> new
>  tests with higher numbers.  In this way a guest can scan test numbers until 
> it
>  detects an access type that it does not support on this BAR, then stop.
> +
> +BAR2 is a 64bit memory bar, without backing storage.  It is disabled by
> +default and can be enabled using the membar=<size> property.  This can
> +be used to test whenever guests handles pci bars of a specific (possibly

s/whenever/whether/? (I'm not sure about the intent.) My question
applies to the commit message too.

Also, "guests handle", or "a guest handles".

> +quite large) size correctly.
> diff --git a/hw/misc/pci-testdev.c b/hw/misc/pci-testdev.c
> index 32041f535f..af4d678ee4 100644
> --- a/hw/misc/pci-testdev.c
> +++ b/hw/misc/pci-testdev.c
> @@ -85,6 +85,9 @@ typedef struct PCITestDevState {
>      MemoryRegion portio;
>      IOTest *tests;
>      int current;
> +
> +    size_t membar_size;
> +    MemoryRegion membar;
>  } PCITestDevState;
>  
>  #define TYPE_PCI_TEST_DEV "pci-testdev"
> @@ -253,6 +256,15 @@ static void pci_testdev_realize(PCIDevice *pci_dev, 
> Error **errp)
>      pci_register_bar(pci_dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &d->mmio);
>      pci_register_bar(pci_dev, 1, PCI_BASE_ADDRESS_SPACE_IO, &d->portio);
>  
> +    if (d->membar_size) {
> +        memory_region_init(&d->membar, OBJECT(d), "membar", d->membar_size);

For consistency with the other two BARs, and for a more helpful "info
mtree" output, I think "membar" should be renamed to "pci-testdev-membar".

With those changes:

Reviewed-by: Laszlo Ersek <address@hidden>

For the current version (but it can be carried forward to v2):

Tested-by: Laszlo Ersek <address@hidden>

Thank you!
Laszlo

> +        pci_register_bar(pci_dev, 2,
> +                         PCI_BASE_ADDRESS_SPACE_MEMORY |
> +                         PCI_BASE_ADDRESS_MEM_PREFETCH |
> +                         PCI_BASE_ADDRESS_MEM_TYPE_64,
> +                         &d->membar);
> +    }
> +
>      d->current = -1;
>      d->tests = g_malloc0(IOTEST_MAX * sizeof *d->tests);
>      for (i = 0; i < IOTEST_MAX; ++i) {
> @@ -305,6 +317,11 @@ static void qdev_pci_testdev_reset(DeviceState *dev)
>      pci_testdev_reset(d);
>  }
>  
> +static Property pci_testdev_properties[] = {
> +    DEFINE_PROP_SIZE("membar", PCITestDevState, membar_size, 0),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
>  static void pci_testdev_class_init(ObjectClass *klass, void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(klass);
> @@ -319,6 +336,7 @@ static void pci_testdev_class_init(ObjectClass *klass, 
> void *data)
>      dc->desc = "PCI Test Device";
>      set_bit(DEVICE_CATEGORY_MISC, dc->categories);
>      dc->reset = qdev_pci_testdev_reset;
> +    dc->props = pci_testdev_properties;
>  }
>  
>  static const TypeInfo pci_testdev_info = {
>