Re: [PATCH 10/13] hw/ide/piix: Reuse PCIIDEState::{cmd,data}_ops

[Mark Cave-Ayland]

On 22/04/2023 16:07, Bernhard Beschow wrote:

> Now that PCIIDEState::{cmd,data}_ops are initialized in the base class
> constructor there is an opportunity for PIIX to reuse these attributes. This
> resolves usage of ide_init_ioport() which would fall back internally to using
> the isabus global due to NULL being passed as ISADevice by PIIX.
>
> Signed-off-by: Bernhard Beschow <shentey@gmail.com>
> ---
>   hw/ide/piix.c | 30 +++++++++++++-----------------
>   1 file changed, 13 insertions(+), 17 deletions(-)
>
> diff --git a/hw/ide/piix.c b/hw/ide/piix.c
> index a3a15dc7db..406a67fa0f 100644
> --- a/hw/ide/piix.c
> +++ b/hw/ide/piix.c
> @@ -104,34 +104,32 @@ static void piix_ide_reset(DeviceState *dev)
>       pci_set_byte(pci_conf + 0x20, 0x01);  /* BMIBA: 20-23h */
>   }
>   
> -static bool pci_piix_init_bus(PCIIDEState *d, unsigned i, ISABus *isa_bus,
> -                              Error **errp)
> +static void pci_piix_init_bus(PCIIDEState *d, unsigned i, ISABus *isa_bus)
>   {
>       static const struct {
>           int iobase;
>           int iobase2;
>           int isairq;
>       } port_info[] = {
> -        {0x1f0, 0x3f6, 14},
> -        {0x170, 0x376, 15},
> +        {0x1f0, 0x3f4, 14},
> +        {0x170, 0x374, 15},
>       };
> -    int ret;
> +    MemoryRegion *address_space_io = pci_address_space_io(PCI_DEVICE(d));
>   
>       ide_bus_init(&d->bus[i], sizeof(d->bus[i]), DEVICE(d), i, 2);
> -    ret = ide_init_ioport(&d->bus[i], NULL, port_info[i].iobase,
> -                          port_info[i].iobase2);
> -    if (ret) {
> -        error_setg_errno(errp, -ret, "Failed to realize %s port %u",
> -                         object_get_typename(OBJECT(d)), i);
> -        return false;
> -    }
> +    memory_region_add_subregion(address_space_io, port_info[i].iobase,
> +                                &d->data_ops[i]);
> +    /*
> +     * PIIX forwards the last byte of cmd_ops to ISA. Model this using a low
> +     * prio so competing memory regions take precedence.
> +     */
> +    memory_region_add_subregion_overlap(address_space_io, port_info[i].iobase2,
> +                                        &d->cmd_ops[i], -1);

Interesting. Is this behaviour documented somewhere and/or used in one of your test 
images at all? If I'd have seen this myself, I probably thought that the addresses 
were a typo...

>       ide_bus_init_output_irq(&d->bus[i],
>                               isa_bus_get_irq(isa_bus, port_info[i].isairq));
>   
>       bmdma_init(&d->bus[i], &d->bmdma[i], d);
>       ide_bus_register_restart_cb(&d->bus[i]);
> -
> -    return true;
>   }
>   
>   static void pci_piix_ide_realize(PCIDevice *dev, Error **errp)
> @@ -160,9 +158,7 @@ static void pci_piix_ide_realize(PCIDevice *dev, Error 
> **errp)
>       }
>   
>       for (unsigned i = 0; i < 2; i++) {
> -        if (!pci_piix_init_bus(d, i, isa_bus, errp)) {
> -            return;
> -        }
> +        pci_piix_init_bus(d, i, isa_bus);
>       }
>   }
>   


ATB,

Mark.