[Qemu-devel] Re: [PATCH 3/5] Use the correct mask to size the PCI option ROM BAR.

[Gleb Natapov <gleb@redhat.com>]

On Mon, Oct 12, 2009 at 03:20:27PM +0200, Michael S. Tsirkin wrote:
> Right. And there's another bug that I see and that is that size for I/O
> BAR was calculated incorrectly: val & ~0xf is wrong for I/O as the size
> could be 4 bytes.  So here's a patch that addresses all 3 issues:
> Ack?
> 
Pleas do whatever spec recommends and use 0xffffffff to size the BAR.
Specs says this, linux does this, lets not be different.

> 
> ---->
> 
> Subject: [PATCH] seabios: fix low bits in ROM and I/O sizing
> 
> This cleans up handling of low bits during BAR sizing,
> to match PCI spec requirements, and to use symbolic
> constants from pci_regs.h
> 
> Issues fixed:
> For ROM BARs, bit 0 is writeable (enable bit), which we not
> only don't want to set, but it will stick and make us think
> it's an I/O port resource.
> Further, PCI spec defines the following bits as reserved:
> - bit 1 in I/O BAR
> - bits 10:1 in ROM BAR
> and we should be careful and preserve any values there.
> Bits 3:2 in I/O BAR might be writeable, so it
> is wrong to mask them when calculating BAR size.
> 
> Spec references:
> See 6.2.5.1 for I/O and memory, and 6.2.5.2 for ROM,
> 6.1 for reserved bit handling;
> pages 225, 228 and 214 in PCI spec revision 3.0.
> 
> See also Qemu pcbios commit 6ddb9f5c742b2b82b1755d7ec2a127f6e20e3806
> 
> Original-by: Gleb Natapov <gleb@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> 
> diff --git a/src/pciinit.c b/src/pciinit.c
> index 7d2ea00..f9ebd61 100644
> --- a/src/pciinit.c
> +++ b/src/pciinit.c
> @@ -136,16 +136,23 @@ static void pci_bios_init_device(u16 bdf)
>          /* default memory mappings */
>          for (i = 0; i < PCI_NUM_REGIONS; i++) {
>              int ofs;
> -            u32 val, size;
> -
> +            u32 val, mask, size;
>              if (i == PCI_ROM_SLOT)
>                  ofs = PCI_ROM_ADDRESS;
>              else
>                  ofs = PCI_BASE_ADDRESS_0 + i * 4;
> -            pci_config_writel(bdf, ofs, 0xffffffff);
> +
> +            val = pci_config_readl(bdf, ofs);
> +            if (i == PCI_ROM_SLOT)
> +		mask = PCI_ROM_ADDRESS_MASK;
> +            else if (val & PCI_BASE_ADDRESS_SPACE_IO)
> +                mask = PCI_BASE_ADDRESS_IO_MASK;
> +            else
> +                mask = PCI_BASE_ADDRESS_MEM_MASK;
> +            pci_config_writel(bdf, ofs, val | mask);
>              val = pci_config_readl(bdf, ofs);
>              if (val != 0) {
> -                size = (~(val & ~0xf)) + 1;
> +                size = (~(val & mask)) + 1;
>                  if (val & PCI_BASE_ADDRESS_SPACE_IO)
>                      paddr = &pci_bios_io_addr;
>                  else if (size >= 0x04000000)
> -- 
> 1.6.5.rc2
> 

--
			Gleb.