Re: [Xen-devel] [PATCH] hw/passthrough: Prevent QEMU from mapping PCI option ROM at address 0

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2014-05-12 at 13:42 +0100, Malcolm Crossley wrote:
> The PCI option ROM BAR uses the LSB to indicate if the BAR is enabled.
> The AMD graphics driver sets the address bit's of the BAR to 0 but leaves the
> LSB set to 1. Whilst this is not good practice, QEMU should be ignoring the
> non address parts of the BAR.
> 
> This patch adds masking of the non address parts of the BAR before comparing
> the address to 0.

Since you CC Ian J I assume this is against the qemu-xen-traditional
tree. Is the same fix needed against upstream qemu?

> ---
>  hw/pass-through.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/pass-through.c b/hw/pass-through.c
> index 304c438..7d6aefc 100644
> --- a/hw/pass-through.c
> +++ b/hw/pass-through.c
> @@ -2208,7 +2208,7 @@ static void pt_bar_mapping_one(struct pt_dev *ptdev, 
> int bar, int io_enable,
>      }
>  
>      /* prevent guest software mapping memory resource to 00000000h */
> -    if ((base->bar_flag == PT_BAR_FLAG_MEM) && (r_addr == 0))
> +    if ((base->bar_flag == PT_BAR_FLAG_MEM) && ((r_addr & 
> PCI_BASE_ADDRESS_MEM_MASK) == 0))
>          r_addr = -1;
>  
>      /* align resource size (memory type only) */



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