Re: [Xen-devel] [v3][PATCH 07/16] hvmloader/pci: skip reserved ranges

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Chen, Tiejun
> Sent: Thursday, June 11, 2015 9:15 AM
> 
> When allocating mmio address for PCI bars, we need to make
> sure they don't overlap with reserved regions.
> 
> Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> ---
>  tools/firmware/hvmloader/pci.c | 36
> ++++++++++++++++++++++++++++++++++--
>  1 file changed, 34 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/firmware/hvmloader/pci.c b/tools/firmware/hvmloader/pci.c
> index 5ff87a7..98af568 100644
> --- a/tools/firmware/hvmloader/pci.c
> +++ b/tools/firmware/hvmloader/pci.c
> @@ -59,8 +59,8 @@ void pci_setup(void)
>          uint32_t bar_reg;
>          uint64_t bar_sz;
>      } *bars = (struct bars *)scratch_start;
> -    unsigned int i, nr_bars = 0;
> -    uint64_t mmio_hole_size = 0;
> +    unsigned int i, j, nr_bars = 0;
> +    uint64_t mmio_hole_size = 0, reserved_end, max_bar_sz = 0;
> 
>      const char *s;
>      /*
> @@ -226,6 +226,8 @@ void pci_setup(void)
>              bars[i].devfn   = devfn;
>              bars[i].bar_reg = bar_reg;
>              bars[i].bar_sz  = bar_sz;
> +            if ( bar_sz > max_bar_sz )
> +                max_bar_sz = bar_sz;
> 
>              if ( ((bar_data & PCI_BASE_ADDRESS_SPACE) ==
>                    PCI_BASE_ADDRESS_SPACE_MEMORY) ||
> @@ -301,6 +303,21 @@ void pci_setup(void)
>              pci_mem_start <<= 1;
>      }
> 
> +    /* Relocate PCI memory that overlaps reserved space, like RDM. */
> +    for ( j = 0; j < memory_map.nr_map ; j++ )
> +    {
> +        if ( memory_map.map[j].type != E820_RAM )
> +        {
> +            reserved_end = memory_map.map[j].addr + memory_map.map[j].size;
> +            if ( check_overlap(pci_mem_start, pci_mem_end,
> +                               memory_map.map[j].addr,
> +                               memory_map.map[j].size) )
> +                pci_mem_start -= memory_map.map[j].size >> PAGE_SHIFT;

what's the point of subtracting reserved size here? I think you want
to move pci_mem_start higher instead of lower to avoid conflict, right?

> +                pci_mem_start = (pci_mem_start + max_bar_sz - 1) &
> +                                    ~(uint64_t)(max_bar_sz - 1);

better have some comment to explain what exactly you're trying to
achieve here.

> +        }
> +    }
> +
>      if ( mmio_total > (pci_mem_end - pci_mem_start) )
>      {
>          printf("Low MMIO hole not large enough for all devices,"
> @@ -407,8 +424,23 @@ void pci_setup(void)
>          }
> 
>          base = (resource->base  + bar_sz - 1) & ~(uint64_t)(bar_sz - 1);
> + reallocate_mmio:

In earlier comment you said:

> +    /* Relocate PCI memory that overlaps reserved space, like RDM. */

If pci_mem_start has been relocated to avoid overlapping, how will actual
allocation here will conflict again? Sorry I may miss the two relocations 
here...

>          bar_data |= (uint32_t)base;
>          bar_data_upper = (uint32_t)(base >> 32);
> +        for ( j = 0; j < memory_map.nr_map ; j++ )
> +        {
> +            if ( memory_map.map[j].type != E820_RAM )
> +            {
> +                reserved_end = memory_map.map[j].addr +
> memory_map.map[j].size;
> +                if ( check_overlap(base, bar_sz,
> +                                   memory_map.map[j].addr,
> +                                   memory_map.map[j].size) )
> +                {
> +                    base = (reserved_end  + bar_sz - 1) & ~(uint64_t)(bar_sz 
> - 1);
> +                    goto reallocate_mmio;
> +                }
> +            }
> +        }
>          base += bar_sz;
> 
>          if ( (base < resource->base) || (base > resource->max) )
> --
> 1.9.1


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