Re: [Xen-devel] [PATCH v2 2/5] hvmloader: Load large devices into high MMIO space as needed

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 18 Jun 2013, George Dunlap wrote:
> Keep track of how much mmio space is left total, as well as the amount
> of "low" MMIO space (<4GiB), and only load devices into high memory
> if there is not enough low memory for the rest of the devices to fit.
> 
> Because devices are processed by size in order from large to small,
> this should preferentially relocate devices with large BARs to 64-bit
> space.
> 
> Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> CC: Ian Jackson <ian.jackson@xxxxxxxxxx>
> CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
> CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
> CC: Hanweidong <hanweidong@xxxxxxxxxx>
> ---
>  tools/firmware/hvmloader/pci.c |   12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/firmware/hvmloader/pci.c b/tools/firmware/hvmloader/pci.c
> index 8691a19..7f306a1 100644
> --- a/tools/firmware/hvmloader/pci.c
> +++ b/tools/firmware/hvmloader/pci.c
> @@ -38,7 +38,8 @@ void pci_setup(void)
>  {
>      uint8_t is_64bar, using_64bar, bar64_relocate = 0;
>      uint32_t devfn, bar_reg, cmd, bar_data, bar_data_upper;
> -    uint64_t base, bar_sz, bar_sz_upper, low_mmio_left, mmio_total = 0;
> +    uint64_t base, bar_sz, bar_sz_upper, low_mmio_left, mmio_total = 0,
> +        mmio_left;

It think you can just use mmio_total instead of reintroducing mmio_left


>      uint32_t vga_devfn = 256;
>      uint16_t class, vendor_id, device_id;
>      unsigned int bar, pin, link, isa_irq;
> @@ -244,6 +245,7 @@ void pci_setup(void)
>      io_resource.max = 0x10000;
>  
>      low_mmio_left = pci_mem_end - pci_mem_start;
> +    mmio_left = mmio_total;
>  
>      /* Assign iomem and ioport resources in descending order of size. */
>      for ( i = 0; i < nr_bars; i++ )
> @@ -252,7 +254,12 @@ void pci_setup(void)
>          bar_reg = bars[i].bar_reg;
>          bar_sz  = bars[i].bar_sz;
>  
> -        using_64bar = bars[i].is_64bar && bar64_relocate && (low_mmio_left < 
> bar_sz);
> +        /* Relocate to high memory if the total amount of MMIO needed
> +         * is more than the low MMIO available.  Because devices are
> +         * processed in order of bar_sz, this will preferentially
> +         * relocate larger devices to high memory first. */
> +        using_64bar = bars[i].is_64bar && bar64_relocate
> +                       && (mmio_left > low_mmio_left);
>          bar_data = pci_readl(devfn, bar_reg);
>  
>          if ( (bar_data & PCI_BASE_ADDRESS_SPACE) ==
> @@ -276,6 +283,7 @@ void pci_setup(void)
>                      low_mmio_left -= bar_sz;
>                  bar_data &= ~PCI_BASE_ADDRESS_MEM_MASK;
>              }
> +            mmio_left -= bar_sz;

As I wrote above, I would just decrement mmio_total

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