Re: [PATCH] acpi/gpex: Inform os to keep firmware resource map

[Michael S. Tsirkin]

On Thu, Dec 17, 2020 at 09:29:26PM +0800, Jiahui Cen wrote:
> There may be some differences in pci resource assignment between guest os
> and firmware.
> 
> Eg. A Bridge with Bus [d2]
>     -+-[0000:d2]---01.0-[d3]----01.0
> 
>     where [d2:01.00] is a pcie-pci-bridge with BAR0 (mem, 64-bit, non-pref) 
> [size=256]
>           [d3:01.00] is a PCI Device with BAR0 (mem, 64-bit, pref) [size=128K]
>                                           BAR4 (mem, 64-bit, pref) [size=64M]
> 
>     In EDK2, the Resource Map would be:
>         PciBus: Resource Map for Bridge [D2|01|00]
>         Type = PMem64; Base = 0x8004000000;     Length = 0x4100000;     
> Alignment = 0x3FFFFFF
>            Base = 0x8004000000; Length = 0x4000000;     Alignment = 
> 0x3FFFFFF;  Owner = PCI [D3|01|00:20]
>            Base = 0x8008000000; Length = 0x20000;       Alignment = 0x1FFFF;  
>   Owner = PCI [D3|01|00:10]
>         Type =  Mem64; Base = 0x8008100000;     Length = 0x100; Alignment = 
> 0xFFF
> 
>     While in Linux, kernel will use 0x2FFFFFF as the alignment to calculate
>     the PMem64 size, which would be 0x6000000.
> 
> The diffences could result in resource assignment failure.

A bit more data here please. When does this result in a failure?

> Using _DSM #5 method to inform guest os not to ignore the PCI configuration
> that firmware has done at boot time could handle the differences.
> 
> Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
> ---
>  hw/pci-host/gpex-acpi.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
> index 071aa11b5c..2b490f3379 100644
> --- a/hw/pci-host/gpex-acpi.c
> +++ b/hw/pci-host/gpex-acpi.c
> @@ -112,10 +112,19 @@ static void acpi_dsdt_add_pci_osc(Aml *dev)
>      UUID = aml_touuid("E5C937D0-3553-4D7A-9117-EA4D19C3434D");
>      ifctx = aml_if(aml_equal(aml_arg(0), UUID));
>      ifctx1 = aml_if(aml_equal(aml_arg(2), aml_int(0)));
> -    uint8_t byte_list[1] = {1};
> +    uint8_t byte_list[1] = {0x21};
>      buf = aml_buffer(1, byte_list);
>      aml_append(ifctx1, aml_return(buf));
>      aml_append(ifctx, ifctx1);
> +
> +    /* PCI Firmware Specification 3.2
> +     * 4.6.5. _DSM for Ignoring PCI Boot Configurations
> +     * The UUID in _DSM in this context is
> +     * {E5C937D0-3553-4D7A-9117-EA4D19C3434D}
> +     */
> +    ifctx1 = aml_if(aml_equal(aml_arg(2), aml_int(5)));
> +    aml_append(ifctx1, aml_return(aml_int(0)));
> +    aml_append(ifctx, ifctx1);
>      aml_append(method, ifctx);
>  
>      byte_list[0] = 0;
> -- 
> 2.28.0