Re: [Qemu-devel] [PATCH v2] spapr-pci: Enable huge BARs

[Alexander Graf <agraf@suse.de>]

On 12.12.14 23:30, Alexey Kardashevskiy wrote:
> On 12/12/2014 08:38 PM, Alexey Kardashevskiy wrote:
>> At the moment sPAPR only supports 512MB window for MMIO BARs. However
>> modern devices might want bigger 64bit BARs.
>>
>> This extends MMIO window from 512MB to 62GB (aligned to
>> SPAPR_PCI_WINDOW_SPACING) and advertises it in 2 records in
>> the PHB's "ranges" property. 32bit has all the space from
>> SPAPR_PCI_MEM_WIN_BUS_OFFSET till the end of 4GB, 64bit has the rest
>> of the window.
>>
>> Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>> Changes:
>> v2:
>> * do not change existing memory layout
>> * do not create another mmio window
>> ---
>>  hw/ppc/spapr_pci.c          | 8 +++++++-
>>  include/hw/pci-host/spapr.h | 7 ++++---
>>  2 files changed, 11 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>> index 21b95b3..3641f87 100644
>> --- a/hw/ppc/spapr_pci.c
>> +++ b/hw/ppc/spapr_pci.c
>> @@ -862,6 +862,7 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
>>      int bus_off, i, j;
>>      char nodename[256];
>>      uint32_t bus_range[] = { cpu_to_be32(0), cpu_to_be32(0xff) };
>> +    const uint32_t win32size = (1ULL << 32) - SPAPR_PCI_MEM_WIN_BUS_OFFSET;
>>      struct {
>>          uint32_t hi;
>>          uint64_t child;
>> @@ -876,7 +877,12 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
>>          {
>>              cpu_to_be32(b_ss(2)), cpu_to_be64(SPAPR_PCI_MEM_WIN_BUS_OFFSET),
>>              cpu_to_be64(phb->mem_win_addr),
>> -            cpu_to_be64(memory_region_size(&phb->memwindow)),
>> +            cpu_to_be64(win32size),
>> +        },
>> +        {
>> +            cpu_to_be32(b_ss(3)), cpu_to_be64(1ULL << 32),
>> +            cpu_to_be64(phb->mem_win_addr + win32size),
>> +            cpu_to_be64(memory_region_size(&phb->memwindow) - win32size)

This also changes the device tree compared to older versions. I also
don't see any compat code that makes older machine types stay at the
smaller window?


Alex