[SeaBIOS] [PATCH v3 3/5] hw/pci: introduce bridge-only vendor-specific capability to provide some hints to firmware

[Alexander Bezzubikov]

2017-07-31 14:29 GMT+03:00 Marcel Apfelbaum <marcel at redhat.com>:
> On 29/07/2017 2:37, Aleksandr Bezzubikov wrote:
>>
>> On PCI init PCI bridges may need some
>> extra info about bus number to reserve, IO, memory and
>> prefetchable memory limits. QEMU can provide this
>> with a special vendor-specific PCI capability.
>>
>> Signed-off-by: Aleksandr Bezzubikov <zuban32s at gmail.com>
>> ---
>>   hw/pci/pci_bridge.c         | 37 +++++++++++++++++++++++++++++++++++++
>>   include/hw/pci/pci_bridge.h | 28 ++++++++++++++++++++++++++++
>>   2 files changed, 65 insertions(+)
>>
>> diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
>> index 720119b..e9f12d6 100644
>> --- a/hw/pci/pci_bridge.c
>> +++ b/hw/pci/pci_bridge.c
>> @@ -408,6 +408,43 @@ void pci_bridge_map_irq(PCIBridge *br, const char*
>> bus_name,
>>       br->bus_name = bus_name;
>>   }
>>
>
> Hi Alexksander,
>
>
>> +
>> +int pci_bridge_qemu_cap_init(PCIDevice *dev, int cap_offset,
>> +                              uint8_t bus_reserve, uint32_t io_reserve,
>> +                              uint16_t non_pref_reserve, uint64_t
>> pref_reserve,
>> +                              Error **errp)
>
>
> Maybe we should change it to something like
> pci_bridge_res_reseve_cap_init ? Maybe we will
> have other caps in the future.
>
>
>> +{
>> +    size_t cap_len = sizeof(PCIBridgeQemuCap);
>> +    PCIBridgeQemuCap cap = {
>> +            .len = cap_len,
>> +            .type = REDHAT_PCI_CAP_QEMU,
>> +            .bus_res = bus_reserve,
>> +            .non_pref_16 = non_pref_reserve
>> +    };
>> +
>> +    if ((uint8_t)io_reserve == io_reserve) {
>> +        cap.io_8 = io_reserve;
>> +    } else {
>> +        cap.io_32 = io_reserve;
>> +    }
>> +    if ((uint16_t)pref_reserve == pref_reserve) {
>> +        cap.pref_32 = pref_reserve;
>> +    } else {
>> +        cap.pref_64 = pref_reserve;
>> +    }
>> +
>> +    int offset = pci_add_capability(dev, PCI_CAP_ID_VNDR,
>> +                                    cap_offset, cap_len, errp);
>> +    if (offset < 0) {
>> +        return offset;
>> +    }
>> +
>> +    memcpy(dev->config + offset + PCI_CAP_FLAGS,
>> +            (char *)&cap + PCI_CAP_FLAGS,
>> +            cap_len - PCI_CAP_FLAGS);
>> +    return 0;
>> +}
>> +
>>   static const TypeInfo pci_bridge_type_info = {
>>       .name = TYPE_PCI_BRIDGE,
>>       .parent = TYPE_PCI_DEVICE,
>> diff --git a/include/hw/pci/pci_bridge.h b/include/hw/pci/pci_bridge.h
>> index ff7cbaa..e9b7cf4 100644
>> --- a/include/hw/pci/pci_bridge.h
>> +++ b/include/hw/pci/pci_bridge.h
>> @@ -67,4 +67,32 @@ void pci_bridge_map_irq(PCIBridge *br, const char*
>> bus_name,
>>   #define  PCI_BRIDGE_CTL_DISCARD_STATUS        0x400   /* Discard timer
>> status */
>>   #define  PCI_BRIDGE_CTL_DISCARD_SERR  0x800   /* Discard timer SERR#
>> enable */
>>   +typedef struct PCIBridgeQemuCap {
>> +    uint8_t id;     /* Standard PCI capability header field */
>> +    uint8_t next;   /* Standard PCI capability header field */
>> +    uint8_t len;    /* Standard PCI vendor-specific capability header
>> field */
>> +    uint8_t type;   /* Red Hat vendor-specific capability type.
>> +                       Types are defined with REDHAT_PCI_CAP_ prefix */
>> +
>> +    uint16_t non_pref_16;   /* Non-prefetchable memory limit */
>> +    uint8_t bus_res;        /* Minimum number of buses to reserve */
>> +    uint8_t io_8;           /* IO space limit in case of 8-bit value */
>> +    uint32_t io_32;         /* IO space limit in case of 32-bit value
>> +                               This 2 values are mutually exclusive,
>> +                               i.e. they can't be  >0 both*/
>> +    uint32_t pref_32;       /* Prefetchable memory limit
>> +                               in case of 32-bit value */
>> +    uint64_t pref_64;       /* Prefetchable memory limit
>> +                               in case of 64-bit value
>> +                               This 2 values are mutually exclusive (just
>> as
>> +                               IO limit), i.e. they can't be  >0 both */
>
>
> The same comments as for the SeaBIOS series, can the capability
> be more simple?
>    uint32_t bus_res
>    uint32_t io_res
>    uint32_t mem_res
>    uint32_t pref_32_res
>    uint64_t pref_64_res
>

In this version I've designed it just as Laszlo suggested -
whenever we have variable-size fields - like IO and prefetchable -
we use mutually exclusive fields.
I think now we should choose one common format and fix it for the future,
otherwise every next version it will cause new questions.

> It is possible I missed some arguments, I'll have another look
> on the thread.
>
> Thanks,
> Marcel
>
>
>
>> +} PCIBridgeQemuCap;
>> +
>> +#define REDHAT_PCI_CAP_QEMU     1
>> +
>> +int pci_bridge_qemu_cap_init(PCIDevice *dev, int cap_offset,
>> +                              uint8_t bus_reserve, uint32_t io_reserve,
>> +                              uint16_t mem_reserve, uint64_t
>> pref_reserve,
>> +                              Error **errp);
>> +
>>   #endif /* QEMU_PCI_BRIDGE_H */
>>
>



-- 
Alexander Bezzubikov