Re: [Qemu-devel] [PATCH v18 1/2] sPAPR: Implement EEH RTAS calls

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

On Mon, Feb 16, 2015 at 12:52:48PM +1100, David Gibson wrote:
>On Mon, Feb 16, 2015 at 10:16:01AM +1100, Gavin Shan wrote:
>> The emulation for EEH RTAS requests from guest isn't covered
>> by QEMU yet and the patch implements them.
>> 
>> The patch defines constants used by EEH RTAS calls and adds
>> callbacks sPAPRPHBClass::{eeh_set_option, eeh_get_state, eeh_reset,
>> eeh_configure}, which are going to be used as follows:
>> 
>>   * RTAS calls are received in spapr_pci.c, sanity check is done
>>     there.
>>   * RTAS handlers handle what they can. If there is something it
>>     cannot handle and the corresponding sPAPRPHBClass callback is
>>     defined, it is called.
>>   * Those callbacks are only implemented for VFIO now. They do ioctl()
>>     to the IOMMU container fd to complete the calls. Error codes from
>>     that ioctl() are transferred back to the guest.
>> 
>> [aik: defined RTAS tokens for EEH RTAS calls]
>> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
>> ---
>>  hw/ppc/spapr_pci.c          | 281 ++++++++++++++++++++++++++++++++++++++++++++
>>  include/hw/pci-host/spapr.h |   4 +
>>  include/hw/ppc/spapr.h      |  43 ++++++-
>>  3 files changed, 326 insertions(+), 2 deletions(-)
>> 
>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>> index cebdeb3..29b071d 100644
>> --- a/hw/ppc/spapr_pci.c
>> +++ b/hw/ppc/spapr_pci.c
>> @@ -406,6 +406,268 @@ static void rtas_ibm_query_interrupt_source_number(PowerPCCPU *cpu,
>>      rtas_st(rets, 2, 1);/* 0 == level; 1 == edge */
>>  }
>>  
>> +static void rtas_ibm_set_eeh_option(PowerPCCPU *cpu,
>> +                                    sPAPREnvironment *spapr,
>> +                                    uint32_t token, uint32_t nargs,
>> +                                    target_ulong args, uint32_t nret,
>> +                                    target_ulong rets)
>> +{
>> +    sPAPRPHBState *sphb;
>> +    sPAPRPHBClass *spc;
>> +    uint32_t addr, option;
>> +    uint64_t buid;
>> +    int ret;
>> +
>> +    if ((nargs != 4) || (nret != 1)) {
>> +        goto param_error_exit;
>> +    }
>> +
>> +    buid = ((uint64_t)rtas_ld(args, 1) << 32) | rtas_ld(args, 2);
>> +    addr = rtas_ld(args, 0);
>> +    option = rtas_ld(args, 3);
>> +
>> +    sphb = find_phb(spapr, buid);
>> +    if (!sphb) {
>> +        goto param_error_exit;
>> +    }
>> +
>> +    spc = SPAPR_PCI_HOST_BRIDGE_GET_CLASS(sphb);
>> +    if (!spc->eeh_set_option) {
>> +        goto param_error_exit;
>> +    }
>> +
>> +    /*
>> +     * The EEH functionality is enabled on basis of PCI device,
>> +     * instead of PE. We need check the validity of the PCI
>> +     * device address.
>> +     */
>> +    if (option == RTAS_EEH_ENABLE &&
>> +        !find_dev(spapr, buid, addr)) {
>> +        goto param_error_exit;
>> +    }
>
>You're still breaking your layering by doing checks dependent on the
>specific option both here and in the callback.
>
>What I meant by my comments on the previous version was that this
>find_dev() test should also move into the eeh_set_option callback.
>Obviously that means adding addr into the parameters - but surely if
>the addr has any meaning whatsoever, it must be at least potentially
>needed by the callback anyway.
>

Ok. Either simply dropping the check here, or moving find_dev() to
sPAPRPHBClass::eeh_set_option() as you suggested. However, there're more
things needed for sPAPRPHBClass::eeh_set_option() to do the check as follows.
David, could you help to confirm which way you prefer?

- Rename find_dev() to spapr_find_pci_dev() and make it public. It will be
  called in spapr_pci_vfio.c
- Add one field sPAPRPHBState::spapr to reference the associated sPAPREnvironment,
  which is required by spapr_find_pci_dev(). Otherwise, we have to pass sPAPREnvironment
  to sPAPRPHBClass::eeh_set_option().

Thanks,
Gavin

>Apart from that,
>
>Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
>
>-- 
>David Gibson			| I'll have my music baroque, and my code
>david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
>				| _way_ _around_!
>http://www.ozlabs.org/~dgibson