Re: [Qemu-devel] [PATCH v13 2/3] sPAPR: Implement EEH RTAS calls

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

On Tue, Dec 23, 2014 at 03:22:06PM +1100, David Gibson wrote:
>On Mon, Dec 15, 2014 at 11:15:07AM +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
>> callback sPAPRPHBClass::eeh_handler, which is going to be used
>> this way:
>> 
>>   * 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 sPAPRPHBClass::eeh_handler callback is defined,
>>     it is called.
>>   * sPAPRPHBClass::eeh_handler is only implemented for VFIO now. It
>>     does ioctl() to the IOMMU container fd to complete the call. 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          | 246 ++++++++++++++++++++++++++++++++++++++++++++
>>  include/hw/pci-host/spapr.h |   7 ++
>>  include/hw/ppc/spapr.h      |  43 +++++++-
>>  3 files changed, 294 insertions(+), 2 deletions(-)
>> 
>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>> index 3d70efe..3bb1971 100644
>> --- a/hw/ppc/spapr_pci.c
>> +++ b/hw/ppc/spapr_pci.c
>> @@ -406,6 +406,233 @@ static void rtas_ibm_query_interrupt_source_number(PowerPCCPU *cpu,
>>      rtas_st(rets, 2, 1);/* 0 == level; 1 == edge */
>>  }
>>  
>> +static int rtas_handle_eeh_request(sPAPREnvironment *spapr,
>> +                                   uint64_t buid, uint32_t req, uint32_t opt)
>> +{
>> +    sPAPRPHBState *sphb = spapr_pci_find_phb(spapr, buid);
>> +    sPAPRPHBClass *info = SPAPR_PCI_HOST_BRIDGE_GET_CLASS(sphb);
>> +
>> +    if (!sphb || !info->eeh_handler) {
>> +        return -ENOENT;
>> +    }
>> +
>> +    return info->eeh_handler(sphb, req, opt);
>> +}
>> +
>> +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)
>> +{
>> +    uint32_t addr, option;
>> +    uint64_t buid = ((uint64_t)rtas_ld(args, 1) << 32) | rtas_ld(args, 2);
>
>You're dereferencing RTAS parameters here before you've checked the
>number of parameters, which isn't safe.  Similar problem in the other
>entry points as well.
>

Yep, I'll fix it in next version. Thanks for review and pointing
it out.

>> +    int ret;
>> +
>> +    if ((nargs != 4) || (nret != 1)) {
>> +        goto param_error_exit;
>> +    }
>> +
>> +    addr = rtas_ld(args, 0);
>> +    option = rtas_ld(args, 3);
>> +    switch (option) {
>> +    case RTAS_EEH_ENABLE:
>> +        if (!spapr_pci_find_dev(spapr, buid, addr)) {
>> +            goto param_error_exit;
>> +        }
>> +        break;
>> +    case RTAS_EEH_DISABLE:
>> +    case RTAS_EEH_THAW_IO:
>> +    case RTAS_EEH_THAW_DMA:
>> +        break;
>> +    default:
>> +        goto param_error_exit;
>> +    }
>> +
>> +    ret = rtas_handle_eeh_request(spapr, buid,
>> +                                  RTAS_EEH_REQ_SET_OPTION, option);
>> +    if (ret >= 0) {
>> +        rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>> +        return;
>> +    }
>
>The fall through here means that any failure in
>rtas_handle_eeh_request will be reported as RTAS_OUT_PARAM_ERROR,
>which doesn't sound like it would always be the right error code.
>Similar in the other entry points.
>

Yes, Varied error code to indicate different failure cases will
be better. I'll check PAPR spec again and return more precise
error code in next version.

Thanks,
Gavin

>-- 
>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