On Tuesday, 16 October 2018 1:22:53 PM AEDT Alexey Kardashevskiy wrote: > > On 16/10/2018 13:19, Alistair Popple wrote: > >> reset_ntl() does what npu2_dev_procedure_reset() does plus more stuff, > >> there nothing really in npu2_dev_procedure_reset() which reset_ntl() > >> does not do already from the hardware standpoint. And it did stop HMIs > >> for me though. > >> > >> but ok, what will be sufficient then if not reset_ntl()? > > > > Argh, yes you are correct. Specifically both npu2_dev_procedure_reset() and > > reset_ntl() contain: > > > > /* NTL Reset */ > > val = npu2_read(ndev->npu, NPU2_NTL_MISC_CFG1(ndev)); > > val |= PPC_BIT(8) | PPC_BIT(9); > > npu2_write(ndev->npu, NPU2_NTL_MISC_CFG1(ndev), val); > > > > Which should fence the brick. However from what I recall there was more to > > reliably preventing HMIs than merely fencing the brick. It invovled a > > sequence > > of fencing and flushing the cache with dcbf instructions at the right time > > which > > is why we also have the FLR. Unfortunately I don't know the precise details, > > perhaps if we send enough coffee Balbir's way he might be able remind us? > > > He suggested and ack'ed that skiboot patch, I can repeat beers^wcoffee > but it won't change much ;)
Ha. Couldn't hurt ;) I was pretty sure flushing the caches was an important part of the sequence to avoid HMI's. I believe you are trying to deal with unexpected guest terminations which means the driver won't have a chance to flush the caches prior to termination so wouldn't you also need to do that somewhere? Unless the driver does it at startup? - Alistair > > > > - Alistair > > > >> > >> > >>> > >>> - Alistair > >>> > >>>> > >>>> > >>>> > >>>>> > >>>>> - Alistair > >>>>> > >>>>> On Monday, 15 October 2018 6:17:51 PM AEDT Alexey Kardashevskiy wrote: > >>>>>> Ping? > >>>>>> > >>>>>> > >>>>>> On 02/10/2018 13:20, Alexey Kardashevskiy wrote: > >>>>>>> The skiboot firmware has a hot reset handler which fences the NVIDIA > >>>>>>> V100 > >>>>>>> GPU RAM on Witherspoons and makes accesses no-op instead of throwing > >>>>>>> HMIs: > >>>>>>> https://github.com/open-power/skiboot/commit/fca2b2b839a67 > >>>>>>> > >>>>>>> Now we are going to pass V100 via VFIO which most certainly involves > >>>>>>> KVM guests which are often terminated without getting a chance to > >>>>>>> offline > >>>>>>> GPU RAM so we end up with a running machine with misconfigured memory. > >>>>>>> Accessing this memory produces hardware management interrupts (HMI) > >>>>>>> which bring the host down. > >>>>>>> > >>>>>>> To suppress HMIs, this wires up this hot reset hook to > >>>>>>> vfio_pci_disable() > >>>>>>> via pci_disable_device() which switches NPU2 to a safe mode and > >>>>>>> prevents > >>>>>>> HMIs. > >>>>>>> > >>>>>>> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> > >>>>>>> --- > >>>>>>> Changes: > >>>>>>> v2: > >>>>>>> * updated the commit log > >>>>>>> --- > >>>>>>> arch/powerpc/platforms/powernv/pci-ioda.c | 10 ++++++++++ > >>>>>>> 1 file changed, 10 insertions(+) > >>>>>>> > >>>>>>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c > >>>>>>> b/arch/powerpc/platforms/powernv/pci-ioda.c > >>>>>>> index cde7102..e37b9cc 100644 > >>>>>>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c > >>>>>>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c > >>>>>>> @@ -3688,6 +3688,15 @@ static void pnv_pci_release_device(struct > >>>>>>> pci_dev *pdev) > >>>>>>> pnv_ioda_release_pe(pe); > >>>>>>> } > >>>>>>> > >>>>>>> +static void pnv_npu_disable_device(struct pci_dev *pdev) > >>>>>>> +{ > >>>>>>> + struct eeh_dev *edev = pci_dev_to_eeh_dev(pdev); > >>>>>>> + struct eeh_pe *eehpe = edev ? edev->pe : NULL; > >>>>>>> + > >>>>>>> + if (eehpe && eeh_ops && eeh_ops->reset) > >>>>>>> + eeh_ops->reset(eehpe, EEH_RESET_HOT); > >>>>>>> +} > >>>>>>> + > >>>>>>> static void pnv_pci_ioda_shutdown(struct pci_controller *hose) > >>>>>>> { > >>>>>>> struct pnv_phb *phb = hose->private_data; > >>>>>>> @@ -3732,6 +3741,7 @@ static const struct pci_controller_ops > >>>>>>> pnv_npu_ioda_controller_ops = { > >>>>>>> .reset_secondary_bus = pnv_pci_reset_secondary_bus, > >>>>>>> .dma_set_mask = pnv_npu_dma_set_mask, > >>>>>>> .shutdown = pnv_pci_ioda_shutdown, > >>>>>>> + .disable_device = pnv_npu_disable_device, > >>>>>>> }; > >>>>>>> > >>>>>>> static const struct pci_controller_ops > >>>>>>> pnv_npu_ocapi_ioda_controller_ops = { > >>>>>>> > >>>>>> > >>>>>> > >>>>> > >>>>> > >>>> > >>>> > >>> > >>> > >> > >> > > > > > >
