[kernel,v4,01/19] powerpc/ioda/npu: Call skiboot's hot reset hook when disabling NPU2

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 <aik@ozlabs.ru>
Acked-by: Alistair Popple <alistair@popple.id.au>
---
Changes:
v2:
* updated the commit log
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

On Fri, Nov 23, 2018 at 04:52:46PM +1100, 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 <aik@ozlabs.ru>
> Acked-by: Alistair Popple <alistair@popple.id.au>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
> 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 9ee7a30..29c6837 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -3676,6 +3676,15 @@ 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;
> @@ -3720,6 +3729,7 @@ 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 = {