Re: [RFC PATCH kernel 2/2] powerpc/pci: Remove LSI mappings on device teardown

["Cédric Le Goater" <clg@kaod.org>]

On 10/27/20 10:06 AM, Alexey Kardashevskiy wrote:
> From: Oliver O'Halloran <oohall@gmail.com>
> 
> When a passthrough IO adapter is removed from a pseries machine using hash
> MMU and the XIVE interrupt mode, the POWER hypervisor expects the guest OS
> to clear all page table entries related to the adapter. If some are still
> present, the RTAS call which isolates the PCI slot returns error 9001
> "valid outstanding translations" and the removal of the IO adapter fails.
> This is because when the PHBs are scanned, Linux maps automatically the
> INTx interrupts in the Linux interrupt number space but these are never
> removed.
> 
> This problem can be fixed by adding the corresponding unmap operation when
> the device is removed. There's no pcibios_* hook for the remove case, but
> the same effect can be achieved using a bus notifier.
> 
> Cc: Cédric Le Goater <clg@kaod.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>


Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks taking care of this.

C. 

> ---
>  arch/powerpc/kernel/pci-common.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> index be108616a721..95f4e173368a 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -404,6 +404,27 @@ static int pci_read_irq_line(struct pci_dev *pci_dev)
>  	return 0;
>  }
>  
> +static int ppc_pci_unmap_irq_line(struct notifier_block *nb,
> +			       unsigned long action, void *data)
> +{
> +	struct pci_dev *pdev = to_pci_dev(data);
> +
> +	if (action == BUS_NOTIFY_DEL_DEVICE)
> +		irq_dispose_mapping(pdev->irq);
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block ppc_pci_unmap_irq_notifier = {
> +	.notifier_call = ppc_pci_unmap_irq_line,
> +};
> +
> +static int ppc_pci_register_irq_notifier(void)
> +{
> +	return bus_register_notifier(&pci_bus_type, &ppc_pci_unmap_irq_notifier);
> +}
> +arch_initcall(ppc_pci_register_irq_notifier);
> +
>  /*
>   * Platform support for /proc/bus/pci/X/Y mmap()s.
>   *  -- paulus.
>