[PATCH v2 0/2] powerpc/pci: unmap interrupts when a PHB is removed

[Cédric Le Goater]

On 6/17/20 6:29 PM, Cédric Le Goater wrote:
> Hello,
> 
> 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 some interrupts in the Linux interrupt number space
> but these are never removed.
> 
> To solve this problem, we introduce a PPC platform specific
> pcibios_remove_bus() routine which clears all interrupt mappings when
> the bus is removed. This also clears the associated page table entries
> of the ESB pages when using XIVE.
> 
> For this purpose, we record the logical interrupt numbers of the
> mapped interrupt under the PHB structure and let pcibios_remove_bus()
> do the clean up.
> 
> Tested on :
> 
>   - PowerNV with PCI, OpenCAPI, CAPI and GPU adapters. I don't know
>     how to inject a failure on a PHB but that would be a good test.

I found out that powering down the slot is enough :

	echo 0 > /sys/bus/pci/slots/<slot name>/power

The IRQ cleanup is done as expected on baremetal also.

Cheers,

C. 

>   - KVM P8+P9 guests with passthrough PCI adapters, but PHBs can not
>     be removed under QEMU/KVM.   
>   - PowerVM with passthrough PCI adapters (main target)
>   
> Thanks,
> 
> C.
> 
> Changes since v1:
> 
>  - extended the removal to interrupts other than the legacy INTx.
> 
> Cédric Le Goater (2):
>   powerpc/pci: unmap legacy INTx interrupts when a PHB is removed
>   powerpc/pci: unmap all interrupts when a PHB is removed
> 
>  arch/powerpc/include/asm/pci-bridge.h |   6 ++
>  arch/powerpc/kernel/pci-common.c      | 114 ++++++++++++++++++++++++++
>  2 files changed, 120 insertions(+)
>