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Date: Mon, 30 Oct 2017 17:59:37 +0100
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Subject: Re: [Qemu-devel] [PATCH v1 0/5][RFC] Refactoring of AIS support
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To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Pierre Morel <pmorel@linux.vnet.ibm.com>, qemu-devel@nongnu.org, agraf@suse.de, zyimin@linux.vnet.ibm.com, pasic@linux.vnet.ibm.com, qemu-s390x@nongnu.org

On Mon, 30 Oct 2017 14:48:23 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:


> FWIW, I am testing a guest patch that enables zPCI without AIS. Its as simple as
> 
> 
> diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
> index 7b30af5..9b24836 100644
> --- a/arch/s390/pci/pci.c
> +++ b/arch/s390/pci/pci.c
> @@ -953,7 +953,7 @@ static int __init pci_base_init(void)
>         if (!s390_pci_probe)
>                 return 0;
>  
> -       if (!test_facility(69) || !test_facility(71) || !test_facility(72))
> +       if (!test_facility(69) || !test_facility(71))
>                 return 0;
>  
>         rc = zpci_debug_init();
> diff --git a/arch/s390/pci/pci_insn.c b/arch/s390/pci/pci_insn.c
> index ea34086..61f8c82 100644
> --- a/arch/s390/pci/pci_insn.c
> +++ b/arch/s390/pci/pci_insn.c
> @@ -7,6 +7,7 @@
>  #include <linux/export.h>
>  #include <linux/errno.h>
>  #include <linux/delay.h>
> +#include <asm/facility.h>
>  #include <asm/pci_insn.h>
>  #include <asm/pci_debug.h>
>  #include <asm/processor.h>
> @@ -93,6 +94,8 @@ int zpci_refresh_trans(u64 fn, u64 addr, u64 range)
>  /* Set Interruption Controls */
>  void zpci_set_irq_ctrl(u16 ctl, char *unused, u8 isc)
>  {
> +       if (!test_facility(72))
> +               return;
>         asm volatile (
>                 "       .insn   rsy,0xeb00000000d1,%[ctl],%[isc],%[u]\n"
>                 : : [ctl] "d" (ctl), [isc] "d" (isc << 27), [u] "Q" (*unused));
> 

Sounds good. Presumably this makes the adapter interrupt handling work
as for virtio (and qdio)? Is there any ais-less pci hardware out in the
wild?