Re: [PATCH v2] xen/pci: Refactor PCI MSI interrupts related code

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Apr 21, 2021 at 08:07:08AM +0000, Rahul Singh wrote:
> Hi Jan,
> 
> > On 20 Apr 2021, at 4:36 pm, Jan Beulich <jbeulich@xxxxxxxx> wrote:
> > 
> > On 20.04.2021 15:45, Rahul Singh wrote:
> >>> On 19 Apr 2021, at 1:33 pm, Jan Beulich <jbeulich@xxxxxxxx> wrote:
> >>> On 19.04.2021 13:54, Julien Grall wrote:
> >>>> For the time being, I think move this code in x86 is a lot better than 
> >>>> #ifdef or keep the code in common code.
> >>> 
> >>> Well, I would perhaps agree if it ended up being #ifdef CONFIG_X86.
> >>> I would perhaps not agree if there was a new CONFIG_* which other
> >>> (future) arch-es could select if desired.
> >> 
> >> I agree with Julien moving the code to x86 file as currently it is 
> >> referenced only in x86 code
> >> and as of now we are not sure how other architecture will implement the 
> >> Interrupt remapping
> >> (via IOMMU or any other means).  
> >> 
> >> Let me know if you are ok with moving the code to x86.
> > 
> > I can't answer this with "yes" or "no" without knowing what the alternative
> > would be. As said, if the alternative is CONFIG_X86 #ifdef-ary, then yes.
> > If a separate CONFIG_* gets introduced (and selected by X86), then a
> > separate file (getting built only when that new setting is y) would seem
> > better to me.
> 
> I just made a quick patch. Please let me know if below patch is ok. I move 
> the definition to  "passthrough/x86/iommu.c” file.
> 
> diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
> index 705137f8be..199ce08612 100644
> --- a/xen/drivers/passthrough/pci.c
> +++ b/xen/drivers/passthrough/pci.c
> @@ -1303,13 +1303,6 @@ static int __init setup_dump_pcidevs(void)
>  }
>  __initcall(setup_dump_pcidevs);
>  
> -int iommu_update_ire_from_msi(
> -    struct msi_desc *msi_desc, struct msi_msg *msg)
> -{
> -    return iommu_intremap
> -           ? iommu_call(&iommu_ops, update_ire_from_msi, msi_desc, msg) : 0;
> -}
> -
>  static int iommu_add_device(struct pci_dev *pdev)
>  {
>      const struct domain_iommu *hd;
> diff --git a/xen/drivers/passthrough/x86/iommu.c 
> b/xen/drivers/passthrough/x86/iommu.c
> index b90bb31bfe..cf51dec564 100644
> --- a/xen/drivers/passthrough/x86/iommu.c
> +++ b/xen/drivers/passthrough/x86/iommu.c
> @@ -340,6 +340,13 @@ bool arch_iommu_use_permitted(const struct domain *d)
>              likely(!p2m_get_hostp2m(d)->global_logdirty));
>  }
>  
> +int iommu_update_ire_from_msi(
> +    struct msi_desc *msi_desc, struct msi_msg *msg)
> +{
> +    return iommu_intremap
> +           ? iommu_call(&iommu_ops, update_ire_from_msi, msi_desc, msg) : 0;
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
> index ea0cd0f1a2..bd42d87b72 100644
> --- a/xen/include/xen/iommu.h
> +++ b/xen/include/xen/iommu.h
> @@ -243,7 +243,6 @@ struct iommu_ops {
>                             u8 devfn, device_t *dev);
>  #ifdef CONFIG_HAS_PCI
>      int (*get_device_group_id)(u16 seg, u8 bus, u8 devfn);
> -    int (*update_ire_from_msi)(struct msi_desc *msi_desc, struct msi_msg 
> *msg);
>  #endif /* HAS_PCI */
>  
>      void (*teardown)(struct domain *d);
> @@ -272,6 +271,7 @@ struct iommu_ops {
>      int (*adjust_irq_affinities)(void);
>      void (*sync_cache)(const void *addr, unsigned int size);
>      void (*clear_root_pgtable)(struct domain *d);
> +    int (*update_ire_from_msi)(struct msi_desc *msi_desc, struct msi_msg 
> *msg);

You also need to move the function prototype
(iommu_update_ire_from_msi) from iommu.h into asm-x86/iommu.h, or
maybe you could just define the function itself as static inline in
asm-x86/iommu.h?

Thanks, Roger.