Re: [patch V2 25/36] PCI/MSI: Provide MSI_FLAG_MSIX_CONTIGUOUS

[Bjorn Helgaas]

On Mon, Dec 06, 2021 at 11:39:36PM +0100, Thomas Gleixner wrote:
> Provide a domain info flag which makes the core code check for a contiguous
> MSI-X index on allocation. That's simpler than checking it at some other
> domain callback in architecture code.
> 
> Signed-off-by: Thomas Gleixner 
> Reviewed-by: Greg Kroah-Hartman 
> Reviewed-by: Jason Gunthorpe 

Acked-by: Bjorn Helgaas 

> ---
>  drivers/pci/msi/irqdomain.c |   16 ++--
>  include/linux/msi.h |2 ++
>  2 files changed, 16 insertions(+), 2 deletions(-)
> 
> --- a/drivers/pci/msi/irqdomain.c
> +++ b/drivers/pci/msi/irqdomain.c
> @@ -89,9 +89,21 @@ static int pci_msi_domain_check_cap(stru
>   if (pci_msi_desc_is_multi_msi(desc) &&
>   !(info->flags & MSI_FLAG_MULTI_PCI_MSI))
>   return 1;
> - else if (desc->pci.msi_attrib.is_msix && !(info->flags & 
> MSI_FLAG_PCI_MSIX))
> - return -ENOTSUPP;
>  
> + if (desc->pci.msi_attrib.is_msix) {
> + if (!(info->flags & MSI_FLAG_PCI_MSIX))
> + return -ENOTSUPP;
> +
> + if (info->flags & MSI_FLAG_MSIX_CONTIGUOUS) {
> + unsigned int idx = 0;
> +
> + /* Check for gaps in the entry indices */
> + for_each_msi_entry(desc, dev) {
> + if (desc->msi_index != idx++)
> + return -ENOTSUPP;
> + }
> + }
> + }
>   return 0;
>  }
>  
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -376,6 +376,8 @@ enum {
>   MSI_FLAG_LEVEL_CAPABLE  = (1 << 6),
>   /* Populate sysfs on alloc() and destroy it on free() */
>   MSI_FLAG_DEV_SYSFS  = (1 << 7),
> + /* MSI-X entries must be contiguous */
> + MSI_FLAG_MSIX_CONTIGUOUS= (1 << 8),
>  };
>  
>  int msi_domain_set_affinity(struct irq_data *data, const struct cpumask 
> *mask,
> 
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[patch V2 25/36] PCI/MSI: Provide MSI_FLAG_MSIX_CONTIGUOUS

[Thomas Gleixner]

Provide a domain info flag which makes the core code check for a contiguous
MSI-X index on allocation. That's simpler than checking it at some other
domain callback in architecture code.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Jason Gunthorpe 
---
 drivers/pci/msi/irqdomain.c |   16 ++--
 include/linux/msi.h |2 ++
 2 files changed, 16 insertions(+), 2 deletions(-)

--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -89,9 +89,21 @@ static int pci_msi_domain_check_cap(stru
if (pci_msi_desc_is_multi_msi(desc) &&
!(info->flags & MSI_FLAG_MULTI_PCI_MSI))
return 1;
-   else if (desc->pci.msi_attrib.is_msix && !(info->flags & 
MSI_FLAG_PCI_MSIX))
-   return -ENOTSUPP;
 
+   if (desc->pci.msi_attrib.is_msix) {
+   if (!(info->flags & MSI_FLAG_PCI_MSIX))
+   return -ENOTSUPP;
+
+   if (info->flags & MSI_FLAG_MSIX_CONTIGUOUS) {
+   unsigned int idx = 0;
+
+   /* Check for gaps in the entry indices */
+   for_each_msi_entry(desc, dev) {
+   if (desc->msi_index != idx++)
+   return -ENOTSUPP;
+   }
+   }
+   }
return 0;
 }
 
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -376,6 +376,8 @@ enum {
MSI_FLAG_LEVEL_CAPABLE  = (1 << 6),
/* Populate sysfs on alloc() and destroy it on free() */
MSI_FLAG_DEV_SYSFS  = (1 << 7),
+   /* MSI-X entries must be contiguous */
+   MSI_FLAG_MSIX_CONTIGUOUS= (1 << 8),
 };
 
 int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask,

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