Hi
On 4/29/19 4:44 PM, Julien Grall wrote:
> When an MSI doorbell is located downstream of an IOMMU, it is required
> to swizzle the physical address with an appropriately-mapped IOVA for any
> device attached to one of our DMA ops domain.
>
> At the moment, the allocation of the mapping may be done when composing
> the message. However, the composing may be done in non-preemtible
> context while the allocation requires to be called from preemptible
> context.
>
> A follow-up change will split the current logic in two functions
> requiring to keep an IOMMU cookie per MSI.
>
> A new field is introduced in msi_desc to store an IOMMU cookie. As the
> cookie may not be required in some configuration, the field is protected
> under a new config CONFIG_IRQ_MSI_IOMMU.
>
> A pair of helpers has also been introduced to access the field.
>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Besides other's comments
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
Thanks
Eric
>
> ---
> Changes in v2:
> - Update the commit message to use imperative mood
> - Protect the field with a new config that will be selected by
> IOMMU_DMA later on
> - Add a set of helpers to access the new field
> ---
> include/linux/msi.h | 26 ++++++++++++++++++++++++++
> kernel/irq/Kconfig | 3 +++
> 2 files changed, 29 insertions(+)
>
> diff --git a/include/linux/msi.h b/include/linux/msi.h
> index 7e9b81c3b50d..82a308c19222 100644
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -77,6 +77,9 @@ struct msi_desc {
> struct device *dev;
> struct msi_msg msg;
> struct irq_affinity_desc *affinity;
> +#ifdef CONFIG_IRQ_MSI_IOMMU
> + const void *iommu_cookie;
> +#endif
>
> union {
> /* PCI MSI/X specific data */
> @@ -119,6 +122,29 @@ struct msi_desc {
> #define for_each_msi_entry_safe(desc, tmp, dev) \
> list_for_each_entry_safe((desc), (tmp), dev_to_msi_list((dev)), list)
>
> +#ifdef CONFIG_IRQ_MSI_IOMMU
> +static inline const void *msi_desc_get_iommu_cookie(struct msi_desc *desc)
> +{
> + return desc->iommu_cookie;
> +}
> +
> +static inline void msi_desc_set_iommu_cookie(struct msi_desc *desc,
> + const void *iommu_cookie)
> +{
> + desc->iommu_cookie = iommu_cookie;
> +}
> +#else
> +static inline const void *msi_desc_get_iommu_cookie(struct msi_desc *desc)
> +{
> + return NULL;
> +}
> +
> +static inline void msi_desc_set_iommu_cookie(struct msi_desc *desc,
> + const void *iommu_cookie)
> +{
> +}
> +#endif
> +
> #ifdef CONFIG_PCI_MSI
> #define first_pci_msi_entry(pdev) first_msi_entry(&(pdev)->dev)
> #define for_each_pci_msi_entry(desc, pdev) \
> diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
> index 5f3e2baefca9..8fee06625c37 100644
> --- a/kernel/irq/Kconfig
> +++ b/kernel/irq/Kconfig
> @@ -91,6 +91,9 @@ config GENERIC_MSI_IRQ_DOMAIN
> select IRQ_DOMAIN_HIERARCHY
> select GENERIC_MSI_IRQ
>
> +config IRQ_MSI_IOMMU
> + bool
> +
> config HANDLE_DOMAIN_IRQ
> bool
>
>
