Re: [PATCH] ACPI/IORT: Make dma masks set-up IORT specific

[Rafael J. Wysocki]

On Mon, Dec 5, 2016 at 1:26 PM, Lorenzo Pieralisi
<lorenzo.pieralisi@xxxxxxx> wrote:
> The introduction of acpi_dma_configure() allows to configure DMA
> and related IOMMU for any device that is DMA capable. To achieve
> that goal it ensures DMA masks are set-up to sane default values
> before proceeding with IOMMU and DMA ops configuration.
>
> On x86/ia64 systems, through acpi_bind_one(), acpi_dma_configure() is
> called for every device that has an ACPI companion, in that every device
> is considered DMA capable on x86/ia64 systems (ie acpi_get_dma_attr() API),
> which has the side effect of initializing dma masks also for
> pseudo-devices (eg CPUs and memory nodes) and potentially for devices
> whose dma masks were not set-up before the acpi_dma_configure() API was
> introduced, which may have noxious side effects.
>
> Therefore, in preparation for IORT firmware specific DMA masks set-up,
> wrap the default DMA masks set-up in acpi_dma_configure() inside an IORT
> specific wrapper that reverts to a NOP on x86/ia64 systems, restoring the
> default expected behaviour on x86/ia64 systems and keeping DMA default
> masks set-up on IORT based (ie ARM) arch configurations.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Cc: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: Robin Murphy <robin.murphy@xxxxxxx>
> Cc: Tomasz Nowicki <tn@xxxxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Cc: Sricharan R <sricharan@xxxxxxxxxxxxxx>

Acked -by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

> ---
> Joerg,
>
> pending Rafael's ACK on it, given the 4.10 release timing and that the
> series is queued via the IOMMU tree please consider applying this patch to
> your arm/smmu branch for 4.10, it is not fixing a bug but it is modifying
> the x86/ia64 code path; I prefer preventing any issue related to default
> dma masks on x86/ia64 so I hope it can get merged along with the rest of
> the ACPI IORT SMMU series.
>
> Thanks a lot and apologies,
> Lorenzo
>
>  drivers/acpi/arm64/iort.c | 22 ++++++++++++++++++++++
>  drivers/acpi/scan.c       | 14 +-------------
>  include/linux/acpi_iort.h |  2 ++
>  3 files changed, 25 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 47bace8..e0d2e6e 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -547,6 +547,28 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
>  }
>
>  /**
> + * iort_set_dma_mask - Set-up dma mask for a device.
> + *
> + * @dev: device to configure
> + */
> +void iort_set_dma_mask(struct device *dev)
> +{
> +       /*
> +        * Set default coherent_dma_mask to 32 bit.  Drivers are expected to
> +        * setup the correct supported mask.
> +        */
> +       if (!dev->coherent_dma_mask)
> +               dev->coherent_dma_mask = DMA_BIT_MASK(32);
> +
> +       /*
> +        * Set it to coherent_dma_mask by default if the architecture
> +        * code has not set it.
> +        */
> +       if (!dev->dma_mask)
> +               dev->dma_mask = &dev->coherent_dma_mask;
> +}
> +
> +/**
>   * iort_iommu_configure - Set-up IOMMU configuration for a device.
>   *
>   * @dev: device to configure
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 80698d3..93b00cf 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1380,19 +1380,7 @@ void acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
>  {
>         const struct iommu_ops *iommu;
>
> -       /*
> -        * Set default coherent_dma_mask to 32 bit.  Drivers are expected to
> -        * setup the correct supported mask.
> -        */
> -       if (!dev->coherent_dma_mask)
> -               dev->coherent_dma_mask = DMA_BIT_MASK(32);
> -
> -       /*
> -        * Set it to coherent_dma_mask by default if the architecture
> -        * code has not set it.
> -        */
> -       if (!dev->dma_mask)
> -               dev->dma_mask = &dev->coherent_dma_mask;
> +       iort_set_dma_mask(dev);
>
>         iommu = iort_iommu_configure(dev);
>
> diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
> index dcb2b60..77e0809 100644
> --- a/include/linux/acpi_iort.h
> +++ b/include/linux/acpi_iort.h
> @@ -35,6 +35,7 @@ bool iort_node_match(u8 type);
>  u32 iort_msi_map_rid(struct device *dev, u32 req_id);
>  struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id);
>  /* IOMMU interface */
> +void iort_set_dma_mask(struct device *dev);
>  const struct iommu_ops *iort_iommu_configure(struct device *dev);
>  #else
>  static inline void acpi_iort_init(void) { }
> @@ -45,6 +46,7 @@ static inline struct irq_domain *iort_get_device_domain(struct device *dev,
>                                                         u32 req_id)
>  { return NULL; }
>  /* IOMMU interface */
> +static inline void iort_set_dma_mask(struct device *dev) { }
>  static inline
>  const struct iommu_ops *iort_iommu_configure(struct device *dev)
>  { return NULL; }
> --
> 2.10.0
>
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