On Wed, Jul 25, 2018 at 07:50:30PM +1000, Alexey Kardashevskiy wrote:
> At the moment the kernel does not expect dynamic windows to ever start
> at zero on a PCI bus as PAPR requires the hypervisor to create a 32bit
> default window which starts from zero and the pseries kernel only
> creates additional windows.
>
> However PAPR permits removing the default window and creating another
> one instead, starting from zero as well. In fact, the kernel used to
> remove the default window after sha1 25ebc45b934 but this has been
> reverted later.
>
> Since there are devices capable of more than 32 bits for DMA but less than
> 50, and currently available hardware allows the second window only
> at 1<<59, we will need to be able to create bigger windows starting from
> zero. This does the initial preparation and should not cause any
> behavioral changes.
>
> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> ---
> arch/powerpc/platforms/pseries/iommu.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 06f0296..9ece42f 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -53,6 +53,8 @@
>
> #include "pseries.h"
>
> +#define DDW_INVALID_OFFSET ((uint64_t)-1)
> +
> static struct iommu_table_group *iommu_pseries_alloc_group(int node)
> {
> struct iommu_table_group *table_group;
> @@ -844,7 +846,7 @@ static u64 find_existing_ddw(struct device_node *pdn)
> {
> struct direct_window *window;
> const struct dynamic_dma_window_prop *direct64;
> - u64 dma_addr = 0;
> + u64 dma_addr = DDW_INVALID_OFFSET;
>
> spin_lock(&direct_window_list_lock);
> /* check if we already created a window and dupe that config if so */
> @@ -992,7 +994,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
> mutex_lock(&direct_window_init_mutex);
>
> dma_addr = find_existing_ddw(pdn);
> - if (dma_addr != 0)
> + if (dma_addr != DDW_INVALID_OFFSET)
> goto out_unlock;
>
> /*
> @@ -1228,7 +1230,7 @@ static int dma_set_mask_pSeriesLP(struct device *dev, u64 dma_mask)
> }
> if (pdn && PCI_DN(pdn)) {
> dma_offset = enable_ddw(pdev, pdn);
> - if (dma_offset != 0) {
> + if (dma_offset != DDW_INVALID_OFFSET) {
> dev_info(dev, "Using 64-bit direct DMA at offset %llx\n", dma_offset);
> set_dma_offset(dev, dma_offset);
> set_dma_ops(dev, &dma_nommu_ops);
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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