Re: [PATCH v5 2/4] s390/pci: store DMA offset in bus_dma_region

Niklas Schnelle
2025-02-13T14:02:25Z

On Wed, 2025-02-12 at 16:34 -0500, Matthew Rosato wrote:
> PCI devices on s390 have a DMA offset that is reported via CLP. In
> preparation for allowing identity domains, setup the bus_dma_region
> for all PCI devices using the reported CLP value.
>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
> arch/s390/pci/pci_bus.c | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/arch/s390/pci/pci_bus.c b/arch/s390/pci/pci_bus.c
> index 857afbc4828f..3fa113c4ad8f 100644
> --- a/arch/s390/pci/pci_bus.c
> +++ b/arch/s390/pci/pci_bus.c
> @@ -19,6 +19,7 @@
> #include <linux/jump_label.h>
> #include <linux/pci.h>
> #include <linux/printk.h>
> +#include <linux/dma-direct.h>
>
> #include <asm/pci_clp.h>
> #include <asm/pci_dma.h>
> @@ -283,10 +284,34 @@ static struct zpci_bus *zpci_bus_alloc(int topo, bool topo_is_tid)
> return zbus;
> }
>
> +static void pci_dma_range_setup(struct pci_dev *pdev)
> +{
> + struct zpci_dev *zdev = to_zpci(pdev);
> + struct bus_dma_region *map;
> + u64 aligned_end;
> +
> + map = kzalloc(sizeof(*map), GFP_KERNEL);
> + if (!map)
> + return;
> +
> + map->cpu_start = 0;
> + map->dma_start = PAGE_ALIGN(zdev->start_dma);
> + aligned_end = PAGE_ALIGN_DOWN(zdev->end_dma + 1);
> + if (aligned_end >= map->dma_start)
> + map->size = aligned_end - map->dma_start;
> + else
> + map->size = 0;
> + WARN_ON_ONCE(map->size == 0);
> +
> + pdev->dev.dma_range_map = map;
> +}
> +
> void pcibios_bus_add_device(struct pci_dev *pdev)
> {
> struct zpci_dev *zdev = to_zpci(pdev);
>
> + pci_dma_range_setup(pdev);
> +
> /*
> * With pdev->no_vf_scan the common PCI probing code does not
> * perform PF/VF linking.

Looks good to me and I tested it again. So feel free to add my:

Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>