Hi Bjorn,
On Wed, May 15, 2019 at 04:32:34PM -0700, Bjorn Andersson wrote:
> Describe the memory related to page table walks as non-cachable for iommu
> instances that are not DMA coherent.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> ---
> drivers/iommu/io-pgtable-arm.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 4e21efbc4459..68ff22ffd2cb 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -803,9 +803,15 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
> return NULL;
>
> /* TCR */
> - reg = (ARM_LPAE_TCR_SH_IS << ARM_LPAE_TCR_SH0_SHIFT) |
> - (ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_IRGN0_SHIFT) |
> - (ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_ORGN0_SHIFT);
> + if (cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA) {
> + reg = (ARM_LPAE_TCR_SH_IS << ARM_LPAE_TCR_SH0_SHIFT) |
> + (ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_IRGN0_SHIFT) |
> + (ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_ORGN0_SHIFT);
> + } else {
> + reg = (ARM_LPAE_TCR_SH_IS << ARM_LPAE_TCR_SH0_SHIFT) |
Nit: this should be outer-shareable (ARM_LPAE_TCR_SH_OS).
> + (ARM_LPAE_TCR_RGN_NC << ARM_LPAE_TCR_IRGN0_SHIFT) |
> + (ARM_LPAE_TCR_RGN_NC << ARM_LPAE_TCR_ORGN0_SHIFT);
> + }
Should we also be doing something similar for the short-descriptor code
in io-pgtable-arm-v7s.c? Looks like you just need to use ARM_V7S_RGN_NC
instead of ARM_V7S_RGN_WBWA when initialising ttbr0 for non-coherent
SMMUs.
Will
