On 2020-11-10 17:48, Will Deacon wrote:
On Fri, Oct 30, 2020 at 02:53:08PM +0530, Sai Prakash Ranjan wrote:
Add a quirk IO_PGTABLE_QUIRK_SYS_CACHE to override the
attributes set in TCR for the page table walker when
using system cache.

Signed-off-by: Sai Prakash Ranjan <saiprakash.ran...@codeaurora.org>
---
 drivers/iommu/io-pgtable-arm.c | 7 ++++++-
 include/linux/io-pgtable.h     | 4 ++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index a7a9bc08dcd1..a356caf1683a 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -761,7 +761,8 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)

        if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS |
                            IO_PGTABLE_QUIRK_NON_STRICT |
-                           IO_PGTABLE_QUIRK_ARM_TTBR1))
+                           IO_PGTABLE_QUIRK_ARM_TTBR1 |
+                           IO_PGTABLE_QUIRK_SYS_CACHE))
                return NULL;

        data = arm_lpae_alloc_pgtable(cfg);
@@ -773,6 +774,10 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
                tcr->sh = ARM_LPAE_TCR_SH_IS;
                tcr->irgn = ARM_LPAE_TCR_RGN_WBWA;
                tcr->orgn = ARM_LPAE_TCR_RGN_WBWA;
+       } else if (cfg->quirks & IO_PGTABLE_QUIRK_SYS_CACHE) {
+               tcr->sh = ARM_LPAE_TCR_SH_OS;
+               tcr->irgn = ARM_LPAE_TCR_RGN_NC;
+               tcr->orgn = ARM_LPAE_TCR_RGN_WBWA;

Given that this only applies in the case where then page-table walker is non-coherent, I think we'd be better off renaming the quirk to something
like IO_PGTABLE_QUIRK_ARM_OUTER_WBWA and then rejecting it in the
non-coherent case.


Do you mean like below?

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index a7a9bc08dcd1..94de1f71db42 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -776,7 +776,10 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
        } else {
                tcr->sh = ARM_LPAE_TCR_SH_OS;
                tcr->irgn = ARM_LPAE_TCR_RGN_NC;
-               tcr->orgn = ARM_LPAE_TCR_RGN_NC;
+               if (!(cfg->quirks & IO_PGTABLE_QUIRK_ARM_OUTER_WBWA))
+                       tcr->orgn = ARM_LPAE_TCR_RGN_NC;
+               else
+                       tcr->orgn = ARM_LPAE_TCR_RGN_WBWA;
        }

        tg1 = cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1;


Thanks,
Sai

--
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