[PATCH v3 2/2] iommupt: Encode IOMMU_MMIO/IOMMU_CACHE via RISC-V Svpbmt bits

[fangyu . yu]

From: Fangyu Yu <fangyu.yu@xxxxxxxxxxxxxxxxx>

When the RISC-V IOMMU page table format support Svpbmt, PBMT provides
a way to tag mappings with page-based memory types. Encode memory type
via PBMT in RISC-V IOMMU PTEs:

  - IOMMU_MMIO   -> PBMT=IO
  - !IOMMU_MMIO && !IOMMU_CACHE -> PBMT=NC
  - otherwise    -> PBMT=Normal (PBMT=0)

Only touch PBMT when PT_FEAT_RISCV_SVPBMT is advertised.

Signed-off-by: Fangyu Yu <fangyu.yu@xxxxxxxxxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
Reviewed-by: Guo Ren <guoren@xxxxxxxxxx>
Reviewed-by: Nutty Liu <nutty.liu@xxxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 drivers/iommu/generic_pt/fmt/riscv.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/generic_pt/fmt/riscv.h b/drivers/iommu/generic_pt/fmt/riscv.h
index a7fef6266a36..2648bb57953e 100644
--- a/drivers/iommu/generic_pt/fmt/riscv.h
+++ b/drivers/iommu/generic_pt/fmt/riscv.h
@@ -64,6 +64,8 @@ enum {
 	RISCVPT_PPN64 = GENMASK_ULL(53, 10),
 	RISCVPT_PPN64_64K = GENMASK_ULL(53, 14),
 	RISCVPT_PBMT = GENMASK_ULL(62, 61),
+	RISCVPT_NC = BIT(61),
+	RISCVPT_IO = BIT(62),
 	RISCVPT_N = BIT_ULL(63),
 
 	/* Svnapot encodings for ppn[0] */
@@ -201,7 +203,8 @@ static inline void riscvpt_attr_from_entry(const struct pt_state *pts,
 {
 	attrs->descriptor_bits =
 		pts->entry & (RISCVPT_R | RISCVPT_W | RISCVPT_X | RISCVPT_U |
-			      RISCVPT_G | RISCVPT_A | RISCVPT_D);
+			      RISCVPT_G | RISCVPT_A | RISCVPT_D | RISCVPT_NC |
+			      RISCVPT_IO);
 }
 #define pt_attr_from_entry riscvpt_attr_from_entry
 
@@ -237,6 +240,12 @@ static inline int riscvpt_iommu_set_prot(struct pt_common *common,
 		pte |= RISCVPT_R;
 	if (!(iommu_prot & IOMMU_NOEXEC))
 		pte |= RISCVPT_X;
+	if (common->features & BIT(PT_FEAT_RISCV_SVPBMT)) {
+		if (iommu_prot & IOMMU_MMIO)
+			pte |= RISCVPT_IO;
+		else if (!(iommu_prot & IOMMU_CACHE))
+			pte |= RISCVPT_NC;
+	}
 
 	/* Caller must specify a supported combination of flags */
 	if (unlikely((pte & (RISCVPT_X | RISCVPT_W | RISCVPT_R)) == 0))
-- 
2.50.1