[PATCH v2] hw/riscv/riscv-iommu: Fix process directory table walk

[Jason Chien <jason.chien@sifive.com>]

The PPN field in a non-leaf PDT entry is positioned differently from that
in a leaf PDT entry. The original implementation incorrectly used the leaf
entry's PPN mask to extract the PPN from a non-leaf entry, leading to an
erroneous page table walk.

This commit introduces new macros to properly define the fields for
non-leaf PDT entries and corrects the page table walk.

Signed-off-by: Jason Chien <jason.chien@sifive.com>
---
 hw/riscv/riscv-iommu-bits.h | 6 +++++-
 hw/riscv/riscv-iommu.c      | 4 ++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/hw/riscv/riscv-iommu-bits.h b/hw/riscv/riscv-iommu-bits.h
index b7cb1bc736..1017d73fc6 100644
--- a/hw/riscv/riscv-iommu-bits.h
+++ b/hw/riscv/riscv-iommu-bits.h
@@ -415,12 +415,16 @@ enum riscv_iommu_fq_causes {
 #define RISCV_IOMMU_DC_MSIPTP_MODE_OFF  0
 #define RISCV_IOMMU_DC_MSIPTP_MODE_FLAT 1
 
+/* 2.2 Process Directory Table */
+#define RISCV_IOMMU_PDTE_VALID          BIT_ULL(0)
+#define RISCV_IOMMU_PDTE_PPN            RISCV_IOMMU_PPN_FIELD
+
 /* Translation attributes fields */
 #define RISCV_IOMMU_PC_TA_V             BIT_ULL(0)
 #define RISCV_IOMMU_PC_TA_RESERVED      GENMASK_ULL(63, 32)
 
 /* First stage context fields */
-#define RISCV_IOMMU_PC_FSC_PPN          GENMASK_ULL(43, 0)
+#define RISCV_IOMMU_PC_FSC_PPN          RISCV_IOMMU_ATP_PPN_FIELD
 #define RISCV_IOMMU_PC_FSC_RESERVED     GENMASK_ULL(59, 44)
 
 enum riscv_iommu_fq_ttypes {
diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
index d46beb2d64..76e0fcd873 100644
--- a/hw/riscv/riscv-iommu.c
+++ b/hw/riscv/riscv-iommu.c
@@ -1042,10 +1042,10 @@ static int riscv_iommu_ctx_fetch(RISCVIOMMUState *s, RISCVIOMMUContext *ctx)
             return RISCV_IOMMU_FQ_CAUSE_PDT_LOAD_FAULT;
         }
         le64_to_cpus(&de);
-        if (!(de & RISCV_IOMMU_PC_TA_V)) {
+        if (!(de & RISCV_IOMMU_PDTE_VALID)) {
             return RISCV_IOMMU_FQ_CAUSE_PDT_INVALID;
         }
-        addr = PPN_PHYS(get_field(de, RISCV_IOMMU_PC_FSC_PPN));
+        addr = PPN_PHYS(get_field(de, RISCV_IOMMU_PDTE_PPN));
     }
 
     riscv_iommu_hpm_incr_ctr(s, ctx, RISCV_IOMMU_HPMEVENT_PD_WALK);
-- 
2.43.2