hw/riscv/riscv-iommu.c | 141 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 139 insertions(+), 2 deletions(-)
From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>
Current implementation is wrong when iohgatp != bare. The RISC-V
IOMMU specification has defined that the PDT is based on GPA, not
SPA. So this patch fixes the problem, making PDT walk correctly
when the G-stage table walk is enabled.
Fixes: 0c54acb8243d ("hw/riscv: add RISC-V IOMMU base emulation")
Cc: qemu-stable@nongnu.org
Cc: Sebastien Boeuf <seb@rivosinc.com>
Cc: Tomasz Jeznach <tjeznach@rivosinc.com>
Reviewed-by: Weiwei Li <liwei1518@gmail.com>
Reviewed-by: Nutty Liu <liujingqi@lanxincomputing.com>
Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
---
Changes in V3:
- Fixup inner non-leaf walking for 4KB-align.
- Add two Reviewed-by tags.
Changes in V2:
- Remove nested param to make patch clearer.
---
hw/riscv/riscv-iommu.c | 141 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 139 insertions(+), 2 deletions(-)
diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
index 96a7fbdefcf3..ddb5236f55d1 100644
--- a/hw/riscv/riscv-iommu.c
+++ b/hw/riscv/riscv-iommu.c
@@ -866,6 +866,143 @@ static bool riscv_iommu_validate_process_ctx(RISCVIOMMUState *s,
return true;
}
+/**
+ * pdt_memory_read: PDT wrapper of dma_memory_read.
+ *
+ * @s: IOMMU Device State
+ * @ctx: Device Translation Context with devid and pasid set
+ * @addr: address within that address space
+ * @buf: buffer with the data transferred
+ * @len: length of the data transferred
+ * @attrs: memory transaction attributes
+ */
+static MemTxResult pdt_memory_read(RISCVIOMMUState *s,
+ RISCVIOMMUContext *ctx,
+ dma_addr_t addr,
+ void *buf, dma_addr_t len,
+ MemTxAttrs attrs)
+{
+ uint64_t gatp_mode, pte;
+ struct {
+ unsigned char step;
+ unsigned char levels;
+ unsigned char ptidxbits;
+ unsigned char ptesize;
+ } sc;
+ MemTxResult ret;
+ dma_addr_t base = addr;
+
+ /* G stages translation mode */
+ gatp_mode = get_field(ctx->gatp, RISCV_IOMMU_ATP_MODE_FIELD);
+ if (gatp_mode == RISCV_IOMMU_DC_IOHGATP_MODE_BARE)
+ goto out;
+
+ /* G stages translation tables root pointer */
+ base = PPN_PHYS(get_field(ctx->gatp, RISCV_IOMMU_ATP_PPN_FIELD));
+
+ /* Start at step 0 */
+ sc.step = 0;
+
+ if (s->fctl & RISCV_IOMMU_FCTL_GXL) {
+ /* 32bit mode for GXL == 1 */
+ switch (gatp_mode) {
+ case RISCV_IOMMU_DC_IOHGATP_MODE_SV32X4:
+ if (!(s->cap & RISCV_IOMMU_CAP_SV32X4)) {
+ return MEMTX_ACCESS_ERROR;
+ }
+ sc.levels = 2;
+ sc.ptidxbits = 10;
+ sc.ptesize = 4;
+ break;
+ default:
+ return MEMTX_ACCESS_ERROR;
+ }
+ } else {
+ /* 64bit mode for GXL == 0 */
+ switch (gatp_mode) {
+ case RISCV_IOMMU_DC_IOHGATP_MODE_SV39X4:
+ if (!(s->cap & RISCV_IOMMU_CAP_SV39X4)) {
+ return MEMTX_ACCESS_ERROR;
+ }
+ sc.levels = 3;
+ sc.ptidxbits = 9;
+ sc.ptesize = 8;
+ break;
+ case RISCV_IOMMU_DC_IOHGATP_MODE_SV48X4:
+ if (!(s->cap & RISCV_IOMMU_CAP_SV48X4)) {
+ return MEMTX_ACCESS_ERROR;
+ }
+ sc.levels = 4;
+ sc.ptidxbits = 9;
+ sc.ptesize = 8;
+ break;
+ case RISCV_IOMMU_DC_IOHGATP_MODE_SV57X4:
+ if (!(s->cap & RISCV_IOMMU_CAP_SV57X4)) {
+ return MEMTX_ACCESS_ERROR;
+ }
+ sc.levels = 5;
+ sc.ptidxbits = 9;
+ sc.ptesize = 8;
+ break;
+ default:
+ return MEMTX_ACCESS_ERROR;
+ }
+ }
+
+ do {
+ const unsigned va_bits = (sc.step ? 0 : 2) + sc.ptidxbits;
+ const unsigned va_skip = TARGET_PAGE_BITS + sc.ptidxbits *
+ (sc.levels - 1 - sc.step);
+ const unsigned idx = (addr >> va_skip) & ((1 << va_bits) - 1);
+ const dma_addr_t pte_addr = base + idx * sc.ptesize;
+
+ /* Address range check before first level lookup */
+ if (!sc.step) {
+ const uint64_t va_mask = (1ULL << (va_skip + va_bits)) - 1;
+ if ((addr & va_mask) != addr) {
+ return MEMTX_ACCESS_ERROR;
+ }
+ }
+
+ /* Read page table entry */
+ if (sc.ptesize == 4) {
+ uint32_t pte32 = 0;
+ ret = ldl_le_dma(s->target_as, pte_addr, &pte32, attrs);
+ pte = pte32;
+ } else {
+ ret = ldq_le_dma(s->target_as, pte_addr, &pte, attrs);
+ }
+ if (ret != MEMTX_OK)
+ return ret;
+
+ sc.step++;
+ hwaddr ppn = pte >> PTE_PPN_SHIFT;
+
+ if (!(pte & PTE_V)) {
+ return MEMTX_ACCESS_ERROR; /* Invalid PTE */
+ } else if (!(pte & (PTE_R | PTE_W | PTE_X))) {
+ base = PPN_PHYS(ppn); /* Inner PTE, continue walking */
+ } else if ((pte & (PTE_R | PTE_W | PTE_X)) == PTE_W) {
+ return MEMTX_ACCESS_ERROR; /* Reserved leaf PTE flags: PTE_W */
+ } else if ((pte & (PTE_R | PTE_W | PTE_X)) == (PTE_W | PTE_X)) {
+ return MEMTX_ACCESS_ERROR; /* Reserved leaf PTE flags: PTE_W + PTE_X */
+ } else if (ppn & ((1ULL << (va_skip - TARGET_PAGE_BITS)) - 1)) {
+ return MEMTX_ACCESS_ERROR; /* Misaligned PPN */
+ } else {
+ /* Leaf PTE, translation completed. */
+ base = PPN_PHYS(ppn) | (addr & ((1ULL << va_skip) - 1));
+ break;
+ }
+
+ if (sc.step == sc.levels) {
+ return MEMTX_ACCESS_ERROR; /* Can't find leaf PTE */
+ }
+ } while (1);
+
+out:
+ return dma_memory_read(s->target_as, base, buf, len, attrs);
+}
+
/*
* RISC-V IOMMU Device Context Loopkup - Device Directory Tree Walk
*
@@ -1038,7 +1175,7 @@ static int riscv_iommu_ctx_fetch(RISCVIOMMUState *s, RISCVIOMMUContext *ctx)
*/
const int split = depth * 9 + 8;
addr |= ((ctx->process_id >> split) << 3) & ~TARGET_PAGE_MASK;
- if (dma_memory_read(s->target_as, addr, &de, sizeof(de),
+ if (pdt_memory_read(s, ctx, addr, &de, sizeof(de),
MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
return RISCV_IOMMU_FQ_CAUSE_PDT_LOAD_FAULT;
}
@@ -1053,7 +1190,7 @@ static int riscv_iommu_ctx_fetch(RISCVIOMMUState *s, RISCVIOMMUContext *ctx)
/* Leaf entry in PDT */
addr |= (ctx->process_id << 4) & ~TARGET_PAGE_MASK;
- if (dma_memory_read(s->target_as, addr, &dc.ta, sizeof(uint64_t) * 2,
+ if (pdt_memory_read(s, ctx, addr, &dc.ta, sizeof(uint64_t) * 2,
MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
return RISCV_IOMMU_FQ_CAUSE_PDT_LOAD_FAULT;
}
--
2.40.1On 13.09.2025 07:12, guoren@kernel.org wrote:
> From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>
>
> Current implementation is wrong when iohgatp != bare. The RISC-V
> IOMMU specification has defined that the PDT is based on GPA, not
> SPA. So this patch fixes the problem, making PDT walk correctly
> when the G-stage table walk is enabled.
>
> Fixes: 0c54acb8243d ("hw/riscv: add RISC-V IOMMU base emulation")
> Cc: qemu-stable@nongnu.org
> Cc: Sebastien Boeuf <seb@rivosinc.com>
> Cc: Tomasz Jeznach <tjeznach@rivosinc.com>
> Reviewed-by: Weiwei Li <liwei1518@gmail.com>
> Reviewed-by: Nutty Liu <liujingqi@lanxincomputing.com>
> Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
Ping? Can we merge this one to master, so I can pick it up for
the stable branches?
Thanks,
/mjt
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