Re: [PATCH v2 1/1] hw/riscv/riscv-iommu.c: check for misaligned IOHGATP_PPN

[Chao Liu <chao.liu.zevorn@gmail.com>]

On Thu, Jul 02, 2026 at 05:36:16PM +0800, Daniel Henrique Barboza wrote:
> We must check if IOHGATP_PPN is 16kb aligned for non-bare GATP modes.
> 
> Fixes: 69a9ae4836 ("hw/riscv/riscv-iommu: add ATS support")
> Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3550
> Signed-off-by: Daniel Henrique Barboza <daniel.barboza@oss.qualcomm.com>
Reviewed-by: Chao Liu <chao.liu.zevorn@gmail.com>

> ---
>  hw/riscv/riscv-iommu.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
> index 974042d017..ad8e108a23 100644
> --- a/hw/riscv/riscv-iommu.c
> +++ b/hw/riscv/riscv-iommu.c
> @@ -813,6 +813,21 @@ static bool riscv_iommu_validate_device_ctx(RISCVIOMMUState *s,
>          return false;
>      }
>  
> +    if (gatp != RISCV_IOMMU_DC_IOHGATP_MODE_BARE) {
> +        uint64_t iohgatp_ppn = get_field(ctx->gatp,
> +                                         RISCV_IOMMU_DC_IOHGATP_PPN);
> +
> +        /*
> +         * One of the conditions for a misconfigured DDT entry
> +         * according to the riscv-spec: "DC.iohgatp.MODE is not
> +         * Bare and the root page table (address) determined by
> +         * DC.iohgatp.PPN is not aligned to a 16-KiB boundary."
> +         */
> +        if (PPN_PHYS(iohgatp_ppn) & ((1ULL << 14) - 1)) {
> +            return false;
> +        }
> +    }
> +
>      fsc_mode = get_field(ctx->satp, RISCV_IOMMU_DC_FSC_MODE);
>  
>      if (ctx->tc & RISCV_IOMMU_DC_TC_PDTV) {
> -- 
> 2.43.0
>