Re: [RFC PATCH v5 10/10] iommu/riscv: Add IOTINVAL.GVMA invalidations

["Nutty.Liu" <nutty.liu@hotmail.com>]

On 10/20/2026 5:41 PM, fangyu.yu@linux.alibaba.com wrote:
> From: Fangyu Yu <fangyu.yu@linux.alibaba.com>
>
> Previously, only IOTINVAL.VMA was issued, which is insufficient for
> second-stage address translation consistency.
>
> Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>

Thanks,
Nutty
> ---
>   drivers/iommu/riscv/iommu.c | 18 +++++++++++++++---
>   1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
> index e3791e912af3..a764a172c588 100644
> --- a/drivers/iommu/riscv/iommu.c
> +++ b/drivers/iommu/riscv/iommu.c
> @@ -830,6 +830,15 @@ static int riscv_iommu_iodir_set_mode(struct riscv_iommu_device *iommu,
>   	riscv_iommu_cmd_inval_vma(&cmd);
>   	riscv_iommu_cmd_send(iommu, &cmd);
>   
> +	/*
> +	 * Per the RISC-V IOMMU spec (sec. 5.5), the IOMMU may retain
> +	 * cached translations across mode switches. IOTINVAL.VMA only
> +	 * covers first-stage leaf PTEs, so use a global IOTINVAL.GVMA
> +	 * to flush stale second-stage translations.
> +	 */
> +	riscv_iommu_cmd_inval_gvma(&cmd);
> +	riscv_iommu_cmd_send(iommu, &cmd);
> +
>   	/* IOFENCE.C */
>   	riscv_iommu_cmd_sync(iommu, RISCV_IOMMU_IOTINVAL_TIMEOUT);
>   
> @@ -1175,12 +1184,15 @@ static void riscv_iommu_iodir_iotinval(struct riscv_iommu_device *iommu,
>   		/*
>   		 * else: IOTINVAL.VMA with GV=1,AV=PSCV=0,and
>   		 * GSCID=DC.iohgatp.GSCID
> -		 *
> +		 */
> +		riscv_iommu_cmd_send(iommu, &cmd);
> +		/*
>   		 * IOTINVAL.GVMA with GV=1,AV=0,and
>   		 * GSCID=DC.iohgatp.GSCID
> -		 * TODO: For now, the Second-Stage feature have not yet been merged,
> -		 * also issue IOTINVAL.GVMA once second-stage support is merged.
>   		 */
> +		riscv_iommu_cmd_inval_gvma(&cmd);
> +		riscv_iommu_cmd_inval_set_gscid(&cmd,
> +			FIELD_GET(RISCV_IOMMU_DC_IOHGATP_GSCID, iohgatp));
>   	}
>   	riscv_iommu_cmd_send(iommu, &cmd);
>   }