linux-kernel - Re: [PATCH v1 13/14] iommu/arm-smmu-v3: Add CMDQ_OP_TLBI_NH_VAA and CMDQ_OP_TLBI_NH

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Message-ID: <510e6e1a-884f-ae5a-35f3-4f4db997abfd@arm.com>
Date:   Thu, 9 Mar 2023 13:44:34 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Nicolin Chen <nicolinc@...dia.com>, jgg@...dia.com, will@...nel.org
Cc:     eric.auger@...hat.com, kevin.tian@...el.com,
        baolu.lu@...ux.intel.com, joro@...tes.org,
        shameerali.kolothum.thodi@...wei.com, jean-philippe@...aro.org,
        linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 13/14] iommu/arm-smmu-v3: Add CMDQ_OP_TLBI_NH_VAA and
 CMDQ_OP_TLBI_NH_ALL

On 2023-03-09 10:53, Nicolin Chen wrote:
> With a nested translation setup, a stage-1 Context Descriptor table can be
> managed by a guest OS in the user space. So, the kernel driver should not
> assume that the guest OS will use a user space device driver that doesn't
> support TLBI_NH_VAA and TLBI_NH_ALL commands.
> 
> Add them in the arm_smmu_cmdq_build_cmd(), to prepare for support of these
> two TLBI invalidation requests from the guest level.
> 
> Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
> ---
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 4 ++++
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 ++
>   2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 1f318b5e0921..ac63185ae268 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -277,6 +277,9 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
>   		/* Cover the entire SID range */
>   		cmd[1] |= FIELD_PREP(CMDQ_CFGI_1_RANGE, 31);
>   		break;
> +	case CMDQ_OP_TLBI_NH_VAA:
> +		ent->tlbi.asid = 0;

This is backwards - NH_VA is a superset of NH_VAA (not to mention that 
quietly modifying the input argument is ugly; in fact it might be nice 
if ent was const here).

Please follow the existing pattern, and decouple NH_VA from EL2_VA if 
necessary.

Thanks,
Robin.

> +		fallthrough;
>   	case CMDQ_OP_TLBI_NH_VA:
>   		cmd[0] |= FIELD_PREP(CMDQ_TLBI_0_VMID, ent->tlbi.vmid);
>   		fallthrough;
> @@ -301,6 +304,7 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
>   	case CMDQ_OP_TLBI_NH_ASID:
>   		cmd[0] |= FIELD_PREP(CMDQ_TLBI_0_ASID, ent->tlbi.asid);
>   		fallthrough;
> +	case CMDQ_OP_TLBI_NH_ALL:
>   	case CMDQ_OP_TLBI_S12_VMALL:
>   		cmd[0] |= FIELD_PREP(CMDQ_TLBI_0_VMID, ent->tlbi.vmid);
>   		break;
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> index 6cf516852721..6181d6cd8b51 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -454,8 +454,10 @@ struct arm_smmu_cmdq_ent {
>   			};
>   		} cfgi;
>   
> +		#define CMDQ_OP_TLBI_NH_ALL	0x10
>   		#define CMDQ_OP_TLBI_NH_ASID	0x11
>   		#define CMDQ_OP_TLBI_NH_VA	0x12
> +		#define CMDQ_OP_TLBI_NH_VAA	0x13
>   		#define CMDQ_OP_TLBI_EL2_ALL	0x20
>   		#define CMDQ_OP_TLBI_EL2_ASID	0x21
>   		#define CMDQ_OP_TLBI_EL2_VA	0x22