linux-kernel - Re: [PATCH v7 3/6] iommu/arm-smmu-v3: Enforce arm_smmu_cmdq_build_sync

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Date: Sun, 12 May 2024 12:39:43 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Nicolin Chen <nicolinc@...dia.com>
Cc: will@...nel.org, robin.murphy@....com, joro@...tes.org,
	thierry.reding@...il.com, vdumpa@...dia.com, jonathanh@...dia.com,
	linux-kernel@...r.kernel.org, iommu@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH v7 3/6] iommu/arm-smmu-v3: Enforce
 arm_smmu_cmdq_build_sync_cmd

On Tue, May 07, 2024 at 10:56:51PM -0700, Nicolin Chen wrote:
> There is an existing arm_smmu_cmdq_build_sync_cmd() so the driver should
> call it at all places other than going through arm_smmu_cmdq_build_cmd()
> separately. This helps the following patch that adds a CS_NONE quirk for
> tegra241-cmdqv driver.
> 
> Note that this changes the type of CMD_SYNC in __arm_smmu_cmdq_skip_err,
> for ARM_SMMU_OPT_MSIPOLL=true cases, from previously a non-MSI one to an
> MSI one that is proven to still work by a hacking test:
>   nvme: Adding to iommu group 10
>   nvme: --------hacking-----------
>   arm-smmu-v3: unexpected global error reported (0x00000001),
>                this could be serious
>   arm-smmu-v3: CMDQ error (cons 0x01000022): Illegal command
>   arm-smmu-v3: skipping command in error state:
>   arm-smmu-v3:  0x0000000000000000
>   arm-smmu-v3:  0x0000000000000000
>   nvme: -------recovered----------
>   nvme nvme0: 72/0/0 default/read/poll queues
>    nvme0n1: p1 p2

Nice
 
> @@ -350,20 +340,23 @@ static struct arm_smmu_cmdq *arm_smmu_get_cmdq(struct arm_smmu_device *smmu)
>  static void arm_smmu_cmdq_build_sync_cmd(u64 *cmd, struct arm_smmu_device *smmu,
>  					 struct arm_smmu_queue *q, u32 prod)
>  {
> -	struct arm_smmu_cmdq_ent ent = {
> -		.opcode = CMDQ_OP_CMD_SYNC,
> -	};
> +	memset(cmd, 0, 1 << CMDQ_ENT_SZ_SHIFT);

The command would also benifit from its own type someday :\

Maybe this should just be cmd[1] = 0 ?

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Jason