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Date: Sun, 12 May 2024 13:56:40 -0700
From: Nicolin Chen <nicolinc@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>
CC: <will@kernel.org>, <robin.murphy@arm.com>, <joro@8bytes.org>,
	<thierry.reding@gmail.com>, <vdumpa@nvidia.com>, <jonathanh@nvidia.com>,
	<linux-kernel@vger.kernel.org>, <iommu@lists.linux.dev>,
	<linux-arm-kernel@lists.infradead.org>, <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH v7 3/6] iommu/arm-smmu-v3: Enforce
 arm_smmu_cmdq_build_sync_cmd
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On Sun, May 12, 2024 at 12:39:43PM -0300, Jason Gunthorpe wrote:
> 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 ?

Yes. I will add that.

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

Thanks!
Nicolin