linux-kernel - Re: [PATCH v5 14/14] iommu/arm-smmu-v3: Report events that belong to devices attached to vIOMMU

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Message-ID: <20250113190641.GQ5556@nvidia.com>
Date: Mon, 13 Jan 2025 15:06:41 -0400
From: Jason Gunthorpe <jgg@...dia.com>
To: Nicolin Chen <nicolinc@...dia.com>
Cc: will@...nel.org, kevin.tian@...el.com, corbet@....net,
	oe-kbuild-all@...ts.linux.dev, joro@...tes.org,
	suravee.suthikulpanit@....com, robin.murphy@....com,
	dwmw2@...radead.org, baolu.lu@...ux.intel.com, shuah@...nel.org,
	linux-kernel@...r.kernel.org, iommu@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-kselftest@...r.kernel.org, linux-doc@...r.kernel.org,
	eric.auger@...hat.com, jean-philippe@...aro.org, mdf@...nel.org,
	mshavit@...gle.com, shameerali.kolothum.thodi@...wei.com,
	smostafa@...gle.com, ddutile@...hat.com, yi.l.liu@...el.com,
	patches@...ts.linux.dev
Subject: Re: [PATCH v5 14/14] iommu/arm-smmu-v3: Report events that belong to
 devices attached to vIOMMU

On Mon, Jan 13, 2025 at 11:01:10AM -0800, Nicolin Chen wrote:

> +/* This is basically iommu_vevent_arm_smmuv3 in u64 for conversion */
> +struct arm_vsmmu_evt {
> +	union {
> +		u64 evt[EVTQ_ENT_DWORDS];
> +		struct iommu_vevent_arm_smmuv3 uevt;
> +	};
> +};

This doesn't seem right, don't make unions like this

>  int arm_vmaster_report_event(struct arm_smmu_vmaster *vmaster, u64 *evt)
>  {
> -	struct iommu_vevent_arm_smmuv3 vevt =
> -		*(struct iommu_vevent_arm_smmuv3 *)evt;

evt is clearly not a iommu_vevent_arm_smmuv3 since it has the wrong
endianess? It should stay in its own type.

struct struct iommu_vevent_arm_smmuv3 uevt;

uet.evt[0] = cpu_to_le64((evt[0] & ~EVTQ_0_SID) | FIELD_PREP(EVTQ_0_SID, vmaster->vsid));
for (i = 1; i != EVTQ_ENT_DWORDS; i++)
    uet.evt[i] = cpu_to_le64(evt[i]);

Jason