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From: Nicolin Chen <nicolinc@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Will Deacon <will@kernel.org>, Jason Gunthorpe <jgg@nvidia.com>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Robin Murphy <robin.murphy@arm.com>,
	"joro@8bytes.org" <joro@8bytes.org>,
	David Woodhouse <dwmw2@infradead.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 1/5] iommu/arm-smmu-v3-iommufd: Reject unsupported bits in invalidation commands
Date: Fri, 3 Jul 2026 01:00:27 -0700	[thread overview]
Message-ID: <akdsG46/j21yzEkU@nvidia.com> (raw)
In-Reply-To: <CO1PR11MB4835A412EADC0D56A8BDBBFC8CF42@CO1PR11MB4835.namprd11.prod.outlook.com>

On Fri, Jul 03, 2026 at 06:20:37AM +0000, Tian, Kevin wrote:
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > +	case CMDQ_OP_ATC_INV:
> > +		/*
> > +		 * Exclude the Global bit: it makes the SMMU ignore the SID
> > and
> > +		 * invalidate the ATC of every device, not just the guest's.
> > +		 */
> 
> I suppose the Global bit in vcmdq is guaranteed by HW to be contained within
> the vcmdq, then the SMMU will convert it into multiple INV cmds sent to
> devices associated with the vcmdq?

Actually, this piece is wrong. I double-checked the spec, the
Global bit isn't about SID but SSID (should be provided too).
So, the Global bit should be allowed. I need to fix it..

Similarly for VCMDQ, it is allowed. HW only validates whether
the given SID/BDF is programmed into the VINTF or not.

Thanks (for the question)!
Nicolin

  reply	other threads:[~2026-07-03  8:01 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-29 21:15 [PATCH v1 0/5] iommufd: Iterate the cache invalidation array in the core Nicolin Chen
2026-06-29 21:15 ` [PATCH v1 1/5] iommu/arm-smmu-v3-iommufd: Reject unsupported bits in invalidation commands Nicolin Chen
2026-07-03  6:20   ` Tian, Kevin
2026-07-03  8:00     ` Nicolin Chen [this message]
2026-06-29 21:15 ` [PATCH v1 2/5] iommufd: Iterate the cache invalidation array in the core Nicolin Chen
2026-07-03  6:21   ` Tian, Kevin
2026-06-29 21:15 ` [PATCH v1 3/5] iommufd/selftest: Convert cache invalidation mocks to the core array loop Nicolin Chen
2026-07-03  6:22   ` Tian, Kevin
2026-06-29 21:15 ` [PATCH v1 4/5] iommu/arm-smmu-v3-iommufd: Convert cache invalidation " Nicolin Chen
2026-07-03  6:30   ` Tian, Kevin
2026-06-29 21:15 ` [PATCH v1 5/5] iommu/vt-d: Convert nested " Nicolin Chen
2026-07-03  6:31   ` Tian, Kevin

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