From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jacob Pan <jacob.pan@linux.microsoft.com>
Cc: Yu Zhang <zhangyu1@linux.microsoft.com>,
linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
iommu@lists.linux.dev, linux-pci@vger.kernel.org,
linux-arch@vger.kernel.org, x86@kernel.org, wei.liu@kernel.org,
kys@microsoft.com, haiyangz@microsoft.com, decui@microsoft.com,
longli@microsoft.com, joro@8bytes.org, will@kernel.org,
robin.murphy@arm.com, bhelgaas@google.com,
kwilczynski@kernel.org, lpieralisi@kernel.org, mani@kernel.org,
robh@kernel.org, arnd@arndb.de, mhklinux@outlook.com,
tgopinath@linux.microsoft.com,
easwar.hariharan@linux.microsoft.com,
mrathor@linux.microsoft.com, baolu.lu@linux.intel.com,
suravee.suthikulpanit@amd.com, vasant.hegde@amd.com
Subject: Re: [PATCH v3 4/5] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest
Date: Thu, 13 Aug 2026 19:46:27 -0300 [thread overview]
Message-ID: <20260813224627.GA933791@ziepe.ca> (raw)
In-Reply-To: <20260813152913.00003d8a@linux.microsoft.com>
On Thu, Aug 13, 2026 at 03:29:13PM -0700, Jacob Pan wrote:
> > +static int hv_iommu_blocking_attach_dev(struct iommu_domain *domain,
> > + struct device *dev,
> > + struct iommu_domain *old)
> > +{
> > + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev);
> > + struct hv_iommu_domain *hv_domain =
> > to_hv_iommu_domain(domain);
> > + struct pci_dev *pdev = to_pci_dev(dev);
> > + int ret;
> > +
> > + if (pdev->ats_enabled)
> > + pci_disable_ats(pdev);
> > +
> > + if (vdev->hv_domain == hv_domain)
> > + return 0;
> It may not be needed since the core code will check this. If you keep
> this as extra precaution, should this be moved up before ats? since ats
> must be disabled already if blocking domain is attached.
Why check it at all? Is there an issue with attaching the same thing
twice? Will it blip the DMA or something?
Jason
next prev parent reply other threads:[~2026-08-13 22:46 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-11 15:50 [PATCH v3 0/5] Hyper-V: Add para-virtualized IOMMU support for Linux guests Yu Zhang
2026-08-11 15:50 ` [PATCH v3 1/5] hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU Yu Zhang
2026-08-12 18:08 ` Jacob Pan
2026-08-14 1:31 ` Mukesh R
2026-08-11 15:50 ` [PATCH v3 2/5] Drivers: hv: Add logical device ID registry for vPCI devices Yu Zhang
2026-08-11 15:50 ` [PATCH v3 3/5] iommu/x86: Share the architectural MSI reserved range Yu Zhang
2026-08-11 16:21 ` Jason Gunthorpe
2026-08-12 8:58 ` Yu Zhang
2026-08-12 12:30 ` Jason Gunthorpe
2026-08-11 15:50 ` [PATCH v3 4/5] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest Yu Zhang
2026-08-13 13:49 ` Jason Gunthorpe
2026-08-13 18:02 ` Easwar Hariharan
2026-08-13 22:29 ` Jacob Pan
2026-08-13 22:46 ` Jason Gunthorpe [this message]
2026-08-11 15:50 ` [PATCH v3 5/5] iommu/hyperv: Add page-selective IOTLB flush support Yu Zhang
2026-08-13 23:07 ` Jacob Pan
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