Linux PCI subsystem development
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From: Jacob Pan <jacob.pan@linux.microsoft.com>
To: Yu Zhang <zhangyu1@linux.microsoft.com>
Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
	iommu@lists.linux.dev, linux-pci@vger.kernel.org,
	linux-arch@vger.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, jgg@ziepe.ca,
	mhklinux@outlook.com, tgopinath@linux.microsoft.com,
	easwar.hariharan@linux.microsoft.com,
	mrathor@linux.microsoft.com, jacob.pan@linux.microsoft.com
Subject: Re: [PATCH v2 3/4] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest
Date: Mon, 6 Jul 2026 09:55:10 -0700	[thread overview]
Message-ID: <20260706095510.00007ce1@linux.microsoft.com> (raw)
In-Reply-To: <20260702160518.311234-4-zhangyu1@linux.microsoft.com>

Hi Yu,

On Fri,  3 Jul 2026 00:05:17 +0800
Yu Zhang <zhangyu1@linux.microsoft.com> wrote:

> +static int hv_iommu_attach_dev(struct iommu_domain *domain, struct
> device *dev,
> +			       struct iommu_domain *old)
> +{
> +	u64 status;
> +	u32 prefix;
> +	unsigned long flags;
> +	struct pci_dev *pdev;
> +	struct hv_input_attach_device_domain *input;
> +	struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev);
> +	struct hv_iommu_domain *hv_domain =
> to_hv_iommu_domain(domain);
> +	int ret;
> +
> +	if (vdev->hv_domain == hv_domain)
> +		return 0;
> +
Is this needed? seems the core code already skips same domain attach?
i.e.

static int __iommu_group_set_domain_internal(struct iommu_group *group,
					     struct iommu_domain
*new_domain, unsigned int flags)
{
...
	if (group->domain == new_domain)
		return 0;

  parent reply	other threads:[~2026-07-06 16:55 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-02 16:05 [PATCH v2 0/4] Hyper-V: Add para-virtualized IOMMU support for Linux guests Yu Zhang
2026-07-02 16:05 ` [PATCH v2 1/4] hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU Yu Zhang
2026-07-02 16:36   ` sashiko-bot
2026-07-02 16:05 ` [PATCH v2 2/4] Drivers: hv: Add logical device ID registry for vPCI devices Yu Zhang
2026-07-02 16:42   ` sashiko-bot
2026-07-02 16:05 ` [PATCH v2 3/4] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest Yu Zhang
2026-07-02 17:08   ` sashiko-bot
2026-07-03 17:32   ` Jason Gunthorpe
2026-07-06 16:55   ` Jacob Pan [this message]
2026-07-07  0:08   ` Mukesh R
2026-07-02 16:05 ` [PATCH v2 4/4] iommu/hyperv: Add page-selective IOTLB flush support Yu Zhang
2026-07-02 17:20   ` sashiko-bot
2026-07-03 17:10   ` Jason Gunthorpe

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