From: Jason Gunthorpe <jgg@ziepe.ca>
To: Yu Zhang <zhangyu1@linux.microsoft.com>
Cc: Jacob Pan <jacob.pan@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: Mon, 17 Aug 2026 09:22:16 -0300 [thread overview]
Message-ID: <20260817122216.GD933791@ziepe.ca> (raw)
In-Reply-To: <p7ts4y6lxt7k6ldzaa26v7rckmmp7o5js2gn2r3eantgzut2cc@xxsvso76nefj>
On Fri, Aug 14, 2026 at 05:37:48PM +0800, Yu Zhang wrote:
> > Why check it at all? Is there an issue with attaching the same thing
> > twice? Will it blip the DMA or something?
>
> Actually, I do not think there should be any issue with attaching twice.
> Hyper-V *should* be able to accept such attachment. But I do not want to
> make such assumption just for a redundant hypercall.
>
> Does this reasoning make sense, or would you prefer that I remove the
> check?
I would probably drop it. Having blocking always set blocking to the
HW regardless of what the SW tracking state says feels more robust to
me.
Jason
next prev parent reply other threads:[~2026-08-17 12:22 UTC|newest]
Thread overview: 30+ 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
2026-08-14 10:04 ` Yu Zhang
2026-08-14 15:31 ` Michael Kelley
2026-08-17 2:33 ` Yu Zhang
2026-08-11 15:50 ` [PATCH v3 2/5] Drivers: hv: Add logical device ID registry for vPCI devices Yu Zhang
2026-08-14 15:31 ` Michael Kelley
2026-08-17 10:37 ` Yu Zhang
2026-08-17 17:27 ` Michael Kelley
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
2026-08-14 9:47 ` Yu Zhang
2026-08-13 18:02 ` Easwar Hariharan
2026-08-14 12:49 ` Yu Zhang
2026-08-13 22:29 ` Jacob Pan
2026-08-13 22:46 ` Jason Gunthorpe
2026-08-14 9:37 ` Yu Zhang
2026-08-17 12:22 ` Jason Gunthorpe [this message]
2026-08-17 16:01 ` Yu Zhang
2026-08-17 17:22 ` Yu Zhang
2026-08-17 17:35 ` Jason Gunthorpe
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
2026-08-14 12:07 ` Yu Zhang
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