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Wed, 12 Feb 2025 11:15:38 -0800 (PST) Date: Wed, 12 Feb 2025 19:16:03 +0000 From: Jean-Philippe Brucker To: Jacob Pan Cc: Jason Gunthorpe , iommu@lists.linux.dev, Joerg Roedel , Robin Murphy , virtualization@lists.linux.dev, Will Deacon , Eric Auger , patches@lists.linux.dev Subject: Re: [PATCH 0/5] Convert virtio-iommu to domain_alloc_paging() Message-ID: <20250212191603.GA4085684@myrica> References: <0-v1-91eed9c8014a+53a37-iommu_virtio_domains_jgg@nvidia.com> <67abee53.170a0220.154671.ae28SMTPIN_ADDED_BROKEN@mx.google.com> <20250212115845.GA1627174@myrica> <67acd4e2.630a0220.365aab.e098SMTPIN_ADDED_BROKEN@mx.google.com> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <67acd4e2.630a0220.365aab.e098SMTPIN_ADDED_BROKEN@mx.google.com> On Wed, Feb 12, 2025 at 09:05:35AM -0800, Jacob Pan wrote: > > Does reproducing this require > > modifying QEMU or Linux to disable support for F_BYPASS_CONFIG, or > > just passing QEMU/kernel parameters? > I only modified guest code to pretend F_BYPASS_CONFIG is not supported, > a couple of places like: > > - if (virtio_has_feature(viommu->vdev, > VIRTIO_IOMMU_F_BYPASS_CONFIG)) { > + if (!virtio_has_feature(viommu->vdev, > VIRTIO_IOMMU_F_BYPASS_CONFIG)) { > > Is there a QEMU command line option to disable > VIRTIO_IOMMU_F_BYPASS_CONFIG? No, but I have a patch for testing that didn't seem worth upstreaming: https://jpbrucker.net/git/qemu/commit/?h=virtio-iommu/bypass&id=ab2f435576a95914d2939ef4f0b190548721fe7b With it I'm able to reproduce the issue, looks like I only tested this case with virtual devices and not VFIO. I'll look for a fix Thanks, Jean