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Message-ID: <20211229204202.GA1700874@bhelgaas>
Date: Wed, 29 Dec 2021 14:42:02 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Joerg Roedel <joro@...tes.org>,
Alex Williamson <alex.williamson@...hat.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Jason Gunthorpe <jgg@...dia.com>,
Christoph Hellwig <hch@...radead.org>,
Kevin Tian <kevin.tian@...el.com>,
Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
Robin Murphy <robin.murphy@....com>,
Dan Williams <dan.j.williams@...el.com>, rafael@...nel.org,
Diana Craciun <diana.craciun@....nxp.com>,
Cornelia Huck <cohuck@...hat.com>,
Eric Auger <eric.auger@...hat.com>,
Liu Yi L <yi.l.liu@...el.com>,
Jacob jun Pan <jacob.jun.pan@...el.com>,
Chaitanya Kulkarni <kch@...dia.com>,
Stuart Yoder <stuyoder@...il.com>,
Laurentiu Tudor <laurentiu.tudor@....com>,
Thierry Reding <thierry.reding@...il.com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Jonathan Hunter <jonathanh@...dia.com>,
Li Yang <leoyang.li@....com>,
Dmitry Osipenko <digetx@...il.com>,
iommu@...ts.linux-foundation.org, linux-pci@...r.kernel.org,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 03/13] PCI: pci_stub: Suppress kernel DMA ownership
auto-claiming
On Fri, Dec 17, 2021 at 02:36:58PM +0800, Lu Baolu wrote:
> The pci_dma_configure() marks the iommu_group as containing only devices
> with kernel drivers that manage DMA.
I'm looking at pci_dma_configure(), and I don't see the connection to
iommu_groups.
> Avoid this default behavior for the
> pci_stub because it does not program any DMA itself. This allows the
> pci_stub still able to be used by the admin to block driver binding after
> applying the DMA ownership to vfio.
>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
> drivers/pci/pci-stub.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/pci/pci-stub.c b/drivers/pci/pci-stub.c
> index e408099fea52..6324c68602b4 100644
> --- a/drivers/pci/pci-stub.c
> +++ b/drivers/pci/pci-stub.c
> @@ -36,6 +36,9 @@ static struct pci_driver stub_driver = {
> .name = "pci-stub",
> .id_table = NULL, /* only dynamic id's */
> .probe = pci_stub_probe,
> + .driver = {
> + .suppress_auto_claim_dma_owner = true,
The new .suppress_auto_claim_dma_owner controls whether we call
iommu_device_set_dma_owner(). I guess you added
.suppress_auto_claim_dma_owner because iommu_device_set_dma_owner()
must be done *before* we call the driver's .probe() method?
Otherwise, we could call some new interface from .probe() instead of
adding the flag to struct device_driver.
> + },
> };
>
> static int __init pci_stub_init(void)
> --
> 2.25.1
>
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