linux-kernel - Re: [RESEND PATCH v8 04/11] bus: platform, amba, fsl-mc, PCI: Add device DMA ownership management

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Message-ID: <ZJxFZkxvPNj74uQe@nvidia.com>
Date:   Wed, 28 Jun 2023 11:36:22 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Zenghui Yu <yuzenghui@...wei.com>
Cc:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Kevin Tian <kevin.tian@...el.com>,
        linux-kernel@...r.kernel.org, iommu@...ts.linux.dev
Subject: Re: [RESEND PATCH v8 04/11] bus: platform, amba, fsl-mc, PCI: Add
 device DMA ownership management

On Mon, Jun 26, 2023 at 09:02:40PM +0800, Zenghui Yu wrote:

> It looks like on device probe, with DEBUG_TEST_DRIVER_REMOVE,
> .dma_configure() will be executed *twice* via the
> really_probe()/re_probe path, and *no* .dma_cleanup() will be executed.
> The resulting dev::iommu_group::owner_cnt is 2, which will confuse the
> later iommu_group_dma_owner_claimed() call from VFIO on guest startup.

Does this work for you?

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 9c09ca5c4ab68e..7145d9b940b14b 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -693,6 +693,8 @@ static int really_probe(struct device *dev, struct device_driver *drv)
 
 		device_remove(dev);
 		driver_sysfs_remove(dev);
+		if (dev->bus && dev->bus->dma_cleanup)
+			dev->bus->dma_cleanup(dev);
 		device_unbind_cleanup(dev);
 
 		goto re_probe;