linux-kernel - [PATCH] vfio: Ignore -ENODEV when getting MSI cookie

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Message-Id: <20200401102724.161712-1-andre.przywara@arm.com>
Date:   Wed,  1 Apr 2020 11:27:24 +0100
From:   Andre Przywara <andre.przywara@....com>
To:     Alex Williamson <alex.williamson@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>
Cc:     Robin Murphy <robin.murphy@....com>, Will Deacon <will@...nel.org>,
        Eric Auger <eric.auger@...hat.com>, kvm@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH] vfio: Ignore -ENODEV when getting MSI cookie

When we try to get an MSI cookie for a VFIO device, that can fail if
CONFIG_IOMMU_DMA is not set. In this case iommu_get_msi_cookie() returns
-ENODEV, and that should not be fatal.

Ignore that case and proceed with the initialisation.

This fixes VFIO with a platform device on the Calxeda Midway (no MSIs).

Fixes: f6810c15cf973f ("iommu/arm-smmu: Clean up early-probing workarounds")
Signed-off-by: Andre Przywara <andre.przywara@....com>
Acked-by: Robin Murphy <robin.murphy@....com>
Reviewed-by: Eric Auger <eric.auger@...hat.com>
---
 drivers/vfio/vfio_iommu_type1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 9fdfae1cb17a..85b32c325282 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -1787,7 +1787,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 
 	if (resv_msi) {
 		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
-		if (ret)
+		if (ret && ret != -ENODEV)
 			goto out_detach;
 	}
 
-- 
2.17.1