linux-kernel - [PATCH 5.5 208/399] vfio/spapr/nvlink2: Skip unpinning pages on error exit

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Message-Id: <20200221072423.130034911@linuxfoundation.org>
Date:   Fri, 21 Feb 2020 08:38:53 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alexey Kardashevskiy <aik@...abs.ru>,
        Alex Williamson <alex.williamson@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.5 208/399] vfio/spapr/nvlink2: Skip unpinning pages on error exit

From: Alexey Kardashevskiy <aik@...abs.ru>

[ Upstream commit 338b4e10f939a71194d8ecef7ece205a942cec05 ]

The nvlink2 subdriver for IBM Witherspoon machines preregisters
GPU memory in the IOMMI API so KVM TCE code can map this memory
for DMA as well. This is done by mm_iommu_newdev() called from
vfio_pci_nvgpu_regops::mmap.

In an unlikely event of failure the data->mem remains NULL and
since mm_iommu_put() (which unregisters the region and unpins memory
if that was regular memory) does not expect mem=NULL, it should not be
called.

This adds a check to only call mm_iommu_put() for a valid data->mem.

Fixes: 7f92891778df ("vfio_pci: Add NVIDIA GV100GL [Tesla V100 SXM2] subdriver")
Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/vfio/pci/vfio_pci_nvlink2.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_nvlink2.c b/drivers/vfio/pci/vfio_pci_nvlink2.c
index f2983f0f84bea..3f5f8198a6bb1 100644
--- a/drivers/vfio/pci/vfio_pci_nvlink2.c
+++ b/drivers/vfio/pci/vfio_pci_nvlink2.c
@@ -97,8 +97,10 @@ static void vfio_pci_nvgpu_release(struct vfio_pci_device *vdev,
 
 	/* If there were any mappings at all... */
 	if (data->mm) {
-		ret = mm_iommu_put(data->mm, data->mem);
-		WARN_ON(ret);
+		if (data->mem) {
+			ret = mm_iommu_put(data->mm, data->mem);
+			WARN_ON(ret);
+		}
 
 		mmdrop(data->mm);
 	}
-- 
2.20.1