linux-kernel - [PATCH v2 10/10] vfio: Do not allow !ops->dma_unmap in vfio_pin/unpin

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Message-ID: <59e5eeac675172ab1cb07236a3eb3e166553fe71.1675802050.git.nicolinc@nvidia.com>
Date:   Tue, 7 Feb 2023 13:18:02 -0800
From:   Nicolin Chen <nicolinc@...dia.com>
To:     <jgg@...dia.com>, <kevin.tian@...el.com>, <joro@...tes.org>,
        <will@...nel.org>, <robin.murphy@....com>,
        <alex.williamson@...hat.com>, <shuah@...nel.org>
CC:     <yi.l.liu@...el.com>, <linux-kernel@...r.kernel.org>,
        <iommu@...ts.linux.dev>, <kvm@...r.kernel.org>,
        <linux-kselftest@...r.kernel.org>, <baolu.lu@...ux.intel.com>
Subject: [PATCH v2 10/10] vfio: Do not allow !ops->dma_unmap in vfio_pin/unpin_pages()

A driver that doesn't implement ops->dma_unmap shouldn't be allowed to do
vfio_pin/unpin_pages(), though it can use vfio_dma_rw() to access an iova
range. Deny !ops->dma_unmap cases in vfio_pin/unpin_pages().

Suggested-by: Kevin Tian <kevin.tian@...el.com>
Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
 drivers/vfio/vfio_main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 8559c3dfb335..c7f3251ad6e5 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -1543,6 +1543,8 @@ int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
 
 		if (iova > ULONG_MAX)
 			return -EINVAL;
+		if (!device->ops->dma_unmap)
+			return -EINVAL;
 		/*
 		 * VFIO ignores the sub page offset, npages is from the start of
 		 * a PAGE_SIZE chunk of IOVA. The caller is expected to recover
@@ -1580,6 +1582,8 @@ void vfio_unpin_pages(struct vfio_device *device, dma_addr_t iova, int npage)
 	if (device->iommufd_access) {
 		if (WARN_ON(iova > ULONG_MAX))
 			return;
+		if (!device->ops->dma_unmap)
+			return;
 		iommufd_access_unpin_pages(device->iommufd_access,
 					   ALIGN_DOWN(iova, PAGE_SIZE),
 					   npage * PAGE_SIZE);
-- 
2.39.1