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Subject[PATCH] vfio/pci: Resolve sparse endian warnings in IGD support
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Sparse warns:

sparse warnings: (new ones prefixed by >>)
>> drivers/vfio/pci/vfio_pci_igd.c:146:21: sparse: sparse: incorrect type in assignment (different base types) @@ expected unsigned short [addressable] [usertype] val @@ got restricted __le16 [usertype] @@
drivers/vfio/pci/vfio_pci_igd.c:146:21: sparse: expected unsigned short [addressable] [usertype] val
drivers/vfio/pci/vfio_pci_igd.c:146:21: sparse: got restricted __le16 [usertype]
>> drivers/vfio/pci/vfio_pci_igd.c:161:21: sparse: sparse: incorrect type in assignment (different base types) @@ expected unsigned int [addressable] [usertype] val @@ got restricted __le32 [usertype] @@
drivers/vfio/pci/vfio_pci_igd.c:161:21: sparse: expected unsigned int [addressable] [usertype] val
drivers/vfio/pci/vfio_pci_igd.c:161:21: sparse: got restricted __le32 [usertype]
drivers/vfio/pci/vfio_pci_igd.c:176:21: sparse: sparse: incorrect type in assignment (different base types) @@ expected unsigned short [addressable] [usertype] val @@ got restricted __le16 [usertype] @@
drivers/vfio/pci/vfio_pci_igd.c:176:21: sparse: expected unsigned short [addressable] [usertype] val
drivers/vfio/pci/vfio_pci_igd.c:176:21: sparse: got restricted __le16 [usertype]

These are due to trying to use an unsigned to store the result of
a cpu_to_leXX() conversion. These are small variables, so pointer
tricks are wasteful and casting just generates different sparse
warnings. Store to and copy results from a separate little endian
variable.

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/202111290026.O3vehj03-lkp@intel.com/
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
drivers/vfio/pci/vfio_pci_igd.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_igd.c b/drivers/vfio/pci/vfio_pci_igd.c
index 362f91ec8845..352c725ccf18 100644
--- a/drivers/vfio/pci/vfio_pci_igd.c
+++ b/drivers/vfio/pci/vfio_pci_igd.c
@@ -309,13 +309,14 @@ static ssize_t vfio_pci_igd_cfg_rw(struct vfio_pci_core_device *vdev,

if ((pos & 3) && size > 2) {
u16 val;
+ __le16 lval;

ret = pci_user_read_config_word(pdev, pos, &val);
if (ret)
return ret;

- val = cpu_to_le16(val);
- if (copy_to_user(buf + count - size, &val, 2))
+ lval = cpu_to_le16(val);
+ if (copy_to_user(buf + count - size, &lval, 2))
return -EFAULT;

pos += 2;
@@ -324,13 +325,14 @@ static ssize_t vfio_pci_igd_cfg_rw(struct vfio_pci_core_device *vdev,

while (size > 3) {
u32 val;
+ __le32 lval;

ret = pci_user_read_config_dword(pdev, pos, &val);
if (ret)
return ret;

- val = cpu_to_le32(val);
- if (copy_to_user(buf + count - size, &val, 4))
+ lval = cpu_to_le32(val);
+ if (copy_to_user(buf + count - size, &lval, 4))
return -EFAULT;

pos += 4;
@@ -339,13 +341,14 @@ static ssize_t vfio_pci_igd_cfg_rw(struct vfio_pci_core_device *vdev,

while (size >= 2) {
u16 val;
+ __le16 lval;

ret = pci_user_read_config_word(pdev, pos, &val);
if (ret)
return ret;

- val = cpu_to_le16(val);
- if (copy_to_user(buf + count - size, &val, 2))
+ lval = cpu_to_le16(val);
+ if (copy_to_user(buf + count - size, &lval, 2))
return -EFAULT;

pos += 2;

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