[PATCH v3 3/3] vfio/pci: Continue to refactor vfio_pci_core_do_io_rw

Gerd Bayer
2024-04-25T16:56:16Z

Convert if-elseif-chain into switch-case.
Separate out and generalize the code from the if-clauses so the result
can be used in the switch statement.

Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
---
drivers/vfio/pci/vfio_pci_rdwr.c | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index 8ed06edaee23..634c00b03c71 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -131,6 +131,20 @@ VFIO_IORDWR(32)
VFIO_IORDWR(64)
#endif

+static int fill_size(size_t fillable, loff_t off)
+{
+ unsigned int fill_size;
+#if defined(ioread64) && defined(iowrite64)
+ for (fill_size = 8; fill_size >= 0; fill_size /= 2) {
+#else
+ for (fill_size = 4; fill_size >= 0; fill_size /= 2) {
+#endif /* defined(ioread64) && defined(iowrite64) */
+ if (fillable >= fill_size && !(off % fill_size))
+ return fill_size;
+ }
+ return -1;
+}
+
/*
* Read or write from an __iomem region (MMIO or I/O port) with an excluded
* range which is inaccessible. The excluded range drops writes and fills
@@ -155,34 +169,38 @@ ssize_t vfio_pci_core_do_io_rw(struct vfio_pci_core_device *vdev, bool test_mem,
else
fillable = 0;

+ switch (fill_size(fillable, off)) {
#if defined(ioread64) && defined(iowrite64)
- if (fillable >= 8 && !(off % 8)) {
+ case 8:
ret = vfio_pci_core_iordwr64(vdev, iswrite, test_mem,
io, buf, off, &filled);
if (ret)
return ret;
+ break;

- } else
#endif /* defined(ioread64) && defined(iowrite64) */
- if (fillable >= 4 && !(off % 4)) {
+ case 4:
ret = vfio_pci_core_iordwr32(vdev, iswrite, test_mem,
io, buf, off, &filled);
if (ret)
return ret;
+ break;

- } else if (fillable >= 2 && !(off % 2)) {
+ case 2:
ret = vfio_pci_core_iordwr16(vdev, iswrite, test_mem,
io, buf, off, &filled);
if (ret)
return ret;
+ break;

- } else if (fillable) {
+ case 1:
ret = vfio_pci_core_iordwr8(vdev, iswrite, test_mem,
io, buf, off, &filled);
if (ret)
return ret;
+ break;

- } else {
+ default:
/* Fill reads with -1, drop writes */
filled = min(count, (size_t)(x_end - off));
if (!iswrite) {
--
2.44.0