[Qemu-devel] [PATCH 2/3] vfio/pci: Use endian neutral helpers

[Alex Williamson]

The iowriteXX/ioreadXX functions assume little endian hardware and
convert to little endian on a write and from little endian on a read.
We currently do our own explicit conversion to negate this.  Instead,
add some endian dependent defines to avoid all byte swaps.  There
should be no functional change other than big endian systems aren't
penalized with wasted swaps.

Signed-off-by: Alex Williamson <address@hidden>
---
 drivers/vfio/pci/vfio_pci_rdwr.c |   34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index 5f2b376dcebd..925419e0f459 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -21,6 +21,24 @@
 
 #include "vfio_pci_private.h"
 
+#ifdef __LITTLE_ENDIAN
+#define vfio_ioread64  ioread64
+#define vfio_iowrite64 iowrite64
+#define vfio_ioread32  ioread32
+#define vfio_iowrite32 iowrite32
+#define vfio_ioread16  ioread16
+#define vfio_iowrite16 iowrite16
+#else
+#define vfio_ioread64  ioread64be
+#define vfio_iowrite64 iowrite64be
+#define vfio_ioread32  ioread32be
+#define vfio_iowrite32 iowrite32be
+#define vfio_ioread16  ioread16be
+#define vfio_iowrite16 iowrite16be
+#endif
+#define vfio_ioread8   ioread8
+#define vfio_iowrite8  iowrite8
+
 /*
  * 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
@@ -44,15 +62,15 @@ static ssize_t do_io_rw(void __iomem *io, char __user *buf,
                        fillable = 0;
 
                if (fillable >= 4 && !(off % 4)) {
-                       __le32 val;
+                       u32 val;
 
                        if (iswrite) {
                                if (copy_from_user(&val, buf, 4))
                                        return -EFAULT;
 
-                               iowrite32(le32_to_cpu(val), io + off);
+                               vfio_iowrite32(val, io + off);
                        } else {
-                               val = cpu_to_le32(ioread32(io + off));
+                               val = vfio_ioread32(io + off);
 
                                if (copy_to_user(buf, &val, 4))
                                        return -EFAULT;
@@ -60,15 +78,15 @@ static ssize_t do_io_rw(void __iomem *io, char __user *buf,
 
                        filled = 4;
                } else if (fillable >= 2 && !(off % 2)) {
-                       __le16 val;
+                       u16 val;
 
                        if (iswrite) {
                                if (copy_from_user(&val, buf, 2))
                                        return -EFAULT;
 
-                               iowrite16(le16_to_cpu(val), io + off);
+                               vfio_iowrite16(val, io + off);
                        } else {
-                               val = cpu_to_le16(ioread16(io + off));
+                               val = vfio_ioread16(io + off);
 
                                if (copy_to_user(buf, &val, 2))
                                        return -EFAULT;
@@ -82,9 +100,9 @@ static ssize_t do_io_rw(void __iomem *io, char __user *buf,
                                if (copy_from_user(&val, buf, 1))
                                        return -EFAULT;
 
-                               iowrite8(val, io + off);
+                               vfio_iowrite8(val, io + off);
                        } else {
-                               val = ioread8(io + off);
+                               val = vfio_ioread8(io + off);
 
                                if (copy_to_user(buf, &val, 1))
                                        return -EFAULT;