Re: [PATCH v3 1/3] vfio/pci: Extract duplicated code into macro

Ramesh Thomas
2024-05-17T10:47:14Z

On 4/25/2024 9:56 AM, Gerd Bayer wrote:
> vfio_pci_core_do_io_rw() repeats the same code for multiple access
> widths. Factor this out into a macro
>
> Suggested-by: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
> ---
> drivers/vfio/pci/vfio_pci_rdwr.c | 106 ++++++++++++++-----------------
> 1 file changed, 46 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
> index 03b8f7ada1ac..3335f1b868b1 100644
> --- a/drivers/vfio/pci/vfio_pci_rdwr.c
> +++ b/drivers/vfio/pci/vfio_pci_rdwr.c
> @@ -90,6 +90,40 @@ VFIO_IOREAD(8)
> VFIO_IOREAD(16)
> VFIO_IOREAD(32)
>
> +#define VFIO_IORDWR(size) \
> +static int vfio_pci_core_iordwr##size(struct vfio_pci_core_device *vdev,\
> + bool iswrite, bool test_mem, \
> + void __iomem *io, char __user *buf, \
> + loff_t off, size_t *filled) \
> +{ \
> + u##size val; \
> + int ret; \
> + \
> + if (iswrite) { \
> + if (copy_from_user(&val, buf, sizeof(val))) \

Another way to get the size is (size)/8
"if (copy_from_user(&val, buf, (size)/8))"

> + return -EFAULT; \
> + \
> + ret = vfio_pci_core_iowrite##size(vdev, test_mem, \
> + val, io + off); \
> + if (ret) \
> + return ret; \
> + } else { \
> + ret = vfio_pci_core_ioread##size(vdev, test_mem, \
> + &val, io + off); \
> + if (ret) \
> + return ret; \
> + \
> + if (copy_to_user(buf, &val, sizeof(val))) \
> + return -EFAULT; \
> + } \
> + \
> + *filled = sizeof(val); \
> + return 0; \
> +} \
> +
> +VFIO_IORDWR(8)
> +VFIO_IORDWR(16)
> +VFIO_IORDWR(32)
> /*
> * 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
> @@ -115,71 +149,23 @@ ssize_t vfio_pci_core_do_io_rw(struct vfio_pci_core_device *vdev, bool test_mem,
> fillable = 0;
>
> if (fillable >= 4 && !(off % 4)) {
> - u32 val;
> -
> - if (iswrite) {
> - if (copy_from_user(&val, buf, 4))
> - return -EFAULT;
> -
> - ret = vfio_pci_core_iowrite32(vdev, test_mem,
> - val, io + off);
> - if (ret)
> - return ret;
> - } else {
> - ret = vfio_pci_core_ioread32(vdev, test_mem,
> - &val, io + off);
> - if (ret)
> - return ret;
> -
> - if (copy_to_user(buf, &val, 4))
> - return -EFAULT;
> - }
> + ret = vfio_pci_core_iordwr32(vdev, iswrite, test_mem,
> + io, buf, off, &filled);
> + if (ret)
> + return ret;
>
> - filled = 4;
> } else if (fillable >= 2 && !(off % 2)) {
> - u16 val;
> -
> - if (iswrite) {
> - if (copy_from_user(&val, buf, 2))
> - return -EFAULT;
> -
> - ret = vfio_pci_core_iowrite16(vdev, test_mem,
> - val, io + off);
> - if (ret)
> - return ret;
> - } else {
> - ret = vfio_pci_core_ioread16(vdev, test_mem,
> - &val, io + off);
> - if (ret)
> - return ret;
> -
> - if (copy_to_user(buf, &val, 2))
> - return -EFAULT;
> - }
> + ret = vfio_pci_core_iordwr16(vdev, iswrite, test_mem,
> + io, buf, off, &filled);
> + if (ret)
> + return ret;
>
> - filled = 2;
> } else if (fillable) {
> - u8 val;
> -
> - if (iswrite) {
> - if (copy_from_user(&val, buf, 1))
> - return -EFAULT;
> -
> - ret = vfio_pci_core_iowrite8(vdev, test_mem,
> - val, io + off);
> - if (ret)
> - return ret;
> - } else {
> - ret = vfio_pci_core_ioread8(vdev, test_mem,
> - &val, io + off);
> - if (ret)
> - return ret;
> -
> - if (copy_to_user(buf, &val, 1))
> - return -EFAULT;
> - }
> + ret = vfio_pci_core_iordwr8(vdev, iswrite, test_mem,
> + io, buf, off, &filled);
> + if (ret)
> + return ret;
>
> - filled = 1;
> } else {
> /* Fill reads with -1, drop writes */
> filled = min(count, (size_t)(x_end - off));