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SubjectRe: [PATCH v5 09/10] vfio/fsl-mc: Add read/write support for fsl-mc devices
On Tue, 29 Sep 2020 12:03:38 +0300
Diana Craciun <diana.craciun@oss.nxp.com> wrote:

> The software uses a memory-mapped I/O command interface (MC portals) to
> communicate with the MC hardware. This command interface is used to
> discover, enumerate, configure and remove DPAA2 objects. The DPAA2
> objects use MSIs, so the command interface needs to be emulated
> such that the correct MSI is configured in the hardware (the guest
> has the virtual MSIs).
>
> This patch is adding read/write support for fsl-mc devices. The mc
> commands are emulated by the userspace. The host is just passing
> the correct command to the hardware.
>
> Also the current patch limits userspace to write complete
> 64byte command once and read 64byte response by one ioctl.
>
> Signed-off-by: Bharat Bhushan <Bharat.Bhushan@nxp.com>
> Signed-off-by: Diana Craciun <diana.craciun@oss.nxp.com>
> ---
> drivers/vfio/fsl-mc/vfio_fsl_mc.c | 118 +++++++++++++++++++++-
> drivers/vfio/fsl-mc/vfio_fsl_mc_private.h | 1 +
> 2 files changed, 116 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> index 82157837f37a..0aff99cdf722 100644
> --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> @@ -12,6 +12,7 @@
> #include <linux/types.h>
> #include <linux/vfio.h>
> #include <linux/fsl/mc.h>
> +#include <linux/delay.h>
>
> #include "vfio_fsl_mc_private.h"
>
> @@ -115,7 +116,9 @@ static int vfio_fsl_mc_regions_init(struct vfio_fsl_mc_device *vdev)
> !(vdev->regions[i].size & ~PAGE_MASK))
> vdev->regions[i].flags |=
> VFIO_REGION_INFO_FLAG_MMAP;
> -
> + vdev->regions[i].flags |= VFIO_REGION_INFO_FLAG_READ;
> + if (!(mc_dev->regions[i].flags & IORESOURCE_READONLY))
> + vdev->regions[i].flags |= VFIO_REGION_INFO_FLAG_WRITE;
> }
>
> return 0;
> @@ -123,6 +126,11 @@ static int vfio_fsl_mc_regions_init(struct vfio_fsl_mc_device *vdev)
>
> static void vfio_fsl_mc_regions_cleanup(struct vfio_fsl_mc_device *vdev)
> {
> + struct fsl_mc_device *mc_dev = vdev->mc_dev;
> + int i;
> +
> + for (i = 0; i < mc_dev->obj_desc.region_count; i++)
> + iounmap(vdev->regions[i].ioaddr);
> kfree(vdev->regions);
> }
>
> @@ -301,13 +309,117 @@ static long vfio_fsl_mc_ioctl(void *device_data, unsigned int cmd,
> static ssize_t vfio_fsl_mc_read(void *device_data, char __user *buf,
> size_t count, loff_t *ppos)
> {
> - return -EINVAL;
> + struct vfio_fsl_mc_device *vdev = device_data;
> + unsigned int index = VFIO_FSL_MC_OFFSET_TO_INDEX(*ppos);
> + loff_t off = *ppos & VFIO_FSL_MC_OFFSET_MASK;
> + struct fsl_mc_device *mc_dev = vdev->mc_dev;
> + struct vfio_fsl_mc_region *region;
> + u64 data[8];
> + int i;
> +
> + if (index >= mc_dev->obj_desc.region_count)
> + return -EINVAL;
> +
> + region = &vdev->regions[index];
> +
> + if (!(region->flags & VFIO_REGION_INFO_FLAG_READ))
> + return -EINVAL;

Nit, there are no regions w/o read access according to the regions_init
code above. Maybe this is just for symmetry with write? Keep it if
you prefer. Thanks,

Alex

> +
> + if (!region->ioaddr) {
> + region->ioaddr = ioremap(region->addr, region->size);
> + if (!region->ioaddr)
> + return -ENOMEM;
> + }
> +
> + if (count != 64 || off != 0)
> + return -EINVAL;
> +
> + for (i = 7; i >= 0; i--)
> + data[i] = readq(region->ioaddr + i * sizeof(uint64_t));
> +
> + if (copy_to_user(buf, data, 64))
> + return -EFAULT;
> +
> + return count;
> +}
> +
> +#define MC_CMD_COMPLETION_TIMEOUT_MS 5000
> +#define MC_CMD_COMPLETION_POLLING_MAX_SLEEP_USECS 500
> +
> +static int vfio_fsl_mc_send_command(void __iomem *ioaddr, uint64_t *cmd_data)
> +{
> + int i;
> + enum mc_cmd_status status;
> + unsigned long timeout_usecs = MC_CMD_COMPLETION_TIMEOUT_MS * 1000;
> +
> + /* Write at command parameter into portal */
> + for (i = 7; i >= 1; i--)
> + writeq_relaxed(cmd_data[i], ioaddr + i * sizeof(uint64_t));
> +
> + /* Write command header in the end */
> + writeq(cmd_data[0], ioaddr);
> +
> + /* Wait for response before returning to user-space
> + * This can be optimized in future to even prepare response
> + * before returning to user-space and avoid read ioctl.
> + */
> + for (;;) {
> + u64 header;
> + struct mc_cmd_header *resp_hdr;
> +
> + header = cpu_to_le64(readq_relaxed(ioaddr));
> +
> + resp_hdr = (struct mc_cmd_header *)&header;
> + status = (enum mc_cmd_status)resp_hdr->status;
> + if (status != MC_CMD_STATUS_READY)
> + break;
> +
> + udelay(MC_CMD_COMPLETION_POLLING_MAX_SLEEP_USECS);
> + timeout_usecs -= MC_CMD_COMPLETION_POLLING_MAX_SLEEP_USECS;
> + if (timeout_usecs == 0)
> + return -ETIMEDOUT;
> + }
> +
> + return 0;
> }
>
> static ssize_t vfio_fsl_mc_write(void *device_data, const char __user *buf,
> size_t count, loff_t *ppos)
> {
> - return -EINVAL;
> + struct vfio_fsl_mc_device *vdev = device_data;
> + unsigned int index = VFIO_FSL_MC_OFFSET_TO_INDEX(*ppos);
> + loff_t off = *ppos & VFIO_FSL_MC_OFFSET_MASK;
> + struct fsl_mc_device *mc_dev = vdev->mc_dev;
> + struct vfio_fsl_mc_region *region;
> + u64 data[8];
> + int ret;
> +
> + if (index >= mc_dev->obj_desc.region_count)
> + return -EINVAL;
> +
> + region = &vdev->regions[index];
> +
> + if (!(region->flags & VFIO_REGION_INFO_FLAG_WRITE))
> + return -EINVAL;
> +
> + if (!region->ioaddr) {
> + region->ioaddr = ioremap(region->addr, region->size);
> + if (!region->ioaddr)
> + return -ENOMEM;
> + }
> +
> + if (count != 64 || off != 0)
> + return -EINVAL;
> +
> + if (copy_from_user(&data, buf, 64))
> + return -EFAULT;
> +
> + ret = vfio_fsl_mc_send_command(region->ioaddr, data);
> + if (ret)
> + return ret;
> +
> + return count;
> +
> }
>
> static int vfio_fsl_mc_mmap_mmio(struct vfio_fsl_mc_region region,
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> index 7aa49b9ba60d..a97ee691ed47 100644
> --- a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> @@ -32,6 +32,7 @@ struct vfio_fsl_mc_region {
> u32 type;
> u64 addr;
> resource_size_t size;
> + void __iomem *ioaddr;
> };
>
> struct vfio_fsl_mc_device {

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