Re: [Qemu-devel] [PATCH v4 14/29] libvhost-user+postcopy: Register new regions with the ufd

[Marc-André Lureau]

On Thu, Mar 8, 2018 at 8:57 PM, Dr. David Alan Gilbert (git)
<address@hidden> wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> When new regions are sent to the client using SET_MEM_TABLE, register
> them with the userfaultfd.
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>

Reviewed-by: Marc-André Lureau <address@hidden>


> ---
>  contrib/libvhost-user/libvhost-user.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>
> diff --git a/contrib/libvhost-user/libvhost-user.c 
> b/contrib/libvhost-user/libvhost-user.c
> index 4922b2c722..a18bc74a7c 100644
> --- a/contrib/libvhost-user/libvhost-user.c
> +++ b/contrib/libvhost-user/libvhost-user.c
> @@ -494,6 +494,40 @@ vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMsg 
> *vmsg)
>          close(vmsg->fds[i]);
>      }
>
> +    /* TODO: Get address back to QEMU */
> +    for (i = 0; i < dev->nregions; i++) {
> +        VuDevRegion *dev_region = &dev->regions[i];
> +#ifdef UFFDIO_REGISTER
> +        /* We should already have an open ufd. Mark each memory
> +         * range as ufd.
> +         * Note: Do we need any madvises? Well it's not been accessed
> +         * yet, still probably need no THP to be safe, discard to be safe?
> +         */
> +        struct uffdio_register reg_struct;
> +        reg_struct.range.start = (uintptr_t)dev_region->mmap_addr;
> +        reg_struct.range.len = dev_region->size + dev_region->mmap_offset;
> +        reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
> +
> +        if (ioctl(dev->postcopy_ufd, UFFDIO_REGISTER, &reg_struct)) {
> +            vu_panic(dev, "%s: Failed to userfault region %d "
> +                          "@%p + size:%zx offset: %zx: (ufd=%d)%s\n",
> +                     __func__, i,
> +                     dev_region->mmap_addr,
> +                     dev_region->size, dev_region->mmap_offset,
> +                     dev->postcopy_ufd, strerror(errno));
> +            return false;
> +        }
> +        if (!(reg_struct.ioctls & ((__u64)1 << _UFFDIO_COPY))) {
> +            vu_panic(dev, "%s Region (%d) doesn't support COPY",
> +                     __func__, i);
> +            return false;
> +        }
> +        DPRINT("%s: region %d: Registered userfault for %llx + %llx\n",
> +                __func__, i, reg_struct.range.start, reg_struct.range.len);
> +        /* TODO: Stash 'zero' support flags somewhere */
> +#endif
> +    }
> +
>      return false;
>  }
>
> --
> 2.14.3
>
>



-- 
Marc-André Lureau