Re: [dpdk-dev] [PATCH 21.02 1/3] vhost: refactor postcopy region registration

["Xia, Chenbo" <chenbo.xia@intel.com>]

Hi Maxime,

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Monday, November 16, 2020 7:36 PM
> To: dev@dpdk.org; Xia, Chenbo <chenbo.xia@intel.com>; Ding, Xuan
> <xuan.ding@intel.com>
> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> Subject: [PATCH 21.02 1/3] vhost: refactor postcopy region registration
> 
> This patch moves the registration of memory regions to
> userfaultfd to a dedicated function, with the goal of
> simplifying VHOST_USER_SET_MEM_TABLE request handling
> function.
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  lib/librte_vhost/vhost_user.c | 77 +++++++++++++++++++++--------------
>  1 file changed, 46 insertions(+), 31 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 45c8ac09da..b8a9e41a2d 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -998,6 +998,49 @@ vhost_memory_changed(struct VhostUserMemory *new,
>  	return false;
>  }
> 
> +#ifdef RTE_LIBRTE_VHOST_POSTCOPY
> +static int
> +vhost_user_postcopy_region_register(struct virtio_net *dev,
> +		struct rte_vhost_mem_region *reg)
> +{
> +	struct uffdio_register reg_struct;
> +
> +	/*
> +	 * Let's register all the mmap'ed area to ensure
> +	 * alignment on page boundary.
> +	 */
> +	reg_struct.range.start = (uint64_t)(uintptr_t)reg->mmap_addr;
> +	reg_struct.range.len = reg->mmap_size;
> +	reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
> +
> +	if (ioctl(dev->postcopy_ufd, UFFDIO_REGISTER,
> +				&reg_struct)) {
> +		VHOST_LOG_CONFIG(ERR, "Failed to register ufd for region "
> +				"%" PRIx64 " - %" PRIx64 " (ufd = %d) %s\n",
> +				(uint64_t)reg_struct.range.start,
> +				(uint64_t)reg_struct.range.start +
> +				(uint64_t)reg_struct.range.len - 1,
> +				dev->postcopy_ufd,
> +				strerror(errno));
> +		return -1;
> +	}
> +
> +	VHOST_LOG_CONFIG(INFO, "\t userfaultfd registered for range : %"
> PRIx64 " - %" PRIx64 "\n",
> +			(uint64_t)reg_struct.range.start,
> +			(uint64_t)reg_struct.range.start +
> +			(uint64_t)reg_struct.range.len - 1);
> +
> +	return 0;
> +}
> +#else
> +static int
> +vhost_user_postcopy_region_register(struct virtio_net *dev,
> +		struct rte_vhost_mem_region *reg)
> +{
> +	return -1;
> +}

Better add __rte_unused here to avoid warnings when postcopy not configured 😊

Thanks,
Chenbo

> +#endif
> +
>  static int
>  vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg
> *msg,
>  			int main_fd)
> @@ -1209,38 +1252,10 @@ vhost_user_set_mem_table(struct virtio_net **pdev,
> struct VhostUserMsg *msg,
>  		}
> 
>  		/* Now userfault register and we can use the memory */
> -		for (i = 0; i < memory->nregions; i++) {
> -#ifdef RTE_LIBRTE_VHOST_POSTCOPY
> -			reg = &dev->mem->regions[i];
> -			struct uffdio_register reg_struct;
> -
> -			/*
> -			 * Let's register all the mmap'ed area to ensure
> -			 * alignment on page boundary.
> -			 */
> -			reg_struct.range.start =
> -				(uint64_t)(uintptr_t)reg->mmap_addr;
> -			reg_struct.range.len = reg->mmap_size;
> -			reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
> -
> -			if (ioctl(dev->postcopy_ufd, UFFDIO_REGISTER,
> -						&reg_struct)) {
> -				VHOST_LOG_CONFIG(ERR,
> -					"Failed to register ufd for region %d: (ufd
> = %d) %s\n",
> -					i, dev->postcopy_ufd,
> -					strerror(errno));
> +		for (i = 0; i < memory->nregions; i++)
> +			if (vhost_user_postcopy_region_register(dev,
> +						&dev->mem->regions[i]) < 0)
>  				goto free_mem_table;
> -			}
> -			VHOST_LOG_CONFIG(INFO,
> -				"\t userfaultfd registered for range : "
> -				"%" PRIx64 " - %" PRIx64 "\n",
> -				(uint64_t)reg_struct.range.start,
> -				(uint64_t)reg_struct.range.start +
> -				(uint64_t)reg_struct.range.len - 1);
> -#else
> -			goto free_mem_table;
> -#endif
> -		}
>  	}
> 
>  	for (i = 0; i < dev->nr_vring; i++) {
> --
> 2.26.2