[SPDK] [PATCH] vfio_user: fix the errors in 64K page kernel

[SPDK] [PATCH] vfio_user: fix the errors in 64K page kernel

[Huang Shijie]

We will meet the followings errors in 64K page kernel:
    " vfio_user.c:4454:nvmf_vfio_user_listen: *ERROR*: /tmp/nvme-vfio-user: error to mmap file /tmp/nvme-vfio-user/bar0: Invalid argument."
    " vfio_user.c:3088:vfio_user_log: *ERROR*: /tmp/nvme-vfio-user: migration registers cannot be memory mapped"

Fix them by
    0.) Pass 0 to mmap's offset parameter.
	The doorbell offset is fixed at 0x1000 (kernel NVME driver uses it too).
	But mmap requires the offset must be a multiple of the page size as returned by
	sysconf(_SC_PAGE_SIZE).
	In 64K page size kernel will meet the failure. So set 0 to mmap's offset,
       	and then change to doorbell offset manually.

    1.) convert the hardcode to PAGE_SIZE.

Tested this patch with cloud-hypervisor in 64K page size kernel.

Signed-off-by: Huang Shijie <shijie@os.amperecomputing.com>
---
 lib/nvmf/vfio_user.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/lib/nvmf/vfio_user.c b/lib/nvmf/vfio_user.c
index 2c05a72bd..22ade6f03 100644
--- a/lib/nvmf/vfio_user.c
+++ b/lib/nvmf/vfio_user.c
@@ -1149,7 +1149,8 @@ nvmf_vfio_user_destroy_endpoint(struct nvmf_vfio_user_endpoint *endpoint)
 	spdk_poller_unregister(&endpoint->accept_poller);
 
 	if (endpoint->bar0_doorbells) {
-		munmap((void *)endpoint->bar0_doorbells, NVMF_VFIO_USER_DOORBELLS_SIZE);
+		endpoint->bar0_doorbells = (uint32_t*)(((unsigned long)endpoint->bar0_doorbells) - NVME_DOORBELLS_OFFSET);
+		munmap((void *)endpoint->bar0_doorbells, NVMF_VFIO_USER_DOORBELLS_SIZE + NVME_DOORBELLS_OFFSET);
 	}
 
 	if (endpoint->devmem_fd > 0) {
@@ -4202,7 +4203,7 @@ vfio_user_dev_info_fill(struct nvmf_vfio_user_transport *vu_transport,
 
 	vfu_setup_device_quiesce_cb(vfu_ctx, vfio_user_dev_quiesce_cb);
 
-	migr_sparse_mmap.iov_base = (void *)4096;
+	migr_sparse_mmap.iov_base = (void *)PAGE_SIZE;
 	migr_sparse_mmap.iov_len = vfio_user_migr_data_len();
 	ret = vfu_setup_region(vfu_ctx, VFU_PCI_DEV_MIGR_REGION_IDX,
 			       vfu_get_migr_register_area_size() + vfio_user_migr_data_len(),
@@ -4448,14 +4449,22 @@ nvmf_vfio_user_listen(struct spdk_nvmf_transport *transport,
 		goto out;
 	}
 
-	endpoint->bar0_doorbells = mmap(NULL, NVMF_VFIO_USER_DOORBELLS_SIZE,
-					PROT_READ | PROT_WRITE, MAP_SHARED, endpoint->devmem_fd, NVME_DOORBELLS_OFFSET);
+	/*
+	 * The doorbell offset is fixed at 0x1000.
+	 * But mmap requires the offset must be a multiple of the page size as returned by
+	 * sysconf(_SC_PAGE_SIZE).
+	 * In order to avoid the mmap failure in non-4K page size kernel,
+	 * set 0 to mmap's offset, and then change to doorbell offset manually.
+	 */
+	endpoint->bar0_doorbells = mmap(NULL, NVMF_VFIO_USER_DOORBELLS_SIZE + NVME_DOORBELLS_OFFSET,
+				PROT_READ | PROT_WRITE, MAP_SHARED, endpoint->devmem_fd, 0);
 	if (endpoint->bar0_doorbells == MAP_FAILED) {
 		SPDK_ERRLOG("%s: error to mmap file %s: %s.\n", endpoint_id(endpoint), path, spdk_strerror(errno));
 		endpoint->bar0_doorbells = NULL;
 		ret = -1;
 		goto out;
 	}
+	endpoint->bar0_doorbells = (uint32_t *)(((unsigned long)endpoint->bar0_doorbells) + NVME_DOORBELLS_OFFSET);
 
 	ret = snprintf(path, PATH_MAX, "%s/migr", endpoint_id(endpoint));
 	if (ret < 0 || ret >= PATH_MAX) {
-- 
2.39.2

Re: [SPDK] [PATCH] vfio_user: fix the errors in 64K page kernel

[Sztyber, Konrad]

Hello Shijie,

Thanks for the patch but we don't use the mailing list for posting patches. Instead, we use Gerrit at https://review.spdk.io. You can read more about our development process at https://spdk.io/development.

Thanks,
Konrad

> -----Original Message-----
> From: SPDK <spdk-bounces@lists.linuxfoundation.org> On Behalf Of Huang
> Shijie
> Sent: Friday, June 9, 2023 5:26 AM
> To: spdk@lists.linuxfoundation.org
> Cc: Huang Shijie <shijie@os.amperecomputing.com>;
> patches@amperecomputing.com
> Subject: [SPDK] [PATCH] vfio_user: fix the errors in 64K page kernel
> 
> We will meet the followings errors in 64K page kernel:
>     " vfio_user.c:4454:nvmf_vfio_user_listen: *ERROR*: /tmp/nvme-vfio-
> user: error to mmap file /tmp/nvme-vfio-user/bar0: Invalid argument."
>     " vfio_user.c:3088:vfio_user_log: *ERROR*: /tmp/nvme-vfio-user:
> migration registers cannot be memory mapped"
> 
> Fix them by
>     0.) Pass 0 to mmap's offset parameter.
> 	The doorbell offset is fixed at 0x1000 (kernel NVME driver uses it
> too).
> 	But mmap requires the offset must be a multiple of the page size as
> returned by
> 	sysconf(_SC_PAGE_SIZE).
> 	In 64K page size kernel will meet the failure. So set 0 to mmap's
> offset,
>        	and then change to doorbell offset manually.
> 
>     1.) convert the hardcode to PAGE_SIZE.
> 
> Tested this patch with cloud-hypervisor in 64K page size kernel.
> 
> Signed-off-by: Huang Shijie <shijie@os.amperecomputing.com>
> ---
>  lib/nvmf/vfio_user.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/nvmf/vfio_user.c b/lib/nvmf/vfio_user.c index
> 2c05a72bd..22ade6f03 100644
> --- a/lib/nvmf/vfio_user.c
> +++ b/lib/nvmf/vfio_user.c
> @@ -1149,7 +1149,8 @@ nvmf_vfio_user_destroy_endpoint(struct
> nvmf_vfio_user_endpoint *endpoint)
>  	spdk_poller_unregister(&endpoint->accept_poller);
> 
>  	if (endpoint->bar0_doorbells) {
> -		munmap((void *)endpoint->bar0_doorbells,
> NVMF_VFIO_USER_DOORBELLS_SIZE);
> +		endpoint->bar0_doorbells = (uint32_t*)(((unsigned
> long)endpoint->bar0_doorbells) - NVME_DOORBELLS_OFFSET);
> +		munmap((void *)endpoint->bar0_doorbells,
> +NVMF_VFIO_USER_DOORBELLS_SIZE + NVME_DOORBELLS_OFFSET);
>  	}
> 
>  	if (endpoint->devmem_fd > 0) {
> @@ -4202,7 +4203,7 @@ vfio_user_dev_info_fill(struct
> nvmf_vfio_user_transport *vu_transport,
> 
>  	vfu_setup_device_quiesce_cb(vfu_ctx, vfio_user_dev_quiesce_cb);
> 
> -	migr_sparse_mmap.iov_base = (void *)4096;
> +	migr_sparse_mmap.iov_base = (void *)PAGE_SIZE;
>  	migr_sparse_mmap.iov_len = vfio_user_migr_data_len();
>  	ret = vfu_setup_region(vfu_ctx, VFU_PCI_DEV_MIGR_REGION_IDX,
>  			       vfu_get_migr_register_area_size() +
> vfio_user_migr_data_len(), @@ -4448,14 +4449,22 @@
> nvmf_vfio_user_listen(struct spdk_nvmf_transport *transport,
>  		goto out;
>  	}
> 
> -	endpoint->bar0_doorbells = mmap(NULL, NVMF_VFIO_USER_DOORBELLS_SIZE,
> -					PROT_READ | PROT_WRITE, MAP_SHARED,
> endpoint->devmem_fd, NVME_DOORBELLS_OFFSET);
> +	/*
> +	 * The doorbell offset is fixed at 0x1000.
> +	 * But mmap requires the offset must be a multiple of the page size
> as returned by
> +	 * sysconf(_SC_PAGE_SIZE).
> +	 * In order to avoid the mmap failure in non-4K page size kernel,
> +	 * set 0 to mmap's offset, and then change to doorbell offset
> manually.
> +	 */
> +	endpoint->bar0_doorbells = mmap(NULL, NVMF_VFIO_USER_DOORBELLS_SIZE
> + NVME_DOORBELLS_OFFSET,
> +				PROT_READ | PROT_WRITE, MAP_SHARED, endpoint-
> >devmem_fd, 0);
>  	if (endpoint->bar0_doorbells == MAP_FAILED) {
>  		SPDK_ERRLOG("%s: error to mmap file %s: %s.\n",
> endpoint_id(endpoint), path, spdk_strerror(errno));
>  		endpoint->bar0_doorbells = NULL;
>  		ret = -1;
>  		goto out;
>  	}
> +	endpoint->bar0_doorbells = (uint32_t *)(((unsigned
> +long)endpoint->bar0_doorbells) + NVME_DOORBELLS_OFFSET);
> 
>  	ret = snprintf(path, PATH_MAX, "%s/migr", endpoint_id(endpoint));
>  	if (ret < 0 || ret >= PATH_MAX) {
> --
> 2.39.2
> 
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