Hi Chenbo,

-----Original Message-----
From: Xia, Chenbo <redacted>
Sent: Tuesday, November 2, 2021 10:47 AM
To: Vijay Kumar Srivastava <redacted>; dev@dpdk.org
Cc: maxime.coquelin@redhat.com; andrew.rybchenko@oktetlabs.ru; Praveen
Kumar Jain [off-list ref]
Subject: RE: [PATCH v3 02/10] vdpa/sfc: add support for device initialization

quoted

-----Original Message-----
From: Vijay Kumar Srivastava <redacted>
Sent: Tuesday, November 2, 2021 12:38 PM
To: Xia, Chenbo <redacted>; dev@dpdk.org
Cc: maxime.coquelin@redhat.com; andrew.rybchenko@oktetlabs.ru; Praveen
Kumar Jain [off-list ref]
Subject: RE: [PATCH v3 02/10] vdpa/sfc: add support for device
initialization

Hi Chenbo,

quoted

-----Original Message-----
From: Xia, Chenbo <redacted>
Sent: Monday, November 1, 2021 5:19 PM
To: Vijay Kumar Srivastava <redacted>; dev@dpdk.org
Cc: maxime.coquelin@redhat.com; andrew.rybchenko@oktetlabs.ru; Vijay
Kumar Srivastava [off-list ref]
Subject: RE: [PATCH v3 02/10] vdpa/sfc: add support for device
initialization

Hi Vijay,

quoted

-----Original Message-----
From: Vijay Srivastava <redacted>
Sent: Friday, October 29, 2021 10:47 PM
To: dev@dpdk.org
Cc: maxime.coquelin@redhat.com; Xia, Chenbo <redacted>;
andrew.rybchenko@oktetlabs.ru; Vijay Kumar Srivastava
[off-list ref]
Subject: [PATCH v3 02/10] vdpa/sfc: add support for device
initialization

From: Vijay Kumar Srivastava <redacted>

Add HW initialization and vDPA device registration support.

Signed-off-by: Vijay Kumar Srivastava <redacted>
Acked-by: Andrew Rybchenko <redacted>
---

[SNIP]

quoted

quoted

+
+	do {
+		ret = rte_vfio_container_dma_map(sva->vfio_container_fd,
+						 (uint64_t)mz->addr,

mcdi_iova,

quoted

+						 mcdi_buff_size);
+		if (ret == 0)
+			break;
+
+		mcdi_iova = mcdi_iova >> 1;
+		if (mcdi_iova < mcdi_buff_size)	{
+			sfc_vdpa_err(sva,
+				     "DMA mapping failed for MCDI : %s",
+				     rte_strerror(rte_errno));
+			rte_memzone_free(mz);
+			return ret;
+		}
+
+	} while (ret < 0);

So when QEMU iova and mcdi_iova conflicts, you just let vdpa dev
failed to configure, right?

Why not use re-mapping mcdi dma region as the solution? Any side-effect?
Or you just assume conflict can hardly happen?

MCDI configuration is being done at the very early point of initialization.
Conflict would be detected later when rte_vhost_get_mem_table() would
be invoked in .dev_conf callback and then MCDI re-mapping can be done
in case of conflict,

Agree. It should be done in dev_conf callback.

quoted

for this a patch is in
progress which would be submitted separately.

OK for me, as the initial version, you can just let dev_conf fail if conflict
happens.

Yes. In case of conflict dev_conf would fail. 

Regards,
Vijay

quoted

[SNIP]