From: Alvaro Karsz <alvaro.karsz@solid-run.com>
Date: Thu, 2 Feb 2023 08:42:12 +0000 (+0200)
Subject: vhost-vdpa: print warning when vhost_vdpa_alloc_domain fails
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=6830a6aba9d40f1491f991d7b31bb2b90187111c;p=linux.git

vhost-vdpa: print warning when vhost_vdpa_alloc_domain fails

Add a print explaining why vhost_vdpa_alloc_domain failed if the device
is not IOMMU cache coherent capable.

Without this print, we have no hint why the operation failed.

For example:

$ virsh start <domain>
	error: Failed to start domain <domain>
	error: Unable to open '/dev/vhost-vdpa-<idx>' for vdpa device:
	       Unknown error 524

Suggested-by: Eugenio Perez Martin <eperezma@redhat.com>
Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>

Message-Id: <20230202084212.1328530-1-alvaro.karsz@solid-run.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Eugenio Pérez Martin <eperezma@redhat.com>
---

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 23db92388393f..135f8aa70fb2d 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -1151,8 +1151,11 @@ static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v)
 	if (!bus)
 		return -EFAULT;
 
-	if (!device_iommu_capable(dma_dev, IOMMU_CAP_CACHE_COHERENCY))
+	if (!device_iommu_capable(dma_dev, IOMMU_CAP_CACHE_COHERENCY)) {
+		dev_warn_once(&v->dev,
+			      "Failed to allocate domain, device is not IOMMU cache coherent capable\n");
 		return -ENOTSUPP;
+	}
 
 	v->domain = iommu_domain_alloc(bus);
 	if (!v->domain)