[PATCH v2 2/2] xen/arm: smmuv3: fix xl pci-assignable-remove

[Stewart Hildebrand <stewart.hildebrand@xxxxxxx>]

When attempting to xl pci-assignable-remove a PCI device, we encounter:

$ xl pci-assignable-remove 00:01.0
(XEN) SMMUv3: <no-node>:  not attached to domain 32753
(XEN) d[IO]: deassign (0000:00:01.0) failed (-3)
libxl: error: libxl_pci.c:910:libxl__device_pci_assignable_remove: failed to 
de-quarantine 0000:00:01.0

When a PCI device is being deassigned from domIO,
arm_smmu_deassign_dev() should return before checking the smmu domain.

Fixes: 63919fc4d1ca ("xen/arm: smmuv3: Add PCI devices support for SMMUv3")
Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
Acked-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
---
v1->v2:
* use %pd in print format
* add Bertrand's A-b
---
 xen/drivers/passthrough/arm/smmu-v3.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/xen/drivers/passthrough/arm/smmu-v3.c 
b/xen/drivers/passthrough/arm/smmu-v3.c
index db08d3c04269..5e9e3e048e34 100644
--- a/xen/drivers/passthrough/arm/smmu-v3.c
+++ b/xen/drivers/passthrough/arm/smmu-v3.c
@@ -2747,11 +2747,6 @@ static int arm_smmu_deassign_dev(struct domain *d, 
uint8_t devfn, struct device
        struct arm_smmu_domain *smmu_domain = to_smmu_domain(io_domain);
        struct arm_smmu_master *master = dev_iommu_priv_get(dev);
 
-       if (!smmu_domain || smmu_domain->d != d) {
-               dev_err(dev, " not attached to domain %d\n", d->domain_id);
-               return -ESRCH;
-       }
-
 #ifdef CONFIG_HAS_PCI
        if ( dev_is_pci(dev) )
        {
@@ -2767,6 +2762,11 @@ static int arm_smmu_deassign_dev(struct domain *d, 
uint8_t devfn, struct device
        }
 #endif
 
+       if (!smmu_domain || smmu_domain->d != d) {
+               dev_err(dev, " not attached to %pd\n", d);
+               return -ESRCH;
+       }
+
        spin_lock(&xen_domain->lock);
 
        arm_smmu_detach_dev(master);
-- 
2.50.1