[PATCH 2/2] amd/iommu: Remove dead non-atomic update checking

["Teddy Astie" <teddy.astie@xxxxxxxxxx>]

When updating a DTE, amd_iommu_setup_domain_device() would check if
the update had been non-atomic (i.e rc > 0) and throw a warning if
such non-atomic update could be dangerous.  However since commit
3fc44151d83d, rc can no longer be positive, making this branch
unreachable code.

No functional change intended.

Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx>
---
 xen/drivers/passthrough/amd/pci_amd_iommu.c | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c 
b/xen/drivers/passthrough/amd/pci_amd_iommu.c
index 3a14770855..02eee4e658 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -225,24 +225,6 @@ static int __must_check amd_iommu_setup_domain_device(
             spin_unlock_irqrestore(&iommu->lock, flags);
             return rc;
         }
-        if ( rc &&
-             domain != pdev->domain &&
-             /*
-              * By non-atomically updating the DTE's domain ID field last,
-              * during a short window in time TLB entries with the old domain
-              * ID but the new page tables may have been inserted.  This could
-              * affect I/O of other devices using this same (old) domain ID.
-              * Such updating therefore is not a problem if this was the only
-              * device associated with the old domain ID.  Diverting I/O of any
-              * of a dying domain's devices to the quarantine page tables is
-              * intended anyway.
-              */
-             !pdev->domain->is_dying &&
-             pdev->domain != dom_io &&
-             (any_pdev_behind_iommu(pdev->domain, pdev, iommu) ||
-              pdev->phantom_stride) )
-            AMD_IOMMU_WARN(" %pp: reassignment may cause %pd data 
corruption\n",
-                           &PCI_SBDF(pdev->seg, bus, devfn), pdev->domain);
 
         /*
          * Check remaining settings are still in place from an earlier call
-- 
2.51.2



--
Teddy Astie | Vates XCP-ng Developer

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