[v2,for-4.20?,1/6] AMD/IOMMU: drop stray MSI enabling

Commit Message

Jan Beulich Feb. 3, 2025, 4:24 p.m. UTC

While the 2nd of the commits referenced below should have moved the call
to amd_iommu_msi_enable() instead of adding another one, the situation
wasn't quite right even before: It can't have done any good to enable
MSI when no IRQ was allocated for it, yet.

The other call to amd_iommu_msi_enable(), just out of patch context,
needs to stay there until S3 resume is re-worked. For the boot path that
call should be unnecessary, as iommu{,_maskable}_msi_startup() will have
done it already (by way of invoking iommu_msi_unmask()).

Fixes: 5f569f1ac50e ("AMD/IOMMU: allow enabling with IRQ not yet set up")
Fixes: d9e49d1afe2e ("AMD/IOMMU: adjust setup of internal interrupt for x2APIC mode")
Signed-off-by: Jan Beulich <[e-mail]>
Reviewed-by: Jason Andryuk <[e-mail]>
Tested-by: Jason Andryuk <[e-mail]>
---
v2: Extend description.

Comments

Roger Pau Monné Feb. 3, 2025, 4:54 p.m. UTC | #1

On Mon, Feb 03, 2025 at 05:24:10PM +0100, Jan Beulich wrote:
> While the 2nd of the commits referenced below should have moved the call
> to amd_iommu_msi_enable() instead of adding another one, the situation
> wasn't quite right even before: It can't have done any good to enable
> MSI when no IRQ was allocated for it, yet.
> 
> The other call to amd_iommu_msi_enable(), just out of patch context,
> needs to stay there until S3 resume is re-worked. For the boot path that
> call should be unnecessary, as iommu{,_maskable}_msi_startup() will have
> done it already (by way of invoking iommu_msi_unmask()).
> 
> Fixes: 5f569f1ac50e ("AMD/IOMMU: allow enabling with IRQ not yet set up")
> Fixes: d9e49d1afe2e ("AMD/IOMMU: adjust setup of internal interrupt for x2APIC mode")
> Signed-off-by: Jan Beulich <[e-mail]>
> Reviewed-by: Jason Andryuk <[e-mail]>
> Tested-by: Jason Andryuk <[e-mail]>

Acked-by: Roger Pau Monné <[e-mail]>

Thanks, Roger.

Patch

--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -902,8 +902,6 @@  static void enable_iommu(struct amd_iomm
         }
     }
 
-    amd_iommu_msi_enable(iommu, IOMMU_CONTROL_ENABLED);
-
     set_iommu_ht_flags(iommu);
     set_iommu_command_buffer_control(iommu, IOMMU_CONTROL_ENABLED);