[PATCH 0/2] [PULL REQUEST] iommu/vt-d: Fixes for v6.15-rc2

[PATCH 0/2] [PULL REQUEST] iommu/vt-d: Fixes for v6.15-rc2

[Lu Baolu]

Hi Joerg,

The following fixes have been queued for v6.15-rc2:

- Fix posted MSI issue when users change cpu affinity
- Remove invalid set_dma_ops() call in the iommu driver

They have been reviewed and are ready for merge. Can you please take
them?

Best regards,
baolu

Petr Tesarik (1):
  iommu/vt-d: Remove an unnecessary call set_dma_ops()

Sean Christopherson (1):
  iommu/vt-d: Wire up irq_ack() to irq_move_irq() for posted MSIs

 drivers/iommu/intel/iommu.c         |  1 -
 drivers/iommu/intel/irq_remapping.c | 29 +++++++++++++++--------------
 2 files changed, 15 insertions(+), 15 deletions(-)

-- 
2.43.0

[PATCH 1/2] iommu/vt-d: Wire up irq_ack() to irq_move_irq() for posted MSIs

[Lu Baolu]

From: Sean Christopherson <seanjc@google.com>

Set the posted MSI irq_chip's irq_ack() hook to irq_move_irq() instead of
a dummy/empty callback so that posted MSIs process pending changes to the
IRQ's SMP affinity.  Failure to honor a pending set-affinity results in
userspace being unable to change the effective affinity of the IRQ, as
IRQD_SETAFFINITY_PENDING is never cleared and so irq_set_affinity_locked()
always defers moving the IRQ.

The issue is most easily reproducible by setting /proc/irq/xx/smp_affinity
multiple times in quick succession, as only the first update is likely to
be handled in process context.

Fixes: ed1e48ea4370 ("iommu/vt-d: Enable posted mode for device MSIs")
Cc: Robert Lippert <rlippert@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Wentao Yang <wentaoyang@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20250321194249.1217961-1-seanjc@google.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/irq_remapping.c | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
index ea3ca5203919..3bc2a03cceca 100644
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -1287,43 +1287,44 @@ static struct irq_chip intel_ir_chip = {
 };
 
 /*
- * With posted MSIs, all vectors are multiplexed into a single notification
- * vector. Devices MSIs are then dispatched in a demux loop where
- * EOIs can be coalesced as well.
+ * With posted MSIs, the MSI vectors are multiplexed into a single notification
+ * vector, and only the notification vector is sent to the APIC IRR.  Device
+ * MSIs are then dispatched in a demux loop that harvests the MSIs from the
+ * CPU's Posted Interrupt Request bitmap.  I.e. Posted MSIs never get sent to
+ * the APIC IRR, and thus do not need an EOI.  The notification handler instead
+ * performs a single EOI after processing the PIR.
  *
- * "INTEL-IR-POST" IRQ chip does not do EOI on ACK, thus the dummy irq_ack()
- * function. Instead EOI is performed by the posted interrupt notification
- * handler.
+ * Note!  Pending SMP/CPU affinity changes, which are per MSI, must still be
+ * honored, only the APIC EOI is omitted.
  *
  * For the example below, 3 MSIs are coalesced into one CPU notification. Only
- * one apic_eoi() is needed.
+ * one apic_eoi() is needed, but each MSI needs to process pending changes to
+ * its CPU affinity.
  *
  * __sysvec_posted_msi_notification()
  *	irq_enter();
  *		handle_edge_irq()
  *			irq_chip_ack_parent()
- *				dummy(); // No EOI
+ *				irq_move_irq(); // No EOI
  *			handle_irq_event()
  *				driver_handler()
  *		handle_edge_irq()
  *			irq_chip_ack_parent()
- *				dummy(); // No EOI
+ *				irq_move_irq(); // No EOI
  *			handle_irq_event()
  *				driver_handler()
  *		handle_edge_irq()
  *			irq_chip_ack_parent()
- *				dummy(); // No EOI
+ *				irq_move_irq(); // No EOI
  *			handle_irq_event()
  *				driver_handler()
  *	apic_eoi()
  *	irq_exit()
+ *
  */
-
-static void dummy_ack(struct irq_data *d) { }
-
 static struct irq_chip intel_ir_chip_post_msi = {
 	.name			= "INTEL-IR-POST",
-	.irq_ack		= dummy_ack,
+	.irq_ack		= irq_move_irq,
 	.irq_set_affinity	= intel_ir_set_affinity,
 	.irq_compose_msi_msg	= intel_ir_compose_msi_msg,
 	.irq_set_vcpu_affinity	= intel_ir_set_vcpu_affinity,
-- 
2.43.0

[PATCH 2/2] iommu/vt-d: Remove an unnecessary call set_dma_ops()

[Lu Baolu]

From: Petr Tesarik <ptesarik@suse.com>

Do not touch per-device DMA ops when the driver has been converted to use
the dma-iommu API.

Fixes: c588072bba6b ("iommu/vt-d: Convert intel iommu driver to the iommu ops")
Signed-off-by: Petr Tesarik <ptesarik@suse.com>
Link: https://lore.kernel.org/r/20250403165605.278541-1-ptesarik@suse.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 6e67cc66a204..b29da2d96d0b 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3835,7 +3835,6 @@ static void intel_iommu_release_device(struct device *dev)
 	intel_pasid_free_table(dev);
 	intel_iommu_debugfs_remove_dev(info);
 	kfree(info);
-	set_dma_ops(dev, NULL);
 }
 
 static void intel_iommu_get_resv_regions(struct device *device,
-- 
2.43.0

Re: [PATCH 0/2] [PULL REQUEST] iommu/vt-d: Fixes for v6.15-rc2

[Joerg Roedel]

On Thu, Apr 10, 2025 at 03:32:45PM +0800, Lu Baolu wrote:
> Petr Tesarik (1):
>   iommu/vt-d: Remove an unnecessary call set_dma_ops()
> 
> Sean Christopherson (1):
>   iommu/vt-d: Wire up irq_ack() to irq_move_irq() for posted MSIs
> 
>  drivers/iommu/intel/iommu.c         |  1 -
>  drivers/iommu/intel/irq_remapping.c | 29 +++++++++++++++--------------
>  2 files changed, 15 insertions(+), 15 deletions(-)

Applied, thanks Baolu.