Commit a1610461 authored by Dave Jiang's avatar Dave Jiang Committed by Vinod Koul
Browse files

dmaengine: idxd: remove MSIX masking for interrupt handlers 



Remove interrupt masking and just let the hard irq handler keep
firing for new events. This is less of a performance impact vs
the MMIO readback inside the pci_msi_{mask,unmas}_irq(). Especially
with a loaded system those flushes can be stuck behind large amounts
of MMIO writes to flush. When guest kernel is running on top of VFIO
mdev, mask/unmask causes a vmexit each time and is not desirable.

Suggested-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarDave Jiang <dave.jiang@intel.com>
Reviewed-by: default avatarDan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/161894523436.3210025.1834640110556139277.stgit@djiang5-desk3.ch.intel.com


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent 53b2ee7f

drivers/dma/idxd/idxd.h

+0 −1
Original line number Diff line number Diff line
@@ -377,7 +377,6 @@ void idxd_wqs_quiesce(struct idxd_device *idxd); 
/* device interrupt control */

void idxd_msix_perm_setup(struct idxd_device *idxd);

void idxd_msix_perm_clear(struct idxd_device *idxd);

irqreturn_t idxd_irq_handler(int vec, void *data);

irqreturn_t idxd_misc_thread(int vec, void *data);

irqreturn_t idxd_wq_thread(int irq, void *data);

void idxd_mask_error_interrupts(struct idxd_device *idxd);

drivers/dma/idxd/init.c

+2 −2
Original line number Diff line number Diff line
@@ -102,7 +102,7 @@ static int idxd_setup_interrupts(struct idxd_device *idxd) 
	}



	irq_entry = &idxd->irq_entries[0];

	rc = request_threaded_irq(irq_entry->vector, idxd_irq_handler, idxd_misc_thread,

	rc = request_threaded_irq(irq_entry->vector, NULL, idxd_misc_thread,

				  0, "idxd-misc", irq_entry);

	if (rc < 0) {

		dev_err(dev, "Failed to allocate misc interrupt.\n");
@@ -119,7 +119,7 @@ static int idxd_setup_interrupts(struct idxd_device *idxd) 


		init_llist_head(&idxd->irq_entries[i].pending_llist);

		INIT_LIST_HEAD(&idxd->irq_entries[i].work_list);

		rc = request_threaded_irq(irq_entry->vector, idxd_irq_handler,

		rc = request_threaded_irq(irq_entry->vector, NULL,

					  idxd_wq_thread, 0, "idxd-portal", irq_entry);

		if (rc < 0) {

			dev_err(dev, "Failed to allocate irq %d.\n", irq_entry->vector);

drivers/dma/idxd/irq.c

+0 −12
Original line number Diff line number Diff line
@@ -102,15 +102,6 @@ static int idxd_device_schedule_fault_process(struct idxd_device *idxd, 
	return 0;

}



irqreturn_t idxd_irq_handler(int vec, void *data)

{

	struct idxd_irq_entry *irq_entry = data;

	struct idxd_device *idxd = irq_entry->idxd;



	idxd_mask_msix_vector(idxd, irq_entry->id);

	return IRQ_WAKE_THREAD;

}



static int process_misc_interrupts(struct idxd_device *idxd, u32 cause)

{

	struct device *dev = &idxd->pdev->dev;
@@ -237,7 +228,6 @@ irqreturn_t idxd_misc_thread(int vec, void *data) 
			iowrite32(cause, idxd->reg_base + IDXD_INTCAUSE_OFFSET);

	}



	idxd_unmask_msix_vector(idxd, irq_entry->id);

	return IRQ_HANDLED;

}
@@ -394,8 +384,6 @@ irqreturn_t idxd_wq_thread(int irq, void *data) 
	int processed;



	processed = idxd_desc_process(irq_entry);

	idxd_unmask_msix_vector(irq_entry->idxd, irq_entry->id);



	if (processed == 0)

		return IRQ_NONE;