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: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/161894523436.3210025.1834640110556139277.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index 87330b6940fabcdc37a72473bb69b6ded501c01f..97c96ca6ab70d90a0e89ac9480c555846059fa8d 100644 (file)
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -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);

diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
index 64dab4de217e4a2338a42c70bb3266a74c571a61..8003f8a25fffb6cd000a9933af389839a63635c5 100644 (file)
--- a/drivers/dma/idxd/init.c
+++ b/drivers/dma/idxd/init.c
@@ -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);

diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
index 43eea5c9cbd454d39aa196aba97e693fab736f94..afee571e01949598b970ec397e39cb52ed65b36c 100644 (file)
--- a/drivers/dma/idxd/irq.c
+++ b/drivers/dma/idxd/irq.c
@@ -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;