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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>
This commit is contained in:
Dave Jiang 2021-04-20 12:00:34 -07:00 committed by Vinod Koul
parent 53b2ee7f63
commit a16104617d
3 changed files with 2 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/dma/idxd/idxd.h
View File

@ -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);

4
drivers/dma/idxd/init.c
View File

@ -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);

12
drivers/dma/idxd/irq.c
View File

@ -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;