xen/pciback: Allocate IRQ handler for device that is shared with guest.

If the device that is to be shared with a guest is a level device and
the IRQ is shared with the initial domain we need to take actions.
Mainly we install a dummy IRQ handler that will ACK on the interrupt
line so as to not have the initial domain disable the interrupt line.

This dummy IRQ handler is not enabled when the device MSI/MSI-X lines
are set, nor for edge interrupts. And also not for level interrupts
that are not shared amongst devices. Lastly, if the user passes
to the guest all of the PCI devices on the shared line the we won't
install the dummy handler either.

There is also SysFS instrumentation to check its state and turn
IRQ ACKing on/off if necessary.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
index c1e95e88ee9e..5c140200a5ea 100644
--- a/drivers/xen/xen-pciback/pciback.h
+++ b/drivers/xen/xen-pciback/pciback.h
@@ -45,8 +45,14 @@ struct pciback_device {
 
 struct pciback_dev_data {
 	struct list_head config_fields;
-	int permissive;
-	int warned_on_write;
+	unsigned int permissive:1;
+	unsigned int warned_on_write:1;
+	unsigned int enable_intx:1;
+	unsigned int isr_on:1; /* Whether the IRQ handler is installed. */
+	unsigned int ack_intr:1; /* .. and ACK-ing */
+	unsigned long handled;
+	unsigned int irq; /* Saved in case device transitions to MSI/MSI-X */
+	char irq_name[0]; /* pciback[000:04:00.0] */
 };
 
 /* Used by XenBus and pciback_ops.c */
@@ -131,3 +137,6 @@ extern int verbose_request;
 void test_and_schedule_op(struct pciback_device *pdev);
 #endif
 
+/* Handles shared IRQs that can to device domain and control domain. */
+void pciback_irq_handler(struct pci_dev *dev, int reset);
+irqreturn_t pciback_guest_interrupt(int irq, void *dev_id);