xen: Allow platform PCI interrupt to be shared

When we don't use the per-CPU vector callback, we ask Xen to deliver event
channel interrupts as INTx on the PCI platform device. As such, it can be
shared with INTx on other PCI devices.

Set IRQF_SHARED, and make it return IRQ_HANDLED or IRQ_NONE according to
whether the evtchn_upcall_pending flag was actually set. Now I can share
the interrupt:

 11:         82          0   IO-APIC  11-fasteoi   xen-platform-pci, ens4

Drop the IRQF_TRIGGER_RISING. It has no effect when the IRQ is shared,
and besides, the only effect it was having even beforehand was to trigger
a debug message in both I/OAPIC and legacy PIC cases:

[    0.915441] genirq: No set_type function for IRQ 11 (IO-APIC)
[    0.951939] genirq: No set_type function for IRQ 11 (XT-PIC)

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/f9a29a68d05668a3636dd09acd94d970269eaec6.camel@infradead.org
Signed-off-by: Juergen Gross <jgross@suse.com>

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index c443f04aaad77f39f05c4c04b9279daeac2c55a9..c7715f8bd45221d6d226bc688b625605d6c26f4e 100644 (file)
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1710,9 +1710,10 @@ void handle_irq_for_port(evtchn_port_t port, struct evtchn_loop_ctrl *ctrl)
        generic_handle_irq(irq);
 }
 
-static void __xen_evtchn_do_upcall(void)
+static int __xen_evtchn_do_upcall(void)
 {
        struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
+       int ret = vcpu_info->evtchn_upcall_pending ? IRQ_HANDLED : IRQ_NONE;
        int cpu = smp_processor_id();
        struct evtchn_loop_ctrl ctrl = { 0 };
 
@@ -1737,6 +1738,8 @@ static void __xen_evtchn_do_upcall(void)
         * above.
         */
        __this_cpu_inc(irq_epoch);
+
+       return ret;
 }
 
 void xen_evtchn_do_upcall(struct pt_regs *regs)
@@ -1751,9 +1754,9 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
        set_irq_regs(old_regs);
 }
 
-void xen_hvm_evtchn_do_upcall(void)
+int xen_hvm_evtchn_do_upcall(void)
 {
-       __xen_evtchn_do_upcall();
+       return __xen_evtchn_do_upcall();
 }
 EXPORT_SYMBOL_GPL(xen_hvm_evtchn_do_upcall);
 

diff --git a/drivers/xen/platform-pci.c b/drivers/xen/platform-pci.c
index cd07e3fed0faf6136f22c8702d9b450bbe7026ce..fcc8191315723c6701ec5e7c5b97a73374b899a8 100644 (file)
--- a/drivers/xen/platform-pci.c
+++ b/drivers/xen/platform-pci.c
@@ -64,14 +64,13 @@ static uint64_t get_callback_via(struct pci_dev *pdev)
 
 static irqreturn_t do_hvm_evtchn_intr(int irq, void *dev_id)
 {
-       xen_hvm_evtchn_do_upcall();
-       return IRQ_HANDLED;
+       return xen_hvm_evtchn_do_upcall();
 }
 
 static int xen_allocate_irq(struct pci_dev *pdev)
 {
        return request_irq(pdev->irq, do_hvm_evtchn_intr,
-                       IRQF_NOBALANCING | IRQF_TRIGGER_RISING,
+                       IRQF_NOBALANCING | IRQF_SHARED,
                        "xen-platform-pci", pdev);
 }
 

diff --git a/include/xen/events.h b/include/xen/events.h
index 344081e71584b4e6cd0066fff48cd17389a5dd26..44c2855c76d1fb4d8223820c8ac4b8b95d209c2a 100644 (file)
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -107,7 +107,7 @@ evtchn_port_t evtchn_from_irq(unsigned irq);
 
 int xen_set_callback_via(uint64_t via);
 void xen_evtchn_do_upcall(struct pt_regs *regs);
-void xen_hvm_evtchn_do_upcall(void);
+int xen_hvm_evtchn_do_upcall(void);
 
 /* Bind a pirq for a physical interrupt to an irq. */
 int xen_bind_pirq_gsi_to_irq(unsigned gsi,