linux-kernel - [PATCH] xen/events: Always allocate legacy interrupts on PV guests

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Date:	Tue, 17 Nov 2015 10:36:25 -0500
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	konrad.wilk@...cle.com, david.vrabel@...rix.com
Cc:	xen-devel@...ts.xen.org, linux-kernel@...r.kernel.org,
	jgross@...e.com, tglx@...utronix.de,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: [PATCH] xen/events: Always allocate legacy interrupts on PV guests

After commit 8c058b0b9c34 ("x86/irq: Probe for PIC presence before
allocating descs for legacy IRQs") early_irq_init() will no longer
preallocate descriptors for legacy interrupts if PIT does not
exist.

Therefore we need to allocate those descriptors for PV guests
ourselves.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Suggested-by: Thomas Gleixner <tglx@...utronix.de>
---
 drivers/xen/events/events_base.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 849500e..a2bb333 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -419,8 +419,8 @@ static int __must_check xen_allocate_irq_gsi(unsigned gsi)
 	if (xen_pv_domain() && !xen_initial_domain())
 		return xen_allocate_irq_dynamic();
 
-	/* Legacy IRQ descriptors are already allocated by the arch. */
-	if (gsi < NR_IRQS_LEGACY)
+	/* On HVM legacy IRQ descriptors are already allocated by the arch. */
+	if (xen_hvm_domain() && gsi < NR_IRQS_LEGACY)
 		irq = gsi;
 	else
 		irq = irq_alloc_desc_at(gsi, -1);
@@ -445,8 +445,8 @@ static void xen_free_irq(unsigned irq)
 
 	kfree(info);
 
-	/* Legacy IRQ descriptors are managed by the arch. */
-	if (irq < NR_IRQS_LEGACY)
+	/* On HVM legacy IRQ descriptors are managed by the arch. */
+	if (xen_hvm_domain() && irq < NR_IRQS_LEGACY)
 		return;
 
 	irq_free_desc(irq);
-- 
1.9.3

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