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Message-Id: <1403688530-23273-3-git-send-email-marc.zyngier@arm.com>
Date: Wed, 25 Jun 2014 10:28:43 +0100
From: Marc Zyngier <marc.zyngier@....com>
To: kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Cc: Will Deacon <will.deacon@....com>,
Catalin Marinas <catalin.marinas@....com>,
Thomas Gleixner <tglx@...utronix.de>, eric.auger@...aro.org,
Christoffer Dall <christoffer.dall@...aro.org>
Subject: [RFC PATCH 2/9] genirq: Allow the state of a forwarded irq to be save/restored
When a peripheral is shared between virtual machines, its interrupt
state becomes part of the guest's state, and must be switched accordingly.
Introduce a pair of accessors (irq_get_fwd_state/irq_set_fwd_state) to
retrieve the bits that can be of interest to KVM: pending, active, and masked.
- irq_get_fwd_state returns the state of the interrupt according to a mask
containing any of the IRQ_STATE_PENDING, IRQ_STATE_ACTIVE or IRQ_STATE_MASKED
bits.
- irq_set_fwd_state sets the state of the interrupt according to a similar mask.
Only a forwarded interrupt can be manipulated in such a way.
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
---
include/linux/interrupt.h | 2 ++
include/linux/irq.h | 16 ++++++++++
kernel/irq/manage.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 98 insertions(+)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 698ad05..cfb8006 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -361,6 +361,8 @@ static inline int disable_irq_wake(unsigned int irq)
return irq_set_irq_wake(irq, 0);
}
+extern int irq_get_fwd_state(unsigned int irq, u32 *val, u32 mask);
+extern int irq_set_fwd_state(unsigned int irq, u32 val, u32 mask);
#ifdef CONFIG_IRQ_FORCED_THREADING
extern bool force_irqthreads;
diff --git a/include/linux/irq.h b/include/linux/irq.h
index b4b3120..88ecd58 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -323,6 +323,8 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
* any other callback related to this irq
* @irq_release_resources: optional to release resources acquired with
* irq_request_resources
+ * @irq_get_fwd_state: return the state of a forwarded interrupt
+ * @irq_set_fwd_state: set the state of a forwarded interrupt
* @flags: chip specific flags
*/
struct irq_chip {
@@ -359,6 +361,9 @@ struct irq_chip {
int (*irq_request_resources)(struct irq_data *data);
void (*irq_release_resources)(struct irq_data *data);
+ u32 (*irq_get_fwd_state)(struct irq_data *data, u32 mask);
+ void (*irq_set_fwd_state)(struct irq_data *data, u32 val, u32 mask);
+
unsigned long flags;
};
@@ -384,6 +389,17 @@ enum {
IRQCHIP_EOI_THREADED = (1 << 6),
};
+/*
+ * irq_get_fwd_state/irq_set_fwd_state specific flags (used for both
+ * state and mask). Only valid for an interrupt that has the
+ * IRQD_IRQ_FORWARDED flag.
+ */
+enum {
+ IRQ_FWD_STATE_PENDING = (1 << 0),
+ IRQ_FWD_STATE_ACTIVE = (1 << 1),
+ IRQ_FWD_STATE_MASKED = (1 << 2),
+};
+
/* This include will go away once we isolated irq_desc usage to core code */
#include <linux/irqdesc.h>
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 3dc6a61..c42dd73 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1770,3 +1770,83 @@ int request_percpu_irq(unsigned int irq, irq_handler_t handler,
return retval;
}
+
+/**
+ * irq_get_fwd_state - return the state of a forwarded interrupt.
+ * @irq: Interrupt line that is forwarded to a VM
+ * @val: Pointer where the state is being stored
+ * @mask: Bitmask of IRQ_FWD_STATE_* the caller wants to know about
+ *
+ * This call snapshots the state of a forwarded interrupt,
+ * depending on the mask which indicates the requested bits.
+ *
+ * This function should be called with preemption disabled if the
+ * interrupt controller has per-cpu registers.
+ */
+int irq_get_fwd_state(unsigned int irq, u32 *val, u32 mask)
+{
+ struct irq_desc *desc;
+ struct irq_data *data;
+ struct irq_chip *chip;
+ unsigned long flags;
+
+ desc = irq_to_desc(irq);
+ if (!desc)
+ return -EINVAL;
+
+ data = irq_desc_get_irq_data(desc);
+ if (!irqd_irq_forwarded(data))
+ return -EINVAL;
+
+ chip = irq_desc_get_chip(desc);
+ if (!chip->irq_get_fwd_state)
+ return -EINVAL;
+
+ chip_bus_lock(desc);
+ raw_spin_lock_irqsave(&desc->lock, flags);
+ *val = chip->irq_get_fwd_state(data, mask);
+ raw_spin_unlock_irqrestore(&desc->lock, flags);
+ chip_bus_sync_unlock(desc);
+
+ return 0;
+}
+
+/**
+ * irq_set_fwd_state - set the state of a forwarded interrupt.
+ * @irq: Interrupt line that is forwarded to a VM
+ * @val: State to be restored
+ * @mask: Bitmask of IRQ_FWD_STATE_* defining the valid bits in @val
+ *
+ * This call sets the state of a forwarded interrupt, depending
+ * on the mask which indicates the valid bits.
+ *
+ * This function should be called with preemption disabled if the
+ * interrupt controller has per-cpu registers.
+ */
+int irq_set_fwd_state(unsigned int irq, u32 val, u32 mask)
+{
+ struct irq_desc *desc;
+ struct irq_data *data;
+ struct irq_chip *chip;
+ unsigned long flags;
+
+ desc = irq_to_desc(irq);
+ if (!desc)
+ return -EINVAL;
+
+ data = irq_desc_get_irq_data(desc);
+ if (!irqd_irq_forwarded(data))
+ return -EINVAL;
+
+ chip = irq_desc_get_chip(desc);
+ if (!chip->irq_set_fwd_state)
+ return -EINVAL;
+
+ chip_bus_lock(desc);
+ raw_spin_lock_irqsave(&desc->lock, flags);
+ chip->irq_set_fwd_state(data, val, mask);
+ raw_spin_unlock_irqrestore(&desc->lock, flags);
+ chip_bus_sync_unlock(desc);
+
+ return 0;
+}
--
1.8.3.4
--
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