xen/events: Support event channel rebind on ARM

Currently, the event channel rebind code is gated with the presence of
the vector callback.

The virtual interrupt controller on ARM has the concept of per-CPU
interrupt (PPI) which allow us to support per-VCPU event channel.
Therefore there is no need of vector callback for ARM.

Xen is already using a free PPI to notify the guest VCPU of an event.
Furthermore, the xen code initialization in Linux (see
arch/arm/xen/enlighten.c) is requesting correctly a per-CPU IRQ.

Introduce new helper xen_support_evtchn_rebind to allow architecture
decide whether rebind an event is support or not. It will always return
true on ARM and keep the same behavior on x86.

This is also allow us to drop the usage of xen_have_vector_callback
entirely in the ARM code.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

diff --git a/arch/arm/include/asm/xen/events.h b/arch/arm/include/asm/xen/events.h
index 8b1f37bfeeecf3c2d8af09ed15bcbc4cc8fa991f..71e473d05fcce8a2b869b84272dfcd498c3847dc 100644 (file)
--- a/arch/arm/include/asm/xen/events.h
+++ b/arch/arm/include/asm/xen/events.h
@@ -20,4 +20,10 @@ static inline int xen_irqs_disabled(struct pt_regs *regs)
                                                            atomic64_t, \
                                                            counter), (val))
 
+/* Rebind event channel is supported by default */
+static inline bool xen_support_evtchn_rebind(void)
+{
+       return true;
+}
+
 #endif /* _ASM_ARM_XEN_EVENTS_H */

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 6c09cc440a2b24c4c0acfbd3027c74f9a1dc9efe..40b961d8e953c9ba05a998a4a538a893cc18d98a 100644 (file)
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -45,10 +45,6 @@ static struct vcpu_info __percpu *xen_vcpu_info;
 unsigned long xen_released_pages;
 struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
 
-/* TODO: to be removed */
-__read_mostly int xen_have_vector_callback;
-EXPORT_SYMBOL_GPL(xen_have_vector_callback);
-
 int xen_platform_pci_unplug = XEN_UNPLUG_ALL;
 EXPORT_SYMBOL_GPL(xen_platform_pci_unplug);
 

diff --git a/arch/arm64/include/asm/xen/events.h b/arch/arm64/include/asm/xen/events.h
index 86553213c1322cafd3ca816e8e6e6a762c2bbe3d..4318866d053c513738c5fb3194652ceaf2a7770a 100644 (file)
--- a/arch/arm64/include/asm/xen/events.h
+++ b/arch/arm64/include/asm/xen/events.h
@@ -18,4 +18,10 @@ static inline int xen_irqs_disabled(struct pt_regs *regs)
 
 #define xchg_xen_ulong(ptr, val) xchg((ptr), (val))
 
+/* Rebind event channel is supported by default */
+static inline bool xen_support_evtchn_rebind(void)
+{
+       return true;
+}
+
 #endif /* _ASM_ARM64_XEN_EVENTS_H */

diff --git a/arch/x86/include/asm/xen/events.h b/arch/x86/include/asm/xen/events.h
index 608a79d5a4669ebf3a9060f895d0f5f03ab3286c..e6911caf5bbf16ddc46430c44fcd4186258b713c 100644 (file)
--- a/arch/x86/include/asm/xen/events.h
+++ b/arch/x86/include/asm/xen/events.h
@@ -20,4 +20,15 @@ static inline int xen_irqs_disabled(struct pt_regs *regs)
 /* No need for a barrier -- XCHG is a barrier on x86. */
 #define xchg_xen_ulong(ptr, val) xchg((ptr), (val))
 
+extern int xen_have_vector_callback;
+
+/*
+ * Events delivered via platform PCI interrupts are always
+ * routed to vcpu 0 and hence cannot be rebound.
+ */
+static inline bool xen_support_evtchn_rebind(void)
+{
+       return (!xen_hvm_domain() || xen_have_vector_callback);
+}
+
 #endif /* _ASM_X86_XEN_EVENTS_H */

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 96093ae369a5613938962b4970decda66c19d342..ed620e5857a1e673ddea45df83885bdd7b234f0a 100644 (file)
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1301,11 +1301,7 @@ static int rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
        if (!VALID_EVTCHN(evtchn))
                return -1;
 
-       /*
-        * Events delivered via platform PCI interrupts are always
-        * routed to vcpu 0 and hence cannot be rebound.
-        */
-       if (xen_hvm_domain() && !xen_have_vector_callback)
+       if (!xen_support_evtchn_rebind())
                return -1;
 
        /* Send future instances of this interrupt to other vcpu. */

diff --git a/include/xen/events.h b/include/xen/events.h
index 7d95fdf9cf3e773f3d800194ca43a2f0a7acdd7a..88da2abaf53592c929260dd9a3c7c0f7fb346482 100644 (file)
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -92,7 +92,6 @@ void xen_hvm_callback_vector(void);
 #ifdef CONFIG_TRACING
 #define trace_xen_hvm_callback_vector xen_hvm_callback_vector
 #endif
-extern int xen_have_vector_callback;
 int xen_set_callback_via(uint64_t via);
 void xen_evtchn_do_upcall(struct pt_regs *regs);
 void xen_hvm_evtchn_do_upcall(void);