X86: Handle Hyper-V vmbus interrupts as special hypervisor interrupts

Starting with win8, vmbus interrupts can be delivered on any VCPU in the guest
and furthermore can be concurrently active on multiple VCPUs. Support this
interrupt delivery model by setting up a separate IDT entry for Hyper-V vmbus.
interrupts. I would like to thank Jan Beulich <JBeulich@suse.com> and
Thomas Gleixner <tglx@linutronix.de>, for their help.

In this version of the patch, based on the feedback, I have merged the IDT
vector for Xen and Hyper-V and made the necessary adjustments. Furhermore,
based on Jan's feedback I have added the necessary compilation switches.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1359940959-32168-3-git-send-email-kys@microsoft.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 1508e518c7e3b1b98a8ee19c3c33920a0bcba170..aac5fa62a86caf91c82873712543017f89df1756 100644 (file)
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -109,8 +109,8 @@
 
 #define UV_BAU_MESSAGE                 0xf5
 
-/* Xen vector callback to receive events in a HVM domain */
-#define XEN_HVM_EVTCHN_CALLBACK                0xf3
+/* Vector on which hypervisor callbacks will be delivered */
+#define HYPERVISOR_CALLBACK_VECTOR     0xf3
 
 /*
  * Local APIC timer IRQ vector is on a different priority level,

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 79ce5685ab64168bc8314566a0e9d976aa3335de..c2934be2446a73df2d66c97e32911b5d47860f98 100644 (file)
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -11,4 +11,8 @@ struct ms_hyperv_info {
 
 extern struct ms_hyperv_info ms_hyperv;
 
+void hyperv_callback_vector(void);
+void hyperv_vector_handler(struct pt_regs *regs);
+void hv_register_vmbus_handler(int irq, irq_handler_t handler);
+
 #endif

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 4dab317f79b923b616a57b96bad52c1298b61562..a7d26d83fb700b254eca03d9ff5e8f6d56f7a0c5 100644 (file)
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -14,10 +14,15 @@
 #include <linux/time.h>
 #include <linux/clocksource.h>
 #include <linux/module.h>
+#include <linux/hardirq.h>
+#include <linux/interrupt.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 #include <asm/hyperv.h>
 #include <asm/mshyperv.h>
+#include <asm/desc.h>
+#include <asm/idle.h>
+#include <asm/irq_regs.h>
 
 struct ms_hyperv_info ms_hyperv;
 EXPORT_SYMBOL_GPL(ms_hyperv);
@@ -77,6 +82,12 @@ static void __init ms_hyperv_init_platform(void)
 
        if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
                clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
+#if IS_ENABLED(CONFIG_HYPERV)
+       /*
+        * Setup the IDT for hypervisor callback.
+        */
+       alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
+#endif
 }
 
 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
@@ -85,3 +96,36 @@ const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
        .init_platform          = ms_hyperv_init_platform,
 };
 EXPORT_SYMBOL(x86_hyper_ms_hyperv);
+
+#if IS_ENABLED(CONFIG_HYPERV)
+static int vmbus_irq = -1;
+static irq_handler_t vmbus_isr;
+
+void hv_register_vmbus_handler(int irq, irq_handler_t handler)
+{
+       vmbus_irq = irq;
+       vmbus_isr = handler;
+}
+
+void hyperv_vector_handler(struct pt_regs *regs)
+{
+       struct pt_regs *old_regs = set_irq_regs(regs);
+       struct irq_desc *desc;
+
+       irq_enter();
+       exit_idle();
+
+       desc = irq_to_desc(vmbus_irq);
+
+       if (desc)
+               generic_handle_irq_desc(vmbus_irq, desc);
+
+       irq_exit();
+       set_irq_regs(old_regs);
+}
+#else
+void hv_register_vmbus_handler(int irq, irq_handler_t handler)
+{
+}
+#endif
+EXPORT_SYMBOL_GPL(hv_register_vmbus_handler);

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 6ed91d9980e240b73fa824f7db00d8065d145316..8831176aa5ef09d9ffd99976be4777cbf67bf505 100644 (file)
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1091,11 +1091,18 @@ ENTRY(xen_failsafe_callback)
        _ASM_EXTABLE(4b,9b)
 ENDPROC(xen_failsafe_callback)
 
-BUILD_INTERRUPT3(xen_hvm_callback_vector, XEN_HVM_EVTCHN_CALLBACK,
+BUILD_INTERRUPT3(xen_hvm_callback_vector, HYPERVISOR_CALLBACK_VECTOR,
                xen_evtchn_do_upcall)
 
 #endif /* CONFIG_XEN */
 
+#if IS_ENABLED(CONFIG_HYPERV)
+
+BUILD_INTERRUPT3(hyperv_callback_vector, HYPERVISOR_CALLBACK_VECTOR,
+       hyperv_vector_handler)
+
+#endif /* CONFIG_HYPERV */
+
 #ifdef CONFIG_FUNCTION_TRACER
 #ifdef CONFIG_DYNAMIC_FTRACE
 

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index cb3c591339aa3d4242e420d181b83f3a62ced2c3..048f2240f8e62d222221d1e49b9215c5c512a553 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1454,11 +1454,16 @@ ENTRY(xen_failsafe_callback)
        CFI_ENDPROC
 END(xen_failsafe_callback)
 
-apicinterrupt XEN_HVM_EVTCHN_CALLBACK \
+apicinterrupt HYPERVISOR_CALLBACK_VECTOR \
        xen_hvm_callback_vector xen_evtchn_do_upcall
 
 #endif /* CONFIG_XEN */
 
+#if IS_ENABLED(CONFIG_HYPERV)
+apicinterrupt HYPERVISOR_CALLBACK_VECTOR \
+       hyperv_callback_vector hyperv_vector_handler
+#endif /* CONFIG_HYPERV */
+
 /*
  * Some functions should be protected against kprobes
  */

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 74d77dfa5f636001356b2d27d370708b820c885e..22f77c5f60120ea5d2737294cf08be25e2ce8bf9 100644 (file)
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -1787,7 +1787,7 @@ void xen_callback_vector(void)
        int rc;
        uint64_t callback_via;
        if (xen_have_vector_callback) {
-               callback_via = HVM_CALLBACK_VECTOR(XEN_HVM_EVTCHN_CALLBACK);
+               callback_via = HVM_CALLBACK_VECTOR(HYPERVISOR_CALLBACK_VECTOR);
                rc = xen_set_callback_via(callback_via);
                if (rc) {
                        printk(KERN_ERR "Request for Xen HVM callback vector"
@@ -1798,8 +1798,9 @@ void xen_callback_vector(void)
                printk(KERN_INFO "Xen HVM callback vector for event delivery is "
                                "enabled\n");
                /* in the restore case the vector has already been allocated */
-               if (!test_bit(XEN_HVM_EVTCHN_CALLBACK, used_vectors))
-                       alloc_intr_gate(XEN_HVM_EVTCHN_CALLBACK, xen_hvm_callback_vector);
+               if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
+                       alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
+                                       xen_hvm_callback_vector);
        }
 }
 #else