RE: [tip:x86/hyperv] X86: Handle Hyper-V vmbus interrupts asspecial hypervisor interrupts

From: KY Srinivasan
Date: Tue Feb 12 2013 - 22:33:27 EST



> -----Original Message-----
> From: yhlu.kernel@xxxxxxxxx [mailto:yhlu.kernel@xxxxxxxxx] On Behalf Of
> Yinghai Lu
> Sent: Tuesday, February 12, 2013 9:56 PM
> To: mingo@xxxxxxxxxx; hpa@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; KY
> Srinivasan; tglx@xxxxxxxxxxxxx; hpa@xxxxxxxxxxxxxxx
> Cc: linux-tip-commits@xxxxxxxxxxxxxxx
> Subject: Re: [tip:x86/hyperv] X86: Handle Hyper-V vmbus interrupts as special
> hypervisor interrupts
>
> On Tue, Feb 12, 2013 at 4:58 PM, tip-bot for K. Y. Srinivasan
> <kys@xxxxxxxxxxxxx> wrote:
> > Commit-ID: bc2b0331e077f576369a2b6c75d15ed4de4ef91f
> > Gitweb:
> http://git.kernel.org/tip/bc2b0331e077f576369a2b6c75d15ed4de4ef91f
> > Author: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> > AuthorDate: Sun, 3 Feb 2013 17:22:39 -0800
> > Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
> > CommitDate: Tue, 12 Feb 2013 16:27:15 -0800
> >
> > 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@xxxxxxxx> and
> > Thomas Gleixner <tglx@xxxxxxxxxxxxx>, 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@xxxxxxxxxxxxx>
> > Link: http://lkml.kernel.org/r/1359940959-32168-3-git-send-email-
> kys@xxxxxxxxxxxxx
> > Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
> > ---
> > arch/x86/include/asm/irq_vectors.h | 4 ++--
> > arch/x86/include/asm/mshyperv.h | 4 ++++
> > arch/x86/kernel/cpu/mshyperv.c | 44
> ++++++++++++++++++++++++++++++++++++++
> > arch/x86/kernel/entry_32.S | 9 +++++++-
> > arch/x86/kernel/entry_64.S | 7 +++++-
> > drivers/xen/events.c | 7 +++---
> > 6 files changed, 68 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/irq_vectors.h
> b/arch/x86/include/asm/irq_vectors.h
> > index 1508e51..aac5fa6 100644
> > --- 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 79ce568..c2934be 100644
> > --- 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 4dab317..a7d26d8 100644
> > --- 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 6ed91d9..8831176 100644
> > --- 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 cb3c591..048f224 100644
> > --- 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 */
> > +
>
> so #ifdef CONFIG_HYPERV does not work here?

The issue was that you could turn on CONFIG_HYPERV without enabling
CONFIG_X86_LOCAL_APIC. Peter fixed it.

Regards,

K. Y
>
> Yinghai
>


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