Messages in this thread | | | Date | Mon, 08 Mar 2010 14:16:30 -0800 | From | Jeremy Fitzhardinge <> | Subject | Re: [Xen-devel] [PATCH 7/7] xen: Enable event channel of PV extension of HVM |
| |
On 03/04/2010 10:07 PM, Sheng Yang wrote: > We mapped each IOAPIC pin to a VIRQ, so that we can deliver interrupt through > these VIRQs. > > We used X86_PLATFORM_IPI_VECTOR as the notification vector for hypervisor > to notify guest about the event. > > The patch also enabled SMP support, then we can support IPI through evtchn as well. > > When this feature is enabled, we would relay on Xen PV timer for clockevent, > rather than other hardware emulated ones. > > Then we don't use IOAPIC/LAPIC, eliminated the overhead brought by > unnecessary VMExit caused by LAPIC. > > Signed-off-by: Sheng Yang<sheng@linux.intel.com> > --- > arch/x86/xen/enlighten.c | 6 ++-- > arch/x86/xen/hvmpv.c | 59 +++++++++++++++++++++++++++++++++ > arch/x86/xen/irq.c | 28 ++++++++++++++++ > arch/x86/xen/smp.c | 76 ++++++++++++++++++++++++++++++++++++++++-- > arch/x86/xen/xen-ops.h | 16 +++++++++ > drivers/xen/events.c | 74 ++++++++++++++++++++++++++++++++++++++--- > include/xen/events.h | 4 ++ > include/xen/hvm.h | 5 +++ > include/xen/interface/xen.h | 6 +++- > 9 files changed, 260 insertions(+), 14 deletions(-) > > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > index 36daccb..2d60e70 100644 > --- a/arch/x86/xen/enlighten.c > +++ b/arch/x86/xen/enlighten.c > @@ -717,7 +717,7 @@ static u32 xen_safe_apic_wait_icr_idle(void) > return 0; > } > > -static void set_xen_basic_apic_ops(void) > +void xen_set_basic_apic_ops(void) > { > apic->read = xen_apic_read; > apic->write = xen_apic_write; > @@ -1026,7 +1026,7 @@ static void xen_crash_shutdown(struct pt_regs *regs) > xen_reboot(SHUTDOWN_crash); > } > > -static const struct machine_ops __initdata xen_machine_ops = { > +const struct machine_ops __initdata xen_machine_ops = { > .restart = xen_restart, > .halt = xen_machine_halt, > .power_off = xen_machine_halt, > @@ -1116,7 +1116,7 @@ asmlinkage void __init xen_start_kernel(void) > /* > * set up the basic apic ops. > */ > - set_xen_basic_apic_ops(); > + xen_set_basic_apic_ops(); > #endif > > if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) { > diff --git a/arch/x86/xen/hvmpv.c b/arch/x86/xen/hvmpv.c > index 305dcca..673b036 100644 > --- a/arch/x86/xen/hvmpv.c > +++ b/arch/x86/xen/hvmpv.c > @@ -17,6 +17,7 @@ > #include<xen/interface/version.h> > #include<xen/interface/memory.h> > > +#include<asm/reboot.h> > #include<asm/xen/cpuid.h> > #include<asm/xen/hypercall.h> > #include<asm/xen/hypervisor.h> > @@ -44,6 +45,8 @@ static void __init xen_hvm_pv_banner(void) > printk(KERN_INFO "Xen version: %d.%d%s\n", > version>> 16, version& 0xffff, extra.extraversion); > printk(KERN_INFO "PV feature: PV clocksource enabled\n"); > + if (xen_hvm_pv_evtchn_enabled()) > + printk(KERN_INFO "PV feature: Event channel enabled\n"); > } > > static int __init xen_para_available(void) > @@ -83,6 +86,9 @@ static int __init init_hvm_pv_info(void) > if (!(edx& XEN_CPUID_FEAT2_HVM_PV)) > return -ENODEV; > > + if (edx& XEN_CPUID_FEAT2_HVM_PV_EVTCHN) > + xen_hvm_pv_features |= XEN_HVM_PV_EVTCHN_ENABLED; > + > if (pages< 1) > return -ENODEV; > > @@ -127,9 +133,35 @@ static void __init init_pv_clocksource(void) > xen_register_clocksource(); > } > > +static int set_callback_via(uint64_t via) > +{ > + struct xen_hvm_param a; > + > + a.domid = DOMID_SELF; > + a.index = HVM_PARAM_CALLBACK_IRQ; > + a.value = via; > + return HYPERVISOR_hvm_op(HVMOP_set_param,&a); > +} > + > +void do_hvm_pv_evtchn_intr(void) > +{ > + per_cpu(irq_count, smp_processor_id())++; > + xen_hvm_evtchn_do_upcall(get_irq_regs()); > + per_cpu(irq_count, smp_processor_id())--; > +} > + > +#ifdef CONFIG_X86_LOCAL_APIC > +static void xen_hvm_pv_evtchn_apic_write(u32 reg, u32 val) > +{ > + /* The only one reached here should be EOI */ > + WARN_ON(reg != APIC_EOI); > +} > +#endif > + > void __init xen_guest_init(void) > { > int r; > + uint64_t callback_via; > > /* Ensure the we won't confused with others */ > if (xen_domain()) > @@ -152,4 +184,31 @@ void __init xen_guest_init(void) > init_pv_clocksource(); > > xen_domain_type = XEN_HVM_DOMAIN; > + > + if (xen_hvm_pv_evtchn_enabled()) { > + xen_hvm_pv_init_irq_ops(); > + > + x86_init.timers.timer_init = xen_time_init; > + x86_init.timers.setup_percpu_clockev = x86_init_noop; > + x86_cpuinit.setup_percpu_clockev = x86_init_noop; > + > + pv_apic_ops.startup_ipi_hook = paravirt_nop; > +#ifdef CONFIG_X86_LOCAL_APIC > + /* > + * set up the basic apic ops. > + */ > + xen_set_basic_apic_ops(); > + apic->write = xen_hvm_pv_evtchn_apic_write; > +#endif > + > + callback_via = HVM_CALLBACK_VECTOR(X86_PLATFORM_IPI_VECTOR); > + set_callback_via(callback_via); > + > + x86_platform_ipi_callback = do_hvm_pv_evtchn_intr; > + > + disable_acpi(); > + > + xen_hvm_pv_smp_init(); > + machine_ops = xen_machine_ops; > + } > } > diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c > index 9d30105..e325640 100644 > --- a/arch/x86/xen/irq.c > +++ b/arch/x86/xen/irq.c > @@ -2,6 +2,7 @@ > > #include<asm/x86_init.h> > > +#include<xen/xen.h> > #include<xen/interface/xen.h> > #include<xen/interface/sched.h> > #include<xen/interface/vcpu.h> > @@ -131,3 +132,30 @@ void __init xen_init_irq_ops() > pv_irq_ops = xen_irq_ops; > x86_init.irqs.intr_init = xen_init_IRQ; > } > + > +#ifdef CONFIG_XEN_HVM_PV > +static void xen_hvm_pv_evtchn_disable(void) > +{ > + native_irq_disable(); > + xen_irq_disable(); > +} > +PV_CALLEE_SAVE_REGS_THUNK(xen_hvm_pv_evtchn_disable); > + > +static void xen_hvm_pv_evtchn_enable(void) > +{ > + native_irq_enable(); > + xen_irq_enable(); > +} >
Why is it necessary to disable both the event mask and eflags.IF? Surely IF is enough?
If it is necessary here, why not for save/restore flags?
J
| |