lkml.org 
[lkml]   [2010]   [Mar]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 7/7] xen: Make event channel work with PV extension of HVM
On 03/04/2010 01:36 AM, 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 noficiation vector for hypervisor
>
"notification"

> to notify guest about the event.
>
> The patch also enabled SMP support, then we can support IPI through evtchn as well.
>
> Then we don't use IOAPIC/LAPIC, eliminated the overhead brought by
> unnecessary VMExit caused by LAPIC.
>

I think you need to expand this comment to explain the consequences of
this change on SMP bringup and timers. I still don't see why there are
(or should be) any differences from PV cpu bringup, aside from the tiny
details of syscall setup (and MTRR I guess, but that's all a noop
anyway, right?).

Also, I think you can probably do the timer changes in a separate patch,
as even with evtchns, an emulated timer device interrupt will still be
delivered properly via VIRQ_EMUL_PIN_*.

> Signed-off-by: Sheng Yang<sheng@linux.intel.com>
> ---
> arch/x86/xen/enlighten.c | 6 +-
> arch/x86/xen/hvmpv.c | 68 +++++++++++++++++++++++++++++++-
> arch/x86/xen/irq.c | 28 +++++++++++++
> arch/x86/xen/smp.c | 92 ++++++++++++++++++++++++++++++++++++++++--
> arch/x86/xen/xen-ops.h | 14 +++++++
> drivers/xen/events.c | 74 +++++++++++++++++++++++++++++++---
> include/xen/events.h | 6 +++
> include/xen/hvm.h | 5 ++
> include/xen/interface/xen.h | 6 ++-
> include/xen/xen.h | 2 +
> 10 files changed, 285 insertions(+), 16 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 284e021..233951b 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;
> +
> /* We only support 1 page of hypercall for now */
> if (pages != 1)
> return -ENOMEM;
> @@ -131,12 +137,42 @@ static void __init init_pv_clocksource(void)
> x86_platform.get_wallclock = xen_get_wallclock;
> x86_platform.set_wallclock = xen_set_wallclock;
>
> - clocksource_register(&xen_clocksource);
> + /* It would be done in xen_time_init() if evtchn enabled */
> + if (!xen_hvm_pv_evtchn_enabled())
> + clocksource_register(&xen_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
> +
> +extern struct machine_ops xen_machine_ops;
> +
> void __init xen_guest_init(void)
> {
> int r;
> + uint64_t callback_via;
>
> /* Ensure the we won't confused with others */
> if (xen_domain_type != XEN_NATIVE)
> @@ -150,4 +186,34 @@ void __init xen_guest_init(void)
>
> /* PV clocksource would be enabled by default */
> init_pv_clocksource();
> +
> + if (xen_hvm_pv_evtchn_enabled()) {
> + if (enable_hvm_pv(HVM_PV_EVTCHN))
> + return;
> +
> + 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();
> +}
> +PV_CALLEE_SAVE_REGS_THUNK(xen_hvm_pv_evtchn_enable);
> +
> +void __init xen_hvm_pv_init_irq_ops(void)
> +{
> + if (xen_hvm_pv_evtchn_enabled()) {
> + pv_irq_ops.irq_disable =
> + PV_CALLEE_SAVE(xen_hvm_pv_evtchn_disable);
> + pv_irq_ops.irq_enable =
> + PV_CALLEE_SAVE(xen_hvm_pv_evtchn_enable);
> + x86_init.irqs.intr_init = xen_hvm_pv_evtchn_init_IRQ;
> + }
> +}
> +#endif
> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
> index 563d205..a31429e 100644
> --- a/arch/x86/xen/smp.c
> +++ b/arch/x86/xen/smp.c
> @@ -15,18 +15,24 @@
> #include<linux/sched.h>
> #include<linux/err.h>
> #include<linux/smp.h>
> +#include<linux/nmi.h>
>
> #include<asm/paravirt.h>
> #include<asm/desc.h>
> #include<asm/pgtable.h>
> #include<asm/cpu.h>
> +#include<asm/trampoline.h>
> +#include<asm/tlbflush.h>
> +#include<asm/mtrr.h>
>
> #include<xen/interface/xen.h>
> #include<xen/interface/vcpu.h>
>
> #include<asm/xen/interface.h>
> #include<asm/xen/hypercall.h>
> +#include<asm/xen/hypervisor.h>
>
> +#include<xen/xen.h>
> #include<xen/page.h>
> #include<xen/events.h>
>
> @@ -63,8 +69,13 @@ static __cpuinit void cpu_bringup(void)
> touch_softlockup_watchdog();
> preempt_disable();
>
> - xen_enable_sysenter();
> - xen_enable_syscall();
> + if (xen_pv_domain()) {
> + xen_enable_sysenter();
> + xen_enable_syscall();
> + } else if (xen_hvm_pv_evtchn_enabled())
> + set_mtrr_aps_delayed_init();
> + else
> + BUG();
>
> cpu = smp_processor_id();
> smp_store_cpu_info(cpu);
> @@ -171,7 +182,8 @@ static void __init xen_smp_prepare_boot_cpu(void)
>
> /* We've switched to the "real" per-cpu gdt, so make sure the
> old memory can be recycled */
> - make_lowmem_page_readwrite(xen_initial_gdt);
> + if (xen_feature(XENFEAT_writable_descriptor_tables))
> + make_lowmem_page_readwrite(xen_initial_gdt);
>
> xen_setup_vcpu_info_placement();
> }
> @@ -282,6 +294,47 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
> return 0;
> }
>
> +#ifdef CONFIG_XEN_HVM_PV
>
Rather than #ifdeffing...
> +static __cpuinit int
> +hvm_pv_cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
> +{
> + struct vcpu_guest_context *ctxt;
> + unsigned long start_ip;
>

Just put

if (!xen_hvm_pv_evtchn_enabled())
return -EOPNOTSUPP; /* or something */
and make sure xen_hvm_pv_evtchn_enable() returns constant 0 in the
!CONFIG_XEN_HVM_PV case.

> +
> + if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
> + return 0;
> +
> + ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
> + if (ctxt == NULL)
> + return -ENOMEM;
> +
> + early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu);
> + initial_code = (unsigned long)cpu_bringup_and_idle;
> + stack_start.sp = (void *) idle->thread.sp;
> +
> + /* start_ip had better be page-aligned! */
> + start_ip = setup_trampoline();
>

Why go via trampoline?

> +
> + /* only start_ip is what we want */
> + ctxt->flags = VGCF_HVM_GUEST;
> + ctxt->user_regs.eip = start_ip;
> +
> + printk(KERN_INFO "Booting processor %d ip 0x%lx\n", cpu, start_ip);
> +
> + if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
> + BUG();
> +
> + kfree(ctxt);
> + return 0;
> +}
> +#else
> +static int hvm_pv_cpu_initialize_context(unsigned int cpu,
> + struct task_struct *idle)
> +{
> + return 0;
> +}
> +#endif
> +
> static int __cpuinit xen_cpu_up(unsigned int cpu)
> {
> struct task_struct *idle = idle_task(cpu);
> @@ -292,11 +345,17 @@ static int __cpuinit xen_cpu_up(unsigned int cpu)
> irq_ctx_init(cpu);
> #else
> clear_tsk_thread_flag(idle, TIF_FORK);
> +
> + if (xen_hvm_pv_evtchn_enabled())
> + initial_gs = per_cpu_offset(cpu);
>

Why does this need to be conditional?

> +
> per_cpu(kernel_stack, cpu) =
> (unsigned long)task_stack_page(idle) -
> KERNEL_STACK_OFFSET + THREAD_SIZE;
> #endif
> - xen_setup_runstate_info(cpu);
> + if (xen_pv_domain())
> + xen_setup_runstate_info(cpu);
> +
>
Does HVM not support this? If VCPUOP_register_runstate_memory_area
doesn't work on HVM, then just change xen_setup_runstate_info() to not
BUG on hypercall failure (and presumably nothing tries to use
runstate_info).

> xen_setup_timer(cpu);
> xen_init_lock_cpu(cpu);
>
> @@ -305,7 +364,13 @@ static int __cpuinit xen_cpu_up(unsigned int cpu)
> /* make sure interrupts start blocked */
> per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
>
> - rc = cpu_initialize_context(cpu, idle);
> + if (xen_pv_domain())
> + rc = cpu_initialize_context(cpu, idle);
> + else if (xen_hvm_pv_evtchn_enabled())
> + rc = hvm_pv_cpu_initialize_context(cpu, idle);
> + else
> + BUG();
> +
> if (rc)
> return rc;
>
> @@ -480,3 +545,20 @@ void __init xen_smp_init(void)
> xen_fill_possible_map();
> xen_init_spinlocks();
> }
> +
> +#ifdef CONFIG_XEN_HVM_PV
> +static void xen_hvm_pv_flush_tlb_others(const struct cpumask *cpumask,
> + struct mm_struct *mm, unsigned long va)
> +{
> + /* TODO Make it more specific */
> + flush_tlb_all();
> +}
> +
> +void __init xen_hvm_pv_smp_init(void)
> +{
> + if (xen_hvm_pv_evtchn_enabled()) {
> + smp_ops = xen_smp_ops;
> + pv_mmu_ops.flush_tlb_others = xen_hvm_pv_flush_tlb_others;
> + }
> +}
> +#endif
> diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
> index f9153a3..6f55815 100644
> --- a/arch/x86/xen/xen-ops.h
> +++ b/arch/x86/xen/xen-ops.h
> @@ -51,6 +51,12 @@ void __init xen_time_init(void);
> unsigned long xen_get_wallclock(void);
> int xen_set_wallclock(unsigned long time);
> unsigned long long xen_sched_clock(void);
> +void xen_set_basic_apic_ops(void);
> +
> +#ifdef CONFIG_XEN_HVM_PV
> +void __init xen_hvm_pv_init_irq_ops(void);
> +void __init xen_hvm_pv_evtchn_init_IRQ(void);
> +#endif /* CONFIG_XEN_HVM_PV */
>
> irqreturn_t xen_debug_interrupt(int irq, void *dev_id);
>
> @@ -61,9 +67,17 @@ void xen_setup_vcpu_info_placement(void);
> #ifdef CONFIG_SMP
> void xen_smp_init(void);
>
> +#ifdef CONFIG_XEN_HVM_PV
> +void xen_hvm_pv_smp_init(void);
> +#endif /* CONFIG_XEN_HVM_PV */
> +
> extern cpumask_var_t xen_cpu_initialized_map;
> #else
> static inline void xen_smp_init(void) {}
> +#ifdef CONFIG_XEN_HVM_PV
> +static inline void xen_hvm_pv_smp_init(void) {}
> +#endif /* CONFIG_XEN_HVM_PV */
> +
> #endif
>
> #ifdef CONFIG_PARAVIRT_SPINLOCKS
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index ce602dd..e4b9de6 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -32,14 +32,17 @@
> #include<asm/irq.h>
> #include<asm/idle.h>
> #include<asm/sync_bitops.h>
> +#include<asm/desc.h>
> #include<asm/xen/hypercall.h>
> #include<asm/xen/hypervisor.h>
>
> +#include<xen/xen.h>
> #include<xen/xen-ops.h>
> #include<xen/events.h>
> #include<xen/interface/xen.h>
> #include<xen/interface/event_channel.h>
>
> +
> /*
> * This lock protects updates to the following mapping and reference-count
> * arrays. The lock does not need to be acquired to read the mapping tables.
> @@ -616,17 +619,13 @@ static DEFINE_PER_CPU(unsigned, xed_nesting_count);
> * a bitset of words which contain pending event bits. The second
> * level is a bitset of pending events themselves.
> */
> -void xen_evtchn_do_upcall(struct pt_regs *regs)
> +void __xen_evtchn_do_upcall(struct pt_regs *regs)
> {
> int cpu = get_cpu();
> - struct pt_regs *old_regs = set_irq_regs(regs);
> struct shared_info *s = HYPERVISOR_shared_info;
> struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu);
> unsigned count;
>
> - exit_idle();
> - irq_enter();
> -
> do {
> unsigned long pending_words;
>
> @@ -662,10 +661,25 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
> } while(count != 1);
>
> out:
> + put_cpu();
> +}
> +
> +void xen_evtchn_do_upcall(struct pt_regs *regs)
> +{
> + struct pt_regs *old_regs = set_irq_regs(regs);
> +
> + exit_idle();
> + irq_enter();
> +
> + __xen_evtchn_do_upcall(regs);
> +
> irq_exit();
> set_irq_regs(old_regs);
> +}
>
> - put_cpu();
> +void xen_hvm_evtchn_do_upcall(struct pt_regs *regs)
> +{
> + __xen_evtchn_do_upcall(regs);
> }
>
> /* Rebind a new event channel to an existing irq. */
> @@ -944,3 +958,51 @@ void __init xen_init_IRQ(void)
>
> irq_ctx_init(smp_processor_id());
> }
> +
> +void __init xen_hvm_pv_evtchn_init_IRQ(void)
> +{
> + int i;
> +
> + xen_init_IRQ();
> + for (i = 0; i< NR_IRQS_LEGACY; i++) {
> + struct evtchn_bind_virq bind_virq;
> + struct irq_desc *desc = irq_to_desc(i);
> + int virq, evtchn;
> +
> + virq = i + VIRQ_EMUL_PIN_START;
> + bind_virq.virq = virq;
> + bind_virq.vcpu = 0;
> +
> + if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
> +&bind_virq) != 0)
> + BUG();
> +
> + evtchn = bind_virq.port;
> + evtchn_to_irq[evtchn] = i;
> + irq_info[i] = mk_virq_info(evtchn, virq);
> +
> + desc->status = IRQ_DISABLED;
> + desc->action = NULL;
> + desc->depth = 1;
> +
> + /*
> + * 16 old-style INTA-cycle interrupts:
> + */
> + set_irq_chip_and_handler_name(i,&xen_dynamic_chip,
> + handle_level_irq, "event");
> + }
> +
> + /*
> + * Cover the whole vector space, no vector can escape
> + * us. (some of these will be overridden and become
> + * 'special' SMP interrupts)
> + */
> + for (i = 0; i< (NR_VECTORS - FIRST_EXTERNAL_VECTOR); i++) {
> + int vector = FIRST_EXTERNAL_VECTOR + i;
> + if (vector != IA32_SYSCALL_VECTOR)
> + set_intr_gate(vector, interrupt[i]);
> + }
> +
> + /* generic IPI for platform specific use, now used for HVM evtchn */
> + alloc_intr_gate(X86_PLATFORM_IPI_VECTOR, x86_platform_ipi);
> +}
> diff --git a/include/xen/events.h b/include/xen/events.h
> index e68d59a..6b12725 100644
> --- a/include/xen/events.h
> +++ b/include/xen/events.h
> @@ -56,4 +56,10 @@ void xen_poll_irq(int irq);
> /* Determine the IRQ which is bound to an event channel */
> unsigned irq_from_evtchn(unsigned int evtchn);
>
> +void xen_evtchn_do_upcall(struct pt_regs *regs);
> +
> +#ifdef CONFIG_XEN_HVM_PV
> +void xen_hvm_evtchn_do_upcall(struct pt_regs *regs);
> +#endif
> +
> #endif /* _XEN_EVENTS_H */
> diff --git a/include/xen/hvm.h b/include/xen/hvm.h
> index 4ea8887..c66d788 100644
> --- a/include/xen/hvm.h
> +++ b/include/xen/hvm.h
> @@ -20,4 +20,9 @@ static inline unsigned long hvm_get_parameter(int idx)
> return xhv.value;
> }
>
> +#define HVM_CALLBACK_VIA_TYPE_VECTOR 0x2
> +#define HVM_CALLBACK_VIA_TYPE_SHIFT 56
> +#define HVM_CALLBACK_VECTOR(x) (((uint64_t)HVM_CALLBACK_VIA_TYPE_VECTOR)<<\
> + HVM_CALLBACK_VIA_TYPE_SHIFT | (x))
> +
> #endif /* XEN_HVM_H__ */
> diff --git a/include/xen/interface/xen.h b/include/xen/interface/xen.h
> index 2befa3e..70a6c6e 100644
> --- a/include/xen/interface/xen.h
> +++ b/include/xen/interface/xen.h
> @@ -90,7 +90,11 @@
> #define VIRQ_ARCH_6 22
> #define VIRQ_ARCH_7 23
>
> -#define NR_VIRQS 24
> +#define VIRQ_EMUL_PIN_START 24
> +#define VIRQ_EMUL_PIN_NUM 16
> +
> +#define NR_VIRQS (VIRQ_EMUL_PIN_START + VIRQ_EMUL_PIN_NUM)
> +
> /*
> * MMU-UPDATE REQUESTS
> *
> diff --git a/include/xen/xen.h b/include/xen/xen.h
> index 11f5ced..ce2a256 100644
> --- a/include/xen/xen.h
> +++ b/include/xen/xen.h
> @@ -26,6 +26,8 @@ extern u32 xen_hvm_pv_features;
>
> #define xen_hvm_pv_evtchn_enabled() \
> (xen_hvm_pv_features& XEN_HVM_PV_EVTCHN_ENABLED)
> +#else
> +#define xen_hvm_pv_evtchn_enabled() 0
> #endif /* CONFIG_XEN_HVM_PV */
>
> #ifdef CONFIG_XEN_DOM0
> --
> 1.5.4.5
>
>



\
 
 \ /
  Last update: 2010-03-04 19:27    [from the cache]
©2003-2011 Jasper Spaans