Re: [Xen-devel] [PATCH v2 12/25] arm: domain

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2011-12-09 at 13:26 +0000, Keir Fraser wrote:
> On 09/12/2011 13:13, "stefano.stabellini@xxxxxxxxxxxxx"
> <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> 
> > From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > 
> > Domain creation and destruction, vcpu initialization and destruction,
> > arch specific scheduling functions called by common code.
> 
> It would be nice if xen-arm had per-vcpu stacks (and, optionally, per-cpu
> irq stacks) off the bat. However I won't make it a strict requirement while
> xen-x86 is lagging in this area. That's where you cribbed this logic from
> after all.

I was going to look into this but I've been distracted by other things. 

We did discuss how this would look though -- we expect we will end up
going with per-PCPU page tables (e.g. for per CPU mapcache etc) which
simplifies things in this case as well since we can put per-PCPU stuff
at a fixed VA instead of relying on finding the CPU state info at the
base of the stack (which can be done with per-VCPU stacks but you'd need
to do a bit more book keeping).

Ian.

> 
>  -- Keir
> 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
> > ---
> >  xen/arch/arm/domain.c        |  253
> > ++++++++++++++++++++++++++++++++++++++++++
> >  xen/include/asm-arm/domain.h |   43 +++++++
> >  2 files changed, 296 insertions(+), 0 deletions(-)
> >  create mode 100644 xen/arch/arm/domain.c
> >  create mode 100644 xen/include/asm-arm/domain.h
> > 
> > diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> > new file mode 100644
> > index 0000000..d706b5f
> > --- /dev/null
> > +++ b/xen/arch/arm/domain.c
> > @@ -0,0 +1,253 @@
> > +#include <xen/config.h>
> > +#include <xen/init.h>
> > +#include <xen/lib.h>
> > +#include <xen/sched.h>
> > +#include <xen/softirq.h>
> > +#include <xen/wait.h>
> > +#include <xen/errno.h>
> > +
> > +#include <asm/current.h>
> > +#include <asm/regs.h>
> > +#include <asm/p2m.h>
> > +#include <asm/irq.h>
> > +
> > +DEFINE_PER_CPU(struct vcpu *, curr_vcpu);
> > +
> > +static void continue_idle_domain(struct vcpu *v)
> > +{
> > +    reset_stack_and_jump(idle_loop);
> > +}
> > +
> > +static void continue_nonidle_domain(struct vcpu *v)
> > +{
> > +    /* check_wakeup_from_wait(); */
> > +    reset_stack_and_jump(return_from_trap);
> > +}
> > +
> > +void idle_loop(void)
> > +{
> > +    for ( ; ; )
> > +    {
> > +  /* TODO
> > +     if ( cpu_is_offline(smp_processor_id()) )
> > +     play_dead();
> > +     (*pm_idle)();
> > +     BUG();
> > +  */
> > +        do_tasklet();
> > +        do_softirq();
> > +    }
> > +}
> > +
> > +static void ctxt_switch_from(struct vcpu *p)
> > +{
> > +
> > +}
> > +
> > +static void ctxt_switch_to(struct vcpu *n)
> > +{
> > +    p2m_load_VTTBR(n->domain);
> > +}
> > +
> > +static void __context_switch(void)
> > +{
> > +    struct cpu_user_regs *stack_regs = guest_cpu_user_regs();
> > +    unsigned int          cpu = smp_processor_id();
> > +    struct vcpu          *p = per_cpu(curr_vcpu, cpu);
> > +    struct vcpu          *n = current;
> > +
> > +    ASSERT(p != n);
> > +    ASSERT(cpumask_empty(n->vcpu_dirty_cpumask));
> > +
> > +    if ( !is_idle_vcpu(p) )
> > +    {
> > +        memcpy(&p->arch.user_regs, stack_regs, CTXT_SWITCH_STACK_BYTES);
> > +        ctxt_switch_from(p);
> > +    }
> > +
> > +    if ( !is_idle_vcpu(n) )
> > +    {
> > +        memcpy(stack_regs, &n->arch.user_regs, CTXT_SWITCH_STACK_BYTES);
> > +        ctxt_switch_to(n);
> > +    }
> > +
> > +    per_cpu(curr_vcpu, cpu) = n;
> > +
> > +}
> > +
> > +static void schedule_tail(struct vcpu *v)
> > +{
> > +    if ( is_idle_vcpu(v) )
> > +        continue_idle_domain(v);
> > +    else
> > +        continue_nonidle_domain(v);
> > +}
> > +
> > +void context_switch(struct vcpu *prev, struct vcpu *next)
> > +{
> > +    unsigned int cpu = smp_processor_id();
> > +
> > +    ASSERT(local_irq_is_enabled());
> > +
> > +    printk("context switch %d:%d%s -> %d:%d%s\n",
> > +           prev->domain->domain_id, prev->vcpu_id, is_idle_vcpu(prev) ? "
> > (idle)" : "",
> > +           next->domain->domain_id, next->vcpu_id, is_idle_vcpu(next) ? "
> > (idle)" : "");
> > +
> > + /* TODO
> > +    if (prev != next)
> > +    update_runstate_area(prev);
> > + */
> > +
> > +    local_irq_disable();
> > +
> > +    set_current(next);
> > +
> > +    if ( (per_cpu(curr_vcpu, cpu) == next) ||
> > +         (is_idle_vcpu(next) && cpu_online(cpu)) )
> > +    {
> > +        local_irq_enable();
> > +    }
> > +    else
> > +    {
> > +        __context_switch();
> > +
> > +        /* Re-enable interrupts before restoring state which may fault. */
> > +        local_irq_enable();
> > +    }
> > +
> > +    context_saved(prev);
> > +
> > + /* TODO
> > +    if (prev != next)
> > +    update_runstate_area(next);
> > + */
> > +
> > +    schedule_tail(next);
> > +    BUG();
> > +
> > +}
> > +
> > +void continue_running(struct vcpu *same)
> > +{
> > +    schedule_tail(same);
> > +    BUG();
> > +}
> > +
> > +int __sync_local_execstate(void)
> > +{
> > +    unsigned long flags;
> > +    int switch_required;
> > +
> > +    local_irq_save(flags);
> > +
> > +    switch_required = (this_cpu(curr_vcpu) != current);
> > +
> > +    if ( switch_required )
> > +    {
> > +        ASSERT(current == idle_vcpu[smp_processor_id()]);
> > +        __context_switch();
> > +    }
> > +
> > +    local_irq_restore(flags);
> > +
> > +    return switch_required;
> > +}
> > +
> > +void sync_local_execstate(void)
> > +{
> > +    (void)__sync_local_execstate();
> > +}
> > +
> > +void startup_cpu_idle_loop(void)
> > +{
> > +        struct vcpu *v = current;
> > +
> > +        ASSERT(is_idle_vcpu(v));
> > +  /* TODO
> > +     cpumask_set_cpu(v->processor, v->domain->domain_dirty_cpumask);
> > +     cpumask_set_cpu(v->processor, v->vcpu_dirty_cpumask);
> > +  */
> > +
> > +        reset_stack_and_jump(idle_loop);
> > +}
> > +
> > +struct domain *alloc_domain_struct(void)
> > +{
> > +    struct domain *d;
> > +    BUILD_BUG_ON(sizeof(*d) > PAGE_SIZE);
> > +    d = alloc_xenheap_pages(0, 0);
> > +    if ( d != NULL )
> > +        clear_page(d);
> > +    return d;
> > +}
> > +
> > +void free_domain_struct(struct domain *d)
> > +{
> > +    free_xenheap_page(d);
> > +}
> > +
> > +void dump_pageframe_info(struct domain *d)
> > +{
> > +
> > +}
> > +
> > +struct vcpu *alloc_vcpu_struct(void)
> > +{
> > +    struct vcpu *v;
> > +    BUILD_BUG_ON(sizeof(*v) > PAGE_SIZE);
> > +    v = alloc_xenheap_pages(0, 0);
> > +    if ( v != NULL )
> > +        clear_page(v);
> > +    return v;
> > +}
> > +
> > +void free_vcpu_struct(struct vcpu *v)
> > +{
> > +    free_xenheap_page(v);
> > +}
> > +
> > +int vcpu_initialise(struct vcpu *v)
> > +{
> > +    int rc = 0;
> > +
> > +    return rc;
> > +}
> > +
> > +void vcpu_destroy(struct vcpu *v)
> > +{
> > +
> > +}
> > +
> > +int arch_domain_create(struct domain *d, unsigned int domcr_flags)
> > +{
> > +    int rc;
> > +
> > +    d->max_vcpus = 8;
> > +
> > +    rc = 0;
> > +fail:
> > +    return rc;
> > +}
> > +
> > +void arch_domain_destroy(struct domain *d)
> > +{
> > +    /* p2m_destroy */
> > +    /* domain_vgic_destroy */
> > +}
> > +
> > +void arch_dump_domain_info(struct domain *d)
> > +{
> > +}
> > +
> > +void arch_dump_vcpu_info(struct vcpu *v)
> > +{
> > +}
> > +
> > +/*
> > + * Local variables:
> > + * mode: C
> > + * c-set-style: "BSD"
> > + * c-basic-offset: 4
> > + * indent-tabs-mode: nil
> > + * End:
> > + */
> > diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> > new file mode 100644
> > index 0000000..c226bdf
> > --- /dev/null
> > +++ b/xen/include/asm-arm/domain.h
> > @@ -0,0 +1,43 @@
> > +#ifndef __ASM_DOMAIN_H__
> > +#define __ASM_DOMAIN_H__
> > +
> > +#include <xen/config.h>
> > +#include <xen/cache.h>
> > +#include <asm/page.h>
> > +#include <asm/p2m.h>
> > +
> > +struct pending_irq
> > +{
> > +    int irq;
> > +    struct irq_desc *desc; /* only set it the irq corresponds to a physical
> > irq */
> > +    uint8_t priority;
> > +    struct list_head link;
> > +};
> > +
> > +struct arch_domain
> > +{
> > +}  __cacheline_aligned;
> > +
> > +struct arch_vcpu
> > +{
> > +    struct cpu_user_regs user_regs;
> > +
> > +    uint32_t sctlr;
> > +    uint32_t ttbr0, ttbr1, ttbcr;
> > +
> > +}  __cacheline_aligned;
> > +
> > +void vcpu_show_execution_state(struct vcpu *);
> > +void vcpu_show_registers(const struct vcpu *);
> > +
> > +#endif /* __ASM_DOMAIN_H__ */
> > +
> > +/*
> > + * Local variables:
> > + * mode: C
> > + * c-set-style: "BSD"
> > + * c-basic-offset: 4
> > + * tab-width: 4
> > + * indent-tabs-mode: nil
> > + * End:
> > + */
> 
> 



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