On 05/18/2010 03:22 AM, Stefano Stabellini wrote:
> From: Sheng Yang <sheng@xxxxxxxxxxxxxxx>
>
> Set the callback to receive evtchns from Xen, using the
> callback vector delivery mechanism.
>
Could you expand on this a little? Like, why is this desireable? What
functional difference does it make? Is this patch useful in its own
right, or is it just laying the groundwork for something else?
Thanks,
J
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> Signed-off-by: Sheng Yang <sheng@xxxxxxxxxxxxxxx>
> ---
> arch/x86/xen/enlighten.c | 35 +++++++++++++++++++++++++++++++++++
> drivers/xen/events.c | 31 ++++++++++++++++++++++++-------
> include/xen/events.h | 3 +++
> include/xen/hvm.h | 9 +++++++++
> include/xen/interface/features.h | 3 +++
> 5 files changed, 74 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 87a3b10..502c4f8 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -37,8 +37,11 @@
> #include <xen/interface/vcpu.h>
> #include <xen/interface/memory.h>
> #include <xen/interface/hvm/hvm_op.h>
> +#include <xen/interface/hvm/params.h>
> #include <xen/features.h>
> #include <xen/page.h>
> +#include <xen/hvm.h>
> +#include <xen/events.h>
> #include <xen/hvc-console.h>
>
> #include <asm/paravirt.h>
> @@ -79,6 +82,8 @@ struct shared_info xen_dummy_shared_info;
>
> void *xen_initial_gdt;
>
> +int xen_have_vector_callback;
> +
> /*
> * Point at some empty memory to start with. We map the real shared_info
> * page as soon as fixmap is up and running.
> @@ -1279,6 +1284,31 @@ static void __init init_shared_info(void)
> per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
> }
>
> +int xen_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)
> +{
> + xen_hvm_evtchn_do_upcall(get_irq_regs());
> +}
> +
> +static void xen_callback_vector(void)
> +{
> + uint64_t callback_via;
> + if (xen_feature(XENFEAT_hvm_callback_vector)) {
> + callback_via = HVM_CALLBACK_VECTOR(X86_PLATFORM_IPI_VECTOR);
> + xen_set_callback_via(callback_via);
> + x86_platform_ipi_callback = do_hvm_pv_evtchn_intr;
> + xen_have_vector_callback = 1;
> + }
> +}
> +
> void __init xen_guest_init(void)
> {
> int r;
> @@ -1292,4 +1322,9 @@ void __init xen_guest_init(void)
> return;
>
> init_shared_info();
> +
> + xen_callback_vector();
> +
> + have_vcpu_info_placement = 0;
> + x86_init.irqs.intr_init = xen_init_IRQ;
> }
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index db8f506..3523dbb 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -36,6 +36,8 @@
> #include <asm/xen/hypercall.h>
> #include <asm/xen/hypervisor.h>
>
> +#include <xen/xen.h>
> +#include <xen/hvm.h>
> #include <xen/xen-ops.h>
> #include <xen/events.h>
> #include <xen/interface/xen.h>
> @@ -617,17 +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;
>
> @@ -667,10 +665,26 @@ 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. */
> @@ -947,5 +961,8 @@ void __init xen_init_IRQ(void)
> for (i = 0; i < NR_EVENT_CHANNELS; i++)
> mask_evtchn(i);
>
> - irq_ctx_init(smp_processor_id());
> + if (xen_hvm_domain())
> + native_init_IRQ();
> + else
> + irq_ctx_init(smp_processor_id());
> }
> diff --git a/include/xen/events.h b/include/xen/events.h
> index e68d59a..868e5d6 100644
> --- a/include/xen/events.h
> +++ b/include/xen/events.h
> @@ -56,4 +56,7 @@ 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);
> +void xen_hvm_evtchn_do_upcall(struct pt_regs *regs);
> +
> #endif /* _XEN_EVENTS_H */
> diff --git a/include/xen/hvm.h b/include/xen/hvm.h
> index 6b0d418..5940ee5 100644
> --- a/include/xen/hvm.h
> +++ b/include/xen/hvm.h
> @@ -3,6 +3,7 @@
> #define XEN_HVM_H__
>
> #include <xen/interface/hvm/params.h>
> +#include <asm/xen/hypercall.h>
>
> static inline int hvm_get_parameter(int idx, uint64_t *value)
> {
> @@ -21,4 +22,12 @@ static inline int hvm_get_parameter(int idx, uint64_t
> *value)
> return r;
> }
>
> +int xen_set_callback_via(uint64_t via);
> +extern int xen_have_vector_callback;
> +
> +#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/features.h
> b/include/xen/interface/features.h
> index f51b641..8ab08b9 100644
> --- a/include/xen/interface/features.h
> +++ b/include/xen/interface/features.h
> @@ -41,6 +41,9 @@
> /* x86: Does this Xen host support the MMU_PT_UPDATE_PRESERVE_AD hypercall?
> */
> #define XENFEAT_mmu_pt_update_preserve_ad 5
>
> +/* x86: Does this Xen host support the HVM callback vector type? */
> +#define XENFEAT_hvm_callback_vector 8
> +
> #define XENFEAT_NR_SUBMAPS 1
>
> #endif /* __XEN_PUBLIC_FEATURES_H__ */
>
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