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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH RFC LINUX v1] xen: arm: enable migration on ARM.
Please CC linux-arm for the non-RFC patches
On Wed, 9 Dec 2015, Ian Campbell wrote:
> Replace various stub functions with real functionality, including
> reestablishing the shared info page and the per-vcpu info pages on
> restore.
>
> Reestablishing the vcpu info page is a little subtle. The
> VCPUOP_register_vcpu_info hypercall can only be called on either the
> current VCPU or on an offline different VCPU. Since migration occurs
> with all VCPUS online they are all therefore online at the point of
> resume.
>
> Therefore we must perform a cross VCPU call to each non-boot VCPU,
> which cannot be done in the xen_arch_post_suspend() callback since
> that is run from stop_machine() with interrupts disabled.
>
> Furthermore VCPUOP_register_vcpu_info can only be called once per-VCPU
> in a given domain, so it must not be called after a cancelled suspend
> (which resumes in the same domain).
>
> Therefore xen_arch_resume() gains a suspend_cancelled parameter and we
> resume the secondary VCPUs there only if needed.
It is a bit complex but it seems better than what we do on x86, which
is:
for_each_possible_cpu(cpu) {
bool other_cpu = (cpu != smp_processor_id());
bool is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL);
if (other_cpu && is_up &&
HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL))
BUG();
xen_setup_runstate_info(cpu);
if (have_vcpu_info_placement)
xen_vcpu_setup(cpu);
if (other_cpu && is_up &&
HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL))
BUG();
}
> The VCPU which is running the suspend is resumed earlier in the
> xen_arch_post_suspend callback, again conditionally only for
> non-cancelled suspends.
>
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
> arch/arm/xen/Makefile | 2 +-
> arch/arm/xen/enlighten.c | 54
> +++++++++++++++++++++++++++++++-----------------
> arch/arm/xen/suspend.c | 54
> ++++++++++++++++++++++++++++++++++++++++++++++++
> arch/arm/xen/xen-ops.h | 9 ++++++++
> arch/x86/xen/suspend.c | 2 +-
> drivers/xen/manage.c | 2 +-
> include/xen/xen-ops.h | 2 +-
> 7 files changed, 102 insertions(+), 23 deletions(-)
> create mode 100644 arch/arm/xen/suspend.c
> create mode 100644 arch/arm/xen/xen-ops.h
>
> diff --git a/arch/arm/xen/Makefile b/arch/arm/xen/Makefile
> index 1296952..677022c 100644
> --- a/arch/arm/xen/Makefile
> +++ b/arch/arm/xen/Makefile
> @@ -1 +1 @@
> -obj-y := enlighten.o hypercall.o grant-table.o p2m.o mm.o
> +obj-y := enlighten.o hypercall.o grant-table.o p2m.o mm.o suspend.o
> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> index eeeab07..72f314e 100644
> --- a/arch/arm/xen/enlighten.c
> +++ b/arch/arm/xen/enlighten.c
> @@ -182,10 +182,41 @@ void __init xen_early_init(void)
> add_preferred_console("hvc", 0, NULL);
> }
>
> -static int __init xen_guest_init(void)
> +static struct shared_info *shared_info_page;
> +
> +int xen_register_shared_info(void)
> {
> struct xen_add_to_physmap xatp;
> - struct shared_info *shared_info_page = NULL;
> +
> + /*
> + * This function is called on boot and on restore. On boot we
> + * allocate this page immediately before calling this function
> + * and bail on failure. On resume that allocation must have
> + * succeeded or we couldn't be doing a save/restore.
> + */
> + BUG_ON(!shared_info_page);
> +
> + xatp.domid = DOMID_SELF;
> + xatp.idx = 0;
> + xatp.space = XENMAPSPACE_shared_info;
> + xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT;
> + if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
> + BUG();
> +
> + HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;
> +
> + return 0;
> +}
> +
> +void xen_vcpu_restore(void)
> +{
> + xen_percpu_init();
> +
> + /* XXX TODO: xen_setup_runstate_info(cpu); */
> +}
> +
> +static int __init xen_guest_init(void)
> +{
> struct resource res;
> phys_addr_t grant_frames;
>
> @@ -210,18 +241,12 @@ static int __init xen_guest_init(void)
> pr_err("not enough memory\n");
> return -ENOMEM;
> }
> - xatp.domid = DOMID_SELF;
> - xatp.idx = 0;
> - xatp.space = XENMAPSPACE_shared_info;
> - xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT;
> - if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
> - BUG();
>
> - HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;
> + xen_register_shared_info();
>
> /* xen_vcpu is a pointer to the vcpu_info struct in the shared_info
> * page, we use it in the event channel upcall and in some pvclock
> - * related functions.
> + * related functions.
> * The shared info contains exactly 1 CPU (the boot CPU). The guest
> * is required to use VCPUOP_register_vcpu_info to place vcpu info
> * for secondary CPUs as they are brought up.
> @@ -275,15 +300,6 @@ static int __init xen_pm_init(void)
> }
> late_initcall(xen_pm_init);
>
> -
> -/* empty stubs */
> -void xen_arch_pre_suspend(void) { }
> -void xen_arch_post_suspend(int suspend_cancelled) { }
> -void xen_timer_resume(void) { }
> -void xen_arch_resume(void) { }
> -void xen_arch_suspend(void) { }
> -
> -
> /* In the hypervisor.S file. */
> EXPORT_SYMBOL_GPL(HYPERVISOR_event_channel_op);
> EXPORT_SYMBOL_GPL(HYPERVISOR_grant_table_op);
> diff --git a/arch/arm/xen/suspend.c b/arch/arm/xen/suspend.c
> new file mode 100644
> index 0000000..b420758
> --- /dev/null
> +++ b/arch/arm/xen/suspend.c
> @@ -0,0 +1,54 @@
> +#include <linux/types.h>
> +#include <linux/tick.h>
> +
> +#include <xen/interface/xen.h>
> +
> +#include <asm/xen/hypercall.h>
> +
> +#include "xen-ops.h"
> +
> +void xen_arch_pre_suspend(void) {
> + /* Nothing to do */
> +}
> +
> +void xen_arch_post_suspend(int suspend_cancelled)
> +{
> + xen_register_shared_info();
> + if (!suspend_cancelled)
> + xen_vcpu_restore();
could we wait and call xen_vcpu_restore for cpu0 from
xen_vcpu_notify_resume?
> +}
> +
> +static void xen_vcpu_notify_suspend(void *data)
> +{
> + tick_suspend_local();
> +}
> +
> +static void xen_vcpu_notify_resume(void *data)
> +{
> + int suspend_cancelled = *(int *)data;
> +
> + if (smp_processor_id() == 0)
> + return;
> +
> + /* Boot processor done in post_suspend */
> + if (!suspend_cancelled)
> + xen_vcpu_restore();
> +
> + /* Boot processor notified via generic timekeeping_resume() */
> + tick_resume_local();
> +}
> +
> +void xen_arch_suspend(void)
> +{
> + on_each_cpu(xen_vcpu_notify_suspend, NULL, 1);
> +}
> +
> +void xen_arch_resume(int suspend_cancelled)
> +{
> + on_each_cpu(xen_vcpu_notify_resume, &suspend_cancelled, 1);
> +}
> +
> +void xen_timer_resume(void)
> +{
> + /* Nothing to do */
> +}
> diff --git a/arch/arm/xen/xen-ops.h b/arch/arm/xen/xen-ops.h
> new file mode 100644
> index 0000000..de23e91
> --- /dev/null
> +++ b/arch/arm/xen/xen-ops.h
> @@ -0,0 +1,9 @@
> +#ifndef XEN_OPS_H
> +#define XEN_OPS_H
> +
> +#include <xen/xen-ops.h>
> +
> +void xen_register_shared_info(void);
> +void xen_vcpu_restore(void);
> +
> +#endif /* XEN_OPS_H */
> diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
> index feddabd..ce2545a 100644
> --- a/arch/x86/xen/suspend.c
> +++ b/arch/x86/xen/suspend.c
> @@ -104,7 +104,7 @@ static void xen_vcpu_notify_suspend(void *data)
> tick_suspend_local();
> }
>
> -void xen_arch_resume(void)
> +void xen_arch_resume(int suspend_cancelled)
> {
> on_each_cpu(xen_vcpu_notify_restore, NULL, 1);
> }
> diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
> index b6e4c40..a1a64bc 100644
> --- a/drivers/xen/manage.c
> +++ b/drivers/xen/manage.c
> @@ -156,7 +156,7 @@ static void do_suspend(void)
> si.cancelled = 1;
> }
>
> - xen_arch_resume();
> + xen_arch_resume(si.cancelled);
>
> out_resume:
> if (!si.cancelled)
> diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
> index e4e214a..d93da50 100644
> --- a/include/xen/xen-ops.h
> +++ b/include/xen/xen-ops.h
> @@ -12,7 +12,7 @@ void xen_arch_pre_suspend(void);
> void xen_arch_post_suspend(int suspend_cancelled);
>
> void xen_timer_resume(void);
> -void xen_arch_resume(void);
> +void xen_arch_resume(int suspend_cancelled);
> void xen_arch_suspend(void);
>
> void xen_resume_notifier_register(struct notifier_block *nb);
> --
> 2.1.4
>
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