From ae039001054b34c4a624539b32a8b6ff3403aaf9 Mon Sep 17 00:00:00 2001 From: Ankur Arora Date: Fri, 2 Jun 2017 17:06:02 -0700 Subject: [PATCH] xen/vcpu: Handle xen_vcpu_setup() failure at boot On PVH, PVHVM, at failure in the VCPUOP_register_vcpu_info hypercall we limit the number of cpus to to MAX_VIRT_CPUS. However, if this failure had occurred for a cpu beyond MAX_VIRT_CPUS, we continue to function with > MAX_VIRT_CPUS. This leads to problems at the next save/restore cycle when there are > MAX_VIRT_CPUS threads going into stop_machine() but coming back up there's valid state for only the first MAX_VIRT_CPUS. This patch pulls the excess CPUs down via cpu_down(). Reviewed-by: Boris Ostrovsky Signed-off-by: Ankur Arora Signed-off-by: Juergen Gross --- arch/x86/xen/smp.c | 31 +++++++++++++++++++++++++++++++ arch/x86/xen/smp.h | 2 ++ arch/x86/xen/smp_hvm.c | 1 + arch/x86/xen/smp_pv.c | 6 +----- 4 files changed, 35 insertions(+), 5 deletions(-) diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index 82ac611f2fc1..e7f02eb73727 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -1,4 +1,5 @@ #include +#include #include #include #include @@ -114,6 +115,36 @@ int xen_smp_intr_init(unsigned int cpu) return rc; } +void __init xen_smp_cpus_done(unsigned int max_cpus) +{ + int cpu, rc, count = 0; + + if (xen_hvm_domain()) + native_smp_cpus_done(max_cpus); + + if (xen_have_vcpu_info_placement) + return; + + for_each_online_cpu(cpu) { + if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) + continue; + + rc = cpu_down(cpu); + + if (rc == 0) { + /* + * Reset vcpu_info so this cpu cannot be onlined again. + */ + xen_vcpu_info_reset(cpu); + count++; + } else { + pr_warn("%s: failed to bring CPU %d down, error %d\n", + __func__, cpu, rc); + } + } + WARN(count, "%s: brought %d CPUs offline\n", __func__, count); +} + void xen_smp_send_reschedule(int cpu) { xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR); diff --git a/arch/x86/xen/smp.h b/arch/x86/xen/smp.h index 8ebb6acca64a..87d3c76cba37 100644 --- a/arch/x86/xen/smp.h +++ b/arch/x86/xen/smp.h @@ -14,6 +14,8 @@ extern void xen_smp_intr_free(unsigned int cpu); int xen_smp_intr_init_pv(unsigned int cpu); void xen_smp_intr_free_pv(unsigned int cpu); +void xen_smp_cpus_done(unsigned int max_cpus); + void xen_smp_send_reschedule(int cpu); void xen_smp_send_call_function_ipi(const struct cpumask *mask); void xen_smp_send_call_function_single_ipi(int cpu); diff --git a/arch/x86/xen/smp_hvm.c b/arch/x86/xen/smp_hvm.c index 6c8a805819ff..fd60abedf658 100644 --- a/arch/x86/xen/smp_hvm.c +++ b/arch/x86/xen/smp_hvm.c @@ -71,4 +71,5 @@ void __init xen_hvm_smp_init(void) smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi; smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi; smp_ops.smp_prepare_boot_cpu = xen_hvm_smp_prepare_boot_cpu; + smp_ops.smp_cpus_done = xen_smp_cpus_done; } diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c index aae32535f4ec..1ea598e5f030 100644 --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -371,10 +371,6 @@ static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle) return 0; } -static void xen_pv_smp_cpus_done(unsigned int max_cpus) -{ -} - #ifdef CONFIG_HOTPLUG_CPU static int xen_pv_cpu_disable(void) { @@ -469,7 +465,7 @@ static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id) static const struct smp_ops xen_smp_ops __initconst = { .smp_prepare_boot_cpu = xen_pv_smp_prepare_boot_cpu, .smp_prepare_cpus = xen_pv_smp_prepare_cpus, - .smp_cpus_done = xen_pv_smp_cpus_done, + .smp_cpus_done = xen_smp_cpus_done, .cpu_up = xen_pv_cpu_up, .cpu_die = xen_pv_cpu_die, -- 2.45.2