From ad73fd595c2ab168fdd01a266cbe6e4df95f8db0 Mon Sep 17 00:00:00 2001 From: Ankur Arora Date: Fri, 2 Jun 2017 17:05:58 -0700 Subject: [PATCH] xen/vcpu: Simplify xen_vcpu related code Largely mechanical changes to aid unification of xen_vcpu_restore() logic for PV, PVH and PVHVM. xen_vcpu_setup(): the only change in logic is that clamp_max_cpus() is now handled inside the "if (!xen_have_vcpu_info_placement)" block. xen_vcpu_restore(): code movement from enlighten_pv.c to enlighten.c. xen_vcpu_info_reset(): pulls together all the code where xen_vcpu is set to default. Reviewed-by: Boris Ostrovsky Signed-off-by: Ankur Arora Signed-off-by: Juergen Gross --- arch/x86/xen/enlighten.c | 101 +++++++++++++++++++++++++---------- arch/x86/xen/enlighten_hvm.c | 6 +-- arch/x86/xen/enlighten_pv.c | 47 +++++----------- arch/x86/xen/smp_hvm.c | 3 +- arch/x86/xen/xen-ops.h | 1 + 5 files changed, 89 insertions(+), 69 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index a5ffcbb20cc0..96b745e3f56c 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -106,6 +106,35 @@ int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int), return rc >= 0 ? 0 : rc; } +/* + * On restore, set the vcpu placement up again. + * If it fails, then we're in a bad state, since + * we can't back out from using it... + */ +void xen_vcpu_restore(void) +{ + int cpu; + + for_each_possible_cpu(cpu) { + bool other_cpu = (cpu != smp_processor_id()); + bool is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up, xen_vcpu_nr(cpu), + NULL); + + if (other_cpu && is_up && + HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL)) + BUG(); + + xen_setup_runstate_info(cpu); + + if (xen_have_vcpu_info_placement) + xen_vcpu_setup(cpu); + + if (other_cpu && is_up && + HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL)) + BUG(); + } +} + static void clamp_max_cpus(void) { #ifdef CONFIG_SMP @@ -114,6 +143,17 @@ static void clamp_max_cpus(void) #endif } +void xen_vcpu_info_reset(int cpu) +{ + if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) { + per_cpu(xen_vcpu, cpu) = + &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)]; + } else { + /* Set to NULL so that if somebody accesses it we get an OOPS */ + per_cpu(xen_vcpu, cpu) = NULL; + } +} + void xen_vcpu_setup(int cpu) { struct vcpu_register_vcpu_info info; @@ -137,40 +177,45 @@ void xen_vcpu_setup(int cpu) if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu)) return; } - if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) - per_cpu(xen_vcpu, cpu) = - &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)]; + + xen_vcpu_info_reset(cpu); + + if (xen_have_vcpu_info_placement) { + vcpup = &per_cpu(xen_vcpu_info, cpu); + info.mfn = arbitrary_virt_to_mfn(vcpup); + info.offset = offset_in_page(vcpup); + + /* + * Check to see if the hypervisor will put the vcpu_info + * structure where we want it, which allows direct access via + * a percpu-variable. + * N.B. This hypercall can _only_ be called once per CPU. + * Subsequent calls will error out with -EINVAL. This is due to + * the fact that hypervisor has no unregister variant and this + * hypercall does not allow to over-write info.mfn and + * info.offset. + */ + err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, + xen_vcpu_nr(cpu), &info); + + if (err) { + pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n", + cpu, err); + xen_have_vcpu_info_placement = 0; + } else { + /* + * This cpu is using the registered vcpu info, even if + * later ones fail to. + */ + per_cpu(xen_vcpu, cpu) = vcpup; + } + } if (!xen_have_vcpu_info_placement) { if (cpu >= MAX_VIRT_CPUS) clamp_max_cpus(); return; } - - vcpup = &per_cpu(xen_vcpu_info, cpu); - info.mfn = arbitrary_virt_to_mfn(vcpup); - info.offset = offset_in_page(vcpup); - - /* Check to see if the hypervisor will put the vcpu_info - structure where we want it, which allows direct access via - a percpu-variable. - N.B. This hypercall can _only_ be called once per CPU. Subsequent - calls will error out with -EINVAL. This is due to the fact that - hypervisor has no unregister variant and this hypercall does not - allow to over-write info.mfn and info.offset. - */ - err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, xen_vcpu_nr(cpu), - &info); - - if (err) { - printk(KERN_DEBUG "register_vcpu_info failed: err=%d\n", err); - xen_have_vcpu_info_placement = 0; - clamp_max_cpus(); - } else { - /* This cpu is using the registered vcpu info, even if - later ones fail to. */ - per_cpu(xen_vcpu, cpu) = vcpup; - } } void xen_reboot(int reason) diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c index a6d014f47e52..eb53da6547ee 100644 --- a/arch/x86/xen/enlighten_hvm.c +++ b/arch/x86/xen/enlighten_hvm.c @@ -45,11 +45,7 @@ void __ref xen_hvm_init_shared_info(void) * online but xen_hvm_init_shared_info is run at resume time too and * in that case multiple vcpus might be online. */ for_each_online_cpu(cpu) { - /* Leave it to be NULL. */ - if (xen_vcpu_nr(cpu) >= MAX_VIRT_CPUS) - continue; - per_cpu(xen_vcpu, cpu) = - &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)]; + xen_vcpu_info_reset(cpu); } } diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index f33eef4ebd12..3ec1c4632e12 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -107,35 +107,6 @@ struct tls_descs { */ static DEFINE_PER_CPU(struct tls_descs, shadow_tls_desc); -/* - * On restore, set the vcpu placement up again. - * If it fails, then we're in a bad state, since - * we can't back out from using it... - */ -void xen_vcpu_restore(void) -{ - int cpu; - - for_each_possible_cpu(cpu) { - bool other_cpu = (cpu != smp_processor_id()); - bool is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up, xen_vcpu_nr(cpu), - NULL); - - if (other_cpu && is_up && - HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL)) - BUG(); - - xen_setup_runstate_info(cpu); - - if (xen_have_vcpu_info_placement) - xen_vcpu_setup(cpu); - - if (other_cpu && is_up && - HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL)) - BUG(); - } -} - static void __init xen_banner(void) { unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL); @@ -1332,9 +1303,17 @@ asmlinkage __visible void __init xen_start_kernel(void) */ acpi_numa = -1; #endif - /* Don't do the full vcpu_info placement stuff until we have a - possible map and a non-dummy shared_info. */ - per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0]; + /* Let's presume PV guests always boot on vCPU with id 0. */ + per_cpu(xen_vcpu_id, 0) = 0; + + /* + * Setup xen_vcpu early because start_kernel needs it for + * local_irq_disable(), irqs_disabled(). + * + * Don't do the full vcpu_info placement stuff until we have + * the cpu_possible_mask and a non-dummy shared_info. + */ + xen_vcpu_info_reset(0); WARN_ON(xen_cpuhp_setup(xen_cpu_up_prepare_pv, xen_cpu_dead_pv)); @@ -1431,9 +1410,7 @@ asmlinkage __visible void __init xen_start_kernel(void) #endif xen_raw_console_write("about to get started...\n"); - /* Let's presume PV guests always boot on vCPU with id 0. */ - per_cpu(xen_vcpu_id, 0) = 0; - + /* We need this for printk timestamps */ xen_setup_runstate_info(0); xen_efi_init(); diff --git a/arch/x86/xen/smp_hvm.c b/arch/x86/xen/smp_hvm.c index f18561bbf5c9..9e0fb9a015d4 100644 --- a/arch/x86/xen/smp_hvm.c +++ b/arch/x86/xen/smp_hvm.c @@ -12,7 +12,8 @@ static void __init xen_hvm_smp_prepare_boot_cpu(void) native_smp_prepare_boot_cpu(); /* - * Setup vcpu_info for boot CPU. + * Setup vcpu_info for boot CPU. Secondary CPUs get their vcpu_info + * in xen_cpu_up_prepare_hvm(). */ xen_vcpu_setup(0); diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h index 9a440a42c618..90828256248b 100644 --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -79,6 +79,7 @@ bool xen_vcpu_stolen(int vcpu); extern int xen_have_vcpu_info_placement; void xen_vcpu_setup(int cpu); +void xen_vcpu_info_reset(int cpu); void xen_setup_vcpu_info_placement(void); #ifdef CONFIG_SMP -- 2.39.2