| Message ID | 1253762945-5750-3-git-send-email-zamsden@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Sep 23, 2009 at 05:29:02PM -1000, Zachary Amsden wrote: > Both VMX and SVM require per-cpu memory allocation, which is done at module > init time, for only online cpus. When bringing a new CPU online, we must > also allocate this structure. The method chosen to implement this is to > make the CPU online notifier available via a call to the arch code. This > allows memory allocation to be done smoothly, without any need to allocate > extra structures. > > Note: CPU up notifiers may call KVM callback before calling cpufreq callbacks. > This would causes the CPU frequency not to be detected (and it is not always > clear on non-constant TSC platforms what the bringup TSC rate will be, so the > guess of using tsc_khz could be wrong). So, we clear the rate to zero in such > a case and add logic to query it upon entry. > > Signed-off-by: Zachary Amsden <zamsden@redhat.com> > --- > arch/x86/include/asm/kvm_host.h | 2 ++ > arch/x86/kvm/svm.c | 15 +++++++++++++-- > arch/x86/kvm/vmx.c | 17 +++++++++++++++++ > arch/x86/kvm/x86.c | 14 +++++++++++++- > include/linux/kvm_host.h | 6 ++++++ > virt/kvm/kvm_main.c | 3 ++- > 6 files changed, 53 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 299cc1b..b7dd14b 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -459,6 +459,7 @@ struct descriptor_table { > struct kvm_x86_ops { > int (*cpu_has_kvm_support)(void); /* __init */ > int (*disabled_by_bios)(void); /* __init */ > + int (*cpu_hotadd)(int cpu); > int (*hardware_enable)(void *dummy); > void (*hardware_disable)(void *dummy); > void (*check_processor_compatibility)(void *rtn); > @@ -791,6 +792,7 @@ asmlinkage void kvm_handle_fault_on_reboot(void); > _ASM_PTR " 666b, 667b \n\t" \ > ".popsection" > > +#define KVM_ARCH_WANT_HOTPLUG_NOTIFIER > #define KVM_ARCH_WANT_MMU_NOTIFIER > int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); > int kvm_age_hva(struct kvm *kvm, unsigned long hva); > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 9a4daca..8f99d0c 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -330,13 +330,13 @@ static int svm_hardware_enable(void *garbage) > return -EBUSY; > > if (!has_svm()) { > - printk(KERN_ERR "svm_cpu_init: err EOPNOTSUPP on %d\n", me); > + printk(KERN_ERR "svm_hardware_enable: err EOPNOTSUPP on %d\n", me); > return -EINVAL; > } > svm_data = per_cpu(svm_data, me); > > if (!svm_data) { > - printk(KERN_ERR "svm_cpu_init: svm_data is NULL on %d\n", > + printk(KERN_ERR "svm_hardware_enable: svm_data is NULL on %d\n", > me); > return -EINVAL; > } > @@ -394,6 +394,16 @@ err_1: > > } > > +static __cpuinit int svm_cpu_hotadd(int cpu) > +{ > + struct svm_cpu_data *svm_data = per_cpu(svm_data, cpu); > + > + if (svm_data) > + return 0; > + > + return svm_cpu_init(cpu); > +} > + > static void set_msr_interception(u32 *msrpm, unsigned msr, > int read, int write) > { > @@ -2858,6 +2868,7 @@ static struct kvm_x86_ops svm_x86_ops = { > .hardware_setup = svm_hardware_setup, > .hardware_unsetup = svm_hardware_unsetup, > .check_processor_compatibility = svm_check_processor_compat, > + .cpu_hotadd = svm_cpu_hotadd, > .hardware_enable = svm_hardware_enable, > .hardware_disable = svm_hardware_disable, > .cpu_has_accelerated_tpr = svm_cpu_has_accelerated_tpr, > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 3fe0d42..b8a8428 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -1408,6 +1408,22 @@ static __exit void hardware_unsetup(void) > free_kvm_area(); > } > > +static __cpuinit int vmx_cpu_hotadd(int cpu) > +{ > + struct vmcs *vmcs; > + > + if (per_cpu(vmxarea, cpu)) > + return 0; > + > + vmcs = alloc_vmcs_cpu(cpu); > + if (!vmcs) > + return -ENOMEM; > + > + per_cpu(vmxarea, cpu) = vmcs; > + > + return 0; > +} Have to free in __cpuexit? Is it too wasteful to allocate statically with DEFINE_PER_CPU_PAGE_ALIGNED? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 09/24/2009 05:52 AM, Marcelo Tosatti wrote: > >> +static __cpuinit int vmx_cpu_hotadd(int cpu) >> +{ >> + struct vmcs *vmcs; >> + >> + if (per_cpu(vmxarea, cpu)) >> + return 0; >> + >> + vmcs = alloc_vmcs_cpu(cpu); >> + if (!vmcs) >> + return -ENOMEM; >> + >> + per_cpu(vmxarea, cpu) = vmcs; >> + >> + return 0; >> +} >> > Have to free in __cpuexit? > > Is it too wasteful to allocate statically with DEFINE_PER_CPU_PAGE_ALIGNED? > Unfortunately, I think it is. The VMX / SVM structures are quite large, and we can have a lot of potential CPUs. Zach -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 09/24/2009 11:32 PM, Zachary Amsden wrote: > On 09/24/2009 05:52 AM, Marcelo Tosatti wrote: >> >>> +static __cpuinit int vmx_cpu_hotadd(int cpu) >>> +{ >>> + struct vmcs *vmcs; >>> + >>> + if (per_cpu(vmxarea, cpu)) >>> + return 0; >>> + >>> + vmcs = alloc_vmcs_cpu(cpu); >>> + if (!vmcs) >>> + return -ENOMEM; >>> + >>> + per_cpu(vmxarea, cpu) = vmcs; >>> + >>> + return 0; >>> +} >> Have to free in __cpuexit? >> >> Is it too wasteful to allocate statically with >> DEFINE_PER_CPU_PAGE_ALIGNED? > > Unfortunately, I think it is. The VMX / SVM structures are quite > large, and we can have a lot of potential CPUs. I think percpu is only allocated when the cpu is online (it would still be wasteful if the modules were loaded but unused).
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 299cc1b..b7dd14b 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -459,6 +459,7 @@ struct descriptor_table { struct kvm_x86_ops { int (*cpu_has_kvm_support)(void); /* __init */ int (*disabled_by_bios)(void); /* __init */ + int (*cpu_hotadd)(int cpu); int (*hardware_enable)(void *dummy); void (*hardware_disable)(void *dummy); void (*check_processor_compatibility)(void *rtn); @@ -791,6 +792,7 @@ asmlinkage void kvm_handle_fault_on_reboot(void); _ASM_PTR " 666b, 667b \n\t" \ ".popsection" +#define KVM_ARCH_WANT_HOTPLUG_NOTIFIER #define KVM_ARCH_WANT_MMU_NOTIFIER int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); int kvm_age_hva(struct kvm *kvm, unsigned long hva); diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 9a4daca..8f99d0c 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -330,13 +330,13 @@ static int svm_hardware_enable(void *garbage) return -EBUSY; if (!has_svm()) { - printk(KERN_ERR "svm_cpu_init: err EOPNOTSUPP on %d\n", me); + printk(KERN_ERR "svm_hardware_enable: err EOPNOTSUPP on %d\n", me); return -EINVAL; } svm_data = per_cpu(svm_data, me); if (!svm_data) { - printk(KERN_ERR "svm_cpu_init: svm_data is NULL on %d\n", + printk(KERN_ERR "svm_hardware_enable: svm_data is NULL on %d\n", me); return -EINVAL; } @@ -394,6 +394,16 @@ err_1: } +static __cpuinit int svm_cpu_hotadd(int cpu) +{ + struct svm_cpu_data *svm_data = per_cpu(svm_data, cpu); + + if (svm_data) + return 0; + + return svm_cpu_init(cpu); +} + static void set_msr_interception(u32 *msrpm, unsigned msr, int read, int write) { @@ -2858,6 +2868,7 @@ static struct kvm_x86_ops svm_x86_ops = { .hardware_setup = svm_hardware_setup, .hardware_unsetup = svm_hardware_unsetup, .check_processor_compatibility = svm_check_processor_compat, + .cpu_hotadd = svm_cpu_hotadd, .hardware_enable = svm_hardware_enable, .hardware_disable = svm_hardware_disable, .cpu_has_accelerated_tpr = svm_cpu_has_accelerated_tpr, diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 3fe0d42..b8a8428 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1408,6 +1408,22 @@ static __exit void hardware_unsetup(void) free_kvm_area(); } +static __cpuinit int vmx_cpu_hotadd(int cpu) +{ + struct vmcs *vmcs; + + if (per_cpu(vmxarea, cpu)) + return 0; + + vmcs = alloc_vmcs_cpu(cpu); + if (!vmcs) + return -ENOMEM; + + per_cpu(vmxarea, cpu) = vmcs; + + return 0; +} + static void fix_pmode_dataseg(int seg, struct kvm_save_segment *save) { struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg]; @@ -3925,6 +3941,7 @@ static struct kvm_x86_ops vmx_x86_ops = { .hardware_setup = hardware_setup, .hardware_unsetup = hardware_unsetup, .check_processor_compatibility = vmx_check_processor_compat, + .cpu_hotadd = vmx_cpu_hotadd, .hardware_enable = hardware_enable, .hardware_disable = hardware_disable, .cpu_has_accelerated_tpr = report_flexpriority, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 35082dd..05aea42 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1339,6 +1339,8 @@ out: void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { kvm_x86_ops->vcpu_load(vcpu, cpu); + if (unlikely(per_cpu(cpu_tsc_khz, cpu) == 0)) + kvm_get_cpu_khz(cpu); kvm_request_guest_time_update(vcpu); } @@ -4712,10 +4714,20 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu) return kvm_x86_ops->vcpu_reset(vcpu); } +int kvm_arch_cpu_hotadd(int cpu) +{ + return kvm_x86_ops->cpu_hotadd(cpu); +} + int kvm_arch_hardware_enable(void *garbage) { + /* + * Notifier callback chain may not have called cpufreq code + * yet, thus we must reset TSC khz to zero and recompute it + * before entering. + */ if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) - kvm_get_cpu_khz(raw_smp_processor_id()); + per_cpu(cpu_tsc_khz, raw_smp_processor_id()) = 0; return kvm_x86_ops->hardware_enable(garbage); } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 0bf9ee9..2f075c4 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -345,6 +345,12 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id); int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu); +#ifdef KVM_ARCH_WANT_HOTPLUG_NOTIFIER +int kvm_arch_cpu_hotadd(int cpu); +#else +#define kvm_arch_cpu_hotadd(x) (0) +#endif + int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu); int kvm_arch_hardware_enable(void *garbage); void kvm_arch_hardware_disable(void *garbage); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e27b7a9..1360db4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1734,7 +1734,8 @@ static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val, case CPU_ONLINE: printk(KERN_INFO "kvm: enabling virtualization on CPU%d\n", cpu); - smp_call_function_single(cpu, hardware_enable, NULL, 1); + if (!kvm_arch_cpu_hotadd(cpu)) + smp_call_function_single(cpu, hardware_enable, NULL, 1); break; } return NOTIFY_OK;
Both VMX and SVM require per-cpu memory allocation, which is done at module init time, for only online cpus. When bringing a new CPU online, we must also allocate this structure. The method chosen to implement this is to make the CPU online notifier available via a call to the arch code. This allows memory allocation to be done smoothly, without any need to allocate extra structures. Note: CPU up notifiers may call KVM callback before calling cpufreq callbacks. This would causes the CPU frequency not to be detected (and it is not always clear on non-constant TSC platforms what the bringup TSC rate will be, so the guess of using tsc_khz could be wrong). So, we clear the rate to zero in such a case and add logic to query it upon entry. Signed-off-by: Zachary Amsden <zamsden@redhat.com> --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/svm.c | 15 +++++++++++++-- arch/x86/kvm/vmx.c | 17 +++++++++++++++++ arch/x86/kvm/x86.c | 14 +++++++++++++- include/linux/kvm_host.h | 6 ++++++ virt/kvm/kvm_main.c | 3 ++- 6 files changed, 53 insertions(+), 4 deletions(-)