Re: [PATCH v6 2/2] KVM-INTEL: add a notifier and a bitmap to support VMCLEAR in kdump

[Zhang Yanfei <zhangyanfei@cn.fujitsu.com>]

于 2012年11月22日 09:13, Marcelo Tosatti 写道:
> On Wed, Nov 21, 2012 at 11:27:19PM +0800, Zhang Yanfei wrote:
>> The notifier will be registered in vmclear_notifier_list when loading
>> kvm-intel module. And the bitmap indicates whether we should do
>> VMCLEAR operation in kdump. The bits in the bitmap are set/unset
>> according to different conditions.
>>
>> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>> ---
>>  arch/x86/kvm/vmx.c |   77 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>>  1 files changed, 76 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index 4ff0ab9..eea55b3 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -41,6 +41,7 @@
>>  #include <asm/i387.h>
>>  #include <asm/xcr.h>
>>  #include <asm/perf_event.h>
>> +#include <asm/kexec.h>
>>  
>>  #include "trace.h"
>>  
>> @@ -963,6 +964,49 @@ static void vmcs_load(struct vmcs *vmcs)
>>  		       vmcs, phys_addr);
>>  }
>>  
>> +#ifdef CONFIG_KEXEC
>> +/*
>> + * This bitmap is used to indicate whether the vmclear
>> + * operation is enabled on all cpus. All disabled by
>> + * default.
>> + */
>> +static cpumask_t crash_vmclear_enabled_bitmap = CPU_MASK_NONE;
>> +
>> +static inline void crash_enable_local_vmclear(int cpu)
>> +{
>> +	cpumask_set_cpu(cpu, &crash_vmclear_enabled_bitmap);
>> +}
>> +
>> +static inline void crash_disable_local_vmclear(int cpu)
>> +{
>> +	cpumask_clear_cpu(cpu, &crash_vmclear_enabled_bitmap);
>> +}
>> +
>> +static inline int crash_local_vmclear_enabled(int cpu)
>> +{
>> +	return cpumask_test_cpu(cpu, &crash_vmclear_enabled_bitmap);
>> +}
>> +
>> +static void vmclear_local_loaded_vmcss(void);
>> +static int crash_vmclear_local_loaded_vmcss(struct notifier_block *this,
>> +					    unsigned long val, void *ptr)
>> +{
>> +	int cpu = raw_smp_processor_id();
>> +
>> +	if (crash_local_vmclear_enabled(cpu))
>> +		vmclear_local_loaded_vmcss();
>> +
>> +	return NOTIFY_DONE;
>> +}
>> +
>> +static struct notifier_block crash_vmclear_notifier = {
>> +	.notifier_call = crash_vmclear_local_loaded_vmcss,
>> +};
>> +#else
>> +static inline void crash_enable_local_vmclear(int cpu) { }
>> +static inline void crash_disable_local_vmclear(int cpu) { }
>> +#endif /* CONFIG_KEXEC */
>> +
>>  static void __loaded_vmcs_clear(void *arg)
>>  {
>>  	struct loaded_vmcs *loaded_vmcs = arg;
>> @@ -972,8 +1016,10 @@ static void __loaded_vmcs_clear(void *arg)
>>  		return; /* vcpu migration can race with cpu offline */
>>  	if (per_cpu(current_vmcs, cpu) == loaded_vmcs->vmcs)
>>  		per_cpu(current_vmcs, cpu) = NULL;
>> +	crash_disable_local_vmclear(cpu);
>>  	list_del(&loaded_vmcs->loaded_vmcss_on_cpu_link);
>>  	loaded_vmcs_init(loaded_vmcs);
>> +	crash_enable_local_vmclear(cpu);
>>  }
>>  
>>  static void loaded_vmcs_clear(struct loaded_vmcs *loaded_vmcs)
>> @@ -1491,8 +1537,10 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>>  
>>  		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
>>  		local_irq_disable();
>> +		crash_disable_local_vmclear(cpu);
>>  		list_add(&vmx->loaded_vmcs->loaded_vmcss_on_cpu_link,
>>  			 &per_cpu(loaded_vmcss_on_cpu, cpu));
>> +		crash_enable_local_vmclear(cpu);
>>  		local_irq_enable();
>>  
>>  		/*
>> @@ -2302,6 +2350,18 @@ static int hardware_enable(void *garbage)
>>  		return -EBUSY;
>>  
>>  	INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
>> +
>> +	/*
>> +	 * Now we can enable the vmclear operation in kdump
>> +	 * since the loaded_vmcss_on_cpu list on this cpu
>> +	 * has been initialized.
>> +	 *
>> +	 * Though the cpu is not in VMX operation now, there
>> +	 * is no problem to enable the vmclear operation
>> +	 * for the loaded_vmcss_on_cpu list is empty!
>> +	 */
>> +	crash_enable_local_vmclear(cpu);
>> +
>>  	rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
>>  
>>  	test_bits = FEATURE_CONTROL_LOCKED;
>> @@ -2335,7 +2395,6 @@ static void vmclear_local_loaded_vmcss(void)
>>  		__loaded_vmcs_clear(v);
>>  }
>>  
>> -
>>  /* Just like cpu_vmxoff(), but with the __kvm_handle_fault_on_reboot()
>>   * tricks.
>>   */
>> @@ -2348,6 +2407,12 @@ static void hardware_disable(void *garbage)
>>  {
>>  	if (vmm_exclusive) {
>>  		vmclear_local_loaded_vmcss();
>> +		/*
>> +		 * vmclear operation in kdump should be disabled here
>> +		 * because the cpu is going to exit VMX operation
>> +		 * and the loaded_vmcss_on_cpu list may not be empty!
>> +		 */
>> +		crash_disable_local_vmclear(raw_smp_processor_id());
>>  		kvm_cpu_vmxoff();
> 
> How come its not empty? vmclear_local_loaded_vmcss cleared it, didnt it?

You are right. I forget that vmclear_local_loaded_vmcss will delete the vmcs
when it clears one. 

Thanks, I will fix this and resend the patch.

Zhang


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