diff mbox series

[v2,02/15] kvm: x86: Introduce KVM APICv state

Message ID 1565886293-115836-3-git-send-email-suravee.suthikulpanit@amd.com (mailing list archive)
State New, archived
Headers show
Series kvm: x86: Support AMD SVM AVIC w/ in-kernel irqchip mode | expand

Commit Message

Suthikulpanit, Suravee Aug. 15, 2019, 4:25 p.m. UTC 
Currently, after a VM boots with APICv enabled, it could go into
the following states:
  * activated   = VM is running w/ APICv
  * deactivated = VM deactivate APICv (temporary)
  * disabled    = VM deactivate APICv (permanent)

Introduce KVM APICv state enum to help keep track of the APICv states
along with a new variable struct kvm_arch.apicv_state to store
the current state.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 arch/x86/include/asm/kvm_host.h | 11 +++++++++++
 arch/x86/kvm/x86.c              | 14 +++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

Comments

Alexander Graf Aug. 19, 2019, 9:49 a.m. UTC | #1 
On 15.08.19 18:25, Suthikulpanit, Suravee wrote:
> Currently, after a VM boots with APICv enabled, it could go into
> the following states:
>    * activated   = VM is running w/ APICv
>    * deactivated = VM deactivate APICv (temporary)
>    * disabled    = VM deactivate APICv (permanent)
> 
> Introduce KVM APICv state enum to help keep track of the APICv states
> along with a new variable struct kvm_arch.apicv_state to store
> the current state.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
>   arch/x86/include/asm/kvm_host.h | 11 +++++++++++
>   arch/x86/kvm/x86.c              | 14 +++++++++++++-
>   2 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 56bc702..04d7066 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -845,6 +845,15 @@ enum kvm_irqchip_mode {
>   	KVM_IRQCHIP_SPLIT,        /* created with KVM_CAP_SPLIT_IRQCHIP */
>   };
>   
> +/*
> + * KVM assumes all vcpus in a VM operate in the same mode.
> + */
> +enum kvm_apicv_state {
> +	APICV_DISABLED,		/* Disabled (such as for Hyper-V case) */
> +	APICV_DEACTIVATED,	/* Deactivated tempoerary */

typo

I'm also not sure the name is 100% obvious. How about something like 
"suspended" or "paused"?

> +	APICV_ACTIVATED,	/* Default status when APICV is enabled */
> +};
> +
>   struct kvm_arch {
>   	unsigned long n_used_mmu_pages;
>   	unsigned long n_requested_mmu_pages;
> @@ -873,6 +882,8 @@ struct kvm_arch {
>   	struct kvm_apic_map *apic_map;
>   
>   	bool apic_access_page_done;
> +	struct mutex apicv_lock;
> +	enum kvm_apicv_state apicv_state;
>   
>   	gpa_t wall_clock;
>   
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 7daf0dd..f9c3f63 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4584,6 +4584,8 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
>   		kvm->arch.irqchip_mode = KVM_IRQCHIP_SPLIT;
>   		kvm->arch.nr_reserved_ioapic_pins = cap->args[0];
>   		r = 0;
> +		if (kvm_x86_ops->get_enable_apicv(kvm))
> +			kvm->arch.apicv_state = APICV_ACTIVATED;
>   split_irqchip_unlock:
>   		mutex_unlock(&kvm->lock);
>   		break;
> @@ -4701,6 +4703,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
>   		/* Write kvm->irq_routing before enabling irqchip_in_kernel. */
>   		smp_wmb();
>   		kvm->arch.irqchip_mode = KVM_IRQCHIP_KERNEL;
> +		if (kvm_x86_ops->get_enable_apicv(kvm))
> +			kvm->arch.apicv_state = APICV_ACTIVATED;
>   	create_irqchip_unlock:
>   		mutex_unlock(&kvm->lock);
>   		break;
> @@ -9150,13 +9154,18 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
>   		goto fail_free_pio_data;
>   
>   	if (irqchip_in_kernel(vcpu->kvm)) {
> -		vcpu->arch.apicv_active = kvm_x86_ops->get_enable_apicv(vcpu->kvm);

Why are you moving this into a locked section?

>   		r = kvm_create_lapic(vcpu, lapic_timer_advance_ns);
>   		if (r < 0)
>   			goto fail_mmu_destroy;
>   	} else
>   		static_key_slow_inc(&kvm_no_apic_vcpu);
>   
> +	mutex_lock(&vcpu->kvm->arch.apicv_lock);
> +	if (irqchip_in_kernel(vcpu->kvm) &&
> +	    vcpu->kvm->arch.apicv_state == APICV_ACTIVATED)
> +		vcpu->arch.apicv_active = kvm_x86_ops->get_enable_apicv(vcpu->kvm);
> +	mutex_unlock(&vcpu->kvm->arch.apicv_lock);
> +
>   	vcpu->arch.mce_banks = kzalloc(KVM_MAX_MCE_BANKS * sizeof(u64) * 4,
>   				       GFP_KERNEL_ACCOUNT);
>   	if (!vcpu->arch.mce_banks) {
> @@ -9255,6 +9264,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>   	kvm_page_track_init(kvm);
>   	kvm_mmu_init_vm(kvm);
>   
> +	/* APICV initialization */
> +	mutex_init(&kvm->arch.apicv_lock);

In fact, the whole lock story is not part of the patch description :).


Alex

> +
>   	if (kvm_x86_ops->vm_init)
>   		return kvm_x86_ops->vm_init(kvm);
>   
>
Suthikulpanit, Suravee Aug. 26, 2019, 7:06 p.m. UTC | #2 
Alex,

On 8/19/2019 4:49 AM, Alexander Graf wrote:
> 
> 
> On 15.08.19 18:25, Suthikulpanit, Suravee wrote:
>> Currently, after a VM boots with APICv enabled, it could go into
>> the following states:
>>    * activated   = VM is running w/ APICv
>>    * deactivated = VM deactivate APICv (temporary)
>>    * disabled    = VM deactivate APICv (permanent)
>>
>> Introduce KVM APICv state enum to help keep track of the APICv states
>> along with a new variable struct kvm_arch.apicv_state to store
>> the current state.
>>
>> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>> ---
>>   arch/x86/include/asm/kvm_host.h | 11 +++++++++++
>>   arch/x86/kvm/x86.c              | 14 +++++++++++++-
>>   2 files changed, 24 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index 56bc702..04d7066 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -845,6 +845,15 @@ enum kvm_irqchip_mode {
>>       KVM_IRQCHIP_SPLIT,        /* created with KVM_CAP_SPLIT_IRQCHIP */
>>   };
>> +/*
>> + * KVM assumes all vcpus in a VM operate in the same mode.
>> + */
>> +enum kvm_apicv_state {
>> +    APICV_DISABLED,        /* Disabled (such as for Hyper-V case) */
>> +    APICV_DEACTIVATED,    /* Deactivated tempoerary */
> 
> typo
> 
> I'm also not sure the name is 100% obvious. How about something like "suspended" or "paused"?

Ok, I'll change it to APICV_SUSPENDED.

>> ...
>> @@ -9150,13 +9154,18 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
>>           goto fail_free_pio_data;
>>       if (irqchip_in_kernel(vcpu->kvm)) {
>> -        vcpu->arch.apicv_active = kvm_x86_ops->get_enable_apicv(vcpu->kvm);
> 
> Why are you moving this into a locked section?

Since we introduced the apicv_state to track the VM APICv state, which is accessible
by each vcpu initialization code, we need to lock and check the state before setting
the per-vcpu apicv_active.

> 
>>           r = kvm_create_lapic(vcpu, lapic_timer_advance_ns);
>>           if (r < 0)
>>               goto fail_mmu_destroy;
>>       } else
>>           static_key_slow_inc(&kvm_no_apic_vcpu);
>> +    mutex_lock(&vcpu->kvm->arch.apicv_lock);
>> +    if (irqchip_in_kernel(vcpu->kvm) &&
>> +        vcpu->kvm->arch.apicv_state == APICV_ACTIVATED)
>> +        vcpu->arch.apicv_active = kvm_x86_ops->get_enable_apicv(vcpu->kvm);
>> +    mutex_unlock(&vcpu->kvm->arch.apicv_lock);
>> +
>>       vcpu->arch.mce_banks = kzalloc(KVM_MAX_MCE_BANKS * sizeof(u64) * 4,
>>                          GFP_KERNEL_ACCOUNT);
>>       if (!vcpu->arch.mce_banks) {
>> @@ -9255,6 +9264,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>>       kvm_page_track_init(kvm);
>>       kvm_mmu_init_vm(kvm);
>> +    /* APICV initialization */
>> +    mutex_init(&kvm->arch.apicv_lock);
> 
> In fact, the whole lock story is not part of the patch description :).\\

Ok, I'll update the commit log to describe the lock .

Suravee
diff mbox series

Patch

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 56bc702..04d7066 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -845,6 +845,15 @@  enum kvm_irqchip_mode {
 	KVM_IRQCHIP_SPLIT,        /* created with KVM_CAP_SPLIT_IRQCHIP */
 };
 
+/*
+ * KVM assumes all vcpus in a VM operate in the same mode.
+ */
+enum kvm_apicv_state {
+	APICV_DISABLED,		/* Disabled (such as for Hyper-V case) */
+	APICV_DEACTIVATED,	/* Deactivated tempoerary */
+	APICV_ACTIVATED,	/* Default status when APICV is enabled */
+};
+
 struct kvm_arch {
 	unsigned long n_used_mmu_pages;
 	unsigned long n_requested_mmu_pages;
@@ -873,6 +882,8 @@  struct kvm_arch {
 	struct kvm_apic_map *apic_map;
 
 	bool apic_access_page_done;
+	struct mutex apicv_lock;
+	enum kvm_apicv_state apicv_state;
 
 	gpa_t wall_clock;
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7daf0dd..f9c3f63 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4584,6 +4584,8 @@  int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 		kvm->arch.irqchip_mode = KVM_IRQCHIP_SPLIT;
 		kvm->arch.nr_reserved_ioapic_pins = cap->args[0];
 		r = 0;
+		if (kvm_x86_ops->get_enable_apicv(kvm))
+			kvm->arch.apicv_state = APICV_ACTIVATED;
 split_irqchip_unlock:
 		mutex_unlock(&kvm->lock);
 		break;
@@ -4701,6 +4703,8 @@  long kvm_arch_vm_ioctl(struct file *filp,
 		/* Write kvm->irq_routing before enabling irqchip_in_kernel. */
 		smp_wmb();
 		kvm->arch.irqchip_mode = KVM_IRQCHIP_KERNEL;
+		if (kvm_x86_ops->get_enable_apicv(kvm))
+			kvm->arch.apicv_state = APICV_ACTIVATED;
 	create_irqchip_unlock:
 		mutex_unlock(&kvm->lock);
 		break;
@@ -9150,13 +9154,18 @@  int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 		goto fail_free_pio_data;
 
 	if (irqchip_in_kernel(vcpu->kvm)) {
-		vcpu->arch.apicv_active = kvm_x86_ops->get_enable_apicv(vcpu->kvm);
 		r = kvm_create_lapic(vcpu, lapic_timer_advance_ns);
 		if (r < 0)
 			goto fail_mmu_destroy;
 	} else
 		static_key_slow_inc(&kvm_no_apic_vcpu);
 
+	mutex_lock(&vcpu->kvm->arch.apicv_lock);
+	if (irqchip_in_kernel(vcpu->kvm) &&
+	    vcpu->kvm->arch.apicv_state == APICV_ACTIVATED)
+		vcpu->arch.apicv_active = kvm_x86_ops->get_enable_apicv(vcpu->kvm);
+	mutex_unlock(&vcpu->kvm->arch.apicv_lock);
+
 	vcpu->arch.mce_banks = kzalloc(KVM_MAX_MCE_BANKS * sizeof(u64) * 4,
 				       GFP_KERNEL_ACCOUNT);
 	if (!vcpu->arch.mce_banks) {
@@ -9255,6 +9264,9 @@  int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	kvm_page_track_init(kvm);
 	kvm_mmu_init_vm(kvm);
 
+	/* APICV initialization */
+	mutex_init(&kvm->arch.apicv_lock);
+
 	if (kvm_x86_ops->vm_init)
 		return kvm_x86_ops->vm_init(kvm);