irqchip/gic-v4: Fix VMAPP/VMOVP races

[PATCH 3/3] irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

Posted by Marc Zyngier 1 year, 7 months ago

In order to make sure that vpe->col_idx is correctly sampled
when a VMAPP command is issued, we must hold the lock for the
VPE. This is now possible since the introduction of the per-VM
vmapp_lock, which can be taken before vpe_lock in the locking
order.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/irqchip/irq-gic-v3-its.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index b52d60097cad5..951ec140bcea2 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1810,7 +1810,9 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm)
 		for (i = 0; i < vm->nr_vpes; i++) {
 			struct its_vpe *vpe = vm->vpes[i];
 
-			its_send_vmapp(its, vpe, true);
+			scoped_guard(raw_spinlock, &vpe->vpe_lock)
+				its_send_vmapp(its, vpe, true);
+
 			its_send_vinvall(its, vpe);
 		}
 	}
@@ -1827,8 +1829,10 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
 	if (!--vm->vlpi_count[its->list_nr]) {
 		int i;
 
-		for (i = 0; i < vm->nr_vpes; i++)
+		for (i = 0; i < vm->nr_vpes; i++) {
+			guard(raw_spinlock)(&vm->vpes[i]->vpe_lock);
 			its_send_vmapp(its, vm->vpes[i], false);
+		}
 	}
 }
 
-- 
2.39.2

Re: [PATCH 3/3] irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

Posted by Zhou Wang 1 year, 6 months ago

On 2024/7/5 17:31, Marc Zyngier wrote:
> In order to make sure that vpe->col_idx is correctly sampled
> when a VMAPP command is issued, we must hold the lock for the
> VPE. This is now possible since the introduction of the per-VM
> vmapp_lock, which can be taken before vpe_lock in the locking
> order.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  drivers/irqchip/irq-gic-v3-its.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index b52d60097cad5..951ec140bcea2 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -1810,7 +1810,9 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm)
>  		for (i = 0; i < vm->nr_vpes; i++) {
>  			struct its_vpe *vpe = vm->vpes[i];
>  
> -			its_send_vmapp(its, vpe, true);
> +			scoped_guard(raw_spinlock, &vpe->vpe_lock)
> +				its_send_vmapp(its, vpe, true);
> +
>  			its_send_vinvall(its, vpe);
>  		}
>  	}
> @@ -1827,8 +1829,10 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
>  	if (!--vm->vlpi_count[its->list_nr]) {
>  		int i;
>  
> -		for (i = 0; i < vm->nr_vpes; i++)
> +		for (i = 0; i < vm->nr_vpes; i++) {
> +			guard(raw_spinlock)(&vm->vpes[i]->vpe_lock);
>  			its_send_vmapp(its, vm->vpes[i], false);
> +		}
>  	}
>  }
>  

Hi Marc,

It looks like there is ABBA deadlock after applying this series:

In its_map_vm: vmapp_lock -> vpe_lock
In its_vpe_set_affinity: vpe_to_cpuid_lock(vpe_lock) -> its_send_vmovp(vmapp_lock)

Any idea about this?

Best,
Zhou

Re: [PATCH 3/3] irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

Posted by Marc Zyngier 1 year, 6 months ago

On Fri, 19 Jul 2024 10:42:02 +0100,
Zhou Wang <wangzhou1@hisilicon.com> wrote:
> 
> On 2024/7/5 17:31, Marc Zyngier wrote:
> > In order to make sure that vpe->col_idx is correctly sampled
> > when a VMAPP command is issued, we must hold the lock for the
> > VPE. This is now possible since the introduction of the per-VM
> > vmapp_lock, which can be taken before vpe_lock in the locking
> > order.
> > 
> > Signed-off-by: Marc Zyngier <maz@kernel.org>
> > ---
> >  drivers/irqchip/irq-gic-v3-its.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> > index b52d60097cad5..951ec140bcea2 100644
> > --- a/drivers/irqchip/irq-gic-v3-its.c
> > +++ b/drivers/irqchip/irq-gic-v3-its.c
> > @@ -1810,7 +1810,9 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm)
> >  		for (i = 0; i < vm->nr_vpes; i++) {
> >  			struct its_vpe *vpe = vm->vpes[i];
> >  
> > -			its_send_vmapp(its, vpe, true);
> > +			scoped_guard(raw_spinlock, &vpe->vpe_lock)
> > +				its_send_vmapp(its, vpe, true);
> > +
> >  			its_send_vinvall(its, vpe);
> >  		}
> >  	}
> > @@ -1827,8 +1829,10 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
> >  	if (!--vm->vlpi_count[its->list_nr]) {
> >  		int i;
> >  
> > -		for (i = 0; i < vm->nr_vpes; i++)
> > +		for (i = 0; i < vm->nr_vpes; i++) {
> > +			guard(raw_spinlock)(&vm->vpes[i]->vpe_lock);
> >  			its_send_vmapp(its, vm->vpes[i], false);
> > +		}
> >  	}
> >  }
> >  
> 
> Hi Marc,
> 
> It looks like there is ABBA deadlock after applying this series:
> 
> In its_map_vm: vmapp_lock -> vpe_lock
> In its_vpe_set_affinity: vpe_to_cpuid_lock(vpe_lock) -> its_send_vmovp(vmapp_lock)
> 
> Any idea about this?

Hmmm, well spotted. That's an annoying one.

Can you give the below hack a go? I've only lightly tested it, as my
D05 box is on its last leg (it is literally falling apart) and I don't
have any other GICv4.x box to test on.

Thanks,

	M.

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 951ec140bcea2..b88c6011c8771 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1328,12 +1328,6 @@ static void its_send_vmovp(struct its_vpe *vpe)
 		return;
 	}
 
-	/*
-	 * Protect against concurrent updates of the mapping state on
-	 * individual VMs.
-	 */
-	guard(raw_spinlock_irqsave)(&vpe->its_vm->vmapp_lock);
-
 	/*
 	 * Yet another marvel of the architecture. If using the
 	 * its_list "feature", we need to make sure that all ITSs
@@ -3808,7 +3802,7 @@ static int its_vpe_set_affinity(struct irq_data *d,
 	struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
 	unsigned int from, cpu = nr_cpu_ids;
 	struct cpumask *table_mask;
-	unsigned long flags;
+	unsigned long flags, vmapp_flags;
 
 	/*
 	 * Changing affinity is mega expensive, so let's be as lazy as
@@ -3822,7 +3816,14 @@ static int its_vpe_set_affinity(struct irq_data *d,
 	 * protect us, and that we must ensure nobody samples vpe->col_idx
 	 * during the update, hence the lock below which must also be
 	 * taken on any vLPI handling path that evaluates vpe->col_idx.
+	 *
+	 * Finally, we must protect ourselves against concurrent
+	 * updates of the mapping state on this VM should the ITS list
+	 * be in use.
 	 */
+	if (its_list_map)
+		raw_spin_lock_irqsave(&vpe->its_vm->vmapp_lock, vmapp_flags);
+
 	from = vpe_to_cpuid_lock(vpe, &flags);
 	table_mask = gic_data_rdist_cpu(from)->vpe_table_mask;
 
@@ -3852,6 +3853,9 @@ static int its_vpe_set_affinity(struct irq_data *d,
 	irq_data_update_effective_affinity(d, cpumask_of(cpu));
 	vpe_to_cpuid_unlock(vpe, flags);
 
+	if (its_list_map)
+		raw_spin_unlock_irqrestore(&vpe->its_vm->vmapp_lock, vmapp_flags);
+
 	return IRQ_SET_MASK_OK_DONE;
 }
 

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH 3/3] irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

Posted by Zhou Wang 1 year, 6 months ago

On 2024/7/19 19:31, Marc Zyngier wrote:
> On Fri, 19 Jul 2024 10:42:02 +0100,
> Zhou Wang <wangzhou1@hisilicon.com> wrote:
>>
>> On 2024/7/5 17:31, Marc Zyngier wrote:
>>> In order to make sure that vpe->col_idx is correctly sampled
>>> when a VMAPP command is issued, we must hold the lock for the
>>> VPE. This is now possible since the introduction of the per-VM
>>> vmapp_lock, which can be taken before vpe_lock in the locking
>>> order.
>>>
>>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>>> ---
>>>  drivers/irqchip/irq-gic-v3-its.c | 8 ++++++--
>>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
>>> index b52d60097cad5..951ec140bcea2 100644
>>> --- a/drivers/irqchip/irq-gic-v3-its.c
>>> +++ b/drivers/irqchip/irq-gic-v3-its.c
>>> @@ -1810,7 +1810,9 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm)
>>>  		for (i = 0; i < vm->nr_vpes; i++) {
>>>  			struct its_vpe *vpe = vm->vpes[i];
>>>  
>>> -			its_send_vmapp(its, vpe, true);
>>> +			scoped_guard(raw_spinlock, &vpe->vpe_lock)
>>> +				its_send_vmapp(its, vpe, true);
>>> +
>>>  			its_send_vinvall(its, vpe);
>>>  		}
>>>  	}
>>> @@ -1827,8 +1829,10 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
>>>  	if (!--vm->vlpi_count[its->list_nr]) {
>>>  		int i;
>>>  
>>> -		for (i = 0; i < vm->nr_vpes; i++)
>>> +		for (i = 0; i < vm->nr_vpes; i++) {
>>> +			guard(raw_spinlock)(&vm->vpes[i]->vpe_lock);
>>>  			its_send_vmapp(its, vm->vpes[i], false);
>>> +		}
>>>  	}
>>>  }
>>>  
>>
>> Hi Marc,
>>
>> It looks like there is ABBA deadlock after applying this series:
>>
>> In its_map_vm: vmapp_lock -> vpe_lock
>> In its_vpe_set_affinity: vpe_to_cpuid_lock(vpe_lock) -> its_send_vmovp(vmapp_lock)
>>
>> Any idea about this?
> 
> Hmmm, well spotted. That's an annoying one.
> 
> Can you give the below hack a go? I've only lightly tested it, as my
> D05 box is on its last leg (it is literally falling apart) and I don't
> have any other GICv4.x box to test on.
> 
> Thanks,
> 
> 	M.
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 951ec140bcea2..b88c6011c8771 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -1328,12 +1328,6 @@ static void its_send_vmovp(struct its_vpe *vpe)
>  		return;
>  	}
>  
> -	/*
> -	 * Protect against concurrent updates of the mapping state on
> -	 * individual VMs.
> -	 */
> -	guard(raw_spinlock_irqsave)(&vpe->its_vm->vmapp_lock);
> -
>  	/*
>  	 * Yet another marvel of the architecture. If using the
>  	 * its_list "feature", we need to make sure that all ITSs
> @@ -3808,7 +3802,7 @@ static int its_vpe_set_affinity(struct irq_data *d,
>  	struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
>  	unsigned int from, cpu = nr_cpu_ids;
>  	struct cpumask *table_mask;
> -	unsigned long flags;
> +	unsigned long flags, vmapp_flags;
>  
>  	/*
>  	 * Changing affinity is mega expensive, so let's be as lazy as
> @@ -3822,7 +3816,14 @@ static int its_vpe_set_affinity(struct irq_data *d,
>  	 * protect us, and that we must ensure nobody samples vpe->col_idx
>  	 * during the update, hence the lock below which must also be
>  	 * taken on any vLPI handling path that evaluates vpe->col_idx.
> +	 *
> +	 * Finally, we must protect ourselves against concurrent
> +	 * updates of the mapping state on this VM should the ITS list
> +	 * be in use.
>  	 */
> +	if (its_list_map)
> +		raw_spin_lock_irqsave(&vpe->its_vm->vmapp_lock, vmapp_flags);
> +
>  	from = vpe_to_cpuid_lock(vpe, &flags);
>  	table_mask = gic_data_rdist_cpu(from)->vpe_table_mask;
>  
> @@ -3852,6 +3853,9 @@ static int its_vpe_set_affinity(struct irq_data *d,
>  	irq_data_update_effective_affinity(d, cpumask_of(cpu));
>  	vpe_to_cpuid_unlock(vpe, flags);
>  
> +	if (its_list_map)
> +		raw_spin_unlock_irqrestore(&vpe->its_vm->vmapp_lock, vmapp_flags);
> +
>  	return IRQ_SET_MASK_OK_DONE;
>  }
>

Hi Marc，

We add above code to do test again. Now it is OK.

Bests,
Zhou

>

Re: [PATCH 3/3] irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

Posted by Marc Zyngier 1 year, 6 months ago

On Tue, 23 Jul 2024 02:51:32 +0100,
Zhou Wang <wangzhou1@hisilicon.com> wrote:
> 
> On 2024/7/19 19:31, Marc Zyngier wrote:
> > On Fri, 19 Jul 2024 10:42:02 +0100,
> > Zhou Wang <wangzhou1@hisilicon.com> wrote:
> >>
> >> On 2024/7/5 17:31, Marc Zyngier wrote:
> >>> In order to make sure that vpe->col_idx is correctly sampled
> >>> when a VMAPP command is issued, we must hold the lock for the
> >>> VPE. This is now possible since the introduction of the per-VM
> >>> vmapp_lock, which can be taken before vpe_lock in the locking
> >>> order.
> >>>
> >>> Signed-off-by: Marc Zyngier <maz@kernel.org>
> >>> ---
> >>>  drivers/irqchip/irq-gic-v3-its.c | 8 ++++++--
> >>>  1 file changed, 6 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> >>> index b52d60097cad5..951ec140bcea2 100644
> >>> --- a/drivers/irqchip/irq-gic-v3-its.c
> >>> +++ b/drivers/irqchip/irq-gic-v3-its.c
> >>> @@ -1810,7 +1810,9 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm)
> >>>  		for (i = 0; i < vm->nr_vpes; i++) {
> >>>  			struct its_vpe *vpe = vm->vpes[i];
> >>>  
> >>> -			its_send_vmapp(its, vpe, true);
> >>> +			scoped_guard(raw_spinlock, &vpe->vpe_lock)
> >>> +				its_send_vmapp(its, vpe, true);
> >>> +
> >>>  			its_send_vinvall(its, vpe);
> >>>  		}
> >>>  	}
> >>> @@ -1827,8 +1829,10 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
> >>>  	if (!--vm->vlpi_count[its->list_nr]) {
> >>>  		int i;
> >>>  
> >>> -		for (i = 0; i < vm->nr_vpes; i++)
> >>> +		for (i = 0; i < vm->nr_vpes; i++) {
> >>> +			guard(raw_spinlock)(&vm->vpes[i]->vpe_lock);
> >>>  			its_send_vmapp(its, vm->vpes[i], false);
> >>> +		}
> >>>  	}
> >>>  }
> >>>  
> >>
> >> Hi Marc,
> >>
> >> It looks like there is ABBA deadlock after applying this series:
> >>
> >> In its_map_vm: vmapp_lock -> vpe_lock
> >> In its_vpe_set_affinity: vpe_to_cpuid_lock(vpe_lock) -> its_send_vmovp(vmapp_lock)
> >>
> >> Any idea about this?
> > 
> > Hmmm, well spotted. That's an annoying one.
> > 
> > Can you give the below hack a go? I've only lightly tested it, as my
> > D05 box is on its last leg (it is literally falling apart) and I don't
> > have any other GICv4.x box to test on.
> > 
> > Thanks,
> > 
> > 	M.
> > 
> > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> > index 951ec140bcea2..b88c6011c8771 100644
> > --- a/drivers/irqchip/irq-gic-v3-its.c
> > +++ b/drivers/irqchip/irq-gic-v3-its.c
> > @@ -1328,12 +1328,6 @@ static void its_send_vmovp(struct its_vpe *vpe)
> >  		return;
> >  	}
> >  
> > -	/*
> > -	 * Protect against concurrent updates of the mapping state on
> > -	 * individual VMs.
> > -	 */
> > -	guard(raw_spinlock_irqsave)(&vpe->its_vm->vmapp_lock);
> > -
> >  	/*
> >  	 * Yet another marvel of the architecture. If using the
> >  	 * its_list "feature", we need to make sure that all ITSs
> > @@ -3808,7 +3802,7 @@ static int its_vpe_set_affinity(struct irq_data *d,
> >  	struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
> >  	unsigned int from, cpu = nr_cpu_ids;
> >  	struct cpumask *table_mask;
> > -	unsigned long flags;
> > +	unsigned long flags, vmapp_flags;
> >  
> >  	/*
> >  	 * Changing affinity is mega expensive, so let's be as lazy as
> > @@ -3822,7 +3816,14 @@ static int its_vpe_set_affinity(struct irq_data *d,
> >  	 * protect us, and that we must ensure nobody samples vpe->col_idx
> >  	 * during the update, hence the lock below which must also be
> >  	 * taken on any vLPI handling path that evaluates vpe->col_idx.
> > +	 *
> > +	 * Finally, we must protect ourselves against concurrent
> > +	 * updates of the mapping state on this VM should the ITS list
> > +	 * be in use.
> >  	 */
> > +	if (its_list_map)
> > +		raw_spin_lock_irqsave(&vpe->its_vm->vmapp_lock, vmapp_flags);
> > +
> >  	from = vpe_to_cpuid_lock(vpe, &flags);
> >  	table_mask = gic_data_rdist_cpu(from)->vpe_table_mask;
> >  
> > @@ -3852,6 +3853,9 @@ static int its_vpe_set_affinity(struct irq_data *d,
> >  	irq_data_update_effective_affinity(d, cpumask_of(cpu));
> >  	vpe_to_cpuid_unlock(vpe, flags);
> >  
> > +	if (its_list_map)
> > +		raw_spin_unlock_irqrestore(&vpe->its_vm->vmapp_lock, vmapp_flags);
> > +
> >  	return IRQ_SET_MASK_OK_DONE;
> >  }
> >
> 
> Hi Marc，
> 
> We add above code to do test again. Now it is OK.

Great, thanks for giving it a go. I have just posted an actual patch
(with the exact same change) at [1]. It would be good if you could
give it a Tested-by: tag.

Thanks,

	M.

[1] https://lore.kernel.org/r/20240723175203.3193882-1-maz@kernel.org

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH 3/3] irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

Posted by Zhou Wang 1 year, 6 months ago

On 2024/7/24 1:56, Marc Zyngier wrote:
> On Tue, 23 Jul 2024 02:51:32 +0100,
> Zhou Wang <wangzhou1@hisilicon.com> wrote:
>>
>> On 2024/7/19 19:31, Marc Zyngier wrote:
>>> On Fri, 19 Jul 2024 10:42:02 +0100,
>>> Zhou Wang <wangzhou1@hisilicon.com> wrote:
>>>>
>>>> On 2024/7/5 17:31, Marc Zyngier wrote:
>>>>> In order to make sure that vpe->col_idx is correctly sampled
>>>>> when a VMAPP command is issued, we must hold the lock for the
>>>>> VPE. This is now possible since the introduction of the per-VM
>>>>> vmapp_lock, which can be taken before vpe_lock in the locking
>>>>> order.
>>>>>
>>>>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>>>>> ---
>>>>>  drivers/irqchip/irq-gic-v3-its.c | 8 ++++++--
>>>>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
>>>>> index b52d60097cad5..951ec140bcea2 100644
>>>>> --- a/drivers/irqchip/irq-gic-v3-its.c
>>>>> +++ b/drivers/irqchip/irq-gic-v3-its.c
>>>>> @@ -1810,7 +1810,9 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm)
>>>>>  		for (i = 0; i < vm->nr_vpes; i++) {
>>>>>  			struct its_vpe *vpe = vm->vpes[i];
>>>>>  
>>>>> -			its_send_vmapp(its, vpe, true);
>>>>> +			scoped_guard(raw_spinlock, &vpe->vpe_lock)
>>>>> +				its_send_vmapp(its, vpe, true);
>>>>> +
>>>>>  			its_send_vinvall(its, vpe);
>>>>>  		}
>>>>>  	}
>>>>> @@ -1827,8 +1829,10 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
>>>>>  	if (!--vm->vlpi_count[its->list_nr]) {
>>>>>  		int i;
>>>>>  
>>>>> -		for (i = 0; i < vm->nr_vpes; i++)
>>>>> +		for (i = 0; i < vm->nr_vpes; i++) {
>>>>> +			guard(raw_spinlock)(&vm->vpes[i]->vpe_lock);
>>>>>  			its_send_vmapp(its, vm->vpes[i], false);
>>>>> +		}
>>>>>  	}
>>>>>  }
>>>>>  
>>>>
>>>> Hi Marc,
>>>>
>>>> It looks like there is ABBA deadlock after applying this series:
>>>>
>>>> In its_map_vm: vmapp_lock -> vpe_lock
>>>> In its_vpe_set_affinity: vpe_to_cpuid_lock(vpe_lock) -> its_send_vmovp(vmapp_lock)
>>>>
>>>> Any idea about this?
>>>
>>> Hmmm, well spotted. That's an annoying one.
>>>
>>> Can you give the below hack a go? I've only lightly tested it, as my
>>> D05 box is on its last leg (it is literally falling apart) and I don't
>>> have any other GICv4.x box to test on.
>>>
>>> Thanks,
>>>
>>> 	M.
>>>
>>> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
>>> index 951ec140bcea2..b88c6011c8771 100644
>>> --- a/drivers/irqchip/irq-gic-v3-its.c
>>> +++ b/drivers/irqchip/irq-gic-v3-its.c
>>> @@ -1328,12 +1328,6 @@ static void its_send_vmovp(struct its_vpe *vpe)
>>>  		return;
>>>  	}
>>>  
>>> -	/*
>>> -	 * Protect against concurrent updates of the mapping state on
>>> -	 * individual VMs.
>>> -	 */
>>> -	guard(raw_spinlock_irqsave)(&vpe->its_vm->vmapp_lock);
>>> -
>>>  	/*
>>>  	 * Yet another marvel of the architecture. If using the
>>>  	 * its_list "feature", we need to make sure that all ITSs
>>> @@ -3808,7 +3802,7 @@ static int its_vpe_set_affinity(struct irq_data *d,
>>>  	struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
>>>  	unsigned int from, cpu = nr_cpu_ids;
>>>  	struct cpumask *table_mask;
>>> -	unsigned long flags;
>>> +	unsigned long flags, vmapp_flags;
>>>  
>>>  	/*
>>>  	 * Changing affinity is mega expensive, so let's be as lazy as
>>> @@ -3822,7 +3816,14 @@ static int its_vpe_set_affinity(struct irq_data *d,
>>>  	 * protect us, and that we must ensure nobody samples vpe->col_idx
>>>  	 * during the update, hence the lock below which must also be
>>>  	 * taken on any vLPI handling path that evaluates vpe->col_idx.
>>> +	 *
>>> +	 * Finally, we must protect ourselves against concurrent
>>> +	 * updates of the mapping state on this VM should the ITS list
>>> +	 * be in use.
>>>  	 */
>>> +	if (its_list_map)
>>> +		raw_spin_lock_irqsave(&vpe->its_vm->vmapp_lock, vmapp_flags);
>>> +
>>>  	from = vpe_to_cpuid_lock(vpe, &flags);
>>>  	table_mask = gic_data_rdist_cpu(from)->vpe_table_mask;
>>>  
>>> @@ -3852,6 +3853,9 @@ static int its_vpe_set_affinity(struct irq_data *d,
>>>  	irq_data_update_effective_affinity(d, cpumask_of(cpu));
>>>  	vpe_to_cpuid_unlock(vpe, flags);
>>>  
>>> +	if (its_list_map)
>>> +		raw_spin_unlock_irqrestore(&vpe->its_vm->vmapp_lock, vmapp_flags);
>>> +
>>>  	return IRQ_SET_MASK_OK_DONE;
>>>  }
>>>
>>
>> Hi Marc，
>>
>> We add above code to do test again. Now it is OK.
> 
> Great, thanks for giving it a go. I have just posted an actual patch
> (with the exact same change) at [1]. It would be good if you could
> give it a Tested-by: tag.

Sure, I will give it a Tested-by.

Thanks,
Zhou

> 
> Thanks,
> 
> 	M.
> 
> [1] https://lore.kernel.org/r/20240723175203.3193882-1-maz@kernel.org
>

[tip: irq/core] irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

Posted by tip-bot2 for Marc Zyngier 1 year, 6 months ago

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     a84a07fa3100d7ad46a3d6882af25a3df9c9e7e3
Gitweb:        https://git.kernel.org/tip/a84a07fa3100d7ad46a3d6882af25a3df9c9e7e3
Author:        Marc Zyngier <maz@kernel.org>
AuthorDate:    Fri, 05 Jul 2024 10:31:55 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 15 Jul 2024 15:13:55 +02:00

irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

In order to make sure that vpe->col_idx is correctly sampled when a VMAPP
command is issued, the vpe_lock must be held for the VPE. This is now
possible since the introduction of the per-VM vmapp_lock, which can be
taken before vpe_lock in the correct locking order.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nianyao Tang <tangnianyao@huawei.com>
Link: https://lore.kernel.org/r/20240705093155.871070-4-maz@kernel.org

---
 drivers/irqchip/irq-gic-v3-its.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 215c7ab..c23a64f 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1810,7 +1810,9 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm)
 		for (i = 0; i < vm->nr_vpes; i++) {
 			struct its_vpe *vpe = vm->vpes[i];
 
-			its_send_vmapp(its, vpe, true);
+			scoped_guard(raw_spinlock, &vpe->vpe_lock)
+				its_send_vmapp(its, vpe, true);
+
 			its_send_vinvall(its, vpe);
 		}
 	}
@@ -1827,8 +1829,10 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
 	if (!--vm->vlpi_count[its->list_nr]) {
 		int i;
 
-		for (i = 0; i < vm->nr_vpes; i++)
+		for (i = 0; i < vm->nr_vpes; i++) {
+			guard(raw_spinlock)(&vm->vpes[i]->vpe_lock);
 			its_send_vmapp(its, vm->vpes[i], false);
+		}
 	}
 }

[tip: irq/core] irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

Posted by tip-bot2 for Marc Zyngier 1 year, 7 months ago

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     9fceb7a5e829e6c8de4f018b4c37a5a3a4504447
Gitweb:        https://git.kernel.org/tip/9fceb7a5e829e6c8de4f018b4c37a5a3a4504447
Author:        Marc Zyngier <maz@kernel.org>
AuthorDate:    Fri, 05 Jul 2024 10:31:55 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 10 Jul 2024 18:40:10 +02:00

irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued

In order to make sure that vpe->col_idx is correctly sampled when a VMAPP
command is issued, the vpe_lock must be held for the VPE. This is now
possible since the introduction of the per-VM vmapp_lock, which can be
taken before vpe_lock in the correct locking order.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nianyao Tang <tangnianyao@huawei.com>
Link: https://lore.kernel.org/r/20240705093155.871070-4-maz@kernel.org

---
 drivers/irqchip/irq-gic-v3-its.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index c85826a..1a97391 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1811,7 +1811,9 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm)
 		for (i = 0; i < vm->nr_vpes; i++) {
 			struct its_vpe *vpe = vm->vpes[i];
 
-			its_send_vmapp(its, vpe, true);
+			scoped_guard(raw_spinlock, &vpe->vpe_lock)
+				its_send_vmapp(its, vpe, true);
+
 			its_send_vinvall(its, vpe);
 		}
 	}
@@ -1828,8 +1830,10 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
 	if (!--vm->vlpi_count[its->list_nr]) {
 		int i;
 
-		for (i = 0; i < vm->nr_vpes; i++)
+		for (i = 0; i < vm->nr_vpes; i++) {
+			guard(raw_spinlock)(&vm->vpes[i]->vpe_lock);
 			its_send_vmapp(its, vm->vpes[i], false);
+		}
 	}
 }