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[PATCH 05/67] iommu/amd: Return an error if vCPU affinity is set for non-vCPU IRTE

Sean Christopherson posted 67 patches 8 months, 2 weeks ago
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[PATCH 05/67] iommu/amd: Return an error if vCPU affinity is set for non-vCPU IRTE
Posted by Sean Christopherson 8 months, 2 weeks ago 
Return -EINVAL instead of success if amd_ir_set_vcpu_affinity() is
invoked without use_vapic; lying to KVM about whether or not the IRTE was
configured to post IRQs is all kinds of bad.

Fixes: d98de49a53e4 ("iommu/amd: Enable vAPIC interrupt remapping mode by default")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 drivers/iommu/amd/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index cd5116d8c3b2..b3a01b7757ee 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3850,7 +3850,7 @@ static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *vcpu_info)
 	 * we should not modify the IRTE
 	 */
 	if (!dev_data || !dev_data->use_vapic)
-		return 0;
+		return -EINVAL;
 
 	ir_data->cfg = irqd_cfg(data);
 	pi_data->ir_data = ir_data;
-- 
2.49.0.504.g3bcea36a83-goog
Re: [PATCH 05/67] iommu/amd: Return an error if vCPU affinity is set for non-vCPU IRTE
Posted by Vasant Hegde 8 months ago 
On 4/5/2025 1:08 AM, Sean Christopherson wrote:
> Return -EINVAL instead of success if amd_ir_set_vcpu_affinity() is
> invoked without use_vapic; lying to KVM about whether or not the IRTE was
> configured to post IRQs is all kinds of bad.
> 
> Fixes: d98de49a53e4 ("iommu/amd: Enable vAPIC interrupt remapping mode by default")
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant
Re: [PATCH 05/67] iommu/amd: Return an error if vCPU affinity is set for non-vCPU IRTE
Posted by Sairaj Kodilkar 8 months, 1 week ago 
On 4/5/2025 1:08 AM, Sean Christopherson wrote:
> Return -EINVAL instead of success if amd_ir_set_vcpu_affinity() is
> invoked without use_vapic; lying to KVM about whether or not the IRTE was
> configured to post IRQs is all kinds of bad.
> 
> Fixes: d98de49a53e4 ("iommu/amd: Enable vAPIC interrupt remapping mode by default")
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>   drivers/iommu/amd/iommu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index cd5116d8c3b2..b3a01b7757ee 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -3850,7 +3850,7 @@ static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *vcpu_info)
>   	 * we should not modify the IRTE
>   	 */
>   	if (!dev_data || !dev_data->use_vapic)
> -		return 0;
> +		return -EINVAL;
>   

Hi Sean,
you can update following functions as well to return error when
IOMMU is using legacy interrupt mode.
1. amd_iommu_update_ga
2. amd_iommu_activate_guest_mode
3. amd_iommu_deactivate_guest_mode

Currently these functions return 0 to the kvm layer when they fail to
set the IRTE.

Regards
Sairaj Kodilkar
Re: [PATCH 05/67] iommu/amd: Return an error if vCPU affinity is set for non-vCPU IRTE
Posted by Sean Christopherson 8 months, 1 week ago 
On Fri, Apr 11, 2025, Sairaj Kodilkar wrote:
> On 4/5/2025 1:08 AM, Sean Christopherson wrote:
> > Return -EINVAL instead of success if amd_ir_set_vcpu_affinity() is
> > invoked without use_vapic; lying to KVM about whether or not the IRTE was
> > configured to post IRQs is all kinds of bad.
> > 
> > Fixes: d98de49a53e4 ("iommu/amd: Enable vAPIC interrupt remapping mode by default")
> > Signed-off-by: Sean Christopherson <seanjc@google.com>
> > ---
> >   drivers/iommu/amd/iommu.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> > index cd5116d8c3b2..b3a01b7757ee 100644
> > --- a/drivers/iommu/amd/iommu.c
> > +++ b/drivers/iommu/amd/iommu.c
> > @@ -3850,7 +3850,7 @@ static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *vcpu_info)
> >   	 * we should not modify the IRTE
> >   	 */
> >   	if (!dev_data || !dev_data->use_vapic)
> > -		return 0;
> > +		return -EINVAL;
> 
> Hi Sean,
> you can update following functions as well to return error when
> IOMMU is using legacy interrupt mode.
> 1. amd_iommu_update_ga
> 2. amd_iommu_activate_guest_mode
> 3. amd_iommu_deactivate_guest_mode

Heh, I'm well aware, and this series gets there eventually (the end product WARNs
and returns an error in all three functions).  I fixed amd_ir_set_vcpu_affinity()
early in the series because it's the initial API that KVM will use to configure
an IRTE for posting to a vCPU.  I.e. to reach the other helpers, KVM would need
to ignore the error returned by amd_ir_set_vcpu_affinity().

> Currently these functions return 0 to the kvm layer when they fail to
> set the IRTE.
> 
> Regards
> Sairaj Kodilkar
Re: [PATCH 05/67] iommu/amd: Return an error if vCPU affinity is set for non-vCPU IRTE
Posted by Sairaj Kodilkar 8 months, 1 week ago 

On 4/11/2025 7:35 PM, Sean Christopherson wrote:
> On Fri, Apr 11, 2025, Sairaj Kodilkar wrote:
>> On 4/5/2025 1:08 AM, Sean Christopherson wrote:
>>> Return -EINVAL instead of success if amd_ir_set_vcpu_affinity() is
>>> invoked without use_vapic; lying to KVM about whether or not the IRTE was
>>> configured to post IRQs is all kinds of bad.
>>>
>>> Fixes: d98de49a53e4 ("iommu/amd: Enable vAPIC interrupt remapping mode by default")
>>> Signed-off-by: Sean Christopherson <seanjc@google.com>
>>> ---
>>>    drivers/iommu/amd/iommu.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
>>> index cd5116d8c3b2..b3a01b7757ee 100644
>>> --- a/drivers/iommu/amd/iommu.c
>>> +++ b/drivers/iommu/amd/iommu.c
>>> @@ -3850,7 +3850,7 @@ static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *vcpu_info)
>>>    	 * we should not modify the IRTE
>>>    	 */
>>>    	if (!dev_data || !dev_data->use_vapic)
>>> -		return 0;
>>> +		return -EINVAL;
>>
>> Hi Sean,
>> you can update following functions as well to return error when
>> IOMMU is using legacy interrupt mode.
>> 1. amd_iommu_update_ga
>> 2. amd_iommu_activate_guest_mode
>> 3. amd_iommu_deactivate_guest_mode
> 
> Heh, I'm well aware, and this series gets there eventually (the end product WARNs
> and returns an error in all three functions).  I fixed amd_ir_set_vcpu_affinity()
> early in the series because it's the initial API that KVM will use to configure
> an IRTE for posting to a vCPU.  I.e. to reach the other helpers, KVM would need
> to ignore the error returned by amd_ir_set_vcpu_affinity().
> 

Ohh sorry about that. Since I was reviewing patches sequentially, I did
come across those changes.

Regards
Sairaj Kodilkar

>> Currently these functions return 0 to the kvm layer when they fail to
>> set the IRTE.
>>
>> Regards
>> Sairaj Kodilkar
Re: [PATCH 05/67] iommu/amd: Return an error if vCPU affinity is set for non-vCPU IRTE
Posted by Sean Christopherson 8 months, 1 week ago 
On Fri, Apr 11, 2025, Sairaj Kodilkar wrote:
> 
> 
> On 4/11/2025 7:35 PM, Sean Christopherson wrote:
> > On Fri, Apr 11, 2025, Sairaj Kodilkar wrote:
> > > On 4/5/2025 1:08 AM, Sean Christopherson wrote:
> > > > Return -EINVAL instead of success if amd_ir_set_vcpu_affinity() is
> > > > invoked without use_vapic; lying to KVM about whether or not the IRTE was
> > > > configured to post IRQs is all kinds of bad.
> > > > 
> > > > Fixes: d98de49a53e4 ("iommu/amd: Enable vAPIC interrupt remapping mode by default")
> > > > Signed-off-by: Sean Christopherson <seanjc@google.com>
> > > > ---
> > > >    drivers/iommu/amd/iommu.c | 2 +-
> > > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> > > > index cd5116d8c3b2..b3a01b7757ee 100644
> > > > --- a/drivers/iommu/amd/iommu.c
> > > > +++ b/drivers/iommu/amd/iommu.c
> > > > @@ -3850,7 +3850,7 @@ static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *vcpu_info)
> > > >    	 * we should not modify the IRTE
> > > >    	 */
> > > >    	if (!dev_data || !dev_data->use_vapic)
> > > > -		return 0;
> > > > +		return -EINVAL;
> > > 
> > > Hi Sean,
> > > you can update following functions as well to return error when
> > > IOMMU is using legacy interrupt mode.
> > > 1. amd_iommu_update_ga
> > > 2. amd_iommu_activate_guest_mode
> > > 3. amd_iommu_deactivate_guest_mode
> > 
> > Heh, I'm well aware, and this series gets there eventually (the end product WARNs
> > and returns an error in all three functions).  I fixed amd_ir_set_vcpu_affinity()
> > early in the series because it's the initial API that KVM will use to configure
> > an IRTE for posting to a vCPU.  I.e. to reach the other helpers, KVM would need
> > to ignore the error returned by amd_ir_set_vcpu_affinity().
> > 
> 
> Ohh sorry about that. Since I was reviewing patches sequentially, I did
> come across those changes.

No worries, I wrote most of these patches and I can barely keep track of what all
is happening in this series.  :-)

Patchew 2.1-devel-b67e4c2

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