[PATCH v5 0/2] s390: virtio: let arch validate VIRTIO features

[PATCH v5 0/2] s390: virtio: let arch validate VIRTIO features

[Pierre Morel]

Hi all,

The goal of the series is to give a chance to the architecture
to validate VIRTIO device features.

in this respin:

1) I kept removed the ack from Jason as I reworked the patch
   @Jason, the nature and goal of the patch did not really changed
           please can I get back your acked-by with these changes?

2) I suppressed the unnecessary verbosity of the architecture
   specific patch

3) put back the arch specific code inside arch/s390/mm/init.c
   after offline discussion with Christian.

Regards,
Pierre

Pierre Morel (2):
  virtio: let arch validate VIRTIO features
  s390: virtio: PV needs VIRTIO I/O device protection

 arch/s390/mm/init.c           | 27 +++++++++++++++++++++++++++
 drivers/virtio/virtio.c       | 19 +++++++++++++++++++
 include/linux/virtio_config.h |  1 +
 3 files changed, 47 insertions(+)

-- 
2.25.1

Changelog

to v5:

- return directly from S390 arch_validate_virtio_features()
  when the guest is not protected.
  (Connie)

- Somme rewording
  (Connie, Michael)

- moved back code from arch/s390/ ...kernel/uv.c to ...mm/init.c
  (Christian)

to v4:

- separate virtio and arch code
  (Pierre)

- moved code from arch/s390/mm/init.c to arch/s390/kernel/uv.c
  (as interpreted from Heiko's comment)

- moved validation inside the arch code
  (Connie)

- moved the call to arch validation before VIRTIO_F_1 test
  (Michael)

to v3:

- add warning
  (Connie, Christian)

- add comment
  (Connie)

- change hook name
  (Halil, Connie)

to v2:

- put the test in virtio_finalize_features()
  (Connie)

- put the test inside VIRTIO core
  (Jason)

- pass a virtio device as parameter
  (Halil)

[PATCH v5 1/2] virtio: let arch validate VIRTIO features

[Pierre Morel]

An architecture may need to validate the VIRTIO devices features
based on architecture specifics.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 drivers/virtio/virtio.c       | 19 +++++++++++++++++++
 include/linux/virtio_config.h |  1 +
 2 files changed, 20 insertions(+)

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index a977e32a88f2..c4e14d46a5b6 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -167,6 +167,21 @@ void virtio_add_status(struct virtio_device *dev, unsigned int status)
 }
 EXPORT_SYMBOL_GPL(virtio_add_status);
 
+/*
+ * arch_validate_virtio_features - provide arch specific hook when finalizing
+ *				   features for VIRTIO device dev
+ * @dev: the VIRTIO device being added
+ *
+ * Permits the platform to handle architecture-specific requirements when
+ * device features are finalized. This is the default implementation.
+ * Architecture implementations can override this.
+ */
+
+int __weak arch_validate_virtio_features(struct virtio_device *dev)
+{
+	return 0;
+}
+
 int virtio_finalize_features(struct virtio_device *dev)
 {
 	int ret = dev->config->finalize_features(dev);
@@ -176,6 +191,10 @@ int virtio_finalize_features(struct virtio_device *dev)
 	if (ret)
 		return ret;
 
+	ret = arch_validate_virtio_features(dev);
+	if (ret)
+		return ret;
+
 	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
 		return 0;
 
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index bb4cc4910750..3f4117adf311 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -459,4 +459,5 @@ static inline void virtio_cwrite64(struct virtio_device *vdev,
 		_r;							\
 	})
 
+int arch_validate_virtio_features(struct virtio_device *dev);
 #endif /* _LINUX_VIRTIO_CONFIG_H */
-- 
2.25.1

Re: [PATCH v5 1/2] virtio: let arch validate VIRTIO features

[Halil Pasic]

On Thu,  9 Jul 2020 10:39:18 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> An architecture may need to validate the VIRTIO devices features
> based on architecture specifics.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>

Acked-by: Halil Pasic <pasic@linux.ibm.com>

> ---
>  drivers/virtio/virtio.c       | 19 +++++++++++++++++++
>  include/linux/virtio_config.h |  1 +
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index a977e32a88f2..c4e14d46a5b6 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -167,6 +167,21 @@ void virtio_add_status(struct virtio_device *dev, unsigned int status)
>  }
>  EXPORT_SYMBOL_GPL(virtio_add_status);
>  
> +/*
> + * arch_validate_virtio_features - provide arch specific hook when finalizing
> + *				   features for VIRTIO device dev
> + * @dev: the VIRTIO device being added
> + *
> + * Permits the platform to handle architecture-specific requirements when
> + * device features are finalized. This is the default implementation.
> + * Architecture implementations can override this.
> + */
> +
> +int __weak arch_validate_virtio_features(struct virtio_device *dev)
> +{
> +	return 0;
> +}
> +
>  int virtio_finalize_features(struct virtio_device *dev)
>  {
>  	int ret = dev->config->finalize_features(dev);
> @@ -176,6 +191,10 @@ int virtio_finalize_features(struct virtio_device *dev)
>  	if (ret)
>  		return ret;
>  
> +	ret = arch_validate_virtio_features(dev);
> +	if (ret)
> +		return ret;
> +
>  	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
>  		return 0;
>  
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index bb4cc4910750..3f4117adf311 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -459,4 +459,5 @@ static inline void virtio_cwrite64(struct virtio_device *vdev,
>  		_r;							\
>  	})
>  
> +int arch_validate_virtio_features(struct virtio_device *dev);
>  #endif /* _LINUX_VIRTIO_CONFIG_H */

Re: [PATCH v5 1/2] virtio: let arch validate VIRTIO features

[Pierre Morel]

On 2020-07-09 11:58, Halil Pasic wrote:
> On Thu,  9 Jul 2020 10:39:18 +0200
> Pierre Morel <pmorel@linux.ibm.com> wrote:
> 
>> An architecture may need to validate the VIRTIO devices features
>> based on architecture specifics.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
>> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> 
> Acked-by: Halil Pasic <pasic@linux.ibm.com>


Thanks,
Pierre

-- 
Pierre Morel
IBM Lab Boeblingen

[PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Pierre Morel]

If protected virtualization is active on s390, the virtio queues are
not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been
negotiated. Use the new arch_validate_virtio_features() interface to
fail probe if that's not the case, preventing a host error on access
attempt

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 arch/s390/mm/init.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 6dc7c3b60ef6..b8e6f90117da 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -45,6 +45,7 @@
 #include <asm/kasan.h>
 #include <asm/dma-mapping.h>
 #include <asm/uv.h>
+#include <linux/virtio_config.h>
 
 pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir);
 
@@ -161,6 +162,32 @@ bool force_dma_unencrypted(struct device *dev)
 	return is_prot_virt_guest();
 }
 
+/*
+ * arch_validate_virtio_features
+ * @dev: the VIRTIO device being added
+ *
+ * Return an error if required features are missing on a guest running
+ * with protected virtualization.
+ */
+int arch_validate_virtio_features(struct virtio_device *dev)
+{
+	if (!is_prot_virt_guest())
+		return 0;
+
+	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
+		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
+		return -ENODEV;
+	}
+
+	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
+		dev_warn(&dev->dev,
+			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 /* protected virtualization */
 static void pv_init(void)
 {
-- 
2.25.1

Re: [PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Cornelia Huck]

On Thu,  9 Jul 2020 10:39:19 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> If protected virtualization is active on s390, the virtio queues are
> not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been
> negotiated. Use the new arch_validate_virtio_features() interface to
> fail probe if that's not the case, preventing a host error on access
> attempt
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>  arch/s390/mm/init.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> index 6dc7c3b60ef6..b8e6f90117da 100644
> --- a/arch/s390/mm/init.c
> +++ b/arch/s390/mm/init.c
> @@ -45,6 +45,7 @@
>  #include <asm/kasan.h>
>  #include <asm/dma-mapping.h>
>  #include <asm/uv.h>
> +#include <linux/virtio_config.h>
>  
>  pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir);
>  
> @@ -161,6 +162,32 @@ bool force_dma_unencrypted(struct device *dev)
>  	return is_prot_virt_guest();
>  }
>  
> +/*
> + * arch_validate_virtio_features
> + * @dev: the VIRTIO device being added
> + *
> + * Return an error if required features are missing on a guest running
> + * with protected virtualization.
> + */
> +int arch_validate_virtio_features(struct virtio_device *dev)
> +{
> +	if (!is_prot_virt_guest())
> +		return 0;
> +
> +	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
> +		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");

I'd probably use "legacy virtio not supported with protected
virtualization".

> +		return -ENODEV;
> +	}
> +
> +	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
> +		dev_warn(&dev->dev,
> +			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");

"support for limited memory access required for protected
virtualization"

?

Mentioning the feature flag is shorter in both cases, though.

> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
>  /* protected virtualization */
>  static void pv_init(void)
>  {

Either way,

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Halil Pasic]

On Thu, 9 Jul 2020 10:57:33 +0200
Cornelia Huck <cohuck@redhat.com> wrote:

> On Thu,  9 Jul 2020 10:39:19 +0200
> Pierre Morel <pmorel@linux.ibm.com> wrote:
> 
> > If protected virtualization is active on s390, the virtio queues are
> > not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been
> > negotiated. Use the new arch_validate_virtio_features() interface to
> > fail probe if that's not the case, preventing a host error on access
> > attempt

Punctuation at the end?

Also 'that's not the case' refers to the negation
'VIRTIO_F_IOMMU_PLATFORM has been negotiated',
arch_validate_virtio_features() is however part of
virtio_finalize_features(), which is in turn part of the feature
negotiation. But that is details. I'm fine with keeping the message as
is. 

> > 
> > Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> > ---
> >  arch/s390/mm/init.c | 27 +++++++++++++++++++++++++++
> >  1 file changed, 27 insertions(+)
> > 
> > diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> > index 6dc7c3b60ef6..b8e6f90117da 100644
> > --- a/arch/s390/mm/init.c
> > +++ b/arch/s390/mm/init.c
> > @@ -45,6 +45,7 @@
> >  #include <asm/kasan.h>
> >  #include <asm/dma-mapping.h>
> >  #include <asm/uv.h>
> > +#include <linux/virtio_config.h>
> >  
> >  pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir);
> >  
> > @@ -161,6 +162,32 @@ bool force_dma_unencrypted(struct device *dev)
> >  	return is_prot_virt_guest();
> >  }
> >  
> > +/*
> > + * arch_validate_virtio_features
> > + * @dev: the VIRTIO device being added
> > + *
> > + * Return an error if required features are missing on a guest running
> > + * with protected virtualization.
> > + */
> > +int arch_validate_virtio_features(struct virtio_device *dev)
> > +{
> > +	if (!is_prot_virt_guest())
> > +		return 0;
> > +
> > +	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
> > +		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
> 
> I'd probably use "legacy virtio not supported with protected
> virtualization".
> 
> > +		return -ENODEV;
> > +	}
> > +
> > +	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
> > +		dev_warn(&dev->dev,
> > +			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
> 
> "support for limited memory access required for protected
> virtualization"
> 
> ?
> 
> Mentioning the feature flag is shorter in both cases, though.

I liked the messages in v4. Why did we change those? Did somebody
complain?

I prefer the old ones, but it any case:

Acked-by: Halil Pasic <pasic@linux.ibm.com>


> 
> > +		return -ENODEV;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  /* protected virtualization */
> >  static void pv_init(void)
> >  {
> 
> Either way,
> 
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> 

Re: [PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Pierre Morel]

On 2020-07-09 11:55, Halil Pasic wrote:
> On Thu, 9 Jul 2020 10:57:33 +0200
> Cornelia Huck <cohuck@redhat.com> wrote:
> 
>> On Thu,  9 Jul 2020 10:39:19 +0200
>> Pierre Morel <pmorel@linux.ibm.com> wrote:
>>
>>> If protected virtualization is active on s390, the virtio queues are
>>> not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been
>>> negotiated. Use the new arch_validate_virtio_features() interface to
>>> fail probe if that's not the case, preventing a host error on access
>>> attempt
> 
> Punctuation at the end?
> 
> Also 'that's not the case' refers to the negation
> 'VIRTIO_F_IOMMU_PLATFORM has been negotiated',
> arch_validate_virtio_features() is however part of
> virtio_finalize_features(), which is in turn part of the feature
> negotiation. But that is details. I'm fine with keeping the message as
> is.
> 
>>>
>>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>>> ---
>>>   arch/s390/mm/init.c | 27 +++++++++++++++++++++++++++
>>>   1 file changed, 27 insertions(+)
>>>
>>> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
>>> index 6dc7c3b60ef6..b8e6f90117da 100644
>>> --- a/arch/s390/mm/init.c
>>> +++ b/arch/s390/mm/init.c
>>> @@ -45,6 +45,7 @@
>>>   #include <asm/kasan.h>
>>>   #include <asm/dma-mapping.h>
>>>   #include <asm/uv.h>
>>> +#include <linux/virtio_config.h>
>>>   
>>>   pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir);
>>>   
>>> @@ -161,6 +162,32 @@ bool force_dma_unencrypted(struct device *dev)
>>>   	return is_prot_virt_guest();
>>>   }
>>>   
>>> +/*
>>> + * arch_validate_virtio_features
>>> + * @dev: the VIRTIO device being added
>>> + *
>>> + * Return an error if required features are missing on a guest running
>>> + * with protected virtualization.
>>> + */
>>> +int arch_validate_virtio_features(struct virtio_device *dev)
>>> +{
>>> +	if (!is_prot_virt_guest())
>>> +		return 0;
>>> +
>>> +	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
>>> +		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
>>
>> I'd probably use "legacy virtio not supported with protected
>> virtualization".
>>
>>> +		return -ENODEV;
>>> +	}
>>> +
>>> +	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
>>> +		dev_warn(&dev->dev,
>>> +			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
>>
>> "support for limited memory access required for protected
>> virtualization"
>>
>> ?
>>
>> Mentioning the feature flag is shorter in both cases, though.
> 
> I liked the messages in v4. Why did we change those? Did somebody
> complain?
> 
> I prefer the old ones, but it any case:
> 
> Acked-by: Halil Pasic <pasic@linux.ibm.com>

Thanks,
Pierre


-- 
Pierre Morel
IBM Lab Boeblingen

Re: [PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Pierre Morel]

On 2020-07-09 10:57, Cornelia Huck wrote:
> On Thu,  9 Jul 2020 10:39:19 +0200
> Pierre Morel <pmorel@linux.ibm.com> wrote:
> 
>> If protected virtualization is active on s390, the virtio queues are
>> not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been
>> negotiated. Use the new arch_validate_virtio_features() interface to
>> fail probe if that's not the case, preventing a host error on access
>> attempt
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   arch/s390/mm/init.c | 27 +++++++++++++++++++++++++++
>>   1 file changed, 27 insertions(+)
>>
>> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
>> index 6dc7c3b60ef6..b8e6f90117da 100644
>> --- a/arch/s390/mm/init.c
>> +++ b/arch/s390/mm/init.c
>> @@ -45,6 +45,7 @@
>>   #include <asm/kasan.h>
>>   #include <asm/dma-mapping.h>
>>   #include <asm/uv.h>
>> +#include <linux/virtio_config.h>
>>   
>>   pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir);
>>   
>> @@ -161,6 +162,32 @@ bool force_dma_unencrypted(struct device *dev)
>>   	return is_prot_virt_guest();
>>   }
>>   
>> +/*
>> + * arch_validate_virtio_features
>> + * @dev: the VIRTIO device being added
>> + *
>> + * Return an error if required features are missing on a guest running
>> + * with protected virtualization.
>> + */
>> +int arch_validate_virtio_features(struct virtio_device *dev)
>> +{
>> +	if (!is_prot_virt_guest())
>> +		return 0;
>> +
>> +	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
>> +		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
> 
> I'd probably use "legacy virtio not supported with protected
> virtualization".
> 
>> +		return -ENODEV;
>> +	}
>> +
>> +	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
>> +		dev_warn(&dev->dev,
>> +			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
> 
> "support for limited memory access required for protected
> virtualization"
> 
> ?
> 
> Mentioning the feature flag is shorter in both cases, though.

And I think easier to look for in case of debugging purpose.
I change it if there is more demands.

> 
>> +		return -ENODEV;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   /* protected virtualization */
>>   static void pv_init(void)
>>   {
> 
> Either way,
> 
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> 

Thanks,
Pierre


-- 
Pierre Morel
IBM Lab Boeblingen

Re: [PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Halil Pasic]

On Thu, 9 Jul 2020 12:51:58 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> >> +int arch_validate_virtio_features(struct virtio_device *dev)
> >> +{
> >> +	if (!is_prot_virt_guest())
> >> +		return 0;
> >> +
> >> +	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
> >> +		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");  
> > 
> > I'd probably use "legacy virtio not supported with protected
> > virtualization".
> >   
> >> +		return -ENODEV;
> >> +	}
> >> +
> >> +	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
> >> +		dev_warn(&dev->dev,
> >> +			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");  
> > 
> > "support for limited memory access required for protected
> > virtualization"
> > 
> > ?
> > 
> > Mentioning the feature flag is shorter in both cases, though.  
> 
> And I think easier to look for in case of debugging purpose.
> I change it if there is more demands.

Not all our end users are kernel and/or qemu developers. I find the
messages from v4 less technical, more informative, and way better.

Regards,
Halil

Re: [PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Pierre Morel]

On 2020-07-09 16:47, Halil Pasic wrote:
> On Thu, 9 Jul 2020 12:51:58 +0200
> Pierre Morel <pmorel@linux.ibm.com> wrote:
> 
>>>> +int arch_validate_virtio_features(struct virtio_device *dev)
>>>> +{
>>>> +	if (!is_prot_virt_guest())
>>>> +		return 0;
>>>> +
>>>> +	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
>>>> +		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
>>>
>>> I'd probably use "legacy virtio not supported with protected
>>> virtualization".
>>>    
>>>> +		return -ENODEV;
>>>> +	}
>>>> +
>>>> +	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
>>>> +		dev_warn(&dev->dev,
>>>> +			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
>>>
>>> "support for limited memory access required for protected
>>> virtualization"
>>>
>>> ?
>>>
>>> Mentioning the feature flag is shorter in both cases, though.
>>
>> And I think easier to look for in case of debugging purpose.
>> I change it if there is more demands.
> 
> Not all our end users are kernel and/or qemu developers. I find the
> messages from v4 less technical, more informative, and way better.
> 
> Regards,
> Halil
> 

Can you please tell me the messages you are speaking of, because for me 
the warning's messages are exactly the same in v4 and v5!?

I checked many times, but may be I still missed something.

Regards,
Pierre


-- 
Pierre Morel
IBM Lab Boeblingen

Re: [PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Halil Pasic]

On Thu, 9 Jul 2020 16:51:04 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> 
> 
> On 2020-07-09 16:47, Halil Pasic wrote:
> > On Thu, 9 Jul 2020 12:51:58 +0200
> > Pierre Morel <pmorel@linux.ibm.com> wrote:
> > 
> >>>> +int arch_validate_virtio_features(struct virtio_device *dev)
> >>>> +{
> >>>> +	if (!is_prot_virt_guest())
> >>>> +		return 0;
> >>>> +
> >>>> +	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
> >>>> +		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
> >>>
> >>> I'd probably use "legacy virtio not supported with protected
> >>> virtualization".
> >>>    
> >>>> +		return -ENODEV;
> >>>> +	}
> >>>> +
> >>>> +	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
> >>>> +		dev_warn(&dev->dev,
> >>>> +			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
> >>>
> >>> "support for limited memory access required for protected
> >>> virtualization"
> >>>
> >>> ?
> >>>
> >>> Mentioning the feature flag is shorter in both cases, though.
> >>
> >> And I think easier to look for in case of debugging purpose.
> >> I change it if there is more demands.
> > 
> > Not all our end users are kernel and/or qemu developers. I find the
> > messages from v4 less technical, more informative, and way better.
> > 
> > Regards,
> > Halil
> > 
> 
> Can you please tell me the messages you are speaking of, because for me 
> the warning's messages are exactly the same in v4 and v5!?
> 
> I checked many times, but may be I still missed something.
> 

Sorry, my bad. My brain is over-generating. The messages where discussed
at v3 and Connie made a very similar proposal to the one above which I
seconded (for reference look at Message-ID:
<833c71f2-0057-896a-5e21-2c6263834402@linux.ibm.com>). I was under the
impression that it got implemented in v4, but it was not. That's why I
ended up talking bs.

Regards,
Halil