RE: [PATCH v6 15/15] iommu/vt-d: Support reporting nesting capability info

2020-08-17 Thread Liu, Yi L
Eric,

> From: Auger Eric 
> Sent: Monday, August 17, 2020 3:43 PM
> 
> On 8/17/20 9:05 AM, Liu, Yi L wrote:
> > Hi Eric,
> >
> >> Auger Eric 
> >> Sent: Sunday, August 16, 2020 8:01 PM
> >>
> >> Hi Yi,
> >>
> >> On 7/28/20 8:27 AM, Liu Yi L wrote:
> >>> This patch reports nesting info, and only supports the case where all
> >>> the physical iomms have the same CAP/ECAP MASKS.
> >> s/iomms/iommus
> >
> > yep.
> >
> >>>
> >>> Cc: Kevin Tian 
> >>> CC: Jacob Pan 
> >>> Cc: Alex Williamson 
> >>> Cc: Eric Auger 
> >>> Cc: Jean-Philippe Brucker 
> >>> Cc: Joerg Roedel 
> >>> Cc: Lu Baolu 
> >>> Signed-off-by: Liu Yi L 
> >>> Signed-off-by: Jacob Pan 
> >>> ---
> >>> v2 -> v3:
> >>> *) remove cap/ecap_mask in iommu_nesting_info.
> >>> ---
> >>>  drivers/iommu/intel/iommu.c | 81
> >> +++--
> >>>  include/linux/intel-iommu.h | 16 +
> >>>  2 files changed, 95 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> >>> index 88f4647..0835804 100644
> >>> --- a/drivers/iommu/intel/iommu.c
> >>> +++ b/drivers/iommu/intel/iommu.c
> >>> @@ -5660,12 +5660,16 @@ static inline bool iommu_pasid_support(void)
> >>>  static inline bool nested_mode_support(void)
> >>>  {
> >>>   struct dmar_drhd_unit *drhd;
> >>> - struct intel_iommu *iommu;
> >>> + struct intel_iommu *iommu, *prev = NULL;
> >>>   bool ret = true;
> >>>
> >>>   rcu_read_lock();
> >>>   for_each_active_iommu(iommu, drhd) {
> >>> - if (!sm_supported(iommu) || !ecap_nest(iommu->ecap)) {
> >>> + if (!prev)
> >>> + prev = iommu;
> >>> + if (!sm_supported(iommu) || !ecap_nest(iommu->ecap) ||
> >>> + (VTD_CAP_MASK & (iommu->cap ^ prev->cap)) ||
> >>> + (VTD_ECAP_MASK & (iommu->ecap ^ prev->ecap))) {
> >>>   ret = false;
> >>>   break;
> >> So this changes the behavior of DOMAIN_ATTR_NESTING. Shouldn't it have a
> >> Fixes tag as well? And maybe add the capability getter in a separate patch?
> >
> > yes, this changed the behavior. so it would be better to be a separate patch
> > and upstream along? how about your idea? @Lu, Baolu :-)
> >
> >>>   }
> >>> @@ -6081,6 +6085,78 @@ intel_iommu_domain_set_attr(struct
> iommu_domain
> >> *domain,
> >>>   return ret;
> >>>  }
> >>>
> >>> +static int intel_iommu_get_nesting_info(struct iommu_domain *domain,
> >>> + struct iommu_nesting_info *info)
> >>> +{
> >>> + struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> >>> + u64 cap = VTD_CAP_MASK, ecap = VTD_ECAP_MASK;
> >>> + struct device_domain_info *domain_info;
> >>> + struct iommu_nesting_info_vtd vtd;
> >>> + unsigned long flags;
> >>> + unsigned int size;
> >>> +
> >
> > perhaps better to acquire the lock here. [1]
> >
> >>> + if (domain->type != IOMMU_DOMAIN_UNMANAGED ||
> >>> + !(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE))
> >>> + return -ENODEV;
> >>> +
> >>> + if (!info)
> >>> + return -EINVAL;
> >>> +
> >>> + size = sizeof(struct iommu_nesting_info) +
> >>> + sizeof(struct iommu_nesting_info_vtd);
> >>> + /*
> >>> +  * if provided buffer size is smaller than expected, should
> >>> +  * return 0 and also the expected buffer size to caller.
> >>> +  */
> >>> + if (info->argsz < size) {
> >>> + info->argsz = size;
> >>> + return 0;
> >>> + }
> >>> +
> >>> + spin_lock_irqsave(_domain_lock, flags);
> >>> + /*
> >>> +  * arbitrary select the first domain_info as all nesting
> >>> +  * related capabilities should be consistent across iommu
> >>> +  * units.
> >>> +  */
> >>> + domain_info = list_first_entry(_domain->devices,
> >>> +struct device_domain_info, link);
> >>> + cap &= domain_info->iommu->cap;
> >>> + ecap &= domain_info->iommu->ecap;
> >>> + spin_unlock_irqrestore(_domain_lock, flags);
> >>> +
> >>> + info->format = IOMMU_PASID_FORMAT_INTEL_VTD;
> >>> + info->features = IOMMU_NESTING_FEAT_SYSWIDE_PASID |
> >>> +  IOMMU_NESTING_FEAT_BIND_PGTBL |
> >>> +  IOMMU_NESTING_FEAT_CACHE_INVLD;
> >>> + info->addr_width = dmar_domain->gaw;
> >>> + info->pasid_bits = ilog2(intel_pasid_max_id);
> >>> + info->padding = 0;
> >>> + vtd.flags = 0;
> >>> + vtd.padding = 0;
> >>> + vtd.cap_reg = cap;
> >>> + vtd.ecap_reg = ecap;
> >>> +
> >>> + memcpy(info->data, , sizeof(vtd));
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static int intel_iommu_domain_get_attr(struct iommu_domain *domain,
> >>> +enum iommu_attr attr, void *data)
> >>> +{
> >>> + switch (attr) {
> >>> + case DOMAIN_ATTR_NESTING:
> >>> + {
> >>> + struct iommu_nesting_info *info =
> >>> + (struct iommu_nesting_info *)data;
> >>
> >> don't you need to hold a device_domain_lock earlier to make sure domain
> >> attributes can't change behind your back (unmanaged type and nested mode)?
> >
> > do you 

Re: [PATCH v6 15/15] iommu/vt-d: Support reporting nesting capability info

2020-08-17 Thread Auger Eric



On 8/17/20 9:05 AM, Liu, Yi L wrote:
> Hi Eric,
> 
>> Auger Eric 
>> Sent: Sunday, August 16, 2020 8:01 PM
>>
>> Hi Yi,
>>
>> On 7/28/20 8:27 AM, Liu Yi L wrote:
>>> This patch reports nesting info, and only supports the case where all
>>> the physical iomms have the same CAP/ECAP MASKS.
>> s/iomms/iommus
> 
> yep.
> 
>>>
>>> Cc: Kevin Tian 
>>> CC: Jacob Pan 
>>> Cc: Alex Williamson 
>>> Cc: Eric Auger 
>>> Cc: Jean-Philippe Brucker 
>>> Cc: Joerg Roedel 
>>> Cc: Lu Baolu 
>>> Signed-off-by: Liu Yi L 
>>> Signed-off-by: Jacob Pan 
>>> ---
>>> v2 -> v3:
>>> *) remove cap/ecap_mask in iommu_nesting_info.
>>> ---
>>>  drivers/iommu/intel/iommu.c | 81
>> +++--
>>>  include/linux/intel-iommu.h | 16 +
>>>  2 files changed, 95 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>>> index 88f4647..0835804 100644
>>> --- a/drivers/iommu/intel/iommu.c
>>> +++ b/drivers/iommu/intel/iommu.c
>>> @@ -5660,12 +5660,16 @@ static inline bool iommu_pasid_support(void)
>>>  static inline bool nested_mode_support(void)
>>>  {
>>> struct dmar_drhd_unit *drhd;
>>> -   struct intel_iommu *iommu;
>>> +   struct intel_iommu *iommu, *prev = NULL;
>>> bool ret = true;
>>>
>>> rcu_read_lock();
>>> for_each_active_iommu(iommu, drhd) {
>>> -   if (!sm_supported(iommu) || !ecap_nest(iommu->ecap)) {
>>> +   if (!prev)
>>> +   prev = iommu;
>>> +   if (!sm_supported(iommu) || !ecap_nest(iommu->ecap) ||
>>> +   (VTD_CAP_MASK & (iommu->cap ^ prev->cap)) ||
>>> +   (VTD_ECAP_MASK & (iommu->ecap ^ prev->ecap))) {
>>> ret = false;
>>> break;
>> So this changes the behavior of DOMAIN_ATTR_NESTING. Shouldn't it have a
>> Fixes tag as well? And maybe add the capability getter in a separate patch?
> 
> yes, this changed the behavior. so it would be better to be a separate patch
> and upstream along? how about your idea? @Lu, Baolu :-)
> 
>>> }
>>> @@ -6081,6 +6085,78 @@ intel_iommu_domain_set_attr(struct iommu_domain
>> *domain,
>>> return ret;
>>>  }
>>>
>>> +static int intel_iommu_get_nesting_info(struct iommu_domain *domain,
>>> +   struct iommu_nesting_info *info)
>>> +{
>>> +   struct dmar_domain *dmar_domain = to_dmar_domain(domain);
>>> +   u64 cap = VTD_CAP_MASK, ecap = VTD_ECAP_MASK;
>>> +   struct device_domain_info *domain_info;
>>> +   struct iommu_nesting_info_vtd vtd;
>>> +   unsigned long flags;
>>> +   unsigned int size;
>>> +
> 
> perhaps better to acquire the lock here. [1]
> 
>>> +   if (domain->type != IOMMU_DOMAIN_UNMANAGED ||
>>> +   !(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE))
>>> +   return -ENODEV;
>>> +
>>> +   if (!info)
>>> +   return -EINVAL;
>>> +
>>> +   size = sizeof(struct iommu_nesting_info) +
>>> +   sizeof(struct iommu_nesting_info_vtd);
>>> +   /*
>>> +* if provided buffer size is smaller than expected, should
>>> +* return 0 and also the expected buffer size to caller.
>>> +*/
>>> +   if (info->argsz < size) {
>>> +   info->argsz = size;
>>> +   return 0;
>>> +   }
>>> +
>>> +   spin_lock_irqsave(_domain_lock, flags);
>>> +   /*
>>> +* arbitrary select the first domain_info as all nesting
>>> +* related capabilities should be consistent across iommu
>>> +* units.
>>> +*/
>>> +   domain_info = list_first_entry(_domain->devices,
>>> +  struct device_domain_info, link);
>>> +   cap &= domain_info->iommu->cap;
>>> +   ecap &= domain_info->iommu->ecap;
>>> +   spin_unlock_irqrestore(_domain_lock, flags);
>>> +
>>> +   info->format = IOMMU_PASID_FORMAT_INTEL_VTD;
>>> +   info->features = IOMMU_NESTING_FEAT_SYSWIDE_PASID |
>>> +IOMMU_NESTING_FEAT_BIND_PGTBL |
>>> +IOMMU_NESTING_FEAT_CACHE_INVLD;
>>> +   info->addr_width = dmar_domain->gaw;
>>> +   info->pasid_bits = ilog2(intel_pasid_max_id);
>>> +   info->padding = 0;
>>> +   vtd.flags = 0;
>>> +   vtd.padding = 0;
>>> +   vtd.cap_reg = cap;
>>> +   vtd.ecap_reg = ecap;
>>> +
>>> +   memcpy(info->data, , sizeof(vtd));
>>> +   return 0;
>>> +}
>>> +
>>> +static int intel_iommu_domain_get_attr(struct iommu_domain *domain,
>>> +  enum iommu_attr attr, void *data)
>>> +{
>>> +   switch (attr) {
>>> +   case DOMAIN_ATTR_NESTING:
>>> +   {
>>> +   struct iommu_nesting_info *info =
>>> +   (struct iommu_nesting_info *)data;
>>
>> don't you need to hold a device_domain_lock earlier to make sure domain
>> attributes can't change behind your back (unmanaged type and nested mode)?
> 
> do you mean acquire lock at [1]?
yep either at [1] or before calling intel_iommu_get_nesting_info and
adding a comment saying intel_iommu_get_nesting_info() shall be called
with the lock held

Thanks

Eric
> 
> 

RE: [PATCH v6 15/15] iommu/vt-d: Support reporting nesting capability info

2020-08-17 Thread Liu, Yi L
Hi Eric,

> Auger Eric 
> Sent: Sunday, August 16, 2020 8:01 PM
> 
> Hi Yi,
> 
> On 7/28/20 8:27 AM, Liu Yi L wrote:
> > This patch reports nesting info, and only supports the case where all
> > the physical iomms have the same CAP/ECAP MASKS.
> s/iomms/iommus

yep.

> >
> > Cc: Kevin Tian 
> > CC: Jacob Pan 
> > Cc: Alex Williamson 
> > Cc: Eric Auger 
> > Cc: Jean-Philippe Brucker 
> > Cc: Joerg Roedel 
> > Cc: Lu Baolu 
> > Signed-off-by: Liu Yi L 
> > Signed-off-by: Jacob Pan 
> > ---
> > v2 -> v3:
> > *) remove cap/ecap_mask in iommu_nesting_info.
> > ---
> >  drivers/iommu/intel/iommu.c | 81
> +++--
> >  include/linux/intel-iommu.h | 16 +
> >  2 files changed, 95 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 88f4647..0835804 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -5660,12 +5660,16 @@ static inline bool iommu_pasid_support(void)
> >  static inline bool nested_mode_support(void)
> >  {
> > struct dmar_drhd_unit *drhd;
> > -   struct intel_iommu *iommu;
> > +   struct intel_iommu *iommu, *prev = NULL;
> > bool ret = true;
> >
> > rcu_read_lock();
> > for_each_active_iommu(iommu, drhd) {
> > -   if (!sm_supported(iommu) || !ecap_nest(iommu->ecap)) {
> > +   if (!prev)
> > +   prev = iommu;
> > +   if (!sm_supported(iommu) || !ecap_nest(iommu->ecap) ||
> > +   (VTD_CAP_MASK & (iommu->cap ^ prev->cap)) ||
> > +   (VTD_ECAP_MASK & (iommu->ecap ^ prev->ecap))) {
> > ret = false;
> > break;
> So this changes the behavior of DOMAIN_ATTR_NESTING. Shouldn't it have a
> Fixes tag as well? And maybe add the capability getter in a separate patch?

yes, this changed the behavior. so it would be better to be a separate patch
and upstream along? how about your idea? @Lu, Baolu :-)

> > }
> > @@ -6081,6 +6085,78 @@ intel_iommu_domain_set_attr(struct iommu_domain
> *domain,
> > return ret;
> >  }
> >
> > +static int intel_iommu_get_nesting_info(struct iommu_domain *domain,
> > +   struct iommu_nesting_info *info)
> > +{
> > +   struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > +   u64 cap = VTD_CAP_MASK, ecap = VTD_ECAP_MASK;
> > +   struct device_domain_info *domain_info;
> > +   struct iommu_nesting_info_vtd vtd;
> > +   unsigned long flags;
> > +   unsigned int size;
> > +

perhaps better to acquire the lock here. [1]

> > +   if (domain->type != IOMMU_DOMAIN_UNMANAGED ||
> > +   !(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE))
> > +   return -ENODEV;
> > +
> > +   if (!info)
> > +   return -EINVAL;
> > +
> > +   size = sizeof(struct iommu_nesting_info) +
> > +   sizeof(struct iommu_nesting_info_vtd);
> > +   /*
> > +* if provided buffer size is smaller than expected, should
> > +* return 0 and also the expected buffer size to caller.
> > +*/
> > +   if (info->argsz < size) {
> > +   info->argsz = size;
> > +   return 0;
> > +   }
> > +
> > +   spin_lock_irqsave(_domain_lock, flags);
> > +   /*
> > +* arbitrary select the first domain_info as all nesting
> > +* related capabilities should be consistent across iommu
> > +* units.
> > +*/
> > +   domain_info = list_first_entry(_domain->devices,
> > +  struct device_domain_info, link);
> > +   cap &= domain_info->iommu->cap;
> > +   ecap &= domain_info->iommu->ecap;
> > +   spin_unlock_irqrestore(_domain_lock, flags);
> > +
> > +   info->format = IOMMU_PASID_FORMAT_INTEL_VTD;
> > +   info->features = IOMMU_NESTING_FEAT_SYSWIDE_PASID |
> > +IOMMU_NESTING_FEAT_BIND_PGTBL |
> > +IOMMU_NESTING_FEAT_CACHE_INVLD;
> > +   info->addr_width = dmar_domain->gaw;
> > +   info->pasid_bits = ilog2(intel_pasid_max_id);
> > +   info->padding = 0;
> > +   vtd.flags = 0;
> > +   vtd.padding = 0;
> > +   vtd.cap_reg = cap;
> > +   vtd.ecap_reg = ecap;
> > +
> > +   memcpy(info->data, , sizeof(vtd));
> > +   return 0;
> > +}
> > +
> > +static int intel_iommu_domain_get_attr(struct iommu_domain *domain,
> > +  enum iommu_attr attr, void *data)
> > +{
> > +   switch (attr) {
> > +   case DOMAIN_ATTR_NESTING:
> > +   {
> > +   struct iommu_nesting_info *info =
> > +   (struct iommu_nesting_info *)data;
> 
> don't you need to hold a device_domain_lock earlier to make sure domain
> attributes can't change behind your back (unmanaged type and nested mode)?

do you mean acquire lock at [1]?

Regards,
Yi Liu

> > +
> > +   return intel_iommu_get_nesting_info(domain, info);
> > +   }
> > +   default:
> > +   return -ENOENT;
> > +   }
> > +}
> > +
> >  /*
> >   * Check that the device does not live on an external facing PCI port 

Re: [PATCH v6 15/15] iommu/vt-d: Support reporting nesting capability info

2020-08-16 Thread Auger Eric
Hi Yi,

On 7/28/20 8:27 AM, Liu Yi L wrote:
> This patch reports nesting info, and only supports the case where all
> the physical iomms have the same CAP/ECAP MASKS.
s/iomms/iommus
> 
> Cc: Kevin Tian 
> CC: Jacob Pan 
> Cc: Alex Williamson 
> Cc: Eric Auger 
> Cc: Jean-Philippe Brucker 
> Cc: Joerg Roedel 
> Cc: Lu Baolu 
> Signed-off-by: Liu Yi L 
> Signed-off-by: Jacob Pan 
> ---
> v2 -> v3:
> *) remove cap/ecap_mask in iommu_nesting_info.
> ---
>  drivers/iommu/intel/iommu.c | 81 
> +++--
>  include/linux/intel-iommu.h | 16 +
>  2 files changed, 95 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 88f4647..0835804 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -5660,12 +5660,16 @@ static inline bool iommu_pasid_support(void)
>  static inline bool nested_mode_support(void)
>  {
>   struct dmar_drhd_unit *drhd;
> - struct intel_iommu *iommu;
> + struct intel_iommu *iommu, *prev = NULL;
>   bool ret = true;
>  
>   rcu_read_lock();
>   for_each_active_iommu(iommu, drhd) {
> - if (!sm_supported(iommu) || !ecap_nest(iommu->ecap)) {
> + if (!prev)
> + prev = iommu;
> + if (!sm_supported(iommu) || !ecap_nest(iommu->ecap) ||
> + (VTD_CAP_MASK & (iommu->cap ^ prev->cap)) ||
> + (VTD_ECAP_MASK & (iommu->ecap ^ prev->ecap))) {
>   ret = false;
>   break;
So this changes the behavior of DOMAIN_ATTR_NESTING. Shouldn't it have a
Fixes tag as well? And maybe add the capability getter in a separate patch?
>   }
> @@ -6081,6 +6085,78 @@ intel_iommu_domain_set_attr(struct iommu_domain 
> *domain,
>   return ret;
>  }
>  
> +static int intel_iommu_get_nesting_info(struct iommu_domain *domain,
> + struct iommu_nesting_info *info)
> +{
> + struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> + u64 cap = VTD_CAP_MASK, ecap = VTD_ECAP_MASK;
> + struct device_domain_info *domain_info;
> + struct iommu_nesting_info_vtd vtd;
> + unsigned long flags;
> + unsigned int size;
> +
> + if (domain->type != IOMMU_DOMAIN_UNMANAGED ||
> + !(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE))
> + return -ENODEV;
> +
> + if (!info)
> + return -EINVAL;
> +
> + size = sizeof(struct iommu_nesting_info) +
> + sizeof(struct iommu_nesting_info_vtd);
> + /*
> +  * if provided buffer size is smaller than expected, should
> +  * return 0 and also the expected buffer size to caller.
> +  */
> + if (info->argsz < size) {
> + info->argsz = size;
> + return 0;
> + }
> +
> + spin_lock_irqsave(_domain_lock, flags);
> + /*
> +  * arbitrary select the first domain_info as all nesting
> +  * related capabilities should be consistent across iommu
> +  * units.
> +  */
> + domain_info = list_first_entry(_domain->devices,
> +struct device_domain_info, link);
> + cap &= domain_info->iommu->cap;
> + ecap &= domain_info->iommu->ecap;
> + spin_unlock_irqrestore(_domain_lock, flags);
> +
> + info->format = IOMMU_PASID_FORMAT_INTEL_VTD;
> + info->features = IOMMU_NESTING_FEAT_SYSWIDE_PASID |
> +  IOMMU_NESTING_FEAT_BIND_PGTBL |
> +  IOMMU_NESTING_FEAT_CACHE_INVLD;
> + info->addr_width = dmar_domain->gaw;
> + info->pasid_bits = ilog2(intel_pasid_max_id);
> + info->padding = 0;
> + vtd.flags = 0;
> + vtd.padding = 0;
> + vtd.cap_reg = cap;
> + vtd.ecap_reg = ecap;
> +
> + memcpy(info->data, , sizeof(vtd));
> + return 0;
> +}
> +
> +static int intel_iommu_domain_get_attr(struct iommu_domain *domain,
> +enum iommu_attr attr, void *data)
> +{
> + switch (attr) {
> + case DOMAIN_ATTR_NESTING:
> + {
> + struct iommu_nesting_info *info =
> + (struct iommu_nesting_info *)data;

don't you need to hold a device_domain_lock earlier to make sure domain
attributes can't change behind your back (unmanaged type and nested mode)?
> +
> + return intel_iommu_get_nesting_info(domain, info);
> + }
> + default:
> + return -ENOENT;
> + }
> +}
> +
>  /*
>   * Check that the device does not live on an external facing PCI port that is
>   * marked as untrusted. Such devices should not be able to apply quirks and
> @@ -6103,6 +6179,7 @@ const struct iommu_ops intel_iommu_ops = {
>   .domain_alloc   = intel_iommu_domain_alloc,
>   .domain_free= intel_iommu_domain_free,
>   .domain_set_attr= intel_iommu_domain_set_attr,
> + .domain_get_attr= intel_iommu_domain_get_attr,
>   

[PATCH v6 15/15] iommu/vt-d: Support reporting nesting capability info

2020-07-28 Thread Liu Yi L
This patch reports nesting info, and only supports the case where all
the physical iomms have the same CAP/ECAP MASKS.

Cc: Kevin Tian 
CC: Jacob Pan 
Cc: Alex Williamson 
Cc: Eric Auger 
Cc: Jean-Philippe Brucker 
Cc: Joerg Roedel 
Cc: Lu Baolu 
Signed-off-by: Liu Yi L 
Signed-off-by: Jacob Pan 
---
v2 -> v3:
*) remove cap/ecap_mask in iommu_nesting_info.
---
 drivers/iommu/intel/iommu.c | 81 +++--
 include/linux/intel-iommu.h | 16 +
 2 files changed, 95 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 88f4647..0835804 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5660,12 +5660,16 @@ static inline bool iommu_pasid_support(void)
 static inline bool nested_mode_support(void)
 {
struct dmar_drhd_unit *drhd;
-   struct intel_iommu *iommu;
+   struct intel_iommu *iommu, *prev = NULL;
bool ret = true;
 
rcu_read_lock();
for_each_active_iommu(iommu, drhd) {
-   if (!sm_supported(iommu) || !ecap_nest(iommu->ecap)) {
+   if (!prev)
+   prev = iommu;
+   if (!sm_supported(iommu) || !ecap_nest(iommu->ecap) ||
+   (VTD_CAP_MASK & (iommu->cap ^ prev->cap)) ||
+   (VTD_ECAP_MASK & (iommu->ecap ^ prev->ecap))) {
ret = false;
break;
}
@@ -6081,6 +6085,78 @@ intel_iommu_domain_set_attr(struct iommu_domain *domain,
return ret;
 }
 
+static int intel_iommu_get_nesting_info(struct iommu_domain *domain,
+   struct iommu_nesting_info *info)
+{
+   struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+   u64 cap = VTD_CAP_MASK, ecap = VTD_ECAP_MASK;
+   struct device_domain_info *domain_info;
+   struct iommu_nesting_info_vtd vtd;
+   unsigned long flags;
+   unsigned int size;
+
+   if (domain->type != IOMMU_DOMAIN_UNMANAGED ||
+   !(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE))
+   return -ENODEV;
+
+   if (!info)
+   return -EINVAL;
+
+   size = sizeof(struct iommu_nesting_info) +
+   sizeof(struct iommu_nesting_info_vtd);
+   /*
+* if provided buffer size is smaller than expected, should
+* return 0 and also the expected buffer size to caller.
+*/
+   if (info->argsz < size) {
+   info->argsz = size;
+   return 0;
+   }
+
+   spin_lock_irqsave(_domain_lock, flags);
+   /*
+* arbitrary select the first domain_info as all nesting
+* related capabilities should be consistent across iommu
+* units.
+*/
+   domain_info = list_first_entry(_domain->devices,
+  struct device_domain_info, link);
+   cap &= domain_info->iommu->cap;
+   ecap &= domain_info->iommu->ecap;
+   spin_unlock_irqrestore(_domain_lock, flags);
+
+   info->format = IOMMU_PASID_FORMAT_INTEL_VTD;
+   info->features = IOMMU_NESTING_FEAT_SYSWIDE_PASID |
+IOMMU_NESTING_FEAT_BIND_PGTBL |
+IOMMU_NESTING_FEAT_CACHE_INVLD;
+   info->addr_width = dmar_domain->gaw;
+   info->pasid_bits = ilog2(intel_pasid_max_id);
+   info->padding = 0;
+   vtd.flags = 0;
+   vtd.padding = 0;
+   vtd.cap_reg = cap;
+   vtd.ecap_reg = ecap;
+
+   memcpy(info->data, , sizeof(vtd));
+   return 0;
+}
+
+static int intel_iommu_domain_get_attr(struct iommu_domain *domain,
+  enum iommu_attr attr, void *data)
+{
+   switch (attr) {
+   case DOMAIN_ATTR_NESTING:
+   {
+   struct iommu_nesting_info *info =
+   (struct iommu_nesting_info *)data;
+
+   return intel_iommu_get_nesting_info(domain, info);
+   }
+   default:
+   return -ENOENT;
+   }
+}
+
 /*
  * Check that the device does not live on an external facing PCI port that is
  * marked as untrusted. Such devices should not be able to apply quirks and
@@ -6103,6 +6179,7 @@ const struct iommu_ops intel_iommu_ops = {
.domain_alloc   = intel_iommu_domain_alloc,
.domain_free= intel_iommu_domain_free,
.domain_set_attr= intel_iommu_domain_set_attr,
+   .domain_get_attr= intel_iommu_domain_get_attr,
.attach_dev = intel_iommu_attach_device,
.detach_dev = intel_iommu_detach_device,
.aux_attach_dev = intel_iommu_aux_attach_device,
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index f98146b..5acf795 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -197,6 +197,22 @@
 #define ecap_max_handle_mask(e) ((e >> 20) & 0xf)
 #define ecap_sc_support(e) ((e >> 7) & 0x1) /*