RE: [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova region

2015-10-06 Thread Bhushan Bharat 


> -Original Message-
> From: Alex Williamson [mailto:alex.william...@redhat.com]
> Sent: Tuesday, October 06, 2015 4:15 AM
> To: Bhushan Bharat-R65777 <bharat.bhus...@freescale.com>
> Cc: kvm...@lists.cs.columbia.edu; kvm@vger.kernel.org;
> christoffer.d...@linaro.org; eric.au...@linaro.org; pranavku...@linaro.org;
> marc.zyng...@arm.com; will.dea...@arm.com
> Subject: Re: [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova
> region
> 
> On Mon, 2015-10-05 at 04:55 +, Bhushan Bharat wrote:
> > Hi Alex,
> >
> > > -Original Message-
> > > From: Alex Williamson [mailto:alex.william...@redhat.com]
> > > Sent: Saturday, October 03, 2015 4:16 AM
> > > To: Bhushan Bharat-R65777 <bharat.bhus...@freescale.com>
> > > Cc: kvm...@lists.cs.columbia.edu; kvm@vger.kernel.org;
> > > christoffer.d...@linaro.org; eric.au...@linaro.org;
> > > pranavku...@linaro.org; marc.zyng...@arm.com; will.dea...@arm.com
> > > Subject: Re: [RFC PATCH 1/6] vfio: Add interface for add/del
> > > reserved iova region
> > >
> > > On Wed, 2015-09-30 at 20:26 +0530, Bharat Bhushan wrote:
> > > > This Patch adds the VFIO APIs to add and remove reserved iova regions.
> > > > The reserved iova region can be used for mapping some specific
> > > > physical address in iommu.
> > > >
> > > > Currently we are planning to use this interface for adding iova
> > > > regions for creating iommu of msi-pages. But the API are designed
> > > > for future extension where some other physical address can be
> mapped.
> > > >
> > > > Signed-off-by: Bharat Bhushan <bharat.bhus...@freescale.com>
> > > > ---
> > > >  drivers/vfio/vfio_iommu_type1.c | 201
> > > +++-
> > > >  include/uapi/linux/vfio.h   |  43 +
> > > >  2 files changed, 243 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/vfio/vfio_iommu_type1.c
> > > > b/drivers/vfio/vfio_iommu_type1.c index 57d8c37..fa5d3e4 100644
> > > > --- a/drivers/vfio/vfio_iommu_type1.c
> > > > +++ b/drivers/vfio/vfio_iommu_type1.c
> > > > @@ -59,6 +59,7 @@ struct vfio_iommu {
> > > > struct rb_root  dma_list;
> > > > boolv2;
> > > > boolnesting;
> > > > +   struct list_headreserved_iova_list;
> > >
> > > This alignment leads to poor packing in the structure, put it above the
> bools.
> >
> > ok
> >
> > >
> > > >  };
> > > >
> > > >  struct vfio_domain {
> > > > @@ -77,6 +78,15 @@ struct vfio_dma {
> > > > int prot;   /* IOMMU_READ/WRITE */
> > > >  };
> > > >
> > > > +struct vfio_resvd_region {
> > > > +   dma_addr_t  iova;
> > > > +   size_t  size;
> > > > +   int prot;   /* IOMMU_READ/WRITE */
> > > > +   int refcount;   /* ref count of 
> > > > mappings */
> > > > +   uint64_tmap_paddr;  /* Mapped Physical 
> > > > Address
> > > */
> > >
> > > phys_addr_t
> >
> > Ok,
> >
> > >
> > > > +   struct list_head next;
> > > > +};
> > > > +
> > > >  struct vfio_group {
> > > > struct iommu_group  *iommu_group;
> > > > struct list_headnext;
> > > > @@ -106,6 +116,38 @@ static struct vfio_dma *vfio_find_dma(struct
> > > vfio_iommu *iommu,
> > > > return NULL;
> > > >  }
> > > >
> > > > +/* This function must be called with iommu->lock held */ static
> > > > +bool vfio_overlap_with_resvd_region(struct vfio_iommu *iommu,
> > > > +  dma_addr_t start, size_t 
> > > > size) {
> > > > +   struct vfio_resvd_region *region;
> > > > +
> > > > +   list_for_each_entry(region, >reserved_iova_list, next) {
> > > > +   if (region->iova < start)
> > > > +   return (start - region->iova < region->size);
> > > > +   else if (start < region->iova)
> > > > +   return (region->iova

Re: [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova region

2015-10-06 Thread Alex Williamson 
On Tue, 2015-10-06 at 09:39 +, Bhushan Bharat wrote:
> 
> 
> > -Original Message-
> > From: Alex Williamson [mailto:alex.william...@redhat.com]
> > Sent: Tuesday, October 06, 2015 4:15 AM
> > To: Bhushan Bharat-R65777 <bharat.bhus...@freescale.com>
> > Cc: kvm...@lists.cs.columbia.edu; kvm@vger.kernel.org;
> > christoffer.d...@linaro.org; eric.au...@linaro.org; pranavku...@linaro.org;
> > marc.zyng...@arm.com; will.dea...@arm.com
> > Subject: Re: [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova
> > region
> > 
> > On Mon, 2015-10-05 at 04:55 +, Bhushan Bharat wrote:
> > > Hi Alex,
> > >
> > > > -Original Message-
> > > > From: Alex Williamson [mailto:alex.william...@redhat.com]
> > > > Sent: Saturday, October 03, 2015 4:16 AM
> > > > To: Bhushan Bharat-R65777 <bharat.bhus...@freescale.com>
> > > > Cc: kvm...@lists.cs.columbia.edu; kvm@vger.kernel.org;
> > > > christoffer.d...@linaro.org; eric.au...@linaro.org;
> > > > pranavku...@linaro.org; marc.zyng...@arm.com; will.dea...@arm.com
> > > > Subject: Re: [RFC PATCH 1/6] vfio: Add interface for add/del
> > > > reserved iova region
> > > >
> > > > On Wed, 2015-09-30 at 20:26 +0530, Bharat Bhushan wrote:
> > > > > This Patch adds the VFIO APIs to add and remove reserved iova regions.
> > > > > The reserved iova region can be used for mapping some specific
> > > > > physical address in iommu.
> > > > >
> > > > > Currently we are planning to use this interface for adding iova
> > > > > regions for creating iommu of msi-pages. But the API are designed
> > > > > for future extension where some other physical address can be
> > mapped.
> > > > >
> > > > > Signed-off-by: Bharat Bhushan <bharat.bhus...@freescale.com>
> > > > > ---
> > > > >  drivers/vfio/vfio_iommu_type1.c | 201
> > > > +++-
> > > > >  include/uapi/linux/vfio.h   |  43 +
> > > > >  2 files changed, 243 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/vfio/vfio_iommu_type1.c
> > > > > b/drivers/vfio/vfio_iommu_type1.c index 57d8c37..fa5d3e4 100644
> > > > > --- a/drivers/vfio/vfio_iommu_type1.c
> > > > > +++ b/drivers/vfio/vfio_iommu_type1.c
> > > > > @@ -59,6 +59,7 @@ struct vfio_iommu {
> > > > >   struct rb_root  dma_list;
> > > > >   boolv2;
> > > > >   boolnesting;
> > > > > + struct list_headreserved_iova_list;
> > > >
> > > > This alignment leads to poor packing in the structure, put it above the
> > bools.
> > >
> > > ok
> > >
> > > >
> > > > >  };
> > > > >
> > > > >  struct vfio_domain {
> > > > > @@ -77,6 +78,15 @@ struct vfio_dma {
> > > > >   int prot;   /* IOMMU_READ/WRITE */
> > > > >  };
> > > > >
> > > > > +struct vfio_resvd_region {
> > > > > + dma_addr_t  iova;
> > > > > + size_t  size;
> > > > > + int prot;   /* IOMMU_READ/WRITE */
> > > > > + int refcount;   /* ref count of 
> > > > > mappings */
> > > > > + uint64_tmap_paddr;  /* Mapped Physical 
> > > > > Address
> > > > */
> > > >
> > > > phys_addr_t
> > >
> > > Ok,
> > >
> > > >
> > > > > + struct list_head next;
> > > > > +};
> > > > > +
> > > > >  struct vfio_group {
> > > > >   struct iommu_group  *iommu_group;
> > > > >   struct list_headnext;
> > > > > @@ -106,6 +116,38 @@ static struct vfio_dma *vfio_find_dma(struct
> > > > vfio_iommu *iommu,
> > > > >   return NULL;
> > > > >  }
> > > > >
> > > > > +/* This function must be called with iommu->lock held */ static
> > > > > +bool vfio_overlap_with_resvd_region(struct vfio_iommu *iommu,
> > > > > +dma_addr_t start, size

Re: [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova region

2015-10-05 Thread Alex Williamson 
On Mon, 2015-10-05 at 04:55 +, Bhushan Bharat wrote:
> Hi Alex,
> 
> > -Original Message-
> > From: Alex Williamson [mailto:alex.william...@redhat.com]
> > Sent: Saturday, October 03, 2015 4:16 AM
> > To: Bhushan Bharat-R65777 <bharat.bhus...@freescale.com>
> > Cc: kvm...@lists.cs.columbia.edu; kvm@vger.kernel.org;
> > christoffer.d...@linaro.org; eric.au...@linaro.org; pranavku...@linaro.org;
> > marc.zyng...@arm.com; will.dea...@arm.com
> > Subject: Re: [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova
> > region
> > 
> > On Wed, 2015-09-30 at 20:26 +0530, Bharat Bhushan wrote:
> > > This Patch adds the VFIO APIs to add and remove reserved iova regions.
> > > The reserved iova region can be used for mapping some specific
> > > physical address in iommu.
> > >
> > > Currently we are planning to use this interface for adding iova
> > > regions for creating iommu of msi-pages. But the API are designed for
> > > future extension where some other physical address can be mapped.
> > >
> > > Signed-off-by: Bharat Bhushan <bharat.bhus...@freescale.com>
> > > ---
> > >  drivers/vfio/vfio_iommu_type1.c | 201
> > +++-
> > >  include/uapi/linux/vfio.h   |  43 +
> > >  2 files changed, 243 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/vfio/vfio_iommu_type1.c
> > > b/drivers/vfio/vfio_iommu_type1.c index 57d8c37..fa5d3e4 100644
> > > --- a/drivers/vfio/vfio_iommu_type1.c
> > > +++ b/drivers/vfio/vfio_iommu_type1.c
> > > @@ -59,6 +59,7 @@ struct vfio_iommu {
> > >   struct rb_root  dma_list;
> > >   boolv2;
> > >   boolnesting;
> > > + struct list_headreserved_iova_list;
> > 
> > This alignment leads to poor packing in the structure, put it above the 
> > bools.
> 
> ok
> 
> > 
> > >  };
> > >
> > >  struct vfio_domain {
> > > @@ -77,6 +78,15 @@ struct vfio_dma {
> > >   int prot;   /* IOMMU_READ/WRITE */
> > >  };
> > >
> > > +struct vfio_resvd_region {
> > > + dma_addr_t  iova;
> > > + size_t  size;
> > > + int prot;   /* IOMMU_READ/WRITE */
> > > + int refcount;   /* ref count of mappings */
> > > + uint64_tmap_paddr;  /* Mapped Physical Address
> > */
> > 
> > phys_addr_t
> 
> Ok,
> 
> > 
> > > + struct list_head next;
> > > +};
> > > +
> > >  struct vfio_group {
> > >   struct iommu_group  *iommu_group;
> > >   struct list_headnext;
> > > @@ -106,6 +116,38 @@ static struct vfio_dma *vfio_find_dma(struct
> > vfio_iommu *iommu,
> > >   return NULL;
> > >  }
> > >
> > > +/* This function must be called with iommu->lock held */ static bool
> > > +vfio_overlap_with_resvd_region(struct vfio_iommu *iommu,
> > > +dma_addr_t start, size_t size) {
> > > + struct vfio_resvd_region *region;
> > > +
> > > + list_for_each_entry(region, >reserved_iova_list, next) {
> > > + if (region->iova < start)
> > > + return (start - region->iova < region->size);
> > > + else if (start < region->iova)
> > > + return (region->iova - start < size);
> > 
> > <= on both of the return lines?
> 
> I think is should be "<" and not "=<", no ?

Yep, looks like you're right.  Maybe there's a more straightforward way
to do this.

> > 
> > > +
> > > + return (region->size > 0 && size > 0);
> > > + }
> > > +
> > > + return false;
> > > +}
> > > +
> > > +/* This function must be called with iommu->lock held */ static
> > > +struct vfio_resvd_region *vfio_find_resvd_region(struct vfio_iommu
> > *iommu,
> > > +  dma_addr_t start, size_t
> > size) {
> > > + struct vfio_resvd_region *region;
> > > +
> > > + list_for_each_entry(region, >reserved_iova_list, next)
> > > + if (region->iova == start && region->size == size)
> > > + return region;
> > > +
> > > + return NULL;
> > > +}
> >

RE: [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova region

2015-10-04 Thread Bhushan Bharat 
Hi Alex,

> -Original Message-
> From: Alex Williamson [mailto:alex.william...@redhat.com]
> Sent: Saturday, October 03, 2015 4:16 AM
> To: Bhushan Bharat-R65777 <bharat.bhus...@freescale.com>
> Cc: kvm...@lists.cs.columbia.edu; kvm@vger.kernel.org;
> christoffer.d...@linaro.org; eric.au...@linaro.org; pranavku...@linaro.org;
> marc.zyng...@arm.com; will.dea...@arm.com
> Subject: Re: [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova
> region
> 
> On Wed, 2015-09-30 at 20:26 +0530, Bharat Bhushan wrote:
> > This Patch adds the VFIO APIs to add and remove reserved iova regions.
> > The reserved iova region can be used for mapping some specific
> > physical address in iommu.
> >
> > Currently we are planning to use this interface for adding iova
> > regions for creating iommu of msi-pages. But the API are designed for
> > future extension where some other physical address can be mapped.
> >
> > Signed-off-by: Bharat Bhushan <bharat.bhus...@freescale.com>
> > ---
> >  drivers/vfio/vfio_iommu_type1.c | 201
> +++-
> >  include/uapi/linux/vfio.h   |  43 +
> >  2 files changed, 243 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/vfio/vfio_iommu_type1.c
> > b/drivers/vfio/vfio_iommu_type1.c index 57d8c37..fa5d3e4 100644
> > --- a/drivers/vfio/vfio_iommu_type1.c
> > +++ b/drivers/vfio/vfio_iommu_type1.c
> > @@ -59,6 +59,7 @@ struct vfio_iommu {
> > struct rb_root  dma_list;
> > boolv2;
> > boolnesting;
> > +   struct list_headreserved_iova_list;
> 
> This alignment leads to poor packing in the structure, put it above the bools.

ok

> 
> >  };
> >
> >  struct vfio_domain {
> > @@ -77,6 +78,15 @@ struct vfio_dma {
> > int prot;   /* IOMMU_READ/WRITE */
> >  };
> >
> > +struct vfio_resvd_region {
> > +   dma_addr_t  iova;
> > +   size_t  size;
> > +   int prot;   /* IOMMU_READ/WRITE */
> > +   int refcount;   /* ref count of mappings */
> > +   uint64_tmap_paddr;  /* Mapped Physical Address
> */
> 
> phys_addr_t

Ok,

> 
> > +   struct list_head next;
> > +};
> > +
> >  struct vfio_group {
> > struct iommu_group  *iommu_group;
> > struct list_headnext;
> > @@ -106,6 +116,38 @@ static struct vfio_dma *vfio_find_dma(struct
> vfio_iommu *iommu,
> > return NULL;
> >  }
> >
> > +/* This function must be called with iommu->lock held */ static bool
> > +vfio_overlap_with_resvd_region(struct vfio_iommu *iommu,
> > +  dma_addr_t start, size_t size) {
> > +   struct vfio_resvd_region *region;
> > +
> > +   list_for_each_entry(region, >reserved_iova_list, next) {
> > +   if (region->iova < start)
> > +   return (start - region->iova < region->size);
> > +   else if (start < region->iova)
> > +   return (region->iova - start < size);
> 
> <= on both of the return lines?

I think is should be "<" and not "=<", no ?

> 
> > +
> > +   return (region->size > 0 && size > 0);
> > +   }
> > +
> > +   return false;
> > +}
> > +
> > +/* This function must be called with iommu->lock held */ static
> > +struct vfio_resvd_region *vfio_find_resvd_region(struct vfio_iommu
> *iommu,
> > +dma_addr_t start, size_t
> size) {
> > +   struct vfio_resvd_region *region;
> > +
> > +   list_for_each_entry(region, >reserved_iova_list, next)
> > +   if (region->iova == start && region->size == size)
> > +   return region;
> > +
> > +   return NULL;
> > +}
> > +
> >  static void vfio_link_dma(struct vfio_iommu *iommu, struct vfio_dma
> > *new)  {
> > struct rb_node **link = >dma_list.rb_node, *parent =
> NULL; @@
> > -580,7 +622,8 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
> >
> > mutex_lock(>lock);
> >
> > -   if (vfio_find_dma(iommu, iova, size)) {
> > +   if (vfio_find_dma(iommu, iova, size) ||
> > +   vfio_overlap_with_resvd_region(iommu, iova, size)) {
> > mutex_unlock(>lock);
> > return -EEXIST;
> > }
> > @@ -626,6 +66

Re: [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova region

2015-10-02 Thread Alex Williamson 
On Wed, 2015-09-30 at 20:26 +0530, Bharat Bhushan wrote:
> This Patch adds the VFIO APIs to add and remove reserved iova
> regions. The reserved iova region can be used for mapping some
> specific physical address in iommu.
> 
> Currently we are planning to use this interface for adding iova
> regions for creating iommu of msi-pages. But the API are designed
> for future extension where some other physical address can be mapped.
> 
> Signed-off-by: Bharat Bhushan 
> ---
>  drivers/vfio/vfio_iommu_type1.c | 201 
> +++-
>  include/uapi/linux/vfio.h   |  43 +
>  2 files changed, 243 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 57d8c37..fa5d3e4 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -59,6 +59,7 @@ struct vfio_iommu {
>   struct rb_root  dma_list;
>   boolv2;
>   boolnesting;
> + struct list_headreserved_iova_list;

This alignment leads to poor packing in the structure, put it above the
bools.

>  };
>  
>  struct vfio_domain {
> @@ -77,6 +78,15 @@ struct vfio_dma {
>   int prot;   /* IOMMU_READ/WRITE */
>  };
>  
> +struct vfio_resvd_region {
> + dma_addr_t  iova;
> + size_t  size;
> + int prot;   /* IOMMU_READ/WRITE */
> + int refcount;   /* ref count of mappings */
> + uint64_tmap_paddr;  /* Mapped Physical Address */

phys_addr_t

> + struct list_head next;
> +};
> +
>  struct vfio_group {
>   struct iommu_group  *iommu_group;
>   struct list_headnext;
> @@ -106,6 +116,38 @@ static struct vfio_dma *vfio_find_dma(struct vfio_iommu 
> *iommu,
>   return NULL;
>  }
>  
> +/* This function must be called with iommu->lock held */
> +static bool vfio_overlap_with_resvd_region(struct vfio_iommu *iommu,
> +dma_addr_t start, size_t size)
> +{
> + struct vfio_resvd_region *region;
> +
> + list_for_each_entry(region, >reserved_iova_list, next) {
> + if (region->iova < start)
> + return (start - region->iova < region->size);
> + else if (start < region->iova)
> + return (region->iova - start < size);

<= on both of the return lines?

> +
> + return (region->size > 0 && size > 0);
> + }
> +
> + return false;
> +}
> +
> +/* This function must be called with iommu->lock held */
> +static
> +struct vfio_resvd_region *vfio_find_resvd_region(struct vfio_iommu *iommu,
> +  dma_addr_t start, size_t size)
> +{
> + struct vfio_resvd_region *region;
> +
> + list_for_each_entry(region, >reserved_iova_list, next)
> + if (region->iova == start && region->size == size)
> + return region;
> +
> + return NULL;
> +}
> +
>  static void vfio_link_dma(struct vfio_iommu *iommu, struct vfio_dma *new)
>  {
>   struct rb_node **link = >dma_list.rb_node, *parent = NULL;
> @@ -580,7 +622,8 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
>  
>   mutex_lock(>lock);
>  
> - if (vfio_find_dma(iommu, iova, size)) {
> + if (vfio_find_dma(iommu, iova, size) ||
> + vfio_overlap_with_resvd_region(iommu, iova, size)) {
>   mutex_unlock(>lock);
>   return -EEXIST;
>   }
> @@ -626,6 +669,127 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
>   return ret;
>  }
>  
> +/* This function must be called with iommu->lock held */
> +static
> +int vfio_iommu_resvd_region_del(struct vfio_iommu *iommu,
> + dma_addr_t iova, size_t size, int prot)
> +{
> + struct vfio_resvd_region *res_region;

Have some consistency in naming, just use "region".
> +
> + res_region = vfio_find_resvd_region(iommu, iova, size);
> + /* Region should not be mapped in iommu */
> + if (res_region == NULL || res_region->map_paddr)
> + return -EINVAL;

Are these two separate errors?  !region is -EINVAL, but being mapped is
-EBUSY.

> +
> + list_del(_region->next);
> + kfree(res_region);
> + return 0;
> +}
> +
> +/* This function must be called with iommu->lock held */
> +static int vfio_iommu_resvd_region_add(struct vfio_iommu *iommu,
> +dma_addr_t iova, size_t size, int prot)
> +{
> + struct vfio_resvd_region *res_region;
> +
> + /* Check overlap with with dma maping and reserved regions */
> + if (vfio_find_dma(iommu, iova, size) ||
> + vfio_find_resvd_region(iommu, iova, size))
> + return -EEXIST;
> +
> + res_region = kzalloc(sizeof(*res_region), GFP_KERNEL);
> + if (res_region == NULL)
> + return -ENOMEM;
> +
> +

[RFC PATCH 1/6] vfio: Add interface for add/del reserved iova region

2015-09-30 Thread Bharat Bhushan 
This Patch adds the VFIO APIs to add and remove reserved iova
regions. The reserved iova region can be used for mapping some
specific physical address in iommu.

Currently we are planning to use this interface for adding iova
regions for creating iommu of msi-pages. But the API are designed
for future extension where some other physical address can be mapped.

Signed-off-by: Bharat Bhushan 
---
 drivers/vfio/vfio_iommu_type1.c | 201 +++-
 include/uapi/linux/vfio.h   |  43 +
 2 files changed, 243 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 57d8c37..fa5d3e4 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -59,6 +59,7 @@ struct vfio_iommu {
struct rb_root  dma_list;
boolv2;
boolnesting;
+   struct list_headreserved_iova_list;
 };
 
 struct vfio_domain {
@@ -77,6 +78,15 @@ struct vfio_dma {
int prot;   /* IOMMU_READ/WRITE */
 };
 
+struct vfio_resvd_region {
+   dma_addr_t  iova;
+   size_t  size;
+   int prot;   /* IOMMU_READ/WRITE */
+   int refcount;   /* ref count of mappings */
+   uint64_tmap_paddr;  /* Mapped Physical Address */
+   struct list_head next;
+};
+
 struct vfio_group {
struct iommu_group  *iommu_group;
struct list_headnext;
@@ -106,6 +116,38 @@ static struct vfio_dma *vfio_find_dma(struct vfio_iommu 
*iommu,
return NULL;
 }
 
+/* This function must be called with iommu->lock held */
+static bool vfio_overlap_with_resvd_region(struct vfio_iommu *iommu,
+  dma_addr_t start, size_t size)
+{
+   struct vfio_resvd_region *region;
+
+   list_for_each_entry(region, >reserved_iova_list, next) {
+   if (region->iova < start)
+   return (start - region->iova < region->size);
+   else if (start < region->iova)
+   return (region->iova - start < size);
+
+   return (region->size > 0 && size > 0);
+   }
+
+   return false;
+}
+
+/* This function must be called with iommu->lock held */
+static
+struct vfio_resvd_region *vfio_find_resvd_region(struct vfio_iommu *iommu,
+dma_addr_t start, size_t size)
+{
+   struct vfio_resvd_region *region;
+
+   list_for_each_entry(region, >reserved_iova_list, next)
+   if (region->iova == start && region->size == size)
+   return region;
+
+   return NULL;
+}
+
 static void vfio_link_dma(struct vfio_iommu *iommu, struct vfio_dma *new)
 {
struct rb_node **link = >dma_list.rb_node, *parent = NULL;
@@ -580,7 +622,8 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
 
mutex_lock(>lock);
 
-   if (vfio_find_dma(iommu, iova, size)) {
+   if (vfio_find_dma(iommu, iova, size) ||
+   vfio_overlap_with_resvd_region(iommu, iova, size)) {
mutex_unlock(>lock);
return -EEXIST;
}
@@ -626,6 +669,127 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
return ret;
 }
 
+/* This function must be called with iommu->lock held */
+static
+int vfio_iommu_resvd_region_del(struct vfio_iommu *iommu,
+   dma_addr_t iova, size_t size, int prot)
+{
+   struct vfio_resvd_region *res_region;
+
+   res_region = vfio_find_resvd_region(iommu, iova, size);
+   /* Region should not be mapped in iommu */
+   if (res_region == NULL || res_region->map_paddr)
+   return -EINVAL;
+
+   list_del(_region->next);
+   kfree(res_region);
+   return 0;
+}
+
+/* This function must be called with iommu->lock held */
+static int vfio_iommu_resvd_region_add(struct vfio_iommu *iommu,
+  dma_addr_t iova, size_t size, int prot)
+{
+   struct vfio_resvd_region *res_region;
+
+   /* Check overlap with with dma maping and reserved regions */
+   if (vfio_find_dma(iommu, iova, size) ||
+   vfio_find_resvd_region(iommu, iova, size))
+   return -EEXIST;
+
+   res_region = kzalloc(sizeof(*res_region), GFP_KERNEL);
+   if (res_region == NULL)
+   return -ENOMEM;
+
+   res_region->iova = iova;
+   res_region->size = size;
+   res_region->prot = prot;
+   res_region->refcount = 0;
+   res_region->map_paddr = 0;
+
+   list_add(_region->next, >reserved_iova_list);
+
+   return 0;
+}
+
+static
+int vfio_handle_reserved_region_add(struct vfio_iommu *iommu,
+   struct vfio_iommu_reserved_region_add *region)
+{
+   dma_addr_t iova = region->iova;
+   size_t size =