Re: [Xen-devel] [v8][PATCH 11/17] xen/x86/p2m: reject populating for reserved device memory mapping

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Chen, Tiejun
> Sent: Monday, December 01, 2014 5:24 PM
> 
> We need to reject to populate reserved device memory mapping, and
> then make sure all reserved device memory can't be accessed by any
> !iommu approach.
> 
> Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> ---
>  xen/arch/x86/mm/p2m.c     | 59
> +++++++++++++++++++++++++++++++++++++++++++++--
>  xen/include/asm-x86/p2m.h |  9 ++++++++
>  2 files changed, 66 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
> index efa49dd..607ecd0 100644
> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -556,6 +556,40 @@ guest_physmap_remove_page(struct domain *d,
> unsigned long gfn,
>      gfn_unlock(p2m, gfn, page_order);
>  }
> 
> +/* Check if we are accessing rdm. */
> +int p2m_check_reserved_device_memory(xen_pfn_t start, xen_ulong_t nr,
> +                                     u32 id, void *ctxt)
> +{
> +    xen_pfn_t end = start + nr;
> +    unsigned int i;
> +    u32 sbdf;
> +    struct p2m_get_reserved_device_memory *pgrdm = ctxt;
> +    struct domain *d = pgrdm->domain;
> +
> +    if ( d->arch.hvm_domain.pci_force )
> +    {
> +        if ( pgrdm->gfn >= start && pgrdm->gfn < end )
> +            return 1;
> +    }
> +    else
> +    {
> +        for ( i = 0; i < d->arch.hvm_domain.num_pcidevs; i++ )
> +        {
> +            sbdf = PCI_SBDF2(d->arch.hvm_domain.pcidevs[i].seg,
> +                             d->arch.hvm_domain.pcidevs[i].bus,
> +                             d->arch.hvm_domain.pcidevs[i].devfn);
> +
> +            if ( sbdf == id )
> +            {
> +                if ( pgrdm->gfn >= start && pgrdm->gfn < end )
> +                    return 1;
> +            }
> +        }
> +    }
> +
> +    return 0;
> +}
> +
>  int
>  guest_physmap_add_entry(struct domain *d, unsigned long gfn,
>                          unsigned long mfn, unsigned int page_order,
> @@ -568,6 +602,7 @@ guest_physmap_add_entry(struct domain *d, unsigned
> long gfn,
>      mfn_t omfn;
>      int pod_count = 0;
>      int rc = 0;
> +    struct p2m_get_reserved_device_memory pgrdm;
> 
>      if ( !paging_mode_translate(d) )
>      {
> @@ -686,8 +721,28 @@ guest_physmap_add_entry(struct domain *d,
> unsigned long gfn,
>      /* Now, actually do the two-way mapping */
>      if ( mfn_valid(_mfn(mfn)) )
>      {
> -        rc = p2m_set_entry(p2m, gfn, _mfn(mfn), page_order, t,
> -                           p2m->default_access);
> +        pgrdm.gfn = gfn;
> +        pgrdm.domain = d;
> +        if ( !is_hardware_domain(d) && iommu_use_hap_pt(d) )

why is this check only for shared case?

> +        {
> +            rc =
> iommu_get_reserved_device_memory(p2m_check_reserved_device_memory,
> +                                                  &pgrdm);
> +            /* We always avoid populating reserved device memory. */
> +            if ( rc == 1 )
> +            {
> +                rc = -EBUSY;
> +                goto out;
> +            }
> +            else if ( rc < 0 )
> +            {
> +                printk(XENLOG_G_WARNING
> +                       "Can't check reserved device memory for
> Dom%d.\n",
> +                       d->domain_id);
> +                goto out;
> +            }
> +        }
> +
> +        rc = p2m_set_entry(p2m, gfn, _mfn(mfn), page_order, t,
> p2m->default_access);
>          if ( rc )
>              goto out; /* Failed to update p2m, bail without updating m2p.
> */
> 
> diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
> index 5f7fe71..99f7fb7 100644
> --- a/xen/include/asm-x86/p2m.h
> +++ b/xen/include/asm-x86/p2m.h
> @@ -709,6 +709,15 @@ static inline unsigned int
> p2m_get_iommu_flags(p2m_type_t p2mt)
>      return flags;
>  }
> 
> +struct p2m_get_reserved_device_memory {
> +    unsigned long gfn;
> +    struct domain *domain;
> +};
> +
> +/* Check if we are accessing rdm. */
> +extern int p2m_check_reserved_device_memory(xen_pfn_t start,
> xen_ulong_t nr,
> +                                            u32 id, void *ctxt);
> +
>  #endif /* _XEN_P2M_H */
> 
>  /*
> --
> 1.9.1


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