Re: [Xen-devel] [RFC PATCH 2/3] arch, arm32: add the XEN_DOMCTL_memory_mapping hypercall

[Eric Trudeau <etrudeau@xxxxxxxxxxxx>]

> -----Original Message-----
> From: Arianna Avanzini [mailto:avanzini.arianna@xxxxxxxxx]
> Sent: Saturday, March 01, 2014 7:49 PM
> To: xen-devel@xxxxxxxxxxxxx
> Cc: avanzini.arianna@xxxxxxxxx; dario.faggioli@xxxxxxxxxx;
> paolo.valente@xxxxxxxxxx; stefano.stabellini@xxxxxxxxxxxxx;
> julien.grall@xxxxxxxxxx; Eric Trudeau; viktor.kleinik@xxxxxxxxxxxxxxx
> Subject: [RFC PATCH 2/3] arch, arm32: add the
> XEN_DOMCTL_memory_mapping hypercall
> 
> This commit introduces a first attempt of implementation of the
> XEN_DOMCTL_memory_mapping hypercall for arm32. The following
> warnings must be taken into consideration:
> . currently, the hypercall simply performs an 1:1 mapping of I/O
>   memory ranges (mfn == gfn);
> . the range of I/O memory addresses is mapped all at once with
>   map_mmio_regions();
> . the hypercall takes for granted that any I/O memory range can
>   be mapped to a domU if the current domain is dom0.
> 
> Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
> Cc: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> Cc: Paolo Valente <paolo.valente@xxxxxxxxxx>
> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxxxxx>
> Cc: Eric Trudeau <etrudeau@xxxxxxxxxxxx>
> Cc: Viktor Kleinik <viktor.kleinik@xxxxxxxxxxxxxxx>
> ---
>  xen/arch/arm/arm32/domctl.c | 74
> +++++++++++++++++++++++++++++++++++++++++++++
>  xen/arch/arm/p2m.c          |  9 ++++++
>  xen/include/asm-arm/p2m.h   |  2 ++
>  3 files changed, 85 insertions(+)
> 
> diff --git a/xen/arch/arm/arm32/domctl.c b/xen/arch/arm/arm32/domctl.c
> index c2ca4d3..67cf734 100644
> --- a/xen/arch/arm/arm32/domctl.c
> +++ b/xen/arch/arm/arm32/domctl.c
> @@ -10,8 +10,11 @@
>  #include <xen/errno.h>
>  #include <xen/sched.h>
>  #include <xen/hypercall.h>
> +#include <xen/iocap.h>
>  #include <public/domctl.h>
> 
> +#include "cpu.h"
> +
>  long subarch_do_domctl(struct xen_domctl *domctl, struct domain *d,
>                 XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
>  {
> @@ -19,6 +22,77 @@ long subarch_do_domctl(struct xen_domctl *domctl,
> struct domain *d,
>      {
>      case XEN_DOMCTL_set_address_size:
>          return domctl->u.address_size.size == 32 ? 0 : -EINVAL;
> +    case XEN_DOMCTL_memory_mapping:
> +    {
> +        unsigned long gfn = domctl->u.memory_mapping.first_gfn;
> +        unsigned long mfn = domctl->u.memory_mapping.first_mfn;
> +        unsigned long nr_mfns = domctl->u.memory_mapping.nr_mfns;
> +        int add = domctl->u.memory_mapping.add_mapping;
> +        long int ret;
> +
> +        ret = -EINVAL;
> +        if ( (mfn + nr_mfns - 1) < mfn || /* wrap? */
> +            ((mfn | (mfn + nr_mfns - 1)) >> (paddr_bits - PAGE_SHIFT)) ||
> +            (gfn + nr_mfns - 1) < gfn ) /* wrap? */
> +            return ret;
> +
> +        ret = -EPERM;
> +     /*
> +      * NOTE: dom0 seems to have empty iomem_caps but to be however
> able to
> +      *       access I/O memory ranges. The following check takes for granted
> +      *       that any iomem range can be mapped to a domU if the current
> +      *       domain is dom0.
> +      */
> +        if ( current->domain->domain_id != 0 &&
> +             !iomem_access_permitted(current->domain, mfn, mfn + nr_mfns - 
> 1) )
> +            return ret;
> +
> +        ret = xsm_iomem_mapping(XSM_HOOK, d, mfn, mfn + nr_mfns - 1, add);
> +        if ( ret )
> +            return ret;
> +
> +        if ( add )
> +        {
> +            printk(XENLOG_G_INFO
> +                   "memory_map:add: dom%d gfn=%lx mfn=%lx nr=%lx\n",
> +                   d->domain_id, gfn, mfn, nr_mfns);
> +            ret = iomem_permit_access(d, mfn, mfn + nr_mfns - 1);
> +            if ( !ret )
> +            {
> +                /* 1:1 iomem mapping (gfn == mfn) */
> +                ret = map_mmio_regions(d, gfn, gfn + nr_mfns - 1, mfn);

Last I checked, map_mmio_regions takes paddr_t, not frame numbers.

Beware:  I found that map_mmio_regions was off by one page unless I changed
"gfn + nr_mfns - 1" to "gfn + nr_mfns".
This may have been fixed in more recent upstream code.

> +                if ( ret )
> +                {
> +                    printk(XENLOG_G_WARNING
> +                           "memory_map:fail: dom%d gfn=%lx mfn=%lx\n",
> +                           d->domain_id, gfn, mfn);
> +                    if ( iomem_deny_access(d, mfn, mfn + nr_mfns - 1) &&
> +                         is_hardware_domain(current->domain) )
> +                        printk(XENLOG_ERR
> +                               "memory_map: failed to deny dom%d access "
> +                               "to [%lx,%lx]\n",
> +                               d->domain_id, mfn, mfn + nr_mfns - 1);
> +                }
> +            }
> +        }
> +     else
> +        {
> +            printk(XENLOG_G_INFO
> +                   "memory_map:remove: dom%d gfn=%lx mfn=%lx nr=%lx\n",
> +                   d->domain_id, gfn, mfn, nr_mfns);
> +
> +            add = unmap_mmio_regions(d, gfn, gfn + nr_mfns - 1, mfn);
> +            ret = iomem_deny_access(d, mfn, mfn + nr_mfns - 1);
> +            if ( ret && add )
> +                ret = -EIO;
> +            if ( ret && is_hardware_domain(current->domain) )
> +                printk(XENLOG_ERR
> +                       "memory_map: error %ld %s dom%d access to 
> [%lx,%lx]\n",
> +                       ret, add ? "removing" : "denying", d->domain_id,
> +                       mfn, mfn + nr_mfns - 1);
> +     }
> +        return ret;
> +    }
>      default:
>          return -ENOSYS;
>      }
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index d00c882..710f74e 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -461,6 +461,15 @@ int map_mmio_regions(struct domain *d,
>                               maddr, MATTR_DEV, p2m_mmio_direct);
>  }
> 
> +int unmap_mmio_regions(struct domain *d,
> +                       paddr_t start_gaddr,
> +                       paddr_t end_gaddr,
> +                       paddr_t maddr)
> +{
> +    return apply_p2m_changes(d, REMOVE, start_gaddr, end_gaddr,
> +                             maddr, MATTR_DEV, p2m_mmio_direct);
> +}
> +
>  int guest_physmap_add_entry(struct domain *d,
>                              unsigned long gpfn,
>                              unsigned long mfn,
> diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
> index 3b39c45..907ce4a 100644
> --- a/xen/include/asm-arm/p2m.h
> +++ b/xen/include/asm-arm/p2m.h
> @@ -88,6 +88,8 @@ int p2m_populate_ram(struct domain *d, paddr_t start,
> paddr_t end);
>   * address maddr. */
>  int map_mmio_regions(struct domain *d, paddr_t start_gaddr,
>                       paddr_t end_gaddr, paddr_t maddr);
> +int unmap_mmio_regions(struct domain *d, paddr_t start_gaddr,
> +                       paddr_t end_gaddr, paddr_t maddr);
> 
>  int guest_physmap_add_entry(struct domain *d,
>                              unsigned long gfn,
> --
> 1.8.5.3


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