Re: [PATCH v2 1/3] x86/ioreq server: Add new functions to get/set memory types.

[George Dunlap <dunlapg@umich.edu>]

On Thu, Mar 31, 2016 at 11:53 AM, Yu Zhang <yu.c.zhang@linux.intel.com> wrote:
> For clarity this patch breaks the code to set/get memory types out
> of do_hvm_op() into dedicated functions: hvmop_set/get_mem_type().
> Also, for clarity, checks for whether a memory type change is allowed
> are broken out into a separate function called by hvmop_set_mem_type().
>
> There is no intentional functional change in this patch.
>
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> Cc: Keir Fraser <keir@xen.org>
> Cc: Jan Beulich <jbeulich@suse.com>
> Cc: Andrew Cooper <andrew.cooper3@citrix.com>

Reviewed-by: George Dunlap <george.dunlap@citrix.com>

> ---
>  xen/arch/x86/hvm/hvm.c | 284 +++++++++++++++++++++++++++----------------------
>  1 file changed, 159 insertions(+), 125 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 80d59ff..f700923 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -6547,6 +6547,61 @@ static int do_altp2m_op(
>      return rc;
>  }
>
> +static int hvmop_get_mem_type(
> +    XEN_GUEST_HANDLE_PARAM(xen_hvm_get_mem_type_t) arg)
> +{
> +    struct xen_hvm_get_mem_type a;
> +    struct domain *d;
> +    p2m_type_t t;
> +    int rc;
> +
> +    if ( copy_from_guest(&a, arg, 1) )
> +        return -EFAULT;
> +
> +    d = rcu_lock_domain_by_any_id(a.domid);
> +    if ( d == NULL )
> +        return -ESRCH;
> +
> +    rc = xsm_hvm_param(XSM_TARGET, d, HVMOP_get_mem_type);
> +    if ( rc )
> +        goto out;
> +
> +    rc = -EINVAL;
> +    if ( !is_hvm_domain(d) )
> +        goto out;
> +
> +    /*
> +     * Use get_gfn query as we are interested in the current
> +     * type, not in allocating or unsharing. That'll happen
> +     * on access.
> +     */
> +    get_gfn_query_unlocked(d, a.pfn, &t);
> +    if ( p2m_is_mmio(t) )
> +        a.mem_type =  HVMMEM_mmio_dm;
> +    else if ( t == p2m_mmio_write_dm )
> +        a.mem_type = HVMMEM_mmio_write_dm;
> +    else if ( p2m_is_readonly(t) )
> +        a.mem_type =  HVMMEM_ram_ro;
> +    else if ( p2m_is_ram(t) )
> +        a.mem_type =  HVMMEM_ram_rw;
> +    else if ( p2m_is_pod(t) )
> +        a.mem_type =  HVMMEM_ram_rw;
> +    else if ( p2m_is_grant(t) )
> +        a.mem_type =  HVMMEM_ram_rw;
> +    else
> +        a.mem_type =  HVMMEM_mmio_dm;
> +
> +    rc = -EFAULT;
> +    if ( __copy_to_guest(arg, &a, 1) )
> +        goto out;
> +    rc = 0;
> +
> + out:
> +    rcu_unlock_domain(d);
> +
> +    return rc;
> +}
> +
>  /*
>   * Note that this value is effectively part of the ABI, even if we don't need
>   * to make it a formal part of it: A guest suspended for migration in the
> @@ -6555,6 +6610,105 @@ static int do_altp2m_op(
>   */
>  #define HVMOP_op_mask 0xff
>
> +static bool_t hvm_allow_p2m_type_change(p2m_type_t old, p2m_type_t new)
> +{
> +    if ( p2m_is_ram(old) ||
> +         (p2m_is_hole(old) && new == p2m_mmio_dm) ||
> +         (old == p2m_mmio_write_dm && new == p2m_ram_rw) )
> +        return 1;
> +
> +    return 0;
> +}
> +
> +static int hvmop_set_mem_type(
> +    XEN_GUEST_HANDLE_PARAM(xen_hvm_set_mem_type_t) arg,
> +    unsigned long *iter)
> +{
> +    unsigned long start_iter = *iter;
> +    struct xen_hvm_set_mem_type a;
> +    struct domain *d;
> +    int rc;
> +
> +    /* Interface types to internal p2m types */
> +    static const p2m_type_t memtype[] = {
> +        [HVMMEM_ram_rw]  = p2m_ram_rw,
> +        [HVMMEM_ram_ro]  = p2m_ram_ro,
> +        [HVMMEM_mmio_dm] = p2m_mmio_dm,
> +        [HVMMEM_mmio_write_dm] = p2m_mmio_write_dm
> +    };
> +
> +    if ( copy_from_guest(&a, arg, 1) )
> +        return -EFAULT;
> +
> +    rc = rcu_lock_remote_domain_by_id(a.domid, &d);
> +    if ( rc != 0 )
> +        return rc;
> +
> +    rc = -EINVAL;
> +    if ( !is_hvm_domain(d) )
> +        goto out;
> +
> +    rc = xsm_hvm_control(XSM_DM_PRIV, d, HVMOP_set_mem_type);
> +    if ( rc )
> +        goto out;
> +
> +    rc = -EINVAL;
> +    if ( a.nr < start_iter ||
> +         ((a.first_pfn + a.nr - 1) < a.first_pfn) ||
> +         ((a.first_pfn + a.nr - 1) > domain_get_maximum_gpfn(d)) )
> +        goto out;
> +
> +    if ( a.hvmmem_type >= ARRAY_SIZE(memtype) )
> +        goto out;
> +
> +    while ( a.nr > start_iter )
> +    {
> +        unsigned long pfn = a.first_pfn + start_iter;
> +        p2m_type_t t;
> +
> +        get_gfn_unshare(d, pfn, &t);
> +        if ( p2m_is_paging(t) )
> +        {
> +            put_gfn(d, pfn);
> +            p2m_mem_paging_populate(d, pfn);
> +            rc = -EAGAIN;
> +            goto out;
> +        }
> +        if ( p2m_is_shared(t) )
> +        {
> +            put_gfn(d, pfn);
> +            rc = -EAGAIN;
> +            goto out;
> +        }
> +        if ( !hvm_allow_p2m_type_change(t, memtype[a.hvmmem_type]) )
> +        {
> +            put_gfn(d, pfn);
> +            goto out;
> +        }
> +
> +        rc = p2m_change_type_one(d, pfn, t, memtype[a.hvmmem_type]);
> +        put_gfn(d, pfn);
> +
> +        if ( rc )
> +            goto out;
> +
> +        /* Check for continuation if it's not the last interation */
> +        if ( a.nr > ++start_iter && !(start_iter & HVMOP_op_mask) &&
> +             hypercall_preempt_check() )
> +        {
> +            rc = -ERESTART;
> +            goto out;
> +        }
> +    }
> +    rc = 0;
> +
> + out:
> +    rcu_unlock_domain(d);
> +    *iter = start_iter;
> +
> +    return rc;
> +}
> +
>  long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
>  {
>      unsigned long start_iter, mask;
> @@ -6744,135 +6898,15 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
>      }
>
>      case HVMOP_get_mem_type:
> -    {
> -        struct xen_hvm_get_mem_type a;
> -        struct domain *d;
> -        p2m_type_t t;
> -
> -        if ( copy_from_guest(&a, arg, 1) )
> -            return -EFAULT;
> -
> -        d = rcu_lock_domain_by_any_id(a.domid);
> -        if ( d == NULL )
> -            return -ESRCH;
> -
> -        rc = xsm_hvm_param(XSM_TARGET, d, op);
> -        if ( unlikely(rc) )
> -            /* nothing */;
> -        else if ( likely(is_hvm_domain(d)) )
> -        {
> -            /* Use get_gfn query as we are interested in the current
> -             * type, not in allocating or unsharing. That'll happen
> -             * on access. */
> -            get_gfn_query_unlocked(d, a.pfn, &t);
> -            if ( p2m_is_mmio(t) )
> -                a.mem_type =  HVMMEM_mmio_dm;
> -            else if ( t == p2m_mmio_write_dm )
> -                a.mem_type = HVMMEM_mmio_write_dm;
> -            else if ( p2m_is_readonly(t) )
> -                a.mem_type =  HVMMEM_ram_ro;
> -            else if ( p2m_is_ram(t) )
> -                a.mem_type =  HVMMEM_ram_rw;
> -            else if ( p2m_is_pod(t) )
> -                a.mem_type =  HVMMEM_ram_rw;
> -            else if ( p2m_is_grant(t) )
> -                a.mem_type =  HVMMEM_ram_rw;
> -            else
> -                a.mem_type =  HVMMEM_mmio_dm;
> -            if ( __copy_to_guest(arg, &a, 1) )
> -                rc = -EFAULT;
> -        }
> -        else
> -            rc = -EINVAL;
> -
> -        rcu_unlock_domain(d);
> +        rc = hvmop_get_mem_type(
> +            guest_handle_cast(arg, xen_hvm_get_mem_type_t));
>          break;
> -    }
>
>      case HVMOP_set_mem_type:
> -    {
> -        struct xen_hvm_set_mem_type a;
> -        struct domain *d;
> -
> -        /* Interface types to internal p2m types */
> -        static const p2m_type_t memtype[] = {
> -            [HVMMEM_ram_rw]  = p2m_ram_rw,
> -            [HVMMEM_ram_ro]  = p2m_ram_ro,
> -            [HVMMEM_mmio_dm] = p2m_mmio_dm,
> -            [HVMMEM_mmio_write_dm] = p2m_mmio_write_dm
> -        };
> -
> -        if ( copy_from_guest(&a, arg, 1) )
> -            return -EFAULT;
> -
> -        rc = rcu_lock_remote_domain_by_id(a.domid, &d);
> -        if ( rc != 0 )
> -            return rc;
> -
> -        rc = -EINVAL;
> -        if ( !is_hvm_domain(d) )
> -            goto setmemtype_fail;
> -
> -        rc = xsm_hvm_control(XSM_DM_PRIV, d, op);
> -        if ( rc )
> -            goto setmemtype_fail;
> -
> -        rc = -EINVAL;
> -        if ( a.nr < start_iter ||
> -             ((a.first_pfn + a.nr - 1) < a.first_pfn) ||
> -             ((a.first_pfn + a.nr - 1) > domain_get_maximum_gpfn(d)) )
> -            goto setmemtype_fail;
> -
> -        if ( a.hvmmem_type >= ARRAY_SIZE(memtype) )
> -            goto setmemtype_fail;
> -
> -        while ( a.nr > start_iter )
> -        {
> -            unsigned long pfn = a.first_pfn + start_iter;
> -            p2m_type_t t;
> -
> -            get_gfn_unshare(d, pfn, &t);
> -            if ( p2m_is_paging(t) )
> -            {
> -                put_gfn(d, pfn);
> -                p2m_mem_paging_populate(d, pfn);
> -                rc = -EAGAIN;
> -                goto setmemtype_fail;
> -            }
> -            if ( p2m_is_shared(t) )
> -            {
> -                put_gfn(d, pfn);
> -                rc = -EAGAIN;
> -                goto setmemtype_fail;
> -            }
> -            if ( !p2m_is_ram(t) &&
> -                 (!p2m_is_hole(t) || a.hvmmem_type != HVMMEM_mmio_dm) &&
> -                 (t != p2m_mmio_write_dm || a.hvmmem_type != HVMMEM_ram_rw) )
> -            {
> -                put_gfn(d, pfn);
> -                goto setmemtype_fail;
> -            }
> -
> -            rc = p2m_change_type_one(d, pfn, t, memtype[a.hvmmem_type]);
> -            put_gfn(d, pfn);
> -            if ( rc )
> -                goto setmemtype_fail;
> -
> -            /* Check for continuation if it's not the last interation */
> -            if ( a.nr > ++start_iter && !(start_iter & HVMOP_op_mask) &&
> -                 hypercall_preempt_check() )
> -            {
> -                rc = -ERESTART;
> -                goto setmemtype_fail;
> -            }
> -        }
> -
> -        rc = 0;
> -
> -    setmemtype_fail:
> -        rcu_unlock_domain(d);
> +        rc = hvmop_set_mem_type(
> +            guest_handle_cast(arg, xen_hvm_set_mem_type_t),
> +            &start_iter);
>          break;
> -    }
>
>      case HVMOP_pagetable_dying:
>      {
> --
> 1.9.1
>
>
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