Re: [Xen-devel] [PATCH 1/3] xen/tools: Remove the XENMEM_get_oustanding_pages and provide the data via xc_phys_info

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

On 05/08/2013 02:35 PM, Konrad Rzeszutek Wilk wrote:
> During the review of the patches it was noticed that there exists
> a race wherein the 'free_memory' value consists of information from
> two hypercalls. That is the XEN_SYSCTL_physinfo and 
> XENMEM_get_outstanding_pages.
>
> The free memory the host has available for guest is the difference between
> the 'free_pages' (from XEN_SYSCTL_physinfo) and 'outstanding_pages'. As they
> are two hypercalls many things can happen in between the execution of them.
>
> This patch resolves this by eliminating the XENMEM_get_outstanding_pages
> hypercall and providing the free_pages and outstanding_pages information
> via the xc_phys_info structure.
>
> It also removes the XSM hooks and adds locking as needed.
>
> CC: dgdera@xxxxxxxxxxxxx
My email address here is missing a "g" (dgdegra).

> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>   tools/libxc/xc_domain.c     |    9 ---------
>   tools/libxc/xenctrl.h       |    2 --
>   tools/libxl/libxl.c         |   15 +--------------
>   tools/libxl/libxl.h         |    1 -
>   tools/libxl/libxl_types.idl |    1 +
>   tools/libxl/xl_cmdimpl.c    |   16 +++-------------
>   xen/common/memory.c         |    8 --------
>   xen/common/page_alloc.c     |    8 ++++++--
>   xen/common/sysctl.c         |    3 ++-
>   xen/include/public/memory.h |    7 -------
>   xen/include/public/sysctl.h |    3 ++-
>   xen/include/xen/mm.h        |    2 +-
>   xen/include/xsm/dummy.h     |    6 ------
>   xen/include/xsm/xsm.h       |    1 -
>   xen/xsm/dummy.c             |    1 -
>   xen/xsm/flask/hooks.c       |    6 ------
>   16 files changed, 16 insertions(+), 73 deletions(-)
[...]
> diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
> index a872056..cc0a5a8 100644
> --- a/xen/include/xsm/dummy.h
> +++ b/xen/include/xsm/dummy.h
> @@ -259,12 +259,6 @@ static XSM_INLINE int xsm_claim_pages(XSM_DEFAULT_ARG 
> struct domain *d)
>       return xsm_default_action(action, current->domain, d);
>   }
>
> -static XSM_INLINE int xsm_xenmem_get_outstanding_pages(XSM_DEFAULT_VOID)
> -{
> -    XSM_ASSERT_ACTION(XSM_PRIV);
> -    return xsm_default_action(action, current->domain, NULL);
> -}
> -
>   static XSM_INLINE int xsm_evtchn_unbound(XSM_DEFAULT_ARG struct domain *d, 
> struct evtchn *chn,
>                                            domid_t id2)
>   {
> diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h
> index 58a4fbb..65150a3 100644
> --- a/xen/include/xsm/xsm.h
> +++ b/xen/include/xsm/xsm.h
> @@ -93,7 +93,6 @@ struct xsm_operations {
>       int (*add_to_physmap) (struct domain *d1, struct domain *d2);
>       int (*remove_from_physmap) (struct domain *d1, struct domain *d2);
>       int (*claim_pages) (struct domain *d);
> -    int (*xenmem_get_outstanding_pages) (void);
>
>       int (*console_io) (struct domain *d, int cmd);
You also need to remove the XSM-enabled function from xsm/xsm.h:

static inline int xsm_xenmem_get_outstanding_pages(xsm_default_t def)
{
    return xsm_ops->xenmem_get_outstanding_pages();
}

> diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
> index 937761f..31e4f73 100644
> --- a/xen/xsm/dummy.c
> +++ b/xen/xsm/dummy.c
> @@ -67,7 +67,6 @@ void xsm_fixup_ops (struct xsm_operations *ops)
>       set_to_dummy_if_null(ops, memory_stat_reservation);
>       set_to_dummy_if_null(ops, memory_pin_page);
>       set_to_dummy_if_null(ops, claim_pages);
> -    set_to_dummy_if_null(ops, xenmem_get_outstanding_pages);
>
>       set_to_dummy_if_null(ops, console_io);
>
> diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
> index bb10de3..8e93cdb 100644
> --- a/xen/xsm/flask/hooks.c
> +++ b/xen/xsm/flask/hooks.c
> @@ -422,12 +422,6 @@ static int flask_claim_pages(struct domain *d)
>       return current_has_perm(d, SECCLASS_DOMAIN2, DOMAIN2__SETCLAIM);
>   }
>
> -static int flask_xenmem_get_outstanding_pages(void)
> -{
> -    return avc_current_has_perm(SECINITSID_XEN, SECCLASS_XEN,
> -                                XEN__HEAP, NULL);
> -}
> -
>   static int flask_console_io(struct domain *d, int cmd)
>   {
>       u32 perm;
And the entry in xsm_operations from flask/hooks.c:

    .xenmem_get_outstanding_pages = flask_xenmem_get_outstanding_pages,

With those two changes:

Acked-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>

--
Daniel De Graaf
National Security Agency

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