[PATCH] libxc: match types of 'subject' and 'foreigndom' between struct xc_mmu and do_mmu_update

[PATCH] libxc: match types of 'subject' and 'foreigndom' between struct xc_mmu and do_mmu_update

[Dario Faggioli]

In do_mmu_update() (in the hypervisor) the parameter 'foreigndom' is
'unsigned int' and both its high (bits 31-16) and low (bits 15-0) are
parts utilised, as explained here:
 http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#Func_HYPERVISOR_mmu_update

However, the actual parameter, i.e., the 'subject' field in
struct xc_mmu is declared as domid_t, which typedef-s to uint16_t.
This means we are never able to pass anything via the higher 16 bits
of 'foreigndom', which in turns may cause the hypercall to fail when
called on an actual foreign domain.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>

diff --git a/tools/libxc/xc_private.c b/tools/libxc/xc_private.c
--- a/tools/libxc/xc_private.c
+++ b/tools/libxc/xc_private.c
@@ -478,13 +478,13 @@ static int flush_mmu_updates(xc_interfac
     return err;
 }
 
-struct xc_mmu *xc_alloc_mmu_updates(xc_interface *xch, domid_t dom)
+struct xc_mmu *xc_alloc_mmu_updates(xc_interface *xch, unsigned int subject)
 {
     struct xc_mmu *mmu = malloc(sizeof(*mmu));
     if ( mmu == NULL )
         return mmu;
     mmu->idx     = 0;
-    mmu->subject = dom;
+    mmu->subject = subject;
     return mmu;
 }
 
diff --git a/tools/libxc/xc_private.h b/tools/libxc/xc_private.h
--- a/tools/libxc/xc_private.h
+++ b/tools/libxc/xc_private.h
@@ -308,10 +308,10 @@ void discard_file_cache(xc_interface *xc
 struct xc_mmu {
     mmu_update_t updates[MAX_MMU_UPDATES];
     int          idx;
-    domid_t      subject;
+    unsigned int subject;
 };
 /* Structure returned by xc_alloc_mmu_updates must be free()'ed by caller. */
-struct xc_mmu *xc_alloc_mmu_updates(xc_interface *xch, domid_t dom);
+struct xc_mmu *xc_alloc_mmu_updates(xc_interface *xch, unsigned int subject);
 int xc_add_mmu_update(xc_interface *xch, struct xc_mmu *mmu,
                    unsigned long long ptr, unsigned long long val);
 int xc_flush_mmu_updates(xc_interface *xch, struct xc_mmu *mmu);

Re: [PATCH] libxc: match types of 'subject' and 'foreigndom' between struct xc_mmu and do_mmu_update

[Ian Campbell]

On Wed, 2013-01-23 at 11:44 +0000, Dario Faggioli wrote:
> In do_mmu_update() (in the hypervisor) the parameter 'foreigndom' is
> 'unsigned int' and both its high (bits 31-16) and low (bits 15-0) are
> parts utilised, as explained here:
>  http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#Func_HYPERVISOR_mmu_update
> 
> However, the actual parameter, i.e., the 'subject' field in
> struct xc_mmu is declared as domid_t, which typedef-s to uint16_t.
> This means we are never able to pass anything via the higher 16 bits
> of 'foreigndom', which in turns may cause the hypercall to fail when
> called on an actual foreign domain.
> 
> Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>

Seems sane, acked + applied, thanks.

> 
> diff --git a/tools/libxc/xc_private.c b/tools/libxc/xc_private.c
> --- a/tools/libxc/xc_private.c
> +++ b/tools/libxc/xc_private.c
> @@ -478,13 +478,13 @@ static int flush_mmu_updates(xc_interfac
>      return err;
>  }
>  
> -struct xc_mmu *xc_alloc_mmu_updates(xc_interface *xch, domid_t dom)
> +struct xc_mmu *xc_alloc_mmu_updates(xc_interface *xch, unsigned int subject)
>  {
>      struct xc_mmu *mmu = malloc(sizeof(*mmu));
>      if ( mmu == NULL )
>          return mmu;
>      mmu->idx     = 0;
> -    mmu->subject = dom;
> +    mmu->subject = subject;
>      return mmu;
>  }
>  
> diff --git a/tools/libxc/xc_private.h b/tools/libxc/xc_private.h
> --- a/tools/libxc/xc_private.h
> +++ b/tools/libxc/xc_private.h
> @@ -308,10 +308,10 @@ void discard_file_cache(xc_interface *xc
>  struct xc_mmu {
>      mmu_update_t updates[MAX_MMU_UPDATES];
>      int          idx;
> -    domid_t      subject;
> +    unsigned int subject;
>  };
>  /* Structure returned by xc_alloc_mmu_updates must be free()'ed by caller. */
> -struct xc_mmu *xc_alloc_mmu_updates(xc_interface *xch, domid_t dom);
> +struct xc_mmu *xc_alloc_mmu_updates(xc_interface *xch, unsigned int subject);
>  int xc_add_mmu_update(xc_interface *xch, struct xc_mmu *mmu,
>                     unsigned long long ptr, unsigned long long val);
>  int xc_flush_mmu_updates(xc_interface *xch, struct xc_mmu *mmu);
> 
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