Re: [Xen-devel] [PATCH 2/2] x86/HVM: fix setting mem access to default

["Aravindh Puthiyaparambil (aravindp)" <aravindp@xxxxxxxxx>]

>commit 3b0bcb89 ("x86/mm/p2m: Move p2m code in
>HVMOP_[gs]et_mem_access into p2m.c") introduced an off-by-one mistake
>forcing an input of HVMMEM_access_default to always fail. Since related, also
>eliminate the inefficient setup of an on-stack array for each function
>invocation.

Thanks for catching this. I do have a question. If the caller wants to set the 
default access by specifying pfn == ~0ul, the call could be made with access = 
HVMMEM_access_default. Should this be allowed?
 
Thanks,
Aravindh

>Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>
>--- a/xen/arch/x86/mm/p2m.c
>+++ b/xen/arch/x86/mm/p2m.c
>@@ -1342,25 +1342,32 @@ long p2m_set_mem_access(struct domain *d
>     mfn_t mfn;
>     long rc = 0;
>
>-    /* N.B. _not_ static: initializer depends on p2m->default_access */
>-    p2m_access_t memaccess[] = {
>-        p2m_access_n,
>-        p2m_access_r,
>-        p2m_access_w,
>-        p2m_access_rw,
>-        p2m_access_x,
>-        p2m_access_rx,
>-        p2m_access_wx,
>-        p2m_access_rwx,
>-        p2m_access_rx2rw,
>-        p2m_access_n2rwx,
>-        p2m->default_access,
>+    static const p2m_access_t memaccess[] = { #define ACCESS(ac)
>+[HVMMEM_access_##ac] = p2m_access_##ac
>+        ACCESS(n),
>+        ACCESS(r),
>+        ACCESS(w),
>+        ACCESS(rw),
>+        ACCESS(x),
>+        ACCESS(rx),
>+        ACCESS(wx),
>+        ACCESS(rwx),
>+        ACCESS(rx2rw),
>+        ACCESS(n2rwx),
>+#undef ACCESS
>     };
>
>-    if ( (unsigned) access >= HVMMEM_access_default )
>+    switch ( access )
>+    {
>+    case 0 ... ARRAY_SIZE(memaccess) - 1:
>+        a = memaccess[access];
>+        break;
>+    case HVMMEM_access_default:
>+        a = p2m->default_access;
>+        break;
>+    default:
>         return -EINVAL;
>-
>-    a = memaccess[access];
>+    }
>
>     /* If request to set default access */
>     if ( pfn == ~0ul )
>
>
>
>
>_______________________________________________
>Xen-devel mailing list
>Xen-devel@xxxxxxxxxxxxx
>http://lists.xen.org/xen-devel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel