Re: [Xen-devel] [PATCH 1 of 3] IOMMU: Add command line param to disable sharing of IOMMU and hap tables

[Tim Deegan <tim@xxxxxxx>]

At 09:17 +0000 on 22 Mar (1332407837), Jan Beulich wrote:
>  >>> On 21.03.12 at 20:22, Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx> 
> wrote:
> > The default is 1, and the command line parameter sets to 1. Disabling may be
> > desired if the host will contain VMs that do paging, sharing or mem access, 
> > and
> > won't be doing passthrough. These two features are mutually exclusive for 
> > AMD
> > processors.
> > 
> > Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
> > 
> > diff -r d7e417afcbe4 -r 642c0e6a01c2 xen/drivers/passthrough/iommu.c
> > --- a/xen/drivers/passthrough/iommu.c
> > +++ b/xen/drivers/passthrough/iommu.c
> > @@ -87,6 +87,8 @@ static void __init parse_iommu_param(cha
> >              iommu_dom0_strict = 1;
> >          else if ( !strcmp(s, "sharept") )
> >              iommu_hap_pt_share = 1;
> > +        else if ( !strcmp(s, "no-sharept") )
> > +            iommu_hap_pt_share = 0;
> 
> Taking the description above into consideration - why not simply
> replace the pointless enabling option with the disabling one?

Let's just fix the whole function to handle 'no-' the way the main
parser does:

-----

IOMMU: clean up handling of 'foo' and 'no-foo' command-line options

Signed-off-by: Tim Deegan <tim@xxxxxxx>

diff -r 8180cb3895af xen/drivers/passthrough/iommu.c
--- a/xen/drivers/passthrough/iommu.c   Thu Mar 22 10:26:45 2012 +0000
+++ b/xen/drivers/passthrough/iommu.c   Thu Mar 22 10:38:48 2012 +0000
@@ -57,36 +57,41 @@ DEFINE_PER_CPU(bool_t, iommu_dont_flush_
 static void __init parse_iommu_param(char *s)
 {
     char *ss;
+    int val;
 
     do {
+        val = !!strncmp(s, "no-", 3);
+        if ( !val )
+            s += 3;
+
         ss = strchr(s, ',');
         if ( ss )
             *ss = '\0';
 
         if ( !parse_bool(s) )
-            iommu_enabled = 0;
+            iommu_enabled = val;
         else if ( !strcmp(s, "force") || !strcmp(s, "required") )
-            force_iommu = 1;
+            force_iommu = val;
         else if ( !strcmp(s, "workaround_bios_bug") )
             iommu_workaround_bios_bug = 1;
         else if ( !strcmp(s, "verbose") )
-            iommu_verbose = 1;
-        else if ( !strcmp(s, "no-snoop") )
-            iommu_snoop = 0;
-        else if ( !strcmp(s, "no-qinval") )
-            iommu_qinval = 0;
-        else if ( !strcmp(s, "no-intremap") )
-            iommu_intremap = 0;
+            iommu_verbose = val;
+        else if ( !strcmp(s, "snoop") )
+            iommu_snoop = val;
+        else if ( !strcmp(s, "qinval") )
+            iommu_qinval = val;
+        else if ( !strcmp(s, "intremap") )
+            iommu_intremap = val;
         else if ( !strcmp(s, "debug") )
-            iommu_debug = 1;
+            iommu_debug = val;
         else if ( !strcmp(s, "amd-iommu-perdev-intremap") )
-            amd_iommu_perdev_intremap = 1;
+            amd_iommu_perdev_intremap = val;
         else if ( !strcmp(s, "dom0-passthrough") )
-            iommu_passthrough = 1;
+            iommu_passthrough = val;
         else if ( !strcmp(s, "dom0-strict") )
-            iommu_dom0_strict = 1;
+            iommu_dom0_strict = val;
         else if ( !strcmp(s, "sharept") )
-            iommu_hap_pt_share = 1;
+            iommu_hap_pt_share = val;
 
         s = ss + 1;
     } while ( ss );

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