Re: [PATCH] VT-d: improve RMRR validity checking

[Noboru Iwamatsu <n_iwamatsu@jp.fujitsu.com>]

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Hi,

Some Q35 mainboard that has buggy BIOS, I have one of this,
reports invalid DRHD in addition to the invalid RMRR.

Attached patch fixes this DRHD issue in the same way as RMRR.
And also, I fixed RMRR validity checking loop.

Noboru.

Signed-off-by: Noboru Iwamatsu <n_iwamatsu@jp.fujitsu.com>


-------- Original Message  --------
Subject: [Xen-devel] [PATCH] VT-d: improve RMRR validity checking
From: Han, Weidong <weidong.han@intel.com>
To: xen-devel@lists.xensource.com <xen-devel@lists.xensource.com>
Date: Thu Jan 21 2010 11:46:12 GMT+0900

> Currently, Xen checks RMRR range and disables VT-d if RMRR range is set incorrectly in BIOS rigorously. But, actually we can ignore the RMRR if the device under its scope are not pci discoverable, because the RMRR won't be used by non-existed or disabled devices.
>
> This patch ignores the RMRR if the device under its scope are not pci discoverable, and only checks the validity of RMRRs that are actually used. In order to avoid duplicate pci device detection code, this patch defines a function pci_device_detect for it.
>
> Signed-off-by: Weidong Han<weidong.han@intel.com>
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel


[-- Attachment #2: 01_vtd-drhd-workaround.patch --]
[-- Type: text/plain, Size: 1086 bytes --]

diff -r bbad08b156e9 -r 072ffd2fa8f7 xen/drivers/passthrough/vtd/dmar.c
--- a/xen/drivers/passthrough/vtd/dmar.c	Thu Jan 21 14:08:42 2010 +0900
+++ b/xen/drivers/passthrough/vtd/dmar.c	Thu Jan 21 16:39:46 2010 +0900
@@ -397,7 +397,34 @@
     if ( ret )
         xfree(dmaru);
     else
-        acpi_register_drhd_unit(dmaru);
+    {
+        u8 b, d, f;
+        int i, ignore = 0;
+
+        for ( i = 0; i < dmaru->scope.devices_cnt; i++ )
+        {
+            b = PCI_BUS(dmaru->scope.devices[i]);
+            d = PCI_SLOT(dmaru->scope.devices[i]);
+            f = PCI_FUNC(dmaru->scope.devices[i]);
+
+            if ( pci_device_detect(b, d, f) == 0 )
+            {
+                ignore = 1;
+                break;
+            }
+        }
+
+        if ( ignore )
+        {
+            dprintk(XENLOG_WARNING VTDPREFIX,
+                "  Ignore the DRHD due to "
+                "devices under its scope are not PCI discoverable!\n");
+            xfree(dmaru);
+        }
+        else
+            acpi_register_drhd_unit(dmaru);
+    }
+
     return ret;
 }
 

[-- Attachment #3: 02_vtd-rmrr-workaround-fix.patch --]
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diff -r 072ffd2fa8f7 -r 958f11b847cc xen/drivers/passthrough/vtd/dmar.c
--- a/xen/drivers/passthrough/vtd/dmar.c	Thu Jan 21 16:39:46 2010 +0900
+++ b/xen/drivers/passthrough/vtd/dmar.c	Thu Jan 21 16:42:04 2010 +0900
@@ -480,10 +480,8 @@
             f = PCI_FUNC(rmrru->scope.devices[i]);
 
             if ( pci_device_detect(b, d, f) == 0 )
+            {
                 ignore = 1;
-            else
-            {
-                ignore = 0;
                 break;
             }
         }

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