From: Keir Fraser <keir@xen.org>
Date: Wed, 9 Feb 2011 08:40:05 +0000 (+0000)
Subject: [VTD][QUIRK] add spin lock across snb pre/postamble functions
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~10801
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks://%22Dat/%22http:/www.example.com/cgi/%22https:/%22bookmarks:/%22Dat?a=commitdiff_plain;h=f4b185362da47e1d9189ed3eb73cd8eca80c364e;p=xen.git

[VTD][QUIRK] add spin lock across snb pre/postamble functions

Added a spinlock across snb_vtd_ops_preamble() and
snb_vtd_ops_postamble() to make modifications to IGD registers atomic.
Continue keeping snb_igd_quirk default off.

Signed-off-by: Allen Kay <allen.m.kay@intel.com>
---

diff --git a/xen/drivers/passthrough/vtd/quirks.c b/xen/drivers/passthrough/vtd/quirks.c
index ef6c8d0f29..0f7db71443 100644
--- a/xen/drivers/passthrough/vtd/quirks.c
+++ b/xen/drivers/passthrough/vtd/quirks.c
@@ -55,6 +55,7 @@ bool_t rwbf_quirk;
 static int is_cantiga_b3;
 static int is_snb_gfx;
 static u8 *igd_reg_va;
+static spinlock_t igd_lock;
 
 /*
  * QUIRK to workaround Xen boot issue on Calpella/Ironlake OEM BIOS
@@ -98,6 +99,7 @@ static void cantiga_b3_errata_init(void)
 static void snb_errata_init(void)
 {
     is_snb_gfx = IS_SNB_GFX(igd_id);
+    spin_lock_init(&igd_lock);
 }
 
 /*
@@ -225,7 +227,12 @@ void vtd_ops_preamble_quirk(struct iommu* iommu)
 {
     cantiga_vtd_ops_preamble(iommu);
     if ( snb_igd_quirk )
+    {
+        spin_lock(&igd_lock);
+
+        /* match unlock in postamble */
         snb_vtd_ops_preamble(iommu);
+    }
 }
 
 /*
@@ -234,7 +241,12 @@ void vtd_ops_preamble_quirk(struct iommu* iommu)
 void vtd_ops_postamble_quirk(struct iommu* iommu)
 {
     if ( snb_igd_quirk )
+    {
         snb_vtd_ops_postamble(iommu);
+
+        /* match the lock in preamble */
+        spin_unlock(&igd_lock);
+    }
 }
 
 /* initialize platform identification flags */