[PATCH]Make the intel-iommu_wait_op macro work when jiffies are not running

[PATCH]Make the intel-iommu_wait_op macro work when jiffies are not running

[mark gross]

The following patch changes the intel-iommu.c code to use the TSC
instead of jiffies for detecting bad DMAR functionality.  Some systems
with bad bios's have been seen to hang in early boot spinning in the
IOMMU_WAIT_IO macro.  This patch will replace the forever spin with a
call to panic.


diffstat:
$ diffstat patches/wait_op_tsc.patch 
 intel-iommu.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--mgross

Signed-off-by:mark gross <mgross@linux.intel.com>


Index: linux-next/drivers/pci/intel-iommu.c
===================================================================
--- linux-next.orig/drivers/pci/intel-iommu.c	2008-05-08 11:02:21.000000000 -0700
+++ linux-next/drivers/pci/intel-iommu.c	2008-05-08 11:13:02.000000000 -0700
@@ -49,7 +49,7 @@
 
 #define DEFAULT_DOMAIN_ADDRESS_WIDTH 48
 
-#define DMAR_OPERATION_TIMEOUT (HZ*60) /* 1m */
+#define DMAR_OPERATION_TIMEOUT ((cycles_t) tsc_khz*10*1000) /* 10sec */
 
 #define DOMAIN_MAX_ADDR(gaw) ((((u64)1) << gaw) - 1)
 
@@ -490,13 +490,13 @@
 
 #define IOMMU_WAIT_OP(iommu, offset, op, cond, sts) \
 {\
-	unsigned long start_time = jiffies;\
+	cycles_t start_time = get_cycles();\
 	while (1) {\
 		sts = op (iommu->reg + offset);\
 		if (cond)\
 			break;\
-		if (time_after(jiffies, start_time + DMAR_OPERATION_TIMEOUT))\
-			panic("DMAR hardware is malfunctioning\n");\
+		if (DMAR_OPERATION_TIMEOUT < (get_cycles() - start_time))\
+			panic("DMAR hardware is malfunctioning\n");\
 		cpu_relax();\
 	}\
 }

Re: [PATCH]Make the intel-iommu_wait_op macro work when jiffies are not running

[Jesse Barnes]

On Monday, May 12, 2008 1:41 pm mark gross wrote:
> The following patch changes the intel-iommu.c code to use the TSC
> instead of jiffies for detecting bad DMAR functionality.  Some systems
> with bad bios's have been seen to hang in early boot spinning in the
> IOMMU_WAIT_IO macro.  This patch will replace the forever spin with a
> call to panic.
>
>
> diffstat:
> $ diffstat patches/wait_op_tsc.patch
>  intel-iommu.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> --mgross
>
> Signed-off-by:mark gross <mgross@linux.intel.com>

Applied to the 'for-linus' tree.

Thanks,
Jesse