iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

perf/x86/amd/ibs: Don't include randomized bits in get_ibs_op_count()

Browse Source 
commit 680d69635005ba0e58fe3f4c52fc162b8fc743b0 upstream.

get_ibs_op_count() adds hardware's current count (IbsOpCurCnt) bits
to its count regardless of hardware's valid status.

According to the PPR for AMD Family 17h Model 31h B0 55803 Rev 0.54,
if the counter rolls over, valid status is set, and the lower 7 bits
of IbsOpCurCnt are randomized by hardware.

Don't include those bits in the driver's event count.

Fixes: 8b1e13638d46 ("perf/x86-ibs: Fix usage of IBS op current count")
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kim Phillips 2020-09-08 16:47:37 -05:00 committed by Greg Kroah-Hartman
parent 4c09a618ed
commit df383f9814
1 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
arch/x86/events/amd/ibs.c
View File

@ -346,11 +346,15 @@ static u64 get_ibs_op_count(u64 config)
{
u64 count = 0;
/*
* If the internal 27-bit counter rolled over, the count is MaxCnt
* and the lower 7 bits of CurCnt are randomized.
* Otherwise CurCnt has the full 27-bit current counter value.
*/
if (config & IBS_OP_VAL)
count += (config & IBS_OP_MAX_CNT) << 4; /* cnt rolled over */
if (ibs_caps & IBS_CAPS_RDWROPCNT)
count += (config & IBS_OP_CUR_CNT) >> 32;
count = (config & IBS_OP_MAX_CNT) << 4;
else if (ibs_caps & IBS_CAPS_RDWROPCNT)
count = (config & IBS_OP_CUR_CNT) >> 32;
return count;
}