Re: [PATCH V4 2/6] perf/amd/iommu: Modify functions to query max banks and counters
From: Suravee Suthikulpanit
Date: Sun Feb 21 2016 - 23:56:04 EST
Hi,
On 02/18/2016 06:11 PM, Borislav Petkov wrote:
On Thu, Feb 11, 2016 at 04:15:23PM +0700, Suravee Suthikulpanit wrote:
Currently, amd_iommu_pc_get_max_[banks|counters]() require devid,
which should not be the case.
Why?
Commit message could use an explanation.
Also, these don't properly support
multi-IOMMU system.
Current and future AMD systems with IOMMU that support perf counter
"with an IOMMU that supports performance counters"
would likely contain homogeneous IOMMUs where multiple IOMMUs are
What are homogeneous IOMMUs?
I intended to mean the same IOMMU version/capability for all IOMMUs in
the system.
availalbe. So, this patch modifies these function to iterate all IOMMU
Please integrate a spellchecker in your patch creation workflow:
s/availalbe/available/
Thanks. I have now rephrased and spell check the new commit message for
the V5.
Reviewed-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
---
arch/x86/events/amd/iommu.c | 17 +++++++----------
arch/x86/include/asm/perf/amd/iommu.h | 7 ++-----
drivers/iommu/amd_iommu_init.c | 20 ++++++++++++--------
3 files changed, 21 insertions(+), 23 deletions(-)
diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
index 2f96072..debf22d 100644
--- a/arch/x86/events/amd/iommu.c
+++ b/arch/x86/events/amd/iommu.c
@@ -232,14 +232,6 @@ static int perf_iommu_event_init(struct perf_event *event)
return -EINVAL;
}
- /* integrate with iommu base devid (0000), assume one iommu */
- perf_iommu->max_banks =
- amd_iommu_pc_get_max_banks(IOMMU_BASE_DEVID);
- perf_iommu->max_counters =
- amd_iommu_pc_get_max_counters(IOMMU_BASE_DEVID);
- if ((perf_iommu->max_banks == 0) || (perf_iommu->max_counters == 0))
- return -EINVAL;
-
/* update the hw_perf_event struct with the iommu config data */
hwc->config = config;
hwc->extra_reg.config = config1;
@@ -450,6 +442,11 @@ static __init int _init_perf_amd_iommu(
Btw, that _init_perf_amd_iommu is unnecessarily split from
amd_iommu_pc_init(). You should merge those two. But that's another
patch. In that same cleanup patch you could do
s/perf_iommu/pi/g
or so because that perf_iommu local var is unnecesarily long and impairs
readability.
Sure, I'll clean up both of these.
if (_init_events_attrs(perf_iommu) != 0)
pr_err("perf: amd_iommu: Only support raw events.\n");
+ perf_iommu->max_banks = amd_iommu_pc_get_max_banks();
+ perf_iommu->max_counters = amd_iommu_pc_get_max_counters();
+ if ((perf_iommu->max_banks == 0) || (perf_iommu->max_counters == 0))
Simplify:
if (!perf_iommu->max_banks ||
!perf_iommu->max_counters)
Ok
[....]
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index d30f4b2..a62b5ce 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2251,15 +2251,17 @@ EXPORT_SYMBOL(amd_iommu_v2_supported);
*
****************************************************************************/
-u8 amd_iommu_pc_get_max_banks(u16 devid)
+u8 amd_iommu_pc_get_max_banks(void)
{
struct amd_iommu *iommu;
u8 ret = 0;
- /* locate the iommu governing the devid */
- iommu = amd_iommu_rlookup_table[devid];
- if (iommu)
+ for_each_iommu(iommu) {
+ if (!iommu->max_banks ||
+ (ret && (iommu->max_banks != ret)))
What is that supposed to do?
Check that the max_banks of a previous IOMMU are == to the max_banks of
the current IOMMU?
Why? Could definitely use a comment.
Current AMD IOMMU perf implementation assumes that all IOMMUs must have
the same value of max_counters. Therefore, this logic iterates through
all IOMMUs to check this. I'll add the comment here.
Thanks,
Suravee