From: "tip-bot2 for Kan Liang" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: John Donnelly <john.p.donnelly@oracle.com>,
Kan Liang <kan.liang@linux.intel.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: perf/urgent] perf/x86/intel/uncore: Fix a kernel WARNING triggered by maxcpus=1
Date: Mon, 31 May 2021 10:40:43 -0000 [thread overview]
Message-ID: <162245764326.29796.16594314779095776973.tip-bot2@tip-bot2> (raw)
In-Reply-To: <1622037527-156028-1-git-send-email-kan.liang@linux.intel.com>
The following commit has been merged into the perf/urgent branch of tip:
Commit-ID: 4a0e3ff30980b7601b13dd3b7ee275212b852843
Gitweb: https://git.kernel.org/tip/4a0e3ff30980b7601b13dd3b7ee275212b852843
Author: Kan Liang <kan.liang@linux.intel.com>
AuthorDate: Wed, 26 May 2021 06:58:47 -07:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 31 May 2021 10:14:51 +02:00
perf/x86/intel/uncore: Fix a kernel WARNING triggered by maxcpus=1
A kernel WARNING may be triggered when setting maxcpus=1.
The uncore counters are Die-scope. When probing a PCI device, only the
BUS information can be retrieved. The uncore driver has to maintain a
mapping table used to calculate the logical Die ID from a given BUS#.
Before the patch ba9506be4e40, the mapping table stores the mapping
information from the BUS# -> a Physical Socket ID. To calculate the
logical die ID, perf does,
- In snbep_pci2phy_map_init(), retrieve the BUS# -> a Physical Socket ID
from the UBOX PCI configure space.
- Calculate the mapping information (a BUS# -> a Physical Socket ID) for
the other PCI BUS.
- In the uncore_pci_probe(), get the physical Socket ID from a given BUS
and the mapping table.
- Calculate the logical Die ID
Since only the logical Die ID is required, with the patch ba9506be4e40,
the mapping table stores the mapping information from the BUS# -> a
logical Die ID. Now perf does,
- In snbep_pci2phy_map_init(), retrieve the BUS# -> a Physical Socket ID
from the UBOX PCI configure space.
- Calculate the logical Die ID
- Calculate the mapping information (a BUS# -> a logical Die ID) for the
other PCI BUS.
- In the uncore_pci_probe(), get the logical die ID from a given BUS and
the mapping table.
When calculating the logical Die ID, -1 may be returned, especially when
maxcpus=1. Here, -1 means the logical Die ID is not found. But when
calculating the mapping information for the other PCI BUS, -1 indicates
that it's the other PCI BUS that requires the calculation of the
mapping. The driver will mistakenly do the calculation.
Uses the -ENODEV to indicate the case which the logical Die ID is not
found. The driver will not mess up the mapping table anymore.
Fixes: ba9506be4e40 ("perf/x86/intel/uncore: Store the logical die id instead of the physical die id.")
Reported-by: John Donnelly <john.p.donnelly@oracle.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Donnelly <john.p.donnelly@oracle.com>
Tested-by: John Donnelly <john.p.donnelly@oracle.com>
Link: https://lkml.kernel.org/r/1622037527-156028-1-git-send-email-kan.liang@linux.intel.com
---
arch/x86/events/intel/uncore_snbep.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 63f0972..1587d32 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -1406,6 +1406,8 @@ static int snbep_pci2phy_map_init(int devid, int nodeid_loc, int idmap_loc, bool
die_id = i;
else
die_id = topology_phys_to_logical_pkg(i);
+ if (die_id < 0)
+ die_id = -ENODEV;
map->pbus_to_dieid[bus] = die_id;
break;
}
@@ -1452,14 +1454,14 @@ static int snbep_pci2phy_map_init(int devid, int nodeid_loc, int idmap_loc, bool
i = -1;
if (reverse) {
for (bus = 255; bus >= 0; bus--) {
- if (map->pbus_to_dieid[bus] >= 0)
+ if (map->pbus_to_dieid[bus] != -1)
i = map->pbus_to_dieid[bus];
else
map->pbus_to_dieid[bus] = i;
}
} else {
for (bus = 0; bus <= 255; bus++) {
- if (map->pbus_to_dieid[bus] >= 0)
+ if (map->pbus_to_dieid[bus] != -1)
i = map->pbus_to_dieid[bus];
else
map->pbus_to_dieid[bus] = i;
prev parent reply other threads:[~2021-05-31 10:41 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-26 13:58 [PATCH] perf/x86/intel/uncore: Fix a kernel WARNING triggered by maxcpus=1 kan.liang
2021-05-27 11:14 ` Peter Zijlstra
2021-05-27 20:13 ` John Donnelly
2021-05-31 10:40 ` tip-bot2 for Kan Liang [this message]
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