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[PATCH V4 3/4] perf/x86/intel/uncore: Fix die ID init and look up bugs

Zide Chen posted 4 patches 3 weeks, 3 days ago
There is a newer version of this series
[PATCH V4 3/4] perf/x86/intel/uncore: Fix die ID init and look up bugs
Posted by Zide Chen 3 weeks, 3 days ago 
In snbep_pci2phy_map_init(), in the nr_node_ids > 8 path,
uncore_device_to_die() may return -1 when all CPUs associated
with the UBOX device are offline.

Remove the WARN_ON_ONCE(die_id == -1) check for two reasons:

- The current code breaks out of the loop. This is incorrect because
  pci_get_device() does not guarantee iteration in domain or bus order,
  so additional UBOX devices may be skipped during the scan.

- Returning -EINVAL is incorrect, since marking offline buses with
  die_id == -1 is expected and should not be treated as an error.

Separately, when NUMA is disabled on a NUMA-capable platform,
pcibus_to_node() returns NUMA_NO_NODE, causing uncore_device_to_die()
to return -1 for all PCI devices.  As a result,
spr_update_device_location(), used on Intel SPR and EMR, ignores the
corresponding PMON units and does not add them to the RB tree.

Fix this by using uncore_pcibus_to_dieid(), which retrieves topology
from the UBOX GIDNIDMAP register and works regardless of whether NUMA
is enabled in Linux.  This requires snbep_pci2phy_map_init() to be
added in spr_uncore_pci_init().

Keep uncore_device_to_die() only for the nr_node_ids > 8 case, where
NUMA is expected to be enabled.

Fixes: 9a7832ce3d92 ("perf/x86/intel/uncore: With > 8 nodes, get pci bus die id from NUMA info")
Fixes: 65248a9a9ee1 ("perf/x86/uncore: Add a quirk for UPI on SPR")
Tested-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
V2:
- Fix the commit message to note that spr_update_device_location() is
  used by EMR, not GNR.
- Rewrite the commit message for clarity.
- Add a Tested-by tag.

V4: no changes.
---
 arch/x86/events/intel/uncore.c       |  1 +
 arch/x86/events/intel/uncore_snbep.c | 13 ++++++-------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 786bd51a0d89..e9cc1ba921c5 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -67,6 +67,7 @@ int uncore_die_to_segment(int die)
 	return bus ? pci_domain_nr(bus) : -EINVAL;
 }
 
+/* Note: This API can only be used when NUMA information is available. */
 int uncore_device_to_die(struct pci_dev *dev)
 {
 	int node = pcibus_to_node(dev->bus);
diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 9b51883fd6fd..421378f681d7 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -1459,13 +1459,7 @@ static int snbep_pci2phy_map_init(int devid, int nodeid_loc, int idmap_loc, bool
 			}
 
 			map->pbus_to_dieid[bus] = die_id = uncore_device_to_die(ubox_dev);
-
 			raw_spin_unlock(&pci2phy_map_lock);
-
-			if (WARN_ON_ONCE(die_id == -1)) {
-				err = -EINVAL;
-				break;
-			}
 		}
 	}
 
@@ -6420,7 +6414,7 @@ static void spr_update_device_location(int type_id)
 
 	while ((dev = pci_get_device(PCI_VENDOR_ID_INTEL, device, dev)) != NULL) {
 
-		die = uncore_device_to_die(dev);
+		die = uncore_pcibus_to_dieid(dev->bus);
 		if (die < 0)
 			continue;
 
@@ -6444,6 +6438,11 @@ static void spr_update_device_location(int type_id)
 
 int spr_uncore_pci_init(void)
 {
+	int ret = snbep_pci2phy_map_init(0x3250, SKX_CPUNODEID, SKX_GIDNIDMAP, true);
+
+	if (ret)
+		return ret;
+
 	/*
 	 * The discovery table of UPI on some SPR variant is broken,
 	 * which impacts the detection of both UPI and M3UPI uncore PMON.
-- 
2.53.0
Re: [PATCH V4 3/4] perf/x86/intel/uncore: Fix die ID init and look up bugs
Posted by Mi, Dapeng 3 weeks, 1 day ago 
On 3/14/2026 1:40 AM, Zide Chen wrote:
> In snbep_pci2phy_map_init(), in the nr_node_ids > 8 path,
> uncore_device_to_die() may return -1 when all CPUs associated
> with the UBOX device are offline.
>
> Remove the WARN_ON_ONCE(die_id == -1) check for two reasons:
>
> - The current code breaks out of the loop. This is incorrect because
>   pci_get_device() does not guarantee iteration in domain or bus order,
>   so additional UBOX devices may be skipped during the scan.
>
> - Returning -EINVAL is incorrect, since marking offline buses with
>   die_id == -1 is expected and should not be treated as an error.
>
> Separately, when NUMA is disabled on a NUMA-capable platform,
> pcibus_to_node() returns NUMA_NO_NODE, causing uncore_device_to_die()
> to return -1 for all PCI devices.  As a result,
> spr_update_device_location(), used on Intel SPR and EMR, ignores the
> corresponding PMON units and does not add them to the RB tree.
>
> Fix this by using uncore_pcibus_to_dieid(), which retrieves topology
> from the UBOX GIDNIDMAP register and works regardless of whether NUMA
> is enabled in Linux.  This requires snbep_pci2phy_map_init() to be
> added in spr_uncore_pci_init().
>
> Keep uncore_device_to_die() only for the nr_node_ids > 8 case, where
> NUMA is expected to be enabled.
>
> Fixes: 9a7832ce3d92 ("perf/x86/intel/uncore: With > 8 nodes, get pci bus die id from NUMA info")
> Fixes: 65248a9a9ee1 ("perf/x86/uncore: Add a quirk for UPI on SPR")
> Tested-by: Steve Wahl <steve.wahl@hpe.com>
> Signed-off-by: Zide Chen <zide.chen@intel.com>
> ---
> V2:
> - Fix the commit message to note that spr_update_device_location() is
>   used by EMR, not GNR.
> - Rewrite the commit message for clarity.
> - Add a Tested-by tag.
>
> V4: no changes.
> ---
>  arch/x86/events/intel/uncore.c       |  1 +
>  arch/x86/events/intel/uncore_snbep.c | 13 ++++++-------
>  2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
> index 786bd51a0d89..e9cc1ba921c5 100644
> --- a/arch/x86/events/intel/uncore.c
> +++ b/arch/x86/events/intel/uncore.c
> @@ -67,6 +67,7 @@ int uncore_die_to_segment(int die)
>  	return bus ? pci_domain_nr(bus) : -EINVAL;
>  }
>  
> +/* Note: This API can only be used when NUMA information is available. */
>  int uncore_device_to_die(struct pci_dev *dev)
>  {
>  	int node = pcibus_to_node(dev->bus);
> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
> index 9b51883fd6fd..421378f681d7 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -1459,13 +1459,7 @@ static int snbep_pci2phy_map_init(int devid, int nodeid_loc, int idmap_loc, bool
>  			}
>  
>  			map->pbus_to_dieid[bus] = die_id = uncore_device_to_die(ubox_dev);

The "die_id" variable is not needed any more after removing below check,
please remove it.

Others look good to me. Thanks.


> -
>  			raw_spin_unlock(&pci2phy_map_lock);
> -
> -			if (WARN_ON_ONCE(die_id == -1)) {
> -				err = -EINVAL;
> -				break;
> -			}
>  		}
>  	}
>  
> @@ -6420,7 +6414,7 @@ static void spr_update_device_location(int type_id)
>  
>  	while ((dev = pci_get_device(PCI_VENDOR_ID_INTEL, device, dev)) != NULL) {
>  
> -		die = uncore_device_to_die(dev);
> +		die = uncore_pcibus_to_dieid(dev->bus);
>  		if (die < 0)
>  			continue;
>  
> @@ -6444,6 +6438,11 @@ static void spr_update_device_location(int type_id)
>  
>  int spr_uncore_pci_init(void)
>  {
> +	int ret = snbep_pci2phy_map_init(0x3250, SKX_CPUNODEID, SKX_GIDNIDMAP, true);
> +
> +	if (ret)
> +		return ret;
> +
>  	/*
>  	 * The discovery table of UPI on some SPR variant is broken,
>  	 * which impacts the detection of both UPI and M3UPI uncore PMON.
Re: [PATCH V4 3/4] perf/x86/intel/uncore: Fix die ID init and look up bugs
Posted by Chen, Zide 3 weeks ago 

On 3/15/2026 11:53 PM, Mi, Dapeng wrote:
> 
> On 3/14/2026 1:40 AM, Zide Chen wrote:
>> In snbep_pci2phy_map_init(), in the nr_node_ids > 8 path,
>> uncore_device_to_die() may return -1 when all CPUs associated
>> with the UBOX device are offline.
>>
>> Remove the WARN_ON_ONCE(die_id == -1) check for two reasons:
>>
>> - The current code breaks out of the loop. This is incorrect because
>>   pci_get_device() does not guarantee iteration in domain or bus order,
>>   so additional UBOX devices may be skipped during the scan.
>>
>> - Returning -EINVAL is incorrect, since marking offline buses with
>>   die_id == -1 is expected and should not be treated as an error.
>>
>> Separately, when NUMA is disabled on a NUMA-capable platform,
>> pcibus_to_node() returns NUMA_NO_NODE, causing uncore_device_to_die()
>> to return -1 for all PCI devices.  As a result,
>> spr_update_device_location(), used on Intel SPR and EMR, ignores the
>> corresponding PMON units and does not add them to the RB tree.
>>
>> Fix this by using uncore_pcibus_to_dieid(), which retrieves topology
>> from the UBOX GIDNIDMAP register and works regardless of whether NUMA
>> is enabled in Linux.  This requires snbep_pci2phy_map_init() to be
>> added in spr_uncore_pci_init().
>>
>> Keep uncore_device_to_die() only for the nr_node_ids > 8 case, where
>> NUMA is expected to be enabled.
>>
>> Fixes: 9a7832ce3d92 ("perf/x86/intel/uncore: With > 8 nodes, get pci bus die id from NUMA info")
>> Fixes: 65248a9a9ee1 ("perf/x86/uncore: Add a quirk for UPI on SPR")
>> Tested-by: Steve Wahl <steve.wahl@hpe.com>
>> Signed-off-by: Zide Chen <zide.chen@intel.com>
>> ---
>> V2:
>> - Fix the commit message to note that spr_update_device_location() is
>>   used by EMR, not GNR.
>> - Rewrite the commit message for clarity.
>> - Add a Tested-by tag.
>>
>> V4: no changes.
>> ---
>>  arch/x86/events/intel/uncore.c       |  1 +
>>  arch/x86/events/intel/uncore_snbep.c | 13 ++++++-------
>>  2 files changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
>> index 786bd51a0d89..e9cc1ba921c5 100644
>> --- a/arch/x86/events/intel/uncore.c
>> +++ b/arch/x86/events/intel/uncore.c
>> @@ -67,6 +67,7 @@ int uncore_die_to_segment(int die)
>>  	return bus ? pci_domain_nr(bus) : -EINVAL;
>>  }
>>  
>> +/* Note: This API can only be used when NUMA information is available. */
>>  int uncore_device_to_die(struct pci_dev *dev)
>>  {
>>  	int node = pcibus_to_node(dev->bus);
>> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
>> index 9b51883fd6fd..421378f681d7 100644
>> --- a/arch/x86/events/intel/uncore_snbep.c
>> +++ b/arch/x86/events/intel/uncore_snbep.c
>> @@ -1459,13 +1459,7 @@ static int snbep_pci2phy_map_init(int devid, int nodeid_loc, int idmap_loc, bool
>>  			}
>>  
>>  			map->pbus_to_dieid[bus] = die_id = uncore_device_to_die(ubox_dev);
> 
> The "die_id" variable is not needed any more after removing below check,
> please remove it.

Good catch, thanks.

> Others look good to me. Thanks.
> 
> 
>> -
>>  			raw_spin_unlock(&pci2phy_map_lock);
>> -
>> -			if (WARN_ON_ONCE(die_id == -1)) {
>> -				err = -EINVAL;
>> -				break;
>> -			}
>>  		}
>>  	}
>>  
>> @@ -6420,7 +6414,7 @@ static void spr_update_device_location(int type_id)
>>  
>>  	while ((dev = pci_get_device(PCI_VENDOR_ID_INTEL, device, dev)) != NULL) {
>>  
>> -		die = uncore_device_to_die(dev);
>> +		die = uncore_pcibus_to_dieid(dev->bus);
>>  		if (die < 0)
>>  			continue;
>>  
>> @@ -6444,6 +6438,11 @@ static void spr_update_device_location(int type_id)
>>  
>>  int spr_uncore_pci_init(void)
>>  {
>> +	int ret = snbep_pci2phy_map_init(0x3250, SKX_CPUNODEID, SKX_GIDNIDMAP, true);
>> +
>> +	if (ret)
>> +		return ret;
>> +
>>  	/*
>>  	 * The discovery table of UPI on some SPR variant is broken,
>>  	 * which impacts the detection of both UPI and M3UPI uncore PMON.
[tip: perf/urgent] perf/x86/intel/uncore: Fix die ID init and look up bugs
Posted by tip-bot2 for Zide Chen 2 hours ago 
The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     a16d1ec4dd0cdcf689f324adde6067083bce9099
Gitweb:        https://git.kernel.org/tip/a16d1ec4dd0cdcf689f324adde6067083bce9099
Author:        Zide Chen <zide.chen@intel.com>
AuthorDate:    Fri, 13 Mar 2026 10:40:49 -07:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 07 Apr 2026 09:05:29 +02:00

perf/x86/intel/uncore: Fix die ID init and look up bugs

In snbep_pci2phy_map_init(), in the nr_node_ids > 8 path,
uncore_device_to_die() may return -1 when all CPUs associated
with the UBOX device are offline.

Remove the WARN_ON_ONCE(die_id == -1) check for two reasons:

- The current code breaks out of the loop. This is incorrect because
  pci_get_device() does not guarantee iteration in domain or bus order,
  so additional UBOX devices may be skipped during the scan.

- Returning -EINVAL is incorrect, since marking offline buses with
  die_id == -1 is expected and should not be treated as an error.

Separately, when NUMA is disabled on a NUMA-capable platform,
pcibus_to_node() returns NUMA_NO_NODE, causing uncore_device_to_die()
to return -1 for all PCI devices.  As a result,
spr_update_device_location(), used on Intel SPR and EMR, ignores the
corresponding PMON units and does not add them to the RB tree.

Fix this by using uncore_pcibus_to_dieid(), which retrieves topology
from the UBOX GIDNIDMAP register and works regardless of whether NUMA
is enabled in Linux.  This requires snbep_pci2phy_map_init() to be
added in spr_uncore_pci_init().

Keep uncore_device_to_die() only for the nr_node_ids > 8 case, where
NUMA is expected to be enabled.

Fixes: 9a7832ce3d92 ("perf/x86/intel/uncore: With > 8 nodes, get pci bus die id from NUMA info")
Fixes: 65248a9a9ee1 ("perf/x86/uncore: Add a quirk for UPI on SPR")
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://patch.msgid.link/20260313174050.171704-4-zide.chen@intel.com
---
 arch/x86/events/intel/uncore.c       |  1 +
 arch/x86/events/intel/uncore_snbep.c | 13 ++++++-------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 786bd51..e9cc1ba 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -67,6 +67,7 @@ int uncore_die_to_segment(int die)
 	return bus ? pci_domain_nr(bus) : -EINVAL;
 }
 
+/* Note: This API can only be used when NUMA information is available. */
 int uncore_device_to_die(struct pci_dev *dev)
 {
 	int node = pcibus_to_node(dev->bus);
diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 0a1d081..a4b337b 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -1459,13 +1459,7 @@ static int snbep_pci2phy_map_init(int devid, int nodeid_loc, int idmap_loc, bool
 			}
 
 			map->pbus_to_dieid[bus] = die_id = uncore_device_to_die(ubox_dev);
-
 			raw_spin_unlock(&pci2phy_map_lock);
-
-			if (WARN_ON_ONCE(die_id == -1)) {
-				err = -EINVAL;
-				break;
-			}
 		}
 	}
 
@@ -6420,7 +6414,7 @@ static void spr_update_device_location(int type_id)
 
 	while ((dev = pci_get_device(PCI_VENDOR_ID_INTEL, device, dev)) != NULL) {
 
-		die = uncore_device_to_die(dev);
+		die = uncore_pcibus_to_dieid(dev->bus);
 		if (die < 0)
 			continue;
 
@@ -6444,6 +6438,11 @@ static void spr_update_device_location(int type_id)
 
 int spr_uncore_pci_init(void)
 {
+	int ret = snbep_pci2phy_map_init(0x3250, SKX_CPUNODEID, SKX_GIDNIDMAP, true);
+
+	if (ret)
+		return ret;
+
 	/*
 	 * The discovery table of UPI on some SPR variant is broken,
 	 * which impacts the detection of both UPI and M3UPI uncore PMON.

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