[PATCH V2 1/7] perf/x86/intel/uncore: Fix discovery unit lookup for multi-die systems

[PATCH V2 1/7] perf/x86/intel/uncore: Fix discovery unit lookup for multi-die systems

[Zide Chen]

In uncore_find_add_unit(), PMON units with the same unit ID may be
added to the uncore discovery RB-tree for different dies. These units
are distinguished by node->die.

However, intel_generic_uncore_box_ctl() uses a fixed die ID of -1 when
looking up the discovery unit, which may retrieve the wrong node on
multi-die systems.

Use box->dieid instead so the correct discovery unit is selected.

No functional issue has been observed so far because currently supported
platforms happen to use the same unit control register for such units.

Remove WARN_ON_ONCE() because with the above change a NULL unit can be
expected, e.g. when a CPU die is offline during uncore enumeration and
the unit is not added to the RB-tree. In this case,
intel_uncore_find_discovery_unit() returns NULL once the die becomes
online, and it is expected that the PMU box is not functional for that
die.

Fixes: b1d9ea2e1ca4 ("perf/x86/uncore: Apply the unit control RB tree to MSR uncore units")
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
v2:
- Remove WARN_ON_ONCE().
---
 arch/x86/events/intel/uncore_discovery.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
index 583cbd06b9b8..60e1200c4691 100644
--- a/arch/x86/events/intel/uncore_discovery.c
+++ b/arch/x86/events/intel/uncore_discovery.c
@@ -481,8 +481,8 @@ static u64 intel_generic_uncore_box_ctl(struct intel_uncore_box *box)
 	struct intel_uncore_discovery_unit *unit;
 
 	unit = intel_uncore_find_discovery_unit(box->pmu->type->boxes,
-						-1, box->pmu->pmu_idx);
-	if (WARN_ON_ONCE(!unit))
+						box->dieid, box->pmu->pmu_idx);
+	if (!unit)
 		return 0;
 
 	return unit->addr;
-- 
2.54.0

[PATCH V2 2/7] perf/x86/intel/uncore: Guard against invalid box control address

[Zide Chen]

Theoretically, intel_uncore_find_discovery_unit() could return NULL,
e.g., when a CPU die is offline during uncore enumeration and its PMU
units are not added to the discovery RB-tree.

Guard against a NULL return value and the resulting invalid box control
address (0) before accessing hardware.

Signed-off-by: Zide Chen <zide.chen@intel.com>
---
V2:
- New patch.
- Address pre-existing invalid box control address issue (Sashiko).
---
 arch/x86/events/intel/uncore_discovery.c | 36 ++++++++++++++++++------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
index 60e1200c4691..af2217b44a81 100644
--- a/arch/x86/events/intel/uncore_discovery.c
+++ b/arch/x86/events/intel/uncore_discovery.c
@@ -490,17 +490,28 @@ static u64 intel_generic_uncore_box_ctl(struct intel_uncore_box *box)
 
 void intel_generic_uncore_msr_init_box(struct intel_uncore_box *box)
 {
-	wrmsrq(intel_generic_uncore_box_ctl(box), GENERIC_PMON_BOX_CTL_INT);
+	u64 box_ctl = intel_generic_uncore_box_ctl(box);
+
+	if (!box_ctl)
+		return;
+
+	wrmsrq(box_ctl, GENERIC_PMON_BOX_CTL_INT);
 }
 
 void intel_generic_uncore_msr_disable_box(struct intel_uncore_box *box)
 {
-	wrmsrq(intel_generic_uncore_box_ctl(box), GENERIC_PMON_BOX_CTL_FRZ);
+	u64 box_ctl = intel_generic_uncore_box_ctl(box);
+
+	if (box_ctl)
+		wrmsrq(box_ctl, GENERIC_PMON_BOX_CTL_FRZ);
 }
 
 void intel_generic_uncore_msr_enable_box(struct intel_uncore_box *box)
 {
-	wrmsrq(intel_generic_uncore_box_ctl(box), 0);
+	u64 box_ctl = intel_generic_uncore_box_ctl(box);
+
+	if (box_ctl)
+		wrmsrq(box_ctl, 0);
 }
 
 static void intel_generic_uncore_msr_enable_event(struct intel_uncore_box *box,
@@ -549,6 +560,10 @@ bool intel_generic_uncore_assign_hw_event(struct perf_event *event,
 
 	if (box->pci_dev) {
 		box_ctl = UNCORE_DISCOVERY_PCI_BOX_CTRL(box_ctl);
+
+		if (!box_ctl)
+			return false;
+
 		hwc->config_base = box_ctl + uncore_pci_event_ctl(box, hwc->idx);
 		hwc->event_base  = box_ctl + uncore_pci_perf_ctr(box, hwc->idx);
 		return true;
@@ -567,27 +582,30 @@ static inline int intel_pci_uncore_box_ctl(struct intel_uncore_box *box)
 
 void intel_generic_uncore_pci_init_box(struct intel_uncore_box *box)
 {
-	struct pci_dev *pdev = box->pci_dev;
 	int box_ctl = intel_pci_uncore_box_ctl(box);
 
+	if (!box_ctl)
+		return;
+
 	__set_bit(UNCORE_BOX_FLAG_CTL_OFFS8, &box->flags);
-	pci_write_config_dword(pdev, box_ctl, GENERIC_PMON_BOX_CTL_INT);
+	pci_write_config_dword(box->pci_dev, box_ctl, GENERIC_PMON_BOX_CTL_INT);
 }
 
 void intel_generic_uncore_pci_disable_box(struct intel_uncore_box *box)
 {
-	struct pci_dev *pdev = box->pci_dev;
 	int box_ctl = intel_pci_uncore_box_ctl(box);
 
-	pci_write_config_dword(pdev, box_ctl, GENERIC_PMON_BOX_CTL_FRZ);
+	if (box_ctl)
+		pci_write_config_dword(box->pci_dev, box_ctl,
+				       GENERIC_PMON_BOX_CTL_FRZ);
 }
 
 void intel_generic_uncore_pci_enable_box(struct intel_uncore_box *box)
 {
-	struct pci_dev *pdev = box->pci_dev;
 	int box_ctl = intel_pci_uncore_box_ctl(box);
 
-	pci_write_config_dword(pdev, box_ctl, 0);
+	if (box_ctl)
+		pci_write_config_dword(box->pci_dev, box_ctl, 0);
 }
 
 static void intel_generic_uncore_pci_enable_event(struct intel_uncore_box *box,
-- 
2.54.0

[PATCH V2 3/7] perf/x86/intel/uncore: Fix PCI device refcount leak in UPI discovery

[Zide Chen]

pci_get_domain_bus_and_slot() increments the reference count of the
returned PCI device and therefore requires a matching pci_dev_put().

In skx_upi_topology_cb() and discover_upi_topology(), the lookup is
performed inside a loop, but pci_dev_put() is only called once after
the loop. As a result, references from all previous iterations are
leaked.

Move pci_dev_put(dev) into the if (dev) block immediately after
upi_fill_topology() returns.

Opportunistically, fix uninitialized variable in skx_upi_topology_cb().

Fixes: 4cfce57fa42d ("perf/x86/intel/uncore: Enable UPI topology discovery for Skylake Server")
Fixes: f680b6e6062e ("perf/x86/intel/uncore: Enable UPI topology discovery for Icelake Server")
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
 arch/x86/events/intel/uncore_snbep.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 215d33e260ed..c9ce206fcbb6 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -4261,7 +4261,7 @@ static int upi_fill_topology(struct pci_dev *dev, struct intel_uncore_topology *
 static int skx_upi_topology_cb(struct intel_uncore_type *type, int segment,
 				int die, u64 cpu_bus_msr)
 {
-	int idx, ret;
+	int idx, ret = 0;
 	struct intel_uncore_topology *upi;
 	unsigned int devfn;
 	struct pci_dev *dev = NULL;
@@ -4274,12 +4274,12 @@ static int skx_upi_topology_cb(struct intel_uncore_type *type, int segment,
 		dev = pci_get_domain_bus_and_slot(segment, bus, devfn);
 		if (dev) {
 			ret = upi_fill_topology(dev, upi, idx);
+			pci_dev_put(dev);
 			if (ret)
 				break;
 		}
 	}
 
-	pci_dev_put(dev);
 	return ret;
 }
 
@@ -5499,6 +5499,7 @@ static int discover_upi_topology(struct intel_uncore_type *type, int ubox_did, i
 							  devfn);
 			if (dev) {
 				ret = upi_fill_topology(dev, upi, idx);
+				pci_dev_put(dev);
 				if (ret)
 					goto err;
 			}
@@ -5506,7 +5507,6 @@ static int discover_upi_topology(struct intel_uncore_type *type, int ubox_did, i
 	}
 err:
 	pci_dev_put(ubox);
-	pci_dev_put(dev);
 	return ret;
 }
 
-- 
2.54.0

[PATCH V2 4/7] perf/x86/intel/uncore: Defer ADL global PMON enable to enable_box()

[Zide Chen]

On some Raptor Cove CPUs, enabling uncore PMON globally at driver init
may increase power consumption even when no perf events are in use.

Drop adl_uncore_msr_init_box() and defer programming the global control
register to enable_box(), so it is only set when a box is actually used.

IMC and IMC freerunning counters use a separate control path and are
unaffected.

Cc: stable@vger.kernel.org
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
 arch/x86/events/intel/uncore_snb.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/arch/x86/events/intel/uncore_snb.c b/arch/x86/events/intel/uncore_snb.c
index 3dbc6bacbd9d..edddd4f9ab5f 100644
--- a/arch/x86/events/intel/uncore_snb.c
+++ b/arch/x86/events/intel/uncore_snb.c
@@ -563,12 +563,6 @@ void tgl_uncore_cpu_init(void)
 	skl_uncore_msr_ops.init_box = rkl_uncore_msr_init_box;
 }
 
-static void adl_uncore_msr_init_box(struct intel_uncore_box *box)
-{
-	if (box->pmu->pmu_idx == 0)
-		wrmsrq(ADL_UNC_PERF_GLOBAL_CTL, SNB_UNC_GLOBAL_CTL_EN);
-}
-
 static void adl_uncore_msr_enable_box(struct intel_uncore_box *box)
 {
 	wrmsrq(ADL_UNC_PERF_GLOBAL_CTL, SNB_UNC_GLOBAL_CTL_EN);
@@ -587,7 +581,6 @@ static void adl_uncore_msr_exit_box(struct intel_uncore_box *box)
 }
 
 static struct intel_uncore_ops adl_uncore_msr_ops = {
-	.init_box	= adl_uncore_msr_init_box,
 	.enable_box	= adl_uncore_msr_enable_box,
 	.disable_box	= adl_uncore_msr_disable_box,
 	.exit_box	= adl_uncore_msr_exit_box,
-- 
2.54.0

[PATCH V2 5/7] perf/x86/intel/uncore: Move die_to_cpu() to uncore.c

[Zide Chen]

Move die_to_cpu() into uncore.c so it can be reused by the MSR
initialization path, preparing for the introduction of an MSR global
initialization callback.

Move the cpus_read_{lock,unlock}() out of the API, in order to make
it possible to be called when the lock is being held.

Add the uncore_ prefix for consistency with other uncore APIs.

Signed-off-by: Zide Chen <zide.chen@intel.com>

V2:
- Move cpus_read_{lock,unlock}() out of uncore_die_to_cpu() and rely
  on callers to manage the lock. (Sashiko)
- Remove "No functional change intended" from the changelog.
---
 arch/x86/events/intel/uncore.c       | 19 +++++++++++++++++++
 arch/x86/events/intel/uncore.h       |  1 +
 arch/x86/events/intel/uncore_snbep.c | 23 +++--------------------
 3 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index e9cc1ba921c5..22256ded2d67 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -83,6 +83,25 @@ int uncore_device_to_die(struct pci_dev *dev)
 	return -1;
 }
 
+/*
+ * Using cpus_read_lock() to ensure cpu is not going down between
+ * looking at cpu_online_mask.
+ *
+ * The lock must be held by the caller.
+ */
+int uncore_die_to_cpu(int die)
+{
+	int res = 0, cpu;
+
+	for_each_online_cpu(cpu) {
+		if (topology_logical_die_id(cpu) == die) {
+			res = cpu;
+			break;
+		}
+	}
+	return res;
+}
+
 static void uncore_free_pcibus_map(void)
 {
 	struct pci2phy_map *map, *tmp;
diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
index c35918c01afa..94c68e3417b6 100644
--- a/arch/x86/events/intel/uncore.h
+++ b/arch/x86/events/intel/uncore.h
@@ -235,6 +235,7 @@ struct pci2phy_map *__find_pci2phy_map(int segment);
 int uncore_pcibus_to_dieid(struct pci_bus *bus);
 int uncore_die_to_segment(int die);
 int uncore_device_to_die(struct pci_dev *dev);
+int uncore_die_to_cpu(int die);
 
 ssize_t uncore_event_show(struct device *dev,
 			  struct device_attribute *attr, char *buf);
diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index c9ce206fcbb6..772b78237424 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -3704,25 +3704,6 @@ static int skx_msr_cpu_bus_read(int cpu, u64 *topology)
 	return 0;
 }
 
-static int die_to_cpu(int die)
-{
-	int res = 0, cpu, current_die;
-	/*
-	 * Using cpus_read_lock() to ensure cpu is not going down between
-	 * looking at cpu_online_mask.
-	 */
-	cpus_read_lock();
-	for_each_online_cpu(cpu) {
-		current_die = topology_logical_die_id(cpu);
-		if (current_die == die) {
-			res = cpu;
-			break;
-		}
-	}
-	cpus_read_unlock();
-	return res;
-}
-
 enum {
 	IIO_TOPOLOGY_TYPE,
 	UPI_TOPOLOGY_TYPE,
@@ -3794,8 +3775,9 @@ static int skx_pmu_get_topology(struct intel_uncore_type *type,
 	int die, ret = -EPERM;
 	u64 cpu_bus_msr;
 
+	cpus_read_lock();
 	for (die = 0; die < uncore_max_dies(); die++) {
-		ret = skx_msr_cpu_bus_read(die_to_cpu(die), &cpu_bus_msr);
+		ret = skx_msr_cpu_bus_read(uncore_die_to_cpu(die), &cpu_bus_msr);
 		if (ret)
 			break;
 
@@ -3807,6 +3789,7 @@ static int skx_pmu_get_topology(struct intel_uncore_type *type,
 		if (ret)
 			break;
 	}
+	cpus_read_unlock();
 
 	return ret;
 }
-- 
2.54.0

[PATCH V2 6/7] perf/x86/intel/uncore: Fix uncore_die_to_cpu() for offline dies

[Zide Chen]

If the die is offline when uncore_die_to_cpu() is called, it silently
returns 0, which is misleading.  Return -1 in this case to indicate
that all CPUs on the die are offline and the caller can take care of
it accordingly.

Opportunistically, replace -EPERM with -ENODEV, as -ENODEV is
the appropriate error when no CPUs are online across all dies.

Signed-off-by: Zide Chen <zide.chen@intel.com>
---
 arch/x86/events/intel/uncore.c       | 2 +-
 arch/x86/events/intel/uncore_snbep.c | 9 +++++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 22256ded2d67..4b3a1fa5b41b 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -91,7 +91,7 @@ int uncore_device_to_die(struct pci_dev *dev)
  */
 int uncore_die_to_cpu(int die)
 {
-	int res = 0, cpu;
+	int res = -1, cpu;
 
 	for_each_online_cpu(cpu) {
 		if (topology_logical_die_id(cpu) == die) {
diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 772b78237424..334dc384b5b9 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -3772,12 +3772,17 @@ static void pmu_free_topology(struct intel_uncore_type *type)
 static int skx_pmu_get_topology(struct intel_uncore_type *type,
 				 int (*topology_cb)(struct intel_uncore_type*, int, int, u64))
 {
-	int die, ret = -EPERM;
+	int die, ret = -ENODEV;
 	u64 cpu_bus_msr;
+	int cpu;
 
 	cpus_read_lock();
 	for (die = 0; die < uncore_max_dies(); die++) {
-		ret = skx_msr_cpu_bus_read(uncore_die_to_cpu(die), &cpu_bus_msr);
+		cpu = uncore_die_to_cpu(die);
+		if (cpu == -1)
+			continue;
+
+		ret = skx_msr_cpu_bus_read(cpu, &cpu_bus_msr);
 		if (ret)
 			break;
 
-- 
2.54.0

[PATCH V2 7/7] perf/x86/intel/uncore: Implement global init callback for GNR uncore

[Zide Chen]

On Sierra Forest and Clearwater Forest, the FRZ_ALL bit in the global
control register defaults to 0 at boot, but UBOX PMON units do not
work until the global control register is explicitly written with 0
to trigger hardware initialization properly.

Implement the generic uncore_msr_global_init() callback and add it to
gnr_uncore_init[], which is shared by GNR, GRR, SRF, and CWF.

Signed-off-by: Zide Chen <zide.chen@intel.com>
---
V2:
- Propagate return value of wrmsrq_on_cpu() to global_init().
---
 arch/x86/events/intel/uncore.c           | 13 ++++++++++++-
 arch/x86/events/intel/uncore.h           |  2 +-
 arch/x86/events/intel/uncore_discovery.c |  2 +-
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 4b3a1fa5b41b..7857959c6e82 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -1716,7 +1716,7 @@ static int __init uncore_mmio_init(void)
 	return ret;
 }
 
-static int uncore_mmio_global_init(u64 ctl)
+static int uncore_mmio_global_init(int die, u64 ctl)
 {
 	void __iomem *io_addr;
 
@@ -1731,6 +1731,16 @@ static int uncore_mmio_global_init(u64 ctl)
 	return 0;
 }
 
+static int uncore_msr_global_init(int die, u64 msr)
+{
+	int cpu = uncore_die_to_cpu(die);
+
+	if (cpu == -1)
+		return -ENODEV;
+
+	return wrmsrq_on_cpu(cpu, msr, 0);
+}
+
 static const struct uncore_plat_init nhm_uncore_init __initconst = {
 	.cpu_init = nhm_uncore_cpu_init,
 };
@@ -1871,6 +1881,7 @@ static const struct uncore_plat_init gnr_uncore_init __initconst = {
 	.domain[0].base_is_pci = true,
 	.domain[0].discovery_base = UNCORE_DISCOVERY_TABLE_DEVICE,
 	.domain[0].units_ignore = gnr_uncore_units_ignore,
+	.domain[0].global_init = uncore_msr_global_init,
 };
 
 static const struct uncore_plat_init dmr_uncore_init __initconst = {
diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
index 94c68e3417b6..c2e5ccb1d72c 100644
--- a/arch/x86/events/intel/uncore.h
+++ b/arch/x86/events/intel/uncore.h
@@ -53,7 +53,7 @@ struct uncore_discovery_domain {
 	/* MSR address or PCI device used as the discovery base */
 	u32	discovery_base;
 	bool	base_is_pci;
-	int	(*global_init)(u64 ctl);
+	int	(*global_init)(int die, u64 ctl);
 
 	/* The units in the discovery table should be ignored. */
 	int	*units_ignore;
diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
index af2217b44a81..e36613d934b1 100644
--- a/arch/x86/events/intel/uncore_discovery.c
+++ b/arch/x86/events/intel/uncore_discovery.c
@@ -287,7 +287,7 @@ static int __parse_discovery_table(struct uncore_discovery_domain *domain,
 	if (!io_addr)
 		return -ENOMEM;
 
-	if (domain->global_init && domain->global_init(global.ctl)) {
+	if (domain->global_init && domain->global_init(die, global.ctl)) {
 		ret = -ENODEV;
 		goto out;
 	}
-- 
2.54.0

Re: [PATCH V2 1/7] perf/x86/intel/uncore: Fix discovery unit lookup for multi-die systems

[Mi, Dapeng]

LGTM.

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>

On 5/27/2026 11:11 PM, Zide Chen wrote:
> In uncore_find_add_unit(), PMON units with the same unit ID may be
> added to the uncore discovery RB-tree for different dies. These units
> are distinguished by node->die.
>
> However, intel_generic_uncore_box_ctl() uses a fixed die ID of -1 when
> looking up the discovery unit, which may retrieve the wrong node on
> multi-die systems.
>
> Use box->dieid instead so the correct discovery unit is selected.
>
> No functional issue has been observed so far because currently supported
> platforms happen to use the same unit control register for such units.
>
> Remove WARN_ON_ONCE() because with the above change a NULL unit can be
> expected, e.g. when a CPU die is offline during uncore enumeration and
> the unit is not added to the RB-tree. In this case,
> intel_uncore_find_discovery_unit() returns NULL once the die becomes
> online, and it is expected that the PMU box is not functional for that
> die.
>
> Fixes: b1d9ea2e1ca4 ("perf/x86/uncore: Apply the unit control RB tree to MSR uncore units")
> Signed-off-by: Zide Chen <zide.chen@intel.com>
> ---
> v2:
> - Remove WARN_ON_ONCE().
> ---
>  arch/x86/events/intel/uncore_discovery.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
> index 583cbd06b9b8..60e1200c4691 100644
> --- a/arch/x86/events/intel/uncore_discovery.c
> +++ b/arch/x86/events/intel/uncore_discovery.c
> @@ -481,8 +481,8 @@ static u64 intel_generic_uncore_box_ctl(struct intel_uncore_box *box)
>  	struct intel_uncore_discovery_unit *unit;
>  
>  	unit = intel_uncore_find_discovery_unit(box->pmu->type->boxes,
> -						-1, box->pmu->pmu_idx);
> -	if (WARN_ON_ONCE(!unit))
> +						box->dieid, box->pmu->pmu_idx);
> +	if (!unit)
>  		return 0;
>  
>  	return unit->addr;

Re: [PATCH V2 2/7] perf/x86/intel/uncore: Guard against invalid box control address

[Mi, Dapeng]

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>


On 5/27/2026 11:11 PM, Zide Chen wrote:
> Theoretically, intel_uncore_find_discovery_unit() could return NULL,
> e.g., when a CPU die is offline during uncore enumeration and its PMU
> units are not added to the discovery RB-tree.
>
> Guard against a NULL return value and the resulting invalid box control
> address (0) before accessing hardware.
>
> Signed-off-by: Zide Chen <zide.chen@intel.com>
> ---
> V2:
> - New patch.
> - Address pre-existing invalid box control address issue (Sashiko).
> ---
>  arch/x86/events/intel/uncore_discovery.c | 36 ++++++++++++++++++------
>  1 file changed, 27 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
> index 60e1200c4691..af2217b44a81 100644
> --- a/arch/x86/events/intel/uncore_discovery.c
> +++ b/arch/x86/events/intel/uncore_discovery.c
> @@ -490,17 +490,28 @@ static u64 intel_generic_uncore_box_ctl(struct intel_uncore_box *box)
>  
>  void intel_generic_uncore_msr_init_box(struct intel_uncore_box *box)
>  {
> -	wrmsrq(intel_generic_uncore_box_ctl(box), GENERIC_PMON_BOX_CTL_INT);
> +	u64 box_ctl = intel_generic_uncore_box_ctl(box);
> +
> +	if (!box_ctl)
> +		return;
> +
> +	wrmsrq(box_ctl, GENERIC_PMON_BOX_CTL_INT);
>  }
>  
>  void intel_generic_uncore_msr_disable_box(struct intel_uncore_box *box)
>  {
> -	wrmsrq(intel_generic_uncore_box_ctl(box), GENERIC_PMON_BOX_CTL_FRZ);
> +	u64 box_ctl = intel_generic_uncore_box_ctl(box);
> +
> +	if (box_ctl)
> +		wrmsrq(box_ctl, GENERIC_PMON_BOX_CTL_FRZ);
>  }
>  
>  void intel_generic_uncore_msr_enable_box(struct intel_uncore_box *box)
>  {
> -	wrmsrq(intel_generic_uncore_box_ctl(box), 0);
> +	u64 box_ctl = intel_generic_uncore_box_ctl(box);
> +
> +	if (box_ctl)
> +		wrmsrq(box_ctl, 0);
>  }
>  
>  static void intel_generic_uncore_msr_enable_event(struct intel_uncore_box *box,
> @@ -549,6 +560,10 @@ bool intel_generic_uncore_assign_hw_event(struct perf_event *event,
>  
>  	if (box->pci_dev) {
>  		box_ctl = UNCORE_DISCOVERY_PCI_BOX_CTRL(box_ctl);
> +
> +		if (!box_ctl)
> +			return false;
> +
>  		hwc->config_base = box_ctl + uncore_pci_event_ctl(box, hwc->idx);
>  		hwc->event_base  = box_ctl + uncore_pci_perf_ctr(box, hwc->idx);
>  		return true;
> @@ -567,27 +582,30 @@ static inline int intel_pci_uncore_box_ctl(struct intel_uncore_box *box)
>  
>  void intel_generic_uncore_pci_init_box(struct intel_uncore_box *box)
>  {
> -	struct pci_dev *pdev = box->pci_dev;
>  	int box_ctl = intel_pci_uncore_box_ctl(box);
>  
> +	if (!box_ctl)
> +		return;
> +
>  	__set_bit(UNCORE_BOX_FLAG_CTL_OFFS8, &box->flags);
> -	pci_write_config_dword(pdev, box_ctl, GENERIC_PMON_BOX_CTL_INT);
> +	pci_write_config_dword(box->pci_dev, box_ctl, GENERIC_PMON_BOX_CTL_INT);
>  }
>  
>  void intel_generic_uncore_pci_disable_box(struct intel_uncore_box *box)
>  {
> -	struct pci_dev *pdev = box->pci_dev;
>  	int box_ctl = intel_pci_uncore_box_ctl(box);
>  
> -	pci_write_config_dword(pdev, box_ctl, GENERIC_PMON_BOX_CTL_FRZ);
> +	if (box_ctl)
> +		pci_write_config_dword(box->pci_dev, box_ctl,
> +				       GENERIC_PMON_BOX_CTL_FRZ);
>  }
>  
>  void intel_generic_uncore_pci_enable_box(struct intel_uncore_box *box)
>  {
> -	struct pci_dev *pdev = box->pci_dev;
>  	int box_ctl = intel_pci_uncore_box_ctl(box);
>  
> -	pci_write_config_dword(pdev, box_ctl, 0);
> +	if (box_ctl)
> +		pci_write_config_dword(box->pci_dev, box_ctl, 0);
>  }
>  
>  static void intel_generic_uncore_pci_enable_event(struct intel_uncore_box *box,

Re: [PATCH V2 3/7] perf/x86/intel/uncore: Fix PCI device refcount leak in UPI discovery

[Mi, Dapeng]

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>


On 5/27/2026 11:11 PM, Zide Chen wrote:
> pci_get_domain_bus_and_slot() increments the reference count of the
> returned PCI device and therefore requires a matching pci_dev_put().
>
> In skx_upi_topology_cb() and discover_upi_topology(), the lookup is
> performed inside a loop, but pci_dev_put() is only called once after
> the loop. As a result, references from all previous iterations are
> leaked.
>
> Move pci_dev_put(dev) into the if (dev) block immediately after
> upi_fill_topology() returns.
>
> Opportunistically, fix uninitialized variable in skx_upi_topology_cb().
>
> Fixes: 4cfce57fa42d ("perf/x86/intel/uncore: Enable UPI topology discovery for Skylake Server")
> Fixes: f680b6e6062e ("perf/x86/intel/uncore: Enable UPI topology discovery for Icelake Server")
> Signed-off-by: Zide Chen <zide.chen@intel.com>
> ---
>  arch/x86/events/intel/uncore_snbep.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
> index 215d33e260ed..c9ce206fcbb6 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -4261,7 +4261,7 @@ static int upi_fill_topology(struct pci_dev *dev, struct intel_uncore_topology *
>  static int skx_upi_topology_cb(struct intel_uncore_type *type, int segment,
>  				int die, u64 cpu_bus_msr)
>  {
> -	int idx, ret;
> +	int idx, ret = 0;
>  	struct intel_uncore_topology *upi;
>  	unsigned int devfn;
>  	struct pci_dev *dev = NULL;
> @@ -4274,12 +4274,12 @@ static int skx_upi_topology_cb(struct intel_uncore_type *type, int segment,
>  		dev = pci_get_domain_bus_and_slot(segment, bus, devfn);
>  		if (dev) {
>  			ret = upi_fill_topology(dev, upi, idx);
> +			pci_dev_put(dev);
>  			if (ret)
>  				break;
>  		}
>  	}
>  
> -	pci_dev_put(dev);
>  	return ret;
>  }
>  
> @@ -5499,6 +5499,7 @@ static int discover_upi_topology(struct intel_uncore_type *type, int ubox_did, i
>  							  devfn);
>  			if (dev) {
>  				ret = upi_fill_topology(dev, upi, idx);
> +				pci_dev_put(dev);
>  				if (ret)
>  					goto err;
>  			}
> @@ -5506,7 +5507,6 @@ static int discover_upi_topology(struct intel_uncore_type *type, int ubox_did, i
>  	}
>  err:
>  	pci_dev_put(ubox);
> -	pci_dev_put(dev);
>  	return ret;
>  }
>  

Re: [PATCH V2 4/7] perf/x86/intel/uncore: Defer ADL global PMON enable to enable_box()

[Mi, Dapeng]

On 5/27/2026 11:11 PM, Zide Chen wrote:
> On some Raptor Cove CPUs, enabling uncore PMON globally at driver init
> may increase power consumption even when no perf events are in use.
>
> Drop adl_uncore_msr_init_box() and defer programming the global control
> register to enable_box(), so it is only set when a box is actually used.
>
> IMC and IMC freerunning counters use a separate control path and are
> unaffected.
>
> Cc: stable@vger.kernel.org

Need a "Fixes" tag?

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>


> Signed-off-by: Zide Chen <zide.chen@intel.com>
> ---
>  arch/x86/events/intel/uncore_snb.c | 7 -------
>  1 file changed, 7 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore_snb.c b/arch/x86/events/intel/uncore_snb.c
> index 3dbc6bacbd9d..edddd4f9ab5f 100644
> --- a/arch/x86/events/intel/uncore_snb.c
> +++ b/arch/x86/events/intel/uncore_snb.c
> @@ -563,12 +563,6 @@ void tgl_uncore_cpu_init(void)
>  	skl_uncore_msr_ops.init_box = rkl_uncore_msr_init_box;
>  }
>  
> -static void adl_uncore_msr_init_box(struct intel_uncore_box *box)
> -{
> -	if (box->pmu->pmu_idx == 0)
> -		wrmsrq(ADL_UNC_PERF_GLOBAL_CTL, SNB_UNC_GLOBAL_CTL_EN);
> -}
> -
>  static void adl_uncore_msr_enable_box(struct intel_uncore_box *box)
>  {
>  	wrmsrq(ADL_UNC_PERF_GLOBAL_CTL, SNB_UNC_GLOBAL_CTL_EN);
> @@ -587,7 +581,6 @@ static void adl_uncore_msr_exit_box(struct intel_uncore_box *box)
>  }
>  
>  static struct intel_uncore_ops adl_uncore_msr_ops = {
> -	.init_box	= adl_uncore_msr_init_box,
>  	.enable_box	= adl_uncore_msr_enable_box,
>  	.disable_box	= adl_uncore_msr_disable_box,
>  	.exit_box	= adl_uncore_msr_exit_box,

Re: [PATCH V2 5/7] perf/x86/intel/uncore: Move die_to_cpu() to uncore.c

[Mi, Dapeng]

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>


On 5/27/2026 11:11 PM, Zide Chen wrote:
> Move die_to_cpu() into uncore.c so it can be reused by the MSR
> initialization path, preparing for the introduction of an MSR global
> initialization callback.
>
> Move the cpus_read_{lock,unlock}() out of the API, in order to make
> it possible to be called when the lock is being held.
>
> Add the uncore_ prefix for consistency with other uncore APIs.
>
> Signed-off-by: Zide Chen <zide.chen@intel.com>
>
> V2:
> - Move cpus_read_{lock,unlock}() out of uncore_die_to_cpu() and rely
>   on callers to manage the lock. (Sashiko)
> - Remove "No functional change intended" from the changelog.
> ---
>  arch/x86/events/intel/uncore.c       | 19 +++++++++++++++++++
>  arch/x86/events/intel/uncore.h       |  1 +
>  arch/x86/events/intel/uncore_snbep.c | 23 +++--------------------
>  3 files changed, 23 insertions(+), 20 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
> index e9cc1ba921c5..22256ded2d67 100644
> --- a/arch/x86/events/intel/uncore.c
> +++ b/arch/x86/events/intel/uncore.c
> @@ -83,6 +83,25 @@ int uncore_device_to_die(struct pci_dev *dev)
>  	return -1;
>  }
>  
> +/*
> + * Using cpus_read_lock() to ensure cpu is not going down between
> + * looking at cpu_online_mask.
> + *
> + * The lock must be held by the caller.
> + */
> +int uncore_die_to_cpu(int die)
> +{
> +	int res = 0, cpu;
> +
> +	for_each_online_cpu(cpu) {
> +		if (topology_logical_die_id(cpu) == die) {
> +			res = cpu;
> +			break;
> +		}
> +	}
> +	return res;
> +}
> +
>  static void uncore_free_pcibus_map(void)
>  {
>  	struct pci2phy_map *map, *tmp;
> diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
> index c35918c01afa..94c68e3417b6 100644
> --- a/arch/x86/events/intel/uncore.h
> +++ b/arch/x86/events/intel/uncore.h
> @@ -235,6 +235,7 @@ struct pci2phy_map *__find_pci2phy_map(int segment);
>  int uncore_pcibus_to_dieid(struct pci_bus *bus);
>  int uncore_die_to_segment(int die);
>  int uncore_device_to_die(struct pci_dev *dev);
> +int uncore_die_to_cpu(int die);
>  
>  ssize_t uncore_event_show(struct device *dev,
>  			  struct device_attribute *attr, char *buf);
> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
> index c9ce206fcbb6..772b78237424 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -3704,25 +3704,6 @@ static int skx_msr_cpu_bus_read(int cpu, u64 *topology)
>  	return 0;
>  }
>  
> -static int die_to_cpu(int die)
> -{
> -	int res = 0, cpu, current_die;
> -	/*
> -	 * Using cpus_read_lock() to ensure cpu is not going down between
> -	 * looking at cpu_online_mask.
> -	 */
> -	cpus_read_lock();
> -	for_each_online_cpu(cpu) {
> -		current_die = topology_logical_die_id(cpu);
> -		if (current_die == die) {
> -			res = cpu;
> -			break;
> -		}
> -	}
> -	cpus_read_unlock();
> -	return res;
> -}
> -
>  enum {
>  	IIO_TOPOLOGY_TYPE,
>  	UPI_TOPOLOGY_TYPE,
> @@ -3794,8 +3775,9 @@ static int skx_pmu_get_topology(struct intel_uncore_type *type,
>  	int die, ret = -EPERM;
>  	u64 cpu_bus_msr;
>  
> +	cpus_read_lock();
>  	for (die = 0; die < uncore_max_dies(); die++) {
> -		ret = skx_msr_cpu_bus_read(die_to_cpu(die), &cpu_bus_msr);
> +		ret = skx_msr_cpu_bus_read(uncore_die_to_cpu(die), &cpu_bus_msr);
>  		if (ret)
>  			break;
>  
> @@ -3807,6 +3789,7 @@ static int skx_pmu_get_topology(struct intel_uncore_type *type,
>  		if (ret)
>  			break;
>  	}
> +	cpus_read_unlock();
>  
>  	return ret;
>  }

Re: [PATCH V2 6/7] perf/x86/intel/uncore: Fix uncore_die_to_cpu() for offline dies

[Mi, Dapeng]

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>


On 5/27/2026 11:11 PM, Zide Chen wrote:
> If the die is offline when uncore_die_to_cpu() is called, it silently
> returns 0, which is misleading.  Return -1 in this case to indicate
> that all CPUs on the die are offline and the caller can take care of
> it accordingly.
>
> Opportunistically, replace -EPERM with -ENODEV, as -ENODEV is
> the appropriate error when no CPUs are online across all dies.
>
> Signed-off-by: Zide Chen <zide.chen@intel.com>
> ---
>  arch/x86/events/intel/uncore.c       | 2 +-
>  arch/x86/events/intel/uncore_snbep.c | 9 +++++++--
>  2 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
> index 22256ded2d67..4b3a1fa5b41b 100644
> --- a/arch/x86/events/intel/uncore.c
> +++ b/arch/x86/events/intel/uncore.c
> @@ -91,7 +91,7 @@ int uncore_device_to_die(struct pci_dev *dev)
>   */
>  int uncore_die_to_cpu(int die)
>  {
> -	int res = 0, cpu;
> +	int res = -1, cpu;
>  
>  	for_each_online_cpu(cpu) {
>  		if (topology_logical_die_id(cpu) == die) {
> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
> index 772b78237424..334dc384b5b9 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -3772,12 +3772,17 @@ static void pmu_free_topology(struct intel_uncore_type *type)
>  static int skx_pmu_get_topology(struct intel_uncore_type *type,
>  				 int (*topology_cb)(struct intel_uncore_type*, int, int, u64))
>  {
> -	int die, ret = -EPERM;
> +	int die, ret = -ENODEV;
>  	u64 cpu_bus_msr;
> +	int cpu;
>  
>  	cpus_read_lock();
>  	for (die = 0; die < uncore_max_dies(); die++) {
> -		ret = skx_msr_cpu_bus_read(uncore_die_to_cpu(die), &cpu_bus_msr);
> +		cpu = uncore_die_to_cpu(die);
> +		if (cpu == -1)
> +			continue;
> +
> +		ret = skx_msr_cpu_bus_read(cpu, &cpu_bus_msr);
>  		if (ret)
>  			break;
>  

Re: [PATCH V2 7/7] perf/x86/intel/uncore: Implement global init callback for GNR uncore

[Mi, Dapeng]

On 5/27/2026 11:11 PM, Zide Chen wrote:
> On Sierra Forest and Clearwater Forest, the FRZ_ALL bit in the global
> control register defaults to 0 at boot, but UBOX PMON units do not
> work until the global control register is explicitly written with 0
> to trigger hardware initialization properly.
>
> Implement the generic uncore_msr_global_init() callback and add it to
> gnr_uncore_init[], which is shared by GNR, GRR, SRF, and CWF.

Need a "Fixes" tag?

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>


> Signed-off-by: Zide Chen <zide.chen@intel.com>
> ---
> V2:
> - Propagate return value of wrmsrq_on_cpu() to global_init().
> ---
>  arch/x86/events/intel/uncore.c           | 13 ++++++++++++-
>  arch/x86/events/intel/uncore.h           |  2 +-
>  arch/x86/events/intel/uncore_discovery.c |  2 +-
>  3 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
> index 4b3a1fa5b41b..7857959c6e82 100644
> --- a/arch/x86/events/intel/uncore.c
> +++ b/arch/x86/events/intel/uncore.c
> @@ -1716,7 +1716,7 @@ static int __init uncore_mmio_init(void)
>  	return ret;
>  }
>  
> -static int uncore_mmio_global_init(u64 ctl)
> +static int uncore_mmio_global_init(int die, u64 ctl)
>  {
>  	void __iomem *io_addr;
>  
> @@ -1731,6 +1731,16 @@ static int uncore_mmio_global_init(u64 ctl)
>  	return 0;
>  }
>  
> +static int uncore_msr_global_init(int die, u64 msr)
> +{
> +	int cpu = uncore_die_to_cpu(die);
> +
> +	if (cpu == -1)
> +		return -ENODEV;
> +
> +	return wrmsrq_on_cpu(cpu, msr, 0);
> +}
> +
>  static const struct uncore_plat_init nhm_uncore_init __initconst = {
>  	.cpu_init = nhm_uncore_cpu_init,
>  };
> @@ -1871,6 +1881,7 @@ static const struct uncore_plat_init gnr_uncore_init __initconst = {
>  	.domain[0].base_is_pci = true,
>  	.domain[0].discovery_base = UNCORE_DISCOVERY_TABLE_DEVICE,
>  	.domain[0].units_ignore = gnr_uncore_units_ignore,
> +	.domain[0].global_init = uncore_msr_global_init,
>  };
>  
>  static const struct uncore_plat_init dmr_uncore_init __initconst = {
> diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
> index 94c68e3417b6..c2e5ccb1d72c 100644
> --- a/arch/x86/events/intel/uncore.h
> +++ b/arch/x86/events/intel/uncore.h
> @@ -53,7 +53,7 @@ struct uncore_discovery_domain {
>  	/* MSR address or PCI device used as the discovery base */
>  	u32	discovery_base;
>  	bool	base_is_pci;
> -	int	(*global_init)(u64 ctl);
> +	int	(*global_init)(int die, u64 ctl);
>  
>  	/* The units in the discovery table should be ignored. */
>  	int	*units_ignore;
> diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
> index af2217b44a81..e36613d934b1 100644
> --- a/arch/x86/events/intel/uncore_discovery.c
> +++ b/arch/x86/events/intel/uncore_discovery.c
> @@ -287,7 +287,7 @@ static int __parse_discovery_table(struct uncore_discovery_domain *domain,
>  	if (!io_addr)
>  		return -ENOMEM;
>  
> -	if (domain->global_init && domain->global_init(global.ctl)) {
> +	if (domain->global_init && domain->global_init(die, global.ctl)) {
>  		ret = -ENODEV;
>  		goto out;
>  	}

Re: [PATCH V2 4/7] perf/x86/intel/uncore: Defer ADL global PMON enable to enable_box()

[Chen, Zide]

On 5/28/2026 1:35 AM, Mi, Dapeng wrote:
> 
> On 5/27/2026 11:11 PM, Zide Chen wrote:
>> On some Raptor Cove CPUs, enabling uncore PMON globally at driver init
>> may increase power consumption even when no perf events are in use.
>>
>> Drop adl_uncore_msr_init_box() and defer programming the global control
>> register to enable_box(), so it is only set when a box is actually used.
>>
>> IMC and IMC freerunning counters use a separate control path and are
>> unaffected.
>>
>> Cc: stable@vger.kernel.org
> 
> Need a "Fixes" tag?

Not really. This is a workaround for hardware issues rather than a fix
for software bugs.

> Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
> 
> 
>> Signed-off-by: Zide Chen <zide.chen@intel.com>
>> ---
>>  arch/x86/events/intel/uncore_snb.c | 7 -------
>>  1 file changed, 7 deletions(-)
>>
>> diff --git a/arch/x86/events/intel/uncore_snb.c b/arch/x86/events/intel/uncore_snb.c
>> index 3dbc6bacbd9d..edddd4f9ab5f 100644
>> --- a/arch/x86/events/intel/uncore_snb.c
>> +++ b/arch/x86/events/intel/uncore_snb.c
>> @@ -563,12 +563,6 @@ void tgl_uncore_cpu_init(void)
>>  	skl_uncore_msr_ops.init_box = rkl_uncore_msr_init_box;
>>  }
>>  
>> -static void adl_uncore_msr_init_box(struct intel_uncore_box *box)
>> -{
>> -	if (box->pmu->pmu_idx == 0)
>> -		wrmsrq(ADL_UNC_PERF_GLOBAL_CTL, SNB_UNC_GLOBAL_CTL_EN);
>> -}
>> -
>>  static void adl_uncore_msr_enable_box(struct intel_uncore_box *box)
>>  {
>>  	wrmsrq(ADL_UNC_PERF_GLOBAL_CTL, SNB_UNC_GLOBAL_CTL_EN);
>> @@ -587,7 +581,6 @@ static void adl_uncore_msr_exit_box(struct intel_uncore_box *box)
>>  }
>>  
>>  static struct intel_uncore_ops adl_uncore_msr_ops = {
>> -	.init_box	= adl_uncore_msr_init_box,
>>  	.enable_box	= adl_uncore_msr_enable_box,
>>  	.disable_box	= adl_uncore_msr_disable_box,
>>  	.exit_box	= adl_uncore_msr_exit_box,

Re: [PATCH V2 7/7] perf/x86/intel/uncore: Implement global init callback for GNR uncore

[Chen, Zide]

On 5/28/2026 1:46 AM, Mi, Dapeng wrote:
> 
> On 5/27/2026 11:11 PM, Zide Chen wrote:
>> On Sierra Forest and Clearwater Forest, the FRZ_ALL bit in the global
>> control register defaults to 0 at boot, but UBOX PMON units do not
>> work until the global control register is explicitly written with 0
>> to trigger hardware initialization properly.
>>
>> Implement the generic uncore_msr_global_init() callback and add it to
>> gnr_uncore_init[], which is shared by GNR, GRR, SRF, and CWF.
> 
> Need a "Fixes" tag?
No Fixes tag needed. This is a hardware initialization workaround rather
than a fix for a software bug. The register defaults to 0, but the
hardware requires an explicit write to trigger PMON functionality.

> Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
> 
> 
>> Signed-off-by: Zide Chen <zide.chen@intel.com>
>> ---
>> V2:
>> - Propagate return value of wrmsrq_on_cpu() to global_init().
>> ---
>>  arch/x86/events/intel/uncore.c           | 13 ++++++++++++-
>>  arch/x86/events/intel/uncore.h           |  2 +-
>>  arch/x86/events/intel/uncore_discovery.c |  2 +-
>>  3 files changed, 14 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
>> index 4b3a1fa5b41b..7857959c6e82 100644
>> --- a/arch/x86/events/intel/uncore.c
>> +++ b/arch/x86/events/intel/uncore.c
>> @@ -1716,7 +1716,7 @@ static int __init uncore_mmio_init(void)
>>  	return ret;
>>  }
>>  
>> -static int uncore_mmio_global_init(u64 ctl)
>> +static int uncore_mmio_global_init(int die, u64 ctl)
>>  {
>>  	void __iomem *io_addr;
>>  
>> @@ -1731,6 +1731,16 @@ static int uncore_mmio_global_init(u64 ctl)
>>  	return 0;
>>  }
>>  
>> +static int uncore_msr_global_init(int die, u64 msr)
>> +{
>> +	int cpu = uncore_die_to_cpu(die);
>> +
>> +	if (cpu == -1)
>> +		return -ENODEV;
>> +
>> +	return wrmsrq_on_cpu(cpu, msr, 0);
>> +}
>> +
>>  static const struct uncore_plat_init nhm_uncore_init __initconst = {
>>  	.cpu_init = nhm_uncore_cpu_init,
>>  };
>> @@ -1871,6 +1881,7 @@ static const struct uncore_plat_init gnr_uncore_init __initconst = {
>>  	.domain[0].base_is_pci = true,
>>  	.domain[0].discovery_base = UNCORE_DISCOVERY_TABLE_DEVICE,
>>  	.domain[0].units_ignore = gnr_uncore_units_ignore,
>> +	.domain[0].global_init = uncore_msr_global_init,
>>  };
>>  
>>  static const struct uncore_plat_init dmr_uncore_init __initconst = {
>> diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
>> index 94c68e3417b6..c2e5ccb1d72c 100644
>> --- a/arch/x86/events/intel/uncore.h
>> +++ b/arch/x86/events/intel/uncore.h
>> @@ -53,7 +53,7 @@ struct uncore_discovery_domain {
>>  	/* MSR address or PCI device used as the discovery base */
>>  	u32	discovery_base;
>>  	bool	base_is_pci;
>> -	int	(*global_init)(u64 ctl);
>> +	int	(*global_init)(int die, u64 ctl);
>>  
>>  	/* The units in the discovery table should be ignored. */
>>  	int	*units_ignore;
>> diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
>> index af2217b44a81..e36613d934b1 100644
>> --- a/arch/x86/events/intel/uncore_discovery.c
>> +++ b/arch/x86/events/intel/uncore_discovery.c
>> @@ -287,7 +287,7 @@ static int __parse_discovery_table(struct uncore_discovery_domain *domain,
>>  	if (!io_addr)
>>  		return -ENOMEM;
>>  
>> -	if (domain->global_init && domain->global_init(global.ctl)) {
>> +	if (domain->global_init && domain->global_init(die, global.ctl)) {
>>  		ret = -ENODEV;
>>  		goto out;
>>  	}

Re: [PATCH V2 7/7] perf/x86/intel/uncore: Implement global init callback for GNR uncore

[Mi, Dapeng]

On 5/29/2026 2:14 AM, Chen, Zide wrote:
>
> On 5/28/2026 1:46 AM, Mi, Dapeng wrote:
>> On 5/27/2026 11:11 PM, Zide Chen wrote:
>>> On Sierra Forest and Clearwater Forest, the FRZ_ALL bit in the global
>>> control register defaults to 0 at boot, but UBOX PMON units do not
>>> work until the global control register is explicitly written with 0
>>> to trigger hardware initialization properly.
>>>
>>> Implement the generic uncore_msr_global_init() callback and add it to
>>> gnr_uncore_init[], which is shared by GNR, GRR, SRF, and CWF.
>> Need a "Fixes" tag?
> No Fixes tag needed. This is a hardware initialization workaround rather
> than a fix for a software bug. The register defaults to 0, but the
> hardware requires an explicit write to trigger PMON functionality.

Zide, per my understanding, some uncore PMUs can't work for SRF and CWF
without this change. Is it right? If so, we need to add a "Fixes" tag to
ensure this patch is merged to the corresponding stable branches. Thanks.


>
>> Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
>>
>>
>>> Signed-off-by: Zide Chen <zide.chen@intel.com>
>>> ---
>>> V2:
>>> - Propagate return value of wrmsrq_on_cpu() to global_init().
>>> ---
>>>  arch/x86/events/intel/uncore.c           | 13 ++++++++++++-
>>>  arch/x86/events/intel/uncore.h           |  2 +-
>>>  arch/x86/events/intel/uncore_discovery.c |  2 +-
>>>  3 files changed, 14 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
>>> index 4b3a1fa5b41b..7857959c6e82 100644
>>> --- a/arch/x86/events/intel/uncore.c
>>> +++ b/arch/x86/events/intel/uncore.c
>>> @@ -1716,7 +1716,7 @@ static int __init uncore_mmio_init(void)
>>>  	return ret;
>>>  }
>>>  
>>> -static int uncore_mmio_global_init(u64 ctl)
>>> +static int uncore_mmio_global_init(int die, u64 ctl)
>>>  {
>>>  	void __iomem *io_addr;
>>>  
>>> @@ -1731,6 +1731,16 @@ static int uncore_mmio_global_init(u64 ctl)
>>>  	return 0;
>>>  }
>>>  
>>> +static int uncore_msr_global_init(int die, u64 msr)
>>> +{
>>> +	int cpu = uncore_die_to_cpu(die);
>>> +
>>> +	if (cpu == -1)
>>> +		return -ENODEV;
>>> +
>>> +	return wrmsrq_on_cpu(cpu, msr, 0);
>>> +}
>>> +
>>>  static const struct uncore_plat_init nhm_uncore_init __initconst = {
>>>  	.cpu_init = nhm_uncore_cpu_init,
>>>  };
>>> @@ -1871,6 +1881,7 @@ static const struct uncore_plat_init gnr_uncore_init __initconst = {
>>>  	.domain[0].base_is_pci = true,
>>>  	.domain[0].discovery_base = UNCORE_DISCOVERY_TABLE_DEVICE,
>>>  	.domain[0].units_ignore = gnr_uncore_units_ignore,
>>> +	.domain[0].global_init = uncore_msr_global_init,
>>>  };
>>>  
>>>  static const struct uncore_plat_init dmr_uncore_init __initconst = {
>>> diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
>>> index 94c68e3417b6..c2e5ccb1d72c 100644
>>> --- a/arch/x86/events/intel/uncore.h
>>> +++ b/arch/x86/events/intel/uncore.h
>>> @@ -53,7 +53,7 @@ struct uncore_discovery_domain {
>>>  	/* MSR address or PCI device used as the discovery base */
>>>  	u32	discovery_base;
>>>  	bool	base_is_pci;
>>> -	int	(*global_init)(u64 ctl);
>>> +	int	(*global_init)(int die, u64 ctl);
>>>  
>>>  	/* The units in the discovery table should be ignored. */
>>>  	int	*units_ignore;
>>> diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
>>> index af2217b44a81..e36613d934b1 100644
>>> --- a/arch/x86/events/intel/uncore_discovery.c
>>> +++ b/arch/x86/events/intel/uncore_discovery.c
>>> @@ -287,7 +287,7 @@ static int __parse_discovery_table(struct uncore_discovery_domain *domain,
>>>  	if (!io_addr)
>>>  		return -ENOMEM;
>>>  
>>> -	if (domain->global_init && domain->global_init(global.ctl)) {
>>> +	if (domain->global_init && domain->global_init(die, global.ctl)) {
>>>  		ret = -ENODEV;
>>>  		goto out;
>>>  	}
>

Re: [PATCH V2 5/7] perf/x86/intel/uncore: Move die_to_cpu() to uncore.c

[Peter Zijlstra]

On Wed, May 27, 2026 at 08:11:52AM -0700, Zide Chen wrote:
> Move die_to_cpu() into uncore.c so it can be reused by the MSR
> initialization path, preparing for the introduction of an MSR global
> initialization callback.
> 
> Move the cpus_read_{lock,unlock}() out of the API, in order to make
> it possible to be called when the lock is being held.
> 
> Add the uncore_ prefix for consistency with other uncore APIs.
> 
> Signed-off-by: Zide Chen <zide.chen@intel.com>
> 
> V2:
> - Move cpus_read_{lock,unlock}() out of uncore_die_to_cpu() and rely
>   on callers to manage the lock. (Sashiko)
> - Remove "No functional change intended" from the changelog.
> ---

V2 stuff goes under the '---' line. Otherwise I get to manually delete
it.

Re: [PATCH V2 7/7] perf/x86/intel/uncore: Implement global init callback for GNR uncore

[Peter Zijlstra]

On Fri, May 29, 2026 at 04:47:39PM +0800, Mi, Dapeng wrote:
> 
> On 5/29/2026 2:14 AM, Chen, Zide wrote:
> >
> > On 5/28/2026 1:46 AM, Mi, Dapeng wrote:
> >> On 5/27/2026 11:11 PM, Zide Chen wrote:
> >>> On Sierra Forest and Clearwater Forest, the FRZ_ALL bit in the global
> >>> control register defaults to 0 at boot, but UBOX PMON units do not
> >>> work until the global control register is explicitly written with 0
> >>> to trigger hardware initialization properly.
> >>>
> >>> Implement the generic uncore_msr_global_init() callback and add it to
> >>> gnr_uncore_init[], which is shared by GNR, GRR, SRF, and CWF.
> >> Need a "Fixes" tag?
> > No Fixes tag needed. This is a hardware initialization workaround rather
> > than a fix for a software bug. The register defaults to 0, but the
> > hardware requires an explicit write to trigger PMON functionality.
> 
> Zide, per my understanding, some uncore PMUs can't work for SRF and CWF
> without this change. Is it right? If so, we need to add a "Fixes" tag to
> ensure this patch is merged to the corresponding stable branches. Thanks.

If you all agree on Fixes tags, then those patches that end up getting
one should be at the front of the series.

I was about to pick this up, but if you guys want to send a new series,
let me know and I'll hold off.

Re: [PATCH V2 7/7] perf/x86/intel/uncore: Implement global init callback for GNR uncore

[Chen, Zide]

On 5/29/2026 5:55 AM, Peter Zijlstra wrote:
> On Fri, May 29, 2026 at 04:47:39PM +0800, Mi, Dapeng wrote:
>>
>> On 5/29/2026 2:14 AM, Chen, Zide wrote:
>>>
>>> On 5/28/2026 1:46 AM, Mi, Dapeng wrote:
>>>> On 5/27/2026 11:11 PM, Zide Chen wrote:
>>>>> On Sierra Forest and Clearwater Forest, the FRZ_ALL bit in the global
>>>>> control register defaults to 0 at boot, but UBOX PMON units do not
>>>>> work until the global control register is explicitly written with 0
>>>>> to trigger hardware initialization properly.
>>>>>
>>>>> Implement the generic uncore_msr_global_init() callback and add it to
>>>>> gnr_uncore_init[], which is shared by GNR, GRR, SRF, and CWF.
>>>> Need a "Fixes" tag?
>>> No Fixes tag needed. This is a hardware initialization workaround rather
>>> than a fix for a software bug. The register defaults to 0, but the
>>> hardware requires an explicit write to trigger PMON functionality.
>>
>> Zide, per my understanding, some uncore PMUs can't work for SRF and CWF
>> without this change. Is it right? If so, we need to add a "Fixes" tag to
>> ensure this patch is merged to the corresponding stable branches. Thanks.
> 
> If you all agree on Fixes tags, then those patches that end up getting
> one should be at the front of the series.
> 
> I was about to pick this up, but if you guys want to send a new series,
> let me know and I'll hold off.

Yes, please hold off and I can send out a new series to add a Fixes tag,
fix the missing '---' in patch 5/7, etc.