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Message-ID: <ec9373cb-b8a4-4f23-affe-de27f40f8b28@linux.intel.com>
Date: Sun, 4 Jan 2026 10:00:20 +0800
From: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
To: Zide Chen <zide.chen@...el.com>, Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Andi Kleen <ak@...ux.intel.com>, Eranian Stephane <eranian@...gle.com>
Cc: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
Xudong Hao <xudong.hao@...el.com>, Falcon Thomas <thomas.falcon@...el.com>
Subject: Re: [PATCH V2 02/13] perf/x86/intel/uncore: Support per-platform
discovery base devices
On 1/1/2026 6:42 AM, Zide Chen wrote:
> On DMR platforms, IMH discovery tables are enumerated via PCI, while
> CBB domains use MSRs, unlike earlier platforms which relied on either
> PCI or MSR exclusively.
>
> DMR also uses different MSRs and PCI devices, requiring support for
> multiple, platform-specific discovery bases.
>
> Introduce struct uncore_discovery_domain to hold the discovery base and
> other domain-specific configuration.
>
> Move uncore_units_ignore into uncore_discovery_domain so a single
> structure can be passed to uncore_discovery_[pci/msr].
>
> No functional change intended.
>
> Co-developed-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> Signed-off-by: Zide Chen <zide.chen@...el.com>
> ---
> v2:
> - Introduce uncore_discovery_domain[] to support possible any
> combination of MSR or PCI discovery base.
> - Move has_generic_discovery_table() related code to a separate patch
> for easier review.
> - Update commit messages.
>
> arch/x86/events/intel/uncore.c | 32 ++++++++-----
> arch/x86/events/intel/uncore.h | 15 +++++--
> arch/x86/events/intel/uncore_discovery.c | 57 +++++++++++++++---------
> 3 files changed, 69 insertions(+), 35 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
> index cd561290be8c..844030ef87c4 100644
> --- a/arch/x86/events/intel/uncore.c
> +++ b/arch/x86/events/intel/uncore.c
> @@ -1798,7 +1798,7 @@ static const struct uncore_plat_init lnl_uncore_init __initconst = {
> static const struct uncore_plat_init ptl_uncore_init __initconst = {
> .cpu_init = ptl_uncore_cpu_init,
> .mmio_init = ptl_uncore_mmio_init,
> - .use_discovery = true,
> + .domain[0].discovery_base = UNCORE_DISCOVERY_MSR,
> };
>
> static const struct uncore_plat_init icx_uncore_init __initconst = {
> @@ -1817,16 +1817,18 @@ static const struct uncore_plat_init spr_uncore_init __initconst = {
> .cpu_init = spr_uncore_cpu_init,
> .pci_init = spr_uncore_pci_init,
> .mmio_init = spr_uncore_mmio_init,
> - .use_discovery = true,
> - .uncore_units_ignore = spr_uncore_units_ignore,
> + .domain[0].base_is_pci = true,
> + .domain[0].discovery_base = UNCORE_DISCOVERY_TABLE_DEVICE,
> + .domain[0].units_ignore = spr_uncore_units_ignore,
> };
>
> static const struct uncore_plat_init gnr_uncore_init __initconst = {
> .cpu_init = gnr_uncore_cpu_init,
> .pci_init = gnr_uncore_pci_init,
> .mmio_init = gnr_uncore_mmio_init,
> - .use_discovery = true,
> - .uncore_units_ignore = gnr_uncore_units_ignore,
> + .domain[0].base_is_pci = true,
> + .domain[0].discovery_base = UNCORE_DISCOVERY_TABLE_DEVICE,
> + .domain[0].units_ignore = gnr_uncore_units_ignore,
> };
>
> static const struct uncore_plat_init generic_uncore_init __initconst = {
> @@ -1897,6 +1899,17 @@ static const struct x86_cpu_id intel_uncore_match[] __initconst = {
> };
> MODULE_DEVICE_TABLE(x86cpu, intel_uncore_match);
>
> +static bool ucore_use_discovery(struct uncore_plat_init *config)
> +{
> + int i;
> +
> + for (i = 0; i < UNCORE_DISCOVERY_DOMAINS; i++)
> + if (config->domain[i].discovery_base)
> + return true;
> +
> + return false;
> +}
> +
> static int __init intel_uncore_init(void)
> {
> const struct x86_cpu_id *id;
> @@ -1911,15 +1924,14 @@ static int __init intel_uncore_init(void)
>
> id = x86_match_cpu(intel_uncore_match);
> if (!id) {
> - if (!uncore_no_discover && uncore_discovery(NULL))
> - uncore_init = (struct uncore_plat_init *)&generic_uncore_init;
> - else
> + uncore_init = (struct uncore_plat_init *)&generic_uncore_init;
> + if (uncore_no_discover || !uncore_discovery(uncore_init))
> return -ENODEV;
> } else {
> uncore_init = (struct uncore_plat_init *)id->driver_data;
> - if (uncore_no_discover && uncore_init->use_discovery)
> + if (uncore_no_discover && ucore_use_discovery(uncore_init))
> return -ENODEV;
> - if (uncore_init->use_discovery &&
> + if (ucore_use_discovery(uncore_init) &&
> !uncore_discovery(uncore_init))
> return -ENODEV;
> }
> diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
> index 568536ef28ee..1574ffc7ee05 100644
> --- a/arch/x86/events/intel/uncore.h
> +++ b/arch/x86/events/intel/uncore.h
> @@ -47,14 +47,21 @@ struct uncore_event_desc;
> struct freerunning_counters;
> struct intel_uncore_topology;
>
> +struct uncore_discovery_domain {
> + /* MSR address or PCI device used as the discovery base */
> + u32 discovery_base;
> + bool base_is_pci;
> + /* The units in the discovery table should be ignored. */
> + int *units_ignore;
> +};
> +
> +#define UNCORE_DISCOVERY_DOMAINS 2
> struct uncore_plat_init {
> void (*cpu_init)(void);
> int (*pci_init)(void);
> void (*mmio_init)(void);
> - /* Discovery table is required */
> - bool use_discovery;
> - /* The units in the discovery table should be ignored. */
> - int *uncore_units_ignore;
> +
> + struct uncore_discovery_domain domain[UNCORE_DISCOVERY_DOMAINS];
> };
>
> struct intel_uncore_type {
> diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
> index d39f6a0b8cc3..3bcbf974d3a8 100644
> --- a/arch/x86/events/intel/uncore_discovery.c
> +++ b/arch/x86/events/intel/uncore_discovery.c
> @@ -259,23 +259,24 @@ uncore_insert_box_info(struct uncore_unit_discovery *unit,
> }
>
> static bool
> -uncore_ignore_unit(struct uncore_unit_discovery *unit, int *ignore)
> +uncore_ignore_unit(struct uncore_unit_discovery *unit,
> + struct uncore_discovery_domain *domain)
> {
> int i;
>
> - if (!ignore)
> + if (!domain || !domain->units_ignore)
> return false;
>
> - for (i = 0; ignore[i] != UNCORE_IGNORE_END ; i++) {
> - if (unit->box_type == ignore[i])
> + for (i = 0; domain->units_ignore[i] != UNCORE_IGNORE_END ; i++) {
> + if (unit->box_type == domain->units_ignore[i])
> return true;
> }
>
> return false;
> }
>
> -static int __parse_discovery_table(resource_size_t addr, int die,
> - bool *parsed, int *ignore)
> +static int __parse_discovery_table(struct uncore_discovery_domain *domain,
> + resource_size_t addr, int die, bool *parsed)
> {
> struct uncore_global_discovery global;
> struct uncore_unit_discovery unit;
> @@ -314,7 +315,7 @@ static int __parse_discovery_table(resource_size_t addr, int die,
> if (unit.access_type >= UNCORE_ACCESS_MAX)
> continue;
>
> - if (uncore_ignore_unit(&unit, ignore))
> + if (uncore_ignore_unit(&unit, domain))
> continue;
>
> uncore_insert_box_info(&unit, die);
> @@ -325,9 +326,9 @@ static int __parse_discovery_table(resource_size_t addr, int die,
> return 0;
> }
>
> -static int parse_discovery_table(struct pci_dev *dev, int die,
> - u32 bar_offset, bool *parsed,
> - int *ignore)
> +static int parse_discovery_table(struct uncore_discovery_domain *domain,
> + struct pci_dev *dev, int die,
> + u32 bar_offset, bool *parsed)
> {
> resource_size_t addr;
> u32 val;
> @@ -347,17 +348,19 @@ static int parse_discovery_table(struct pci_dev *dev, int die,
> }
> #endif
>
> - return __parse_discovery_table(addr, die, parsed, ignore);
> + return __parse_discovery_table(domain, addr, die, parsed);
> }
>
> -static bool uncore_discovery_pci(int *ignore)
> +static bool uncore_discovery_pci(struct uncore_discovery_domain *domain)
> {
> u32 device, val, entry_id, bar_offset;
> int die, dvsec = 0, ret = true;
> struct pci_dev *dev = NULL;
> bool parsed = false;
>
> - if (has_generic_discovery_table())
> + if (domain->discovery_base)
> + device = domain->discovery_base;
> + else if (has_generic_discovery_table())
> device = UNCORE_DISCOVERY_TABLE_DEVICE;
> else
> device = PCI_ANY_ID;
> @@ -386,7 +389,7 @@ static bool uncore_discovery_pci(int *ignore)
> if (die < 0)
> continue;
>
> - parse_discovery_table(dev, die, bar_offset, &parsed, ignore);
> + parse_discovery_table(domain, dev, die, bar_offset, &parsed);
> }
> }
>
> @@ -399,11 +402,11 @@ static bool uncore_discovery_pci(int *ignore)
> return ret;
> }
>
> -static bool uncore_discovery_msr(int *ignore)
> +static bool uncore_discovery_msr(struct uncore_discovery_domain *domain)
> {
> unsigned long *die_mask;
> bool parsed = false;
> - int cpu, die;
> + int cpu, die, msr;
> u64 base;
>
> die_mask = kcalloc(BITS_TO_LONGS(uncore_max_dies()),
> @@ -411,19 +414,22 @@ static bool uncore_discovery_msr(int *ignore)
> if (!die_mask)
> return false;
>
> + msr = domain->discovery_base ?
> + domain->discovery_base : UNCORE_DISCOVERY_MSR;
> +
> cpus_read_lock();
> for_each_online_cpu(cpu) {
> die = topology_logical_die_id(cpu);
> if (__test_and_set_bit(die, die_mask))
> continue;
>
> - if (rdmsrq_safe_on_cpu(cpu, UNCORE_DISCOVERY_MSR, &base))
> + if (rdmsrq_safe_on_cpu(cpu, msr, &base))
> continue;
>
> if (!base)
> continue;
>
> - __parse_discovery_table(base, die, &parsed, ignore);
> + __parse_discovery_table(domain, base, die, &parsed);
> }
>
> cpus_read_unlock();
> @@ -434,10 +440,19 @@ static bool uncore_discovery_msr(int *ignore)
>
> bool uncore_discovery(struct uncore_plat_init *init)
> {
> - int *ignore = init ? init->uncore_units_ignore : NULL;
> + struct uncore_discovery_domain *domain;
> + bool ret = false;
> + int i;
>
> - return uncore_discovery_msr(ignore) ||
> - uncore_discovery_pci(ignore);
> + for (i = 0; i < UNCORE_DISCOVERY_DOMAINS; i++) {
> + domain = &init->domain[i];
> + if (!domain->base_is_pci)
> + ret |= uncore_discovery_msr(domain);
> + else
> + ret |= uncore_discovery_pci(domain);
> + }
> +
> + return ret;
> }
>
> void intel_uncore_clear_discovery_tables(void)
LGTM.
Reviewed-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
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