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Message-ID: <ef0fc176-ce2e-4ad5-b752-f1d018ae985e@intel.com>
Date: Fri, 11 Apr 2025 14:02:39 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....com>, <tony.luck@...el.com>,
<peternewman@...gle.com>
CC: <corbet@....net>, <tglx@...utronix.de>, <mingo@...hat.com>,
<bp@...en8.de>, <dave.hansen@...ux.intel.com>, <x86@...nel.org>,
<hpa@...or.com>, <paulmck@...nel.org>, <akpm@...ux-foundation.org>,
<thuth@...hat.com>, <rostedt@...dmis.org>, <ardb@...nel.org>,
<gregkh@...uxfoundation.org>, <daniel.sneddon@...ux.intel.com>,
<jpoimboe@...nel.org>, <alexandre.chartre@...cle.com>,
<pawan.kumar.gupta@...ux.intel.com>, <thomas.lendacky@....com>,
<perry.yuan@....com>, <seanjc@...gle.com>, <kai.huang@...el.com>,
<xiaoyao.li@...el.com>, <kan.liang@...ux.intel.com>, <xin3.li@...el.com>,
<ebiggers@...gle.com>, <xin@...or.com>, <sohil.mehta@...el.com>,
<andrew.cooper3@...rix.com>, <mario.limonciello@....com>,
<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<maciej.wieczor-retman@...el.com>, <eranian@...gle.com>
Subject: Re: [PATCH v12 13/26] x86/resctrl: Implement
resctrl_arch_config_cntr() to assign a counter with ABMC
Hi Babu,
On 4/3/25 5:18 PM, Babu Moger wrote:
> The ABMC feature provides an option to the user to assign a hardware
> counter to an RMID, event pair and monitor the bandwidth as long as it
> is assigned. The assigned RMID will be tracked by the hardware until the
> user unassigns it manually.
>
> Implement an architecture-specific handler to assign and unassign the
> counter. Configure counters by writing to the L3_QOS_ABMC_CFG MSR,
> specifying the counter ID, bandwidth source (RMID), and event
> configuration.
>
> The feature details are documented in the APM listed below [1].
> [1] AMD64 Architecture Programmer's Manual Volume 2: System Programming
> Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth
> Monitoring (ABMC).
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
...
> ---
> arch/x86/kernel/cpu/resctrl/monitor.c | 39 +++++++++++++++++++++++++++
> include/linux/resctrl.h | 15 +++++++++++
> 2 files changed, 54 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index 8a88ac29d57d..77f8662dc50b 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -1430,3 +1430,42 @@ int resctrl_arch_mbm_cntr_assign_set(struct rdt_resource *r, bool enable)
>
> return 0;
> }
> +
> +static void resctrl_abmc_config_one_amd(void *info)
> +{
> + union l3_qos_abmc_cfg *abmc_cfg = info;
> +
> + wrmsrl(MSR_IA32_L3_QOS_ABMC_CFG, abmc_cfg->full);
> +}
> +
> +/*
> + * Send an IPI to the domain to assign the counter to RMID, event pair.
> + */
> +int resctrl_arch_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
> + enum resctrl_event_id evtid, u32 rmid, u32 closid,
> + u32 cntr_id, u32 evt_cfg, bool assign)
> +{
> + struct rdt_hw_mon_domain *hw_dom = resctrl_to_arch_mon_dom(d);
> + union l3_qos_abmc_cfg abmc_cfg = { 0 };
> + struct arch_mbm_state *am;
> +
> + abmc_cfg.split.cfg_en = 1;
> + abmc_cfg.split.cntr_en = assign ? 1 : 0;
> + abmc_cfg.split.cntr_id = cntr_id;
> + abmc_cfg.split.bw_src = rmid;
> + abmc_cfg.split.bw_type = evt_cfg;
> +
> + smp_call_function_any(&d->hdr.cpu_mask, resctrl_abmc_config_one_amd, &abmc_cfg, 1);
> +
> + /*
> + * Reset the architectural state so that reading of hardware
> + * counter is not considered as an overflow in next update.
Please add something like: "The hardware counter is reset (because cfg_en == 1)
so there is no need to record initial non-zero counts."
> + */
> + if (assign) {
> + am = get_arch_mbm_state(hw_dom, rmid, evtid);
> + if (am)
> + memset(am, 0, sizeof(*am));
> + }
> +
> + return 0;
> +}
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 294b15de664e..60270606f1b8 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
Please keep the declaration internal to the arch code. It can be moved when
other architecture needs it.
> @@ -394,6 +394,21 @@ void resctrl_arch_mon_event_config_set(void *config_info);
> u32 resctrl_arch_mon_event_config_get(struct rdt_mon_domain *d,
> enum resctrl_event_id eventid);
>
> +/**
> + * resctrl_arch_config_cntr() - Configure the counter on the domain
> + * @r: resource that the counter should be read from.
> + * @d: domain that the counter should be read from.
> + * @evtid: event type to assign
> + * @rmid: rmid of the counter to read.
> + * @closid: closid that matches the rmid.
> + * @cntr_id: Counter ID to configure
> + * @evt_cfg: event configuration
"event configuration" is simply an expansion of member name and does not help to
understand what the value represents.
> + * @assign: assign or unassign
Please rework the kernel doc: consistent sentence structure (starts with upper case,
ends with period), use proper capitalization for acronyms (rmid -> RMID, etc.),
make descriptions informative.
> + */
> +int resctrl_arch_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
> + enum resctrl_event_id evtid, u32 rmid, u32 closid,
> + u32 cntr_id, u32 evt_cfg, bool assign);
> +
> /* For use by arch code to remap resctrl's smaller CDP CLOSID range */
> static inline u32 resctrl_get_config_index(u32 closid,
> enum resctrl_conf_type type)
This patch does not pass checkpatch.pl.
Reinette
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