From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 46C14C55172 for ; Tue, 4 Aug 2026 10:07:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Ch+YtaOuhq6xs3iyaRxQCpw8330TSJM/Zgw2J24fAt8=; b=x7ads073LnAnbz7XuxRD0q173k QNOwUIWfsWBNibdF8z5GoxOZ+E9nEE5qH22cR40IbKjAwk/cvFDA6v/663tzrpSdCeiQ2KuPZsm+j ebf7GLRFS2AuCkILDp9AOfe/pY5Wwe3VJZ2RMylYPGutkHdJvhZ7lQwBhVlTMF+TbIUAD+gzw3ztF UmyN9o60tHV0Xe5aw438yGN3u5tSPKXo8HZYqDYglY05xqclM5IAsOvO3B62Nmu6brUOy7xpMDBDv fSePc0IGVn10LjXtWFlksxikWuDKHDrO3p64turrVDCs1csTx4y63FczGh+iJkOj+ZeJo9Swc5Ewt qBbxqd3w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wrC3W-00000001Ve7-2TdE; Tue, 04 Aug 2026 10:07:30 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wrC3U-00000001VbK-04QF for linux-arm-kernel@lists.infradead.org; Tue, 04 Aug 2026 10:07:29 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DB5A4168F; Tue, 4 Aug 2026 03:07:22 -0700 (PDT) Received: from e142021.fritz.box (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 022E23F86F; Tue, 4 Aug 2026 03:07:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1785838046; bh=oDzxL9GqY2LcqN81eY3tRgvZtE9CixQXG0TT3+ALYMo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oFFRnjuk+iwc/+6ivzigCPcNRX6bnahcAXvNKte9EwHcuMyTO8iTucfWaHw2GQjKn nqOGHkG1LXiMurrtkkIvfORhUvTFhXu8B8XfVa9loqsK37GijlHyCSX1rR+QaoJIkb okjbKAKpg2sA2eXTwxHtDx3CJA8JQB4ac0Li3pew= From: Andre Przywara To: Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Catalin Marinas , Will Deacon , "Rafael J . Wysocki" , Len Brown , James Morse , Ben Horgan , Reinette Chatre , Fenghua Yu Cc: Jonathan Cameron , Srivathsa L Rao , Ganapatrao Kulkarni , Trilok Soni , Srinivas Ramana , Niyas Sait , Lee Trager , Ritwick Sharma , Gavin Shan , linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v8 09/11] arm_mpam: add MPAM-Fb MSC firmware access support Date: Tue, 4 Aug 2026 12:06:25 +0200 Message-ID: <20260804100627.3217149-10-andre.przywara@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260804100627.3217149-1-andre.przywara@arm.com> References: <20260804100627.3217149-1-andre.przywara@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260804_030728_138996_828A84DF X-CRM114-Status: GOOD ( 31.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The Arm MPAM Firmware-backed (Fb) Profile document[1] describes an alternative way of accessing the "Memory System Components" (MSC) in an MPAM enabled system. Normally the MSCs are MMIO mapped, but in some implementations this might not be possible (MSC located outside of the local socket, MSC mapped secure-only) or desirable (direct MMIO access too slow or needs to be mediated through a control processor). MPAM-fb standardises a protocol to abstract MSC accesses, building on the SCMI protocol. Add functions that do an MSC read or write access by redirecting the request through a firmware interface. For now this done via an ACPI PCC shared memory and mailbox combination. Since the protocol used is only a small subset of the full SCMI spec, and the SCMI protocol has no full ACPI support anyway, open-code the (simple) SCMI message generation, for just the fields we need. [1] https://developer.arm.com/documentation/den0144/latest Signed-off-by: Andre Przywara Reviewed-by: Jonathan Cameron Tested-by: Ritwick Sharma # on Arm AGI CPU Reviewed-by: Gavin Shan --- drivers/resctrl/Makefile | 2 +- drivers/resctrl/mpam_devices.c | 57 +++++++-- drivers/resctrl/mpam_fb.c | 211 ++++++++++++++++++++++++++++++++ drivers/resctrl/mpam_internal.h | 18 +++ include/linux/arm_mpam.h | 2 +- 5 files changed, 277 insertions(+), 13 deletions(-) create mode 100644 drivers/resctrl/mpam_fb.c diff --git a/drivers/resctrl/Makefile b/drivers/resctrl/Makefile index 4f6d0e81f9b8..097c036724e9 100644 --- a/drivers/resctrl/Makefile +++ b/drivers/resctrl/Makefile @@ -1,5 +1,5 @@ obj-$(CONFIG_ARM64_MPAM_DRIVER) += mpam.o -mpam-y += mpam_devices.o +mpam-y += mpam_devices.o mpam_fb.o mpam-$(CONFIG_ARM64_MPAM_RESCTRL_FS) += mpam_resctrl.o ccflags-$(CONFIG_ARM64_MPAM_DRIVER_DEBUG) += -DDEBUG diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index cda59864808d..e9818c75443d 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -83,6 +83,21 @@ static DECLARE_WORK(mpam_broken_work, &mpam_disable); /* When mpam is disabled, the printed reason to aid debugging */ static char *mpam_disable_reason; +void mpam_fb_disable_mpam(int err, int mpam_fb_err) +{ + static char mpam_fb_reason[64]; + + /* Prevent repeated calls when mpam_disable() does MSC accesses. */ + if (!mpam_is_enabled()) + return; + + snprintf(mpam_fb_reason, sizeof(mpam_fb_reason), + "MPAM-Fb error %d, kernel error %d", mpam_fb_err, err); + + mpam_disable_reason = mpam_fb_reason; + schedule_work(&mpam_broken_work); +} + /* * Whether resctrl has been setup. Used by cpuhp in preference to * mpam_is_enabled(). The disable call after an error interrupt makes @@ -179,8 +194,11 @@ static void mpam_assert_partid_sizes_fixed(void) static int __mpam_read_reg(struct mpam_msc *msc, u16 reg, u32 *res) { - WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); + if (msc->iface == MPAM_IFACE_PCC) + return mpam_fb_send_read_request(msc, reg, res); + + WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); *res = readl_relaxed(msc->mapped_hwpage + reg); return 0; @@ -197,9 +215,12 @@ static inline int _mpam_read_partsel_reg(struct mpam_msc *msc, u16 reg, static int __mpam_write_reg(struct mpam_msc *msc, u16 reg, u32 val) { - WARN_ON_ONCE(reg + sizeof(u32) > msc->mapped_hwpage_sz); - WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); + if (msc->iface == MPAM_IFACE_PCC) + return mpam_fb_send_write_request(msc, reg, val); + + WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); + WARN_ON_ONCE(reg + sizeof(u32) > msc->mapped_hwpage_sz); writel_relaxed(val, msc->mapped_hwpage + reg); return 0; @@ -1141,8 +1162,11 @@ static int mpam_msc_read_mbwu_l(struct mpam_msc *msc, u64 *res) mpam_mon_sel_lock_held(msc); - WARN_ON_ONCE((MSMON_MBWU_L + sizeof(u64)) > msc->mapped_hwpage_sz); - WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); + if (msc->iface == MPAM_IFACE_MMIO) { + WARN_ON_ONCE((MSMON_MBWU_L + sizeof(u64)) > msc->mapped_hwpage_sz); + WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), + &msc->accessibility)); + } ret = __mpam_read_reg(msc, MSMON_MBWU_L + 4, &mbwu_l_high2); if (ret) @@ -1176,8 +1200,11 @@ static int mpam_msc_zero_mbwu_l(struct mpam_msc *msc) mpam_mon_sel_lock_held(msc); - WARN_ON_ONCE((MSMON_MBWU_L + sizeof(u64)) > msc->mapped_hwpage_sz); - WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); + if (msc->iface == MPAM_IFACE_MMIO) { + WARN_ON_ONCE((MSMON_MBWU_L + sizeof(u64)) > msc->mapped_hwpage_sz); + WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), + &msc->accessibility)); + } ret = __mpam_write_reg(msc, MSMON_MBWU_L, 0); if (ret) @@ -1490,11 +1517,16 @@ static int _msmon_read(struct mpam_component *comp, struct mon_read *arg) srcu_read_lock_held(&mpam_srcu)) { arg->ris = ris; - err = smp_call_function_any(&msc->accessibility, - __ris_msmon_read, arg, - true); - if (!err && arg->err) + if (msc->iface == MPAM_IFACE_MMIO) { + err = smp_call_function_any(&msc->accessibility, + __ris_msmon_read, + arg, true); + if (!err) + err = arg->err; + } else { + __ris_msmon_read(arg); err = arg->err; + } /* * Save one error to be returned to the caller, but @@ -1971,6 +2003,9 @@ static int mpam_get_msc_preferred_cpu(struct mpam_msc *msc) static int mpam_touch_msc(struct mpam_msc *msc, int (*fn)(void *a), void *arg) { + if (msc->iface != MPAM_IFACE_MMIO) + return fn(arg); + lockdep_assert_irqs_enabled(); lockdep_assert_cpus_held(); WARN_ON_ONCE(!srcu_read_lock_held((&mpam_srcu))); diff --git a/drivers/resctrl/mpam_fb.c b/drivers/resctrl/mpam_fb.c new file mode 100644 index 000000000000..bb743ee460a2 --- /dev/null +++ b/drivers/resctrl/mpam_fb.c @@ -0,0 +1,211 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2024-2026 Arm Ltd. + +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +#include "mpam_internal.h" + +#define MPAM_MSC_TOKEN_MASK GENMASK_U32(27, 18) +#define MPAM_MSC_PROT_ID_MASK GENMASK_U32(17, 10) + +#define MPAM_FB_PROTOCOL_ID 0x1a + +#define MPAM_PROTOCOL_VERSION_CMD 0x0 +#define MPAM_MSC_READ_CMD 0x4 +#define MPAM_MSC_WRITE_CMD 0x5 + +#define MPAM_FB_PROT_HEADER_LEN sizeof(u32) + +#define MPAM_FB_SUCCESS 0 +#define MPAM_FB_ERR_NOT_SUPPORTED -1 +#define MPAM_FB_ERR_INVALID_PARAMETERS -2 +#define MPAM_FB_ERR_DENIED -3 +#define MPAM_FB_ERR_NOT_FOUND -4 +#define MPAM_FB_ERR_OUT_OF_RANGE -5 +#define MPAM_FB_ERR_BUSY -6 +#define MPAM_FB_ERR_COMMS_ERROR -7 +#define MPAM_FB_ERR_GENERIC_ERROR -8 +#define MPAM_FB_ERR_HW_ERROR -9 +#define MPAM_FB_ERR_PROTOCOL_ERROR -10 +#define MPAM_FB_ERR_IN_USE -11 + +static atomic_t mpam_fb_token = ATOMIC_INIT(0); + +static int mpam_fb_to_linux_errno(int mpam_fb_code) +{ + switch (mpam_fb_code) { + case MPAM_FB_ERR_NOT_SUPPORTED: + return -EOPNOTSUPP; + case MPAM_FB_ERR_INVALID_PARAMETERS: + return -EINVAL; + case MPAM_FB_ERR_NOT_FOUND: + return -ENOENT; + case MPAM_FB_ERR_OUT_OF_RANGE: + return -ERANGE; + case MPAM_FB_ERR_BUSY: + return -EBUSY; + default: + return -EINVAL; + } +} + +static void mpam_fb_build_version_message(unsigned int token, + void __iomem *msg_buf) +{ + struct acpi_pcct_ext_pcc_shared_memory __iomem *pcc_shmem = msg_buf; + + /* .signature is filled by the platform */ + writel_relaxed(PCC_CMD_COMPLETION_NOTIFY, &pcc_shmem->flags); + writel_relaxed(MPAM_FB_PROT_HEADER_LEN, &pcc_shmem->length); + writel_relaxed(MPAM_PROTOCOL_VERSION_CMD | + FIELD_PREP(MPAM_MSC_TOKEN_MASK, token) | + FIELD_PREP(MPAM_MSC_PROT_ID_MASK, MPAM_FB_PROTOCOL_ID), + &pcc_shmem->command); +} + +static void mpam_fb_build_read_message(int msc_id, int reg, unsigned int token, + void __iomem *msg_buf) +{ + struct acpi_pcct_ext_pcc_shared_memory __iomem *pcc_shmem = msg_buf; + struct mpam_fb_read_payload { + u32 msc_id; + u32 flags; + u32 reg_offset; + } __packed __iomem *payload = msg_buf + sizeof(*pcc_shmem); + int msg_size = MPAM_FB_PROT_HEADER_LEN + sizeof(*payload); + + /* .signature is filled by the platform */ + writel_relaxed(PCC_CMD_COMPLETION_NOTIFY, &pcc_shmem->flags); + writel_relaxed(msg_size, &pcc_shmem->length); + writel_relaxed(MPAM_MSC_READ_CMD | + FIELD_PREP(MPAM_MSC_TOKEN_MASK, token) | + FIELD_PREP(MPAM_MSC_PROT_ID_MASK, MPAM_FB_PROTOCOL_ID), + &pcc_shmem->command); + + writel_relaxed(msc_id, &payload->msc_id); + writel_relaxed(0, &payload->flags); + writel_relaxed(reg, &payload->reg_offset); +} + +static void mpam_fb_build_write_message(int msc_id, int reg, u32 val, + unsigned int token, + void __iomem *msg_buf) +{ + struct acpi_pcct_ext_pcc_shared_memory __iomem *pcc_shmem = msg_buf; + struct mpam_fb_write_payload { + u32 msc_id; + u32 flags; + u32 reg_offset; + u32 value; + } __packed __iomem *payload = msg_buf + sizeof(*pcc_shmem); + int msg_size = MPAM_FB_PROT_HEADER_LEN + sizeof(*payload); + + /* .signature is filled by the platform */ + writel_relaxed(PCC_CMD_COMPLETION_NOTIFY, &pcc_shmem->flags); + writel_relaxed(msg_size, &pcc_shmem->length); + writel_relaxed(MPAM_MSC_WRITE_CMD | + FIELD_PREP(MPAM_MSC_TOKEN_MASK, token) | + FIELD_PREP(MPAM_MSC_PROT_ID_MASK, MPAM_FB_PROTOCOL_ID), + &pcc_shmem->command); + + writel_relaxed(msc_id, &payload->msc_id); + writel_relaxed(0, &payload->flags); + writel_relaxed(reg, &payload->reg_offset); + writel_relaxed(val, &payload->value); +} + +static int mpam_fb_send_request(struct mpam_msc *msc, u32 msc_id, + u16 reg, u32 *result, int mpam_fb_command) +{ + unsigned int token = atomic_inc_return(&mpam_fb_token); + struct acpi_pcct_ext_pcc_shared_memory __iomem *pcc_shmem; + struct mpam_pcc_chan *pcc_chan; + struct pcc_mbox_chan *chan; + void __iomem *payload_ofs; + int mpam_fb_err = 0; + u32 status; + int ret; + + pcc_chan = msc->pcc_chan; + if (!pcc_chan) + return -ENODEV; + + chan = pcc_chan->pcc_chan; + + /* prune token to fit into the 10 bits inside the command register */ + token = FIELD_GET(MPAM_MSC_TOKEN_MASK, + FIELD_PREP(MPAM_MSC_TOKEN_MASK, token)); + + mutex_lock(&pcc_chan->pcc_chan_lock); + + switch (mpam_fb_command) { + case MPAM_PROTOCOL_VERSION_CMD: + mpam_fb_build_version_message(token, chan->shmem); + break; + case MPAM_MSC_READ_CMD: + mpam_fb_build_read_message(msc_id, reg, token, chan->shmem); + break; + case MPAM_MSC_WRITE_CMD: + mpam_fb_build_write_message(msc_id, reg, *result, + token, chan->shmem); + break; + default: + dev_err(&msc->pdev->dev, "unsupported MPAM-Fb command %d\n", + mpam_fb_command); + ret = -EINVAL; + goto out_err; + } + + ret = mbox_send_message(chan->mchan, NULL); + if (ret < 0) + goto out_err; + + pcc_shmem = chan->shmem; + payload_ofs = chan->shmem + sizeof(*pcc_shmem); + status = readl(&pcc_shmem->command); + if (FIELD_GET(MPAM_MSC_TOKEN_MASK, status) != token) { + ret = -ETIMEDOUT; + goto out_err; + } + + mpam_fb_err = readl(payload_ofs + 0x0); + if (mpam_fb_err < 0) { + ret = mpam_fb_to_linux_errno(mpam_fb_err); + goto out_err; + } + + if (mpam_fb_command != MPAM_MSC_WRITE_CMD) + *result = readl(payload_ofs + 0x4); + + mutex_unlock(&pcc_chan->pcc_chan_lock); + + return 0; + +out_err: + mutex_unlock(&pcc_chan->pcc_chan_lock); + + mpam_fb_disable_mpam(ret, mpam_fb_err); + + return ret; +} + +int mpam_fb_send_read_request(struct mpam_msc *msc, u16 reg, u32 *result) +{ + return mpam_fb_send_request(msc, msc->id, reg, result, + MPAM_MSC_READ_CMD); +} + +int mpam_fb_send_write_request(struct mpam_msc *msc, u16 reg, u32 value) +{ + return mpam_fb_send_request(msc, msc->id, reg, &value, + MPAM_MSC_WRITE_CMD); +} diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index 6121cd126510..f13a79a84c58 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -57,6 +58,15 @@ struct mpam_garbage { struct platform_device *pdev; }; +struct mpam_pcc_chan { + struct list_head pcc_chans; + struct mbox_client pcc_cl; + struct pcc_mbox_chan *pcc_chan; + struct mutex pcc_chan_lock; /* only one message at a time */ + struct kref refcount; + int subspace_id; +}; + struct mpam_msc { /* member of mpam_all_msc */ struct list_head all_msc_list; @@ -66,6 +76,7 @@ struct mpam_msc { /* Not modified after mpam_is_enabled() becomes true */ enum mpam_msc_iface iface; + struct mpam_pcc_chan *pcc_chan; u32 nrdy_usec; cpumask_t accessibility; bool has_extd_esr; @@ -484,6 +495,9 @@ extern u8 mpam_pmg_max; void mpam_enable(struct work_struct *work); void mpam_disable(struct work_struct *work); +/* helper function to call from outside mpam_devices.c */ +void mpam_fb_disable_mpam(int err, int mpam_fb_err); + /* Reset all the RIS in a class under cpus_read_lock() */ void mpam_reset_class_locked(struct mpam_class *class); @@ -511,6 +525,10 @@ static inline void mpam_resctrl_offline_cpu(unsigned int cpu) { } static inline void mpam_resctrl_teardown_class(struct mpam_class *class) { } #endif /* CONFIG_RESCTRL_FS */ +/* MPAM-Fb Firmware-backed protocol wrappers */ +int mpam_fb_send_read_request(struct mpam_msc *msc, u16 reg, u32 *result); +int mpam_fb_send_write_request(struct mpam_msc *msc, u16 reg, u32 value); + /* * MPAM MSCs have the following register layout. See: * Arm Memory System Resource Partitioning and Monitoring (MPAM) System diff --git a/include/linux/arm_mpam.h b/include/linux/arm_mpam.h index f92a36187a52..002f56e15362 100644 --- a/include/linux/arm_mpam.h +++ b/include/linux/arm_mpam.h @@ -12,7 +12,7 @@ struct mpam_msc; enum mpam_msc_iface { MPAM_IFACE_MMIO, /* a real MPAM MSC */ - MPAM_IFACE_PCC, /* a fake MPAM MSC */ + MPAM_IFACE_PCC, /* using the MPAM-Fb firmware redirection */ }; enum mpam_class_types { -- 2.43.0