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Message-Id: <20251205215901.17772-35-james.morse@arm.com>
Date: Fri, 5 Dec 2025 21:58:57 +0000
From: James Morse <james.morse@....com>
To: linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Cc: James Morse <james.morse@....com>,
D Scott Phillips OS <scott@...amperecomputing.com>,
carl@...amperecomputing.com,
lcherian@...vell.com,
bobo.shaobowang@...wei.com,
tan.shaopeng@...itsu.com,
baolin.wang@...ux.alibaba.com,
Jamie Iles <quic_jiles@...cinc.com>,
Xin Hao <xhao@...ux.alibaba.com>,
peternewman@...gle.com,
dfustini@...libre.com,
amitsinght@...vell.com,
David Hildenbrand <david@...nel.org>,
Dave Martin <dave.martin@....com>,
Koba Ko <kobak@...dia.com>,
Shanker Donthineni <sdonthineni@...dia.com>,
fenghuay@...dia.com,
baisheng.gao@...soc.com,
Jonathan Cameron <jonathan.cameron@...wei.com>,
Gavin Shan <gshan@...hat.com>,
Ben Horgan <ben.horgan@....com>,
rohit.mathew@....com,
reinette.chatre@...el.com,
Punit Agrawal <punit.agrawal@....qualcomm.com>
Subject: [RFC PATCH 34/38] arm_mpam: Add quirk framework
From: Shanker Donthineni <sdonthineni@...dia.com>
The MPAM specification includes the MPAMF_IIDR, which serves to
uniquely identify the MSC implementation through a combination of
implementer details, product ID, variant, and revision. Certain
hardware issues/errata can be resolved using software workarounds.
Introduce a quirk framework to allow workarounds to be enabled based
on the MPAMF_IIDR value.
Signed-off-by: Shanker Donthineni <sdonthineni@...dia.com>
[ morse: Stash the IIDR so this doesn't need an IPI, enable quirks only
once, move the description to the callback so it can be pr_once()d, add
an enum of workarounds for popular errata. Add macros for making lists
of product/revision/vendor half readable ]
Signed-off-by: James Morse <james.morse@....com>
---
drivers/resctrl/mpam_devices.c | 27 +++++++++++++++++++++++++++
drivers/resctrl/mpam_internal.h | 26 ++++++++++++++++++++++++++
2 files changed, 53 insertions(+)
diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 741e14e1e6cf..f0f6f9b55ad4 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -630,6 +630,25 @@ static struct mpam_msc_ris *mpam_get_or_create_ris(struct mpam_msc *msc,
return ERR_PTR(-ENOENT);
}
+static const struct mpam_quirk mpam_quirks[] = {
+ { NULL }, /* Sentinel */
+};
+
+static void mpam_enable_quirks(struct mpam_msc *msc)
+{
+ const struct mpam_quirk *quirk;
+
+ for (quirk = &mpam_quirks[0]; quirk->iidr_mask; quirk++) {
+ if (quirk->iidr != (msc->iidr & quirk->iidr_mask))
+ continue;
+
+ if (quirk->init)
+ quirk->init(msc, quirk);
+ else
+ mpam_set_quirk(quirk->workaround, msc);
+ }
+}
+
/*
* IHI009A.a has this nugget: "If a monitor does not support automatic behaviour
* of NRDY, software can use this bit for any purpose" - so hardware might not
@@ -864,8 +883,11 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
/* Grab an IDR value to find out how many RIS there are */
mutex_lock(&msc->part_sel_lock);
idr = mpam_msc_read_idr(msc);
+ msc->iidr = mpam_read_partsel_reg(msc, IIDR);
mutex_unlock(&msc->part_sel_lock);
+ mpam_enable_quirks(msc);
+
msc->ris_max = FIELD_GET(MPAMF_IDR_RIS_MAX, idr);
/* Use these values so partid/pmg always starts with a valid value */
@@ -1987,6 +2009,7 @@ static bool mpam_has_cmax_wd_feature(struct mpam_props *props)
* resulting safe value must be compatible with both. When merging values in
* the tree, all the aliasing resources must be handled first.
* On mismatch, parent is modified.
+ * Quirks on an MSC will apply to all MSC in that class.
*/
static void __props_mismatch(struct mpam_props *parent,
struct mpam_props *child, bool alias)
@@ -2106,6 +2129,7 @@ static void __props_mismatch(struct mpam_props *parent,
* nobble the class feature, as we can't configure all the resources.
* e.g. The L3 cache is composed of two resources with 13 and 17 portion
* bitmaps respectively.
+ * Quirks on an MSC will apply to all MSC in that class.
*/
static void
__class_props_mismatch(struct mpam_class *class, struct mpam_vmsc *vmsc)
@@ -2119,6 +2143,9 @@ __class_props_mismatch(struct mpam_class *class, struct mpam_vmsc *vmsc)
dev_dbg(dev, "Merging features for class:0x%lx &= vmsc:0x%lx\n",
(long)cprops->features, (long)vprops->features);
+ /* Merge quirks */
+ class->quirks |= vmsc->msc->quirks;
+
/* Take the safe value for any common features */
__props_mismatch(cprops, vprops, false);
}
diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index d381906545ed..de3e5faa12b2 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -88,6 +88,8 @@ struct mpam_msc {
u8 pmg_max;
unsigned long ris_idxs;
u32 ris_max;
+ u32 iidr;
+ u16 quirks;
/*
* error_irq_lock is taken when registering/unregistering the error
@@ -215,6 +217,29 @@ struct mpam_props {
#define mpam_set_feature(_feat, x) set_bit(_feat, (x)->features)
#define mpam_clear_feature(_feat, x) clear_bit(_feat, (x)->features)
+/* Workaround bits for msc->quirks */
+enum mpam_device_quirks {
+ MPAM_QUIRK_LAST,
+};
+
+#define mpam_has_quirk(_quirk, x) ((1 << (_quirk) & (x)->quirks))
+#define mpam_set_quirk(_quirk, x) ((x)->quirks |= (1 << (_quirk)))
+
+struct mpam_quirk {
+ void (*init)(struct mpam_msc *msc, const struct mpam_quirk *quirk);
+
+ u32 iidr;
+ u32 iidr_mask;
+
+ enum mpam_device_quirks workaround;
+};
+
+#define MPAM_IIDR_MATCH_ONE FIELD_PREP_CONST(MPAMF_IIDR_PRODUCTID, 0xfff) | \
+ FIELD_PREP_CONST(MPAMF_IIDR_VARIANT, 0xf ) | \
+ FIELD_PREP_CONST(MPAMF_IIDR_REVISION, 0xf ) | \
+ FIELD_PREP_CONST(MPAMF_IIDR_IMPLEMENTER, 0xfff)
+
+
/* The values for MSMON_CFG_MBWU_FLT.RWBW */
enum mon_filter_options {
COUNT_BOTH = 0,
@@ -258,6 +283,7 @@ struct mpam_class {
struct mpam_props props;
u32 nrdy_usec;
+ u16 quirks;
u8 level;
enum mpam_class_types type;
--
2.39.5
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