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Subject: [PATCH v6 10/12] x86/resctrl: Add sysfs interface to write
 mbm_local_bytes event configuration
From:   Babu Moger <babu.moger@amd.com>
To:     <corbet@lwn.net>, <reinette.chatre@intel.com>,
        <tglx@linutronix.de>, <mingo@redhat.com>, <bp@alien8.de>
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Date:   Mon, 10 Oct 2022 15:30:10 -0500
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The current event configuration can be changed by the user by writing=0A=
to the configuration file /sys/fs/resctrl/info/L3_MON/mbm_local_config.=0A=
The event configuration settings are domain specific. Changing the=0A=
configuration on one CPU in a domain would affect the whole domain.=0A=
=0A=
Following are the types of events supported:=0A=
=3D=3D=3D=3D  =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
Bits   Description=0A=
=3D=3D=3D=3D  =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
6      Dirty Victims from the QOS domain to all types of memory=0A=
5      Reads to slow memory in the non-local NUMA domain=0A=
4      Reads to slow memory in the local NUMA domain=0A=
3      Non-temporal writes to non-local NUMA domain=0A=
2      Non-temporal writes to local NUMA domain=0A=
1      Reads to memory in the non-local NUMA domain=0A=
0      Reads to memory in the local NUMA domain=0A=
=3D=3D=3D=3D  =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
=0A=
For example:=0A=
To change the mbm_local_bytes to count all the non-temporal writes on=0A=
domain 0. To achieve this, the bits 2 and 3 needs to be set which is=0A=
1100b (in hex 0xc). Run the command.=0A=
    $echo  0=3D0xc > /sys/fs/resctrl/info/L3_MON/mbm_local_config=0A=
=0A=
To change the mbm_local_bytes to count only reads to local NUMA domain 1.=
=0A=
To achieve this, the bit 0 needs to be set which 1b (in hex 0x1).=0A=
Run the command.=0A=
    $echo  1=3D0x1 > /sys/fs/resctrl/info/L3_MON/mbm_local_config=0A=
=0A=
Signed-off-by: Babu Moger <babu.moger@amd.com>=0A=
---=0A=
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |   21 +++++++++++++++++++++=0A=
 1 file changed, 21 insertions(+)=0A=
=0A=
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/r=
esctrl/rdtgroup.c=0A=
index 25ff56ecb817..e744db5dc057 100644=0A=
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c=0A=
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c=0A=
@@ -1639,6 +1639,26 @@ static ssize_t mbm_total_config_write(struct kernfs_=
open_file *of,=0A=
 	return ret ?: nbytes;=0A=
 }=0A=
 =0A=
+static ssize_t mbm_local_config_write(struct kernfs_open_file *of,=0A=
+				      char *buf, size_t nbytes,=0A=
+				      loff_t off)=0A=
+{=0A=
+	struct rdt_resource *r =3D of->kn->parent->priv;=0A=
+	int ret;=0A=
+=0A=
+	/* Valid input requires a trailing newline */=0A=
+	if (nbytes =3D=3D 0 || buf[nbytes - 1] !=3D '\n')=0A=
+		return -EINVAL;=0A=
+=0A=
+	rdt_last_cmd_clear();=0A=
+=0A=
+	buf[nbytes - 1] =3D '\0';=0A=
+=0A=
+	ret =3D mon_config_parse(r, buf, QOS_L3_MBM_LOCAL_EVENT_ID);=0A=
+=0A=
+	return ret ?: nbytes;=0A=
+}=0A=
+=0A=
 /* rdtgroup information files for one cache resource. */=0A=
 static struct rftype res_common_files[] =3D {=0A=
 	{=0A=
@@ -1749,6 +1769,7 @@ static struct rftype res_common_files[] =3D {=0A=
 		.mode		=3D 0644,=0A=
 		.kf_ops		=3D &rdtgroup_kf_single_ops,=0A=
 		.seq_show	=3D mbm_local_config_show,=0A=
+		.write		=3D mbm_local_config_write,=0A=
 	},=0A=
 	{=0A=
 		.name		=3D "cpus",=0A=
=0A=