Received-SPF: pass (google.com: domain of linux-kernel+bounces-98505-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
From: Rex Nie <rex.nie@jaguarmicro.com>
To: james.morse@arm.com
Cc: fenghua.yu@intel.com,
	reinette.chatre@intel.com,
	linux-kernel@vger.kernel.org,
	Rex Nie <rex.nie@jaguarmicro.com>,
	Liming Wu <liming.wu@jaguar.com>
Subject: [PATCH] fs/resctrl: fix domid loss precision issue
Date: Mon, 11 Mar 2024 14:48:22 +0800
Message-Id: <20240311064822.891-1-rex.nie@jaguarmicro.com>
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0:
	=?us-ascii?Q?lIH/nHDz2AHeRQpYP0QGui8/J0gGt54NNdf1MD+ThokcHTpAmsKtyBQQV5rJ?=
 =?us-ascii?Q?wXHchInIJBVQmA+AKZq6uZ1DADDm2iXVepMz/XMwKSF64JQc3gbHHac6NO+M?=
 =?us-ascii?Q?9gHOJy6pr4Ljl6CFH060qLSWshc6EvMSnBBxiJkiOpnBHsuC9uohk6Qxqc1v?=
 =?us-ascii?Q?O9I3S1gt4y317hyTq3oNOVZYJuD2SFlrvqNebpX9o+lCfIDEY1vJ9T1ZPfvN?=
 =?us-ascii?Q?LI5XKk87aGZbKlV8SB3KL4C0klQroNEMKqtDzIZlmcd9VzKJwwwZ3nIRU3zd?=
 =?us-ascii?Q?BCxVhlGnja0C86bZ1zYtQ9Yvzu2zNJ7yAhkTpyGSOxOBnoLk5lQwJVvRjrum?=
 =?us-ascii?Q?0xFsDOQRtA5q6Q7S5r1YZ7Pq1HapU02L9VGEOMWqc08eVBh0/5eU4Qjxnst2?=
 =?us-ascii?Q?ZFYDDYEzCY9X98h70Q9XdXQv6DMaGXm3cVcm+l3A01zWEMVO9eB+aKu7N/+a?=
 =?us-ascii?Q?oSA7GeT7X2nh2urWDHVZHs7RD2rgfFiP/7mlw+oBFkyWiu4rgtoROF4yl0YH?=
 =?us-ascii?Q?lYnBa89DmrxCkGJmkkOh5VGR88PwfbjmITr7B7jJAs24ORmrBSLzKXs22vWK?=
 =?us-ascii?Q?JMzXAGL3XrKs5ydp8JpC21SVEuPNb7TgRKrR4dnfD+tDZdQt7UaoQxvB3E69?=
 =?us-ascii?Q?R27Q6qO1Cj4iWdUH5KOY54jjWMD20QEXASd9eFC9aPtndDSc7g27j0mbeGqi?=
 =?us-ascii?Q?4N98RZ6HU0abXOaKQEkMiGGrf1k9/E3UUasTs75H0Ek0mhCRg+ynnVYNUkMh?=
 =?us-ascii?Q?GOALC16z9ejYfcMYPoWF0h9ZgYuzI8wlPuDtwSZevX5ngc0bOqAOMA4aFV4i?=
 =?us-ascii?Q?WFLjZy79fDbwRjt/RGG+Y+8soPFPScoR1kVeViQkw4SOOyH+kp53MjOiD38G?=
 =?us-ascii?Q?JIHr4KGVKi6Rj42pInEL7Rtj48M18MQfiXQbaeY7zC6DKId8qUXV9m+EoRNx?=
 =?us-ascii?Q?EGvXm2I2d8JcN/xWg6nnh//27Qozzg/ZQSi42J9f5uMkcBhkYOe1wqas/ZX/?=
 =?us-ascii?Q?t4XrryVl+kKKbJFuQM3xAoFkMxBq54ckG8D+63ho13vm/smQaD8d1w/tN5gm?=
 =?us-ascii?Q?XEFoUIcAAg+kOIZTcXiZS4vJadaAtZYYa+C01axGJefmOnPuZMUUJyRMn2Vq?=
 =?us-ascii?Q?MD/FOA/1Wx6ew29MGE0DduRm4A5bxqHWQ8SQjyXcb71a4sf9ZVPJE+qdwdOk?=
 =?us-ascii?Q?Mhiv76UwXy1/wKiX+zGsQSCbqZTIvUSvssUBGxN/+V4IlBxtylQiL3CKHlIV?=
 =?us-ascii?Q?/xtaDY6gzaUQ+/eGvB9Ui1qRkgcrpuCQ75OOOnTZDoSXpDEP2rNTY0dZwjG5?=
 =?us-ascii?Q?iUMny+ZS9x5i88hDuMYPVdSucwbXHgWuQg5tN/28ZP3xJ0IsaYRw5izmqU3A?=
 =?us-ascii?Q?dB0E8X0b2xWEol+YIbynZuODzT/flBGChgz9nkp1GcpQOqzq+rW/eILom1wW?=
 =?us-ascii?Q?93QjluWyFt+q38V+bmQgZO2T8k1xBgYHq5ASX9ekuPrxRQgxYhCHzF9WuMef?=
 =?us-ascii?Q?knRzUctlYcoplROsDRwUZasZPIjy1m9slXPssxfNO/HVzGNr4mm0/0lGA4wK?=
 =?us-ascii?Q?z5MM8WiY/8flmkC6vyX9gDqDtw0B725CgzeDr7Yc?=
X-OriginatorOrg: jaguarmicro.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 5133715e-4896-440b-3c17-08dc41974696
X-MS-Exchange-CrossTenant-AuthSource: KL1PR0601MB5773.apcprd06.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Mar 2024 06:48:36.1514
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 1e45a5c2-d3e1-46b3-a0e6-c5ebf6d8ba7b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: biOVJnQUGaB2ONvbnyHYPHCZvTjbOCY/LrsVtwUtDm6NYvdrObU/s8mMdrq7ioPVgRsHBKZCwYLp/2ghFHQfaw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SEYPR06MB7042

Below statement from mkdir_mondata_subdir function will loss precision,
because it assigns int to 14 bits bitfield.
	priv.u.domid = d->id;

This will cause below issue if cache_id > 0x3fff likes:
/sys/fs/resctrl/mon_groups/p1/mon_data/mon_L3_1048564 # cat llc_occupancy
cat: read error: No such file or directory

This is the call trace when cat llc_occupancy:
rdtgroup_mondata_show()
	domid = md.u.domid
	d = resctrl_arch_find_domain(r, domid)

d is null here because of lossing precision

Signed-off-by: Rex Nie <rex.nie@jaguarmicro.com>
Signed-off-by: Liming Wu <liming.wu@jaguar.com>
---
 fs/resctrl/internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 7a6f46b4edd0..096317610949 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -94,7 +94,7 @@ union mon_data_bits {
 	struct {
 		unsigned int rid		: 10;
 		enum resctrl_event_id evtid	: 8;
-		unsigned int domid		: 14;
+		u32				domid;
 	} u;
 };
 
-- 
2.34.1