linux-kernel - [PATCH] x86/perf: Fixed kernel panic during boot on Nano processor.

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Message-ID: <20221103032304.27753-1-silviazhao-oc@zhaoxin.com>
Date:   Thu, 3 Nov 2022 11:23:04 +0800
From:   silviazhao-oc <silviazhao-oc@...oxin.com>
To:     <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...nel.org>, <namhyung@...nel.org>, <tglx@...utronix.de>,
        <bp@...en8.de>, <dave.hansen@...ux.intel.com>, <x86@...nel.org>,
        <hpa@...or.com>, <linux-perf-users@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <cobechen@...oxin.com>, <louisqi@...oxin.com>,
        <silviazhao@...oxin.com>
Subject: [PATCH] x86/perf: Fixed kernel panic during boot on Nano processor.

Nano processor may not fully support rdpmc instruction, it works well
for reading general pmc counter, but will lead GP(general protection)
when accessing fixed pmc counter. Furthermore, family/mode information
is same between Nano processor and ZX-C processor, it leads to zhaoxin
pmu driver is wrongly loaded for Nano processor, which resulting boot
kernal fail.

To solve this problem, stepping information will be checked to distinguish
between Nano processor and ZX-C processor.

[https://bugzilla.kernel.org/show_bug.cgi?id=212389]

Reported-by: Arjan <8vvbbqzo567a@...pam.xutrox.com>
Signed-off-by: silviazhao-oc <silviazhao-oc@...oxin.com>
---
 arch/x86/events/zhaoxin/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/zhaoxin/core.c b/arch/x86/events/zhaoxin/core.c
index 949d845c922b..cef1de251613 100644
--- a/arch/x86/events/zhaoxin/core.c
+++ b/arch/x86/events/zhaoxin/core.c
@@ -541,7 +541,8 @@ __init int zhaoxin_pmu_init(void)
 
 	switch (boot_cpu_data.x86) {
 	case 0x06:
-		if (boot_cpu_data.x86_model == 0x0f || boot_cpu_data.x86_model == 0x19) {
+		if ((boot_cpu_data.x86_model == 0x0f && boot_cpu_data.x86_stepping >= 0x0e) ||
+			boot_cpu_data.x86_model == 0x19) {
 
 			x86_pmu.max_period = x86_pmu.cntval_mask >> 1;
 
-- 
2.17.1