linux-kernel - [PATCH v1 4/4] x86/msr: Do not allow writes to MSR_IA32_ENERGY_PERF

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Date:   Thu, 29 Oct 2020 20:02:59 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     Thomas Renninger <trenn@...e.com>, Shuah Khan <shuah@...nel.org>,
        Len Brown <lenb@...nel.org>, linux-pm@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v1 4/4] x86/msr: Do not allow writes to MSR_IA32_ENERGY_PERF_BIAS

From: Borislav Petkov <bp@...e.de>

Now that all in-kernel-tree users are converted to using the sysfs file,
remove the MSR from the "allowlist".

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/msr.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index c0d409810658..b1147862730c 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -99,9 +99,6 @@ static int filter_write(u32 reg)
 	if (!__ratelimit(&fw_rs))
 		return 0;
 
-	if (reg == MSR_IA32_ENERGY_PERF_BIAS)
-		return 0;
-
 	pr_err("Write to unrecognized MSR 0x%x by %s (pid: %d). Please report to x86@...nel.org.\n",
 	       reg, current->comm, current->pid);
 
-- 
2.21.0