linux-kernel - [PATCH] platform/x86: intel-uncore-freq: Prevent driver loading in guests

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Message-Id: <20220421184154.747721-1-srinivas.pandruvada@linux.intel.com>
Date:   Thu, 21 Apr 2022 11:41:54 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     hdegoede@...hat.com, markgross@...nel.org
Cc:     platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Borislav Petkov <bp@...e.de>
Subject: [PATCH] platform/x86: intel-uncore-freq: Prevent driver loading in guests

Loading this driver in guests results in unchecked MSR access error for
MSR 0x620.

There is no use of reading and modifying package/die scoped uncore MSRs
in guests. So check for CPU feature X86_FEATURE_HYPERVISOR to prevent
loading of this driver in guests.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215870
Suggested-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
---
 drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c
index c61f804dd44e..8f9c571d7257 100644
--- a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c
+++ b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency.c
@@ -212,6 +212,9 @@ static int __init intel_uncore_init(void)
 	const struct x86_cpu_id *id;
 	int ret;
 
+	if (cpu_feature_enabled(X86_FEATURE_HYPERVISOR))
+		return -ENODEV;
+
 	id = x86_match_cpu(intel_uncore_cpu_ids);
 	if (!id)
 		return -ENODEV;
-- 
2.31.1