linux-kernel - [tip: x86/cpu] x86/rfds: Exclude P-only parts from the RFDS affected list

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Message-ID: <174177327682.14745.7115933447537421556.tip-bot2@tip-bot2>
Date: Wed, 12 Mar 2025 09:54:36 -0000
From: "tip-bot2 for Pawan Gupta" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
 "Borislav Petkov (AMD)" <bp@...en8.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject:
 [tip: x86/cpu] x86/rfds: Exclude P-only parts from the RFDS affected list

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID:     8c7768105a84c16b9d71af2fa2d2c50ff3c80f4e
Gitweb:        https://git.kernel.org/tip/8c7768105a84c16b9d71af2fa2d2c50ff3c80f4e
Author:        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
AuthorDate:    Tue, 11 Mar 2025 08:03:08 -07:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Tue, 11 Mar 2025 20:53:30 +01:00

x86/rfds: Exclude P-only parts from the RFDS affected list

The affected CPU table (cpu_vuln_blacklist) marks Alderlake and Raptorlake
P-only parts affected by RFDS. This is not true because only E-cores are
affected by RFDS. With the current family/model matching it is not possible
to differentiate the unaffected parts, as the affected and unaffected
hybrid variants have the same model number.

Add a cpu-type match as well for such parts so as to exclude P-only parts
being marked as affected.

Note, family/model and cpu-type enumeration could be inaccurate in
virtualized environments. In a guest affected status is decided by RFDS_NO
and RFDS_CLEAR bits exposed by VMMs.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
Link: https://lore.kernel.org/r/20250311-add-cpu-type-v8-5-e8514dcaaff2@linux.intel.com
---
 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst | 8 +-------
 arch/x86/kernel/cpu/common.c                                 | 7 ++++--
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst b/Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
index 0585d02..ad15417 100644
--- a/Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
+++ b/Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
@@ -29,14 +29,6 @@ Below is the list of affected Intel processors [#f1]_:
    RAPTORLAKE_S            06_BFH
    ===================  ============
 
-As an exception to this table, Intel Xeon E family parts ALDERLAKE(06_97H) and
-RAPTORLAKE(06_B7H) codenamed Catlow are not affected. They are reported as
-vulnerable in Linux because they share the same family/model with an affected
-part. Unlike their affected counterparts, they do not enumerate RFDS_CLEAR or
-CPUID.HYBRID. This information could be used to distinguish between the
-affected and unaffected parts, but it is deemed not worth adding complexity as
-the reporting is fixed automatically when these parts enumerate RFDS_NO.
-
 Mitigation
 ==========
 Intel released a microcode update that enables software to clear sensitive
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 5f81c55..92fe56c 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1203,6 +1203,9 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
 #define VULNBL_INTEL_STEPS(vfm, max_stepping, issues)		   \
 	X86_MATCH_VFM_STEPS(vfm, X86_STEP_MIN, max_stepping, issues)
 
+#define VULNBL_INTEL_TYPE(vfm, cpu_type, issues)	\
+	X86_MATCH_VFM_CPU_TYPE(vfm, INTEL_CPU_TYPE_##cpu_type, issues)
+
 #define VULNBL_AMD(family, blacklist)		\
 	VULNBL(AMD, family, X86_MODEL_ANY, blacklist)
 
@@ -1251,9 +1254,9 @@ static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
 	VULNBL_INTEL_STEPS(INTEL_TIGERLAKE,	     X86_STEP_MAX,	GDS),
 	VULNBL_INTEL_STEPS(INTEL_LAKEFIELD,	     X86_STEP_MAX,	MMIO | MMIO_SBDS | RETBLEED),
 	VULNBL_INTEL_STEPS(INTEL_ROCKETLAKE,	     X86_STEP_MAX,	MMIO | RETBLEED | GDS),
-	VULNBL_INTEL_STEPS(INTEL_ALDERLAKE,	     X86_STEP_MAX,	RFDS),
+	VULNBL_INTEL_TYPE(INTEL_ALDERLAKE,		     ATOM,	RFDS),
 	VULNBL_INTEL_STEPS(INTEL_ALDERLAKE_L,	     X86_STEP_MAX,	RFDS),
-	VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE,	     X86_STEP_MAX,	RFDS),
+	VULNBL_INTEL_TYPE(INTEL_RAPTORLAKE,		     ATOM,	RFDS),
 	VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE_P,	     X86_STEP_MAX,	RFDS),
 	VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE_S,	     X86_STEP_MAX,	RFDS),
 	VULNBL_INTEL_STEPS(INTEL_ATOM_GRACEMONT,     X86_STEP_MAX,	RFDS),