[tip: x86/cpu] x86/CPU: Add support for Vortex CPUs
From: tip-bot2 for Marcos Del Sol Vives
Date: Thu Oct 21 2021 - 10:15:15 EST
The following commit has been merged into the x86/cpu branch of tip:
Commit-ID: 639475d434b88b58827e1aae601ed1853803f5be
Gitweb: https://git.kernel.org/tip/639475d434b88b58827e1aae601ed1853803f5be
Author: Marcos Del Sol Vives <marcos@xxxxxxxx>
AuthorDate: Sun, 17 Oct 2021 11:44:10 +02:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 21 Oct 2021 15:49:07 +02:00
x86/CPU: Add support for Vortex CPUs
DM&P devices were not being properly identified, which resulted in
unneeded Spectre/Meltdown mitigations being applied.
The manufacturer states that these devices execute always in-order and
don't support either speculative execution or branch prediction, so
they are not vulnerable to this class of attack. [1]
This is something I've personally tested by a simple timing analysis
on my Vortex86MX CPU, and can confirm it is true.
Add identification for some devices that lack the CPUID product name
call, so they appear properly on /proc/cpuinfo.
¹https://www.ssv-embedded.de/doks/infos/DMP_Ann_180108_Meltdown.pdf
[ bp: Massage commit message. ]
Signed-off-by: Marcos Del Sol Vives <marcos@xxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20211017094408.1512158-1-marcos@xxxxxxxx
---
arch/x86/Kconfig.cpu | 13 ++++++++++-
arch/x86/include/asm/processor.h | 3 +-
arch/x86/kernel/cpu/Makefile | 1 +-
arch/x86/kernel/cpu/common.c | 2 ++-
arch/x86/kernel/cpu/vortex.c | 39 +++++++++++++++++++++++++++++++-
5 files changed, 57 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/kernel/cpu/vortex.c
diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 814fe0d..eefc434 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -508,3 +508,16 @@ config CPU_SUP_ZHAOXIN
CPU might render the kernel unbootable.
If unsure, say N.
+
+config CPU_SUP_VORTEX_32
+ default y
+ bool "Support Vortex processors" if PROCESSOR_SELECT
+ depends on X86_32
+ help
+ This enables detection, tunings and quirks for Vortex processors
+
+ You need this enabled if you want your kernel to run on a
+ Vortex CPU. Disabling this option on other types of CPUs
+ makes the kernel a tiny bit smaller.
+
+ If unsure, say N.
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 9ad2aca..64e5290 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -164,7 +164,8 @@ enum cpuid_regs_idx {
#define X86_VENDOR_NSC 8
#define X86_VENDOR_HYGON 9
#define X86_VENDOR_ZHAOXIN 10
-#define X86_VENDOR_NUM 11
+#define X86_VENDOR_VORTEX 11
+#define X86_VENDOR_NUM 12
#define X86_VENDOR_UNKNOWN 0xff
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 637b499..9661e3e 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o
obj-$(CONFIG_CPU_SUP_TRANSMETA_32) += transmeta.o
obj-$(CONFIG_CPU_SUP_UMC_32) += umc.o
obj-$(CONFIG_CPU_SUP_ZHAOXIN) += zhaoxin.o
+obj-$(CONFIG_CPU_SUP_VORTEX_32) += vortex.o
obj-$(CONFIG_X86_MCE) += mce/
obj-$(CONFIG_MTRR) += mtrr/
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 0f88859..325d602 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1044,6 +1044,8 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
VULNWL(CENTAUR, 5, X86_MODEL_ANY, NO_SPECULATION),
VULNWL(INTEL, 5, X86_MODEL_ANY, NO_SPECULATION),
VULNWL(NSC, 5, X86_MODEL_ANY, NO_SPECULATION),
+ VULNWL(VORTEX, 5, X86_MODEL_ANY, NO_SPECULATION),
+ VULNWL(VORTEX, 6, X86_MODEL_ANY, NO_SPECULATION),
/* Intel Family 6 */
VULNWL_INTEL(ATOM_SALTWELL, NO_SPECULATION | NO_ITLB_MULTIHIT),
diff --git a/arch/x86/kernel/cpu/vortex.c b/arch/x86/kernel/cpu/vortex.c
new file mode 100644
index 0000000..e268547
--- /dev/null
+++ b/arch/x86/kernel/cpu/vortex.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <asm/processor.h>
+#include "cpu.h"
+
+/*
+ * No special init required for Vortex processors.
+ */
+
+static const struct cpu_dev vortex_cpu_dev = {
+ .c_vendor = "Vortex",
+ .c_ident = { "Vortex86 SoC" },
+ .legacy_models = {
+ {
+ .family = 5,
+ .model_names = {
+ [2] = "Vortex86DX",
+ [8] = "Vortex86MX",
+ },
+ },
+ {
+ .family = 6,
+ .model_names = {
+ /*
+ * Both the Vortex86EX and the Vortex86EX2
+ * have the same family and model id.
+ *
+ * However, the -EX2 supports the product name
+ * CPUID call, so this name will only be used
+ * for the -EX, which does not.
+ */
+ [0] = "Vortex86EX",
+ },
+ },
+ },
+ .c_x86_vendor = X86_VENDOR_VORTEX,
+};
+
+cpu_dev_register(vortex_cpu_dev);