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Message-ID: <166903694262.4906.2840275250764271155.tip-bot2@tip-bot2>
Date: Mon, 21 Nov 2022 13:22:22 -0000
From: "tip-bot2 for Pawan Gupta" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Andrew Cooper <andrew.cooper3@...rix.com>,
Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
Borislav Petkov <bp@...e.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, <stable@...nel.org>,
x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/tsx: Add a feature bit for TSX control MSR support
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: aaa65d17eec372c6a9756833f3964ba05b05ea14
Gitweb: https://git.kernel.org/tip/aaa65d17eec372c6a9756833f3964ba05b05ea14
Author: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
AuthorDate: Tue, 15 Nov 2022 11:17:05 -08:00
Committer: Borislav Petkov <bp@...e.de>
CommitterDate: Mon, 21 Nov 2022 14:08:20 +01:00
x86/tsx: Add a feature bit for TSX control MSR support
Support for the TSX control MSR is enumerated in MSR_IA32_ARCH_CAPABILITIES.
This is different from how other CPU features are enumerated i.e. via
CPUID. Currently, a call to tsx_ctrl_is_supported() is required for
enumerating the feature. In the absence of a feature bit for TSX control,
any code that relies on checking feature bits directly will not work.
In preparation for adding a feature bit check in MSR save/restore
during suspend/resume, set a new feature bit X86_FEATURE_TSX_CTRL when
MSR_IA32_TSX_CTRL is present. Also make tsx_ctrl_is_supported() use the
new feature bit to avoid any overhead of reading the MSR.
[ bp: Remove tsx_ctrl_is_supported(), add room for two more feature
bits in word 11 which are coming up in the next merge window. ]
Suggested-by: Andrew Cooper <andrew.cooper3@...rix.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: <stable@...nel.org>
Link: https://lore.kernel.org/r/de619764e1d98afbb7a5fa58424f1278ede37b45.1668539735.git.pawan.kumar.gupta@linux.intel.com
---
arch/x86/include/asm/cpufeatures.h | 3 ++-
arch/x86/kernel/cpu/tsx.c | 38 ++++++++++++-----------------
2 files changed, 20 insertions(+), 21 deletions(-)
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index b71f4f2..b2da7cb 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -305,6 +305,9 @@
#define X86_FEATURE_USE_IBPB_FW (11*32+16) /* "" Use IBPB during runtime firmware calls */
#define X86_FEATURE_RSB_VMEXIT_LITE (11*32+17) /* "" Fill RSB on VM exit when EIBRS is enabled */
+
+#define X86_FEATURE_MSR_TSX_CTRL (11*32+20) /* "" MSR IA32_TSX_CTRL (Intel) implemented */
+
/* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
#define X86_FEATURE_AVX_VNNI (12*32+ 4) /* AVX VNNI instructions */
#define X86_FEATURE_AVX512_BF16 (12*32+ 5) /* AVX512 BFLOAT16 instructions */
diff --git a/arch/x86/kernel/cpu/tsx.c b/arch/x86/kernel/cpu/tsx.c
index ec7bbac..8009c83 100644
--- a/arch/x86/kernel/cpu/tsx.c
+++ b/arch/x86/kernel/cpu/tsx.c
@@ -58,24 +58,6 @@ static void tsx_enable(void)
wrmsrl(MSR_IA32_TSX_CTRL, tsx);
}
-static bool tsx_ctrl_is_supported(void)
-{
- u64 ia32_cap = x86_read_arch_cap_msr();
-
- /*
- * TSX is controlled via MSR_IA32_TSX_CTRL. However, support for this
- * MSR is enumerated by ARCH_CAP_TSX_MSR bit in MSR_IA32_ARCH_CAPABILITIES.
- *
- * TSX control (aka MSR_IA32_TSX_CTRL) is only available after a
- * microcode update on CPUs that have their MSR_IA32_ARCH_CAPABILITIES
- * bit MDS_NO=1. CPUs with MDS_NO=0 are not planned to get
- * MSR_IA32_TSX_CTRL support even after a microcode update. Thus,
- * tsx= cmdline requests will do nothing on CPUs without
- * MSR_IA32_TSX_CTRL support.
- */
- return !!(ia32_cap & ARCH_CAP_TSX_CTRL_MSR);
-}
-
static enum tsx_ctrl_states x86_get_tsx_auto_mode(void)
{
if (boot_cpu_has_bug(X86_BUG_TAA))
@@ -135,7 +117,7 @@ static void tsx_clear_cpuid(void)
rdmsrl(MSR_TSX_FORCE_ABORT, msr);
msr |= MSR_TFA_TSX_CPUID_CLEAR;
wrmsrl(MSR_TSX_FORCE_ABORT, msr);
- } else if (tsx_ctrl_is_supported()) {
+ } else if (cpu_feature_enabled(X86_FEATURE_MSR_TSX_CTRL)) {
rdmsrl(MSR_IA32_TSX_CTRL, msr);
msr |= TSX_CTRL_CPUID_CLEAR;
wrmsrl(MSR_IA32_TSX_CTRL, msr);
@@ -158,7 +140,8 @@ static void tsx_dev_mode_disable(void)
u64 mcu_opt_ctrl;
/* Check if RTM_ALLOW exists */
- if (!boot_cpu_has_bug(X86_BUG_TAA) || !tsx_ctrl_is_supported() ||
+ if (!boot_cpu_has_bug(X86_BUG_TAA) ||
+ !cpu_feature_enabled(X86_FEATURE_MSR_TSX_CTRL) ||
!cpu_feature_enabled(X86_FEATURE_SRBDS_CTRL))
return;
@@ -191,7 +174,20 @@ void __init tsx_init(void)
return;
}
- if (!tsx_ctrl_is_supported()) {
+ /*
+ * TSX is controlled via MSR_IA32_TSX_CTRL. However, support for this
+ * MSR is enumerated by ARCH_CAP_TSX_MSR bit in MSR_IA32_ARCH_CAPABILITIES.
+ *
+ * TSX control (aka MSR_IA32_TSX_CTRL) is only available after a
+ * microcode update on CPUs that have their MSR_IA32_ARCH_CAPABILITIES
+ * bit MDS_NO=1. CPUs with MDS_NO=0 are not planned to get
+ * MSR_IA32_TSX_CTRL support even after a microcode update. Thus,
+ * tsx= cmdline requests will do nothing on CPUs without
+ * MSR_IA32_TSX_CTRL support.
+ */
+ if (x86_read_arch_cap_msr() & ARCH_CAP_TSX_CTRL_MSR) {
+ setup_force_cpu_cap(X86_FEATURE_MSR_TSX_CTRL);
+ } else {
tsx_ctrl_state = TSX_CTRL_NOT_SUPPORTED;
return;
}
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