From 81174145d5f7b76744c8f635165e88735a944fca Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 2 Mar 2022 14:45:02 -0800
Subject: [PATCH] x86: Check RTM_ALWAYS_ABORT for RTM [BZ #28033]
From
https://www.intel.com/content/www/us/en/support/articles/000059422/processors.html
* Intel TSX will be disabled by default.
* The processor will force abort all Restricted Transactional Memory (RTM)
transactions by default.
* A new CPUID bit CPUID.07H.0H.EDX[11](RTM_ALWAYS_ABORT) will be enumerated,
which is set to indicate to updated software that the loaded microcode is
forcing RTM abort.
* On processors that enumerate support for RTM, the CPUID enumeration bits
for Intel TSX (CPUID.07H.0H.EBX[11] and CPUID.07H.0H.EBX[4]) continue to
be set by default after microcode update.
* Workloads that were benefited from Intel TSX might experience a change
in performance.
* System software may use a new bit in Model-Specific Register (MSR) 0x10F
TSX_FORCE_ABORT[TSX_CPUID_CLEAR] functionality to clear the Hardware Lock
Elision (HLE) and RTM bits to indicate to software that Intel TSX is
disabled.
1. Add RTM_ALWAYS_ABORT to CPUID features.
2. Set RTM usable only if RTM_ALWAYS_ABORT isn't set. This skips the
string/tst-memchr-rtm etc. testcases on the affected processors, which
always fail after a microcde update.
3. Check RTM feature, instead of usability, against /proc/cpuinfo.
This fixes BZ #28033.
(cherry picked from commit ea8e465a6b8d0f26c72bcbe453a854de3abf68ec)
---
manual/platform.texi | 3 +++
sysdeps/x86/cpu-features.c | 5 ++++-
sysdeps/x86/sys/platform/x86.h | 6 +++---
sysdeps/x86/tst-cpu-features-supports.c | 2 +-
sysdeps/x86/tst-get-cpu-features.c | 2 ++
5 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/manual/platform.texi b/manual/platform.texi
index 8fec2933..b7e8aef7 100644
--- a/manual/platform.texi
+++ b/manual/platform.texi
@@ -510,6 +510,9 @@ capability.
@item
@code{RTM} -- RTM instruction extensions.
+@item
+@code{RTM_ALWAYS_ABORT} -- Transactions always abort, making RTM unusable.
+
@item
@code{SDBG} -- IA32_DEBUG_INTERFACE MSR for silicon debug.
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index 3610ee5c..4889f062 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -74,7 +74,6 @@ update_usable (struct cpu_features *cpu_features)
CPU_FEATURE_SET_USABLE (cpu_features, HLE);
CPU_FEATURE_SET_USABLE (cpu_features, BMI2);
CPU_FEATURE_SET_USABLE (cpu_features, ERMS);
- CPU_FEATURE_SET_USABLE (cpu_features, RTM);
CPU_FEATURE_SET_USABLE (cpu_features, RDSEED);
CPU_FEATURE_SET_USABLE (cpu_features, ADX);
CPU_FEATURE_SET_USABLE (cpu_features, CLFLUSHOPT);
@@ -90,6 +89,7 @@ update_usable (struct cpu_features *cpu_features)
CPU_FEATURE_SET_USABLE (cpu_features, MOVDIRI);
CPU_FEATURE_SET_USABLE (cpu_features, MOVDIR64B);
CPU_FEATURE_SET_USABLE (cpu_features, FSRM);
+ CPU_FEATURE_SET_USABLE (cpu_features, RTM_ALWAYS_ABORT);
CPU_FEATURE_SET_USABLE (cpu_features, SERIALIZE);
CPU_FEATURE_SET_USABLE (cpu_features, TSXLDTRK);
CPU_FEATURE_SET_USABLE (cpu_features, LAHF64_SAHF64);
@@ -779,6 +779,9 @@ no_cpuid:
GLRO(dl_platform) = "i586";
#endif
+ if (!CPU_FEATURES_CPU_P (cpu_features, RTM_ALWAYS_ABORT))
+ CPU_FEATURE_SET_USABLE (cpu_features, RTM);
+
#if CET_ENABLED
# if HAVE_TUNABLES
TUNABLE_GET (x86_ibt, tunable_val_t *,
diff --git a/sysdeps/x86/sys/platform/x86.h b/sysdeps/x86/sys/platform/x86.h
index e5cc7c68..7a434926 100644
--- a/sysdeps/x86/sys/platform/x86.h
+++ b/sysdeps/x86/sys/platform/x86.h
@@ -247,7 +247,7 @@ extern const struct cpu_features *__x86_get_cpu_features (unsigned int)
#define bit_cpu_AVX512_VP2INTERSECT (1u << 8)
#define bit_cpu_INDEX_7_EDX_9 (1u << 9)
#define bit_cpu_MD_CLEAR (1u << 10)
-#define bit_cpu_INDEX_7_EDX_11 (1u << 11)
+#define bit_cpu_RTM_ALWAYS_ABORT (1u << 11)
#define bit_cpu_INDEX_7_EDX_12 (1u << 12)
#define bit_cpu_INDEX_7_EDX_13 (1u << 13)
#define bit_cpu_SERIALIZE (1u << 14)
@@ -471,7 +471,7 @@ extern const struct cpu_features *__x86_get_cpu_features (unsigned int)
#define index_cpu_AVX512_VP2INTERSECT COMMON_CPUID_INDEX_7
#define index_cpu_INDEX_7_EDX_9 COMMON_CPUID_INDEX_7
#define index_cpu_MD_CLEAR COMMON_CPUID_INDEX_7
-#define index_cpu_INDEX_7_EDX_11 COMMON_CPUID_INDEX_7
+#define index_cpu_RTM_ALWAYS_ABORT COMMON_CPUID_INDEX_7
#define index_cpu_INDEX_7_EDX_12 COMMON_CPUID_INDEX_7
#define index_cpu_INDEX_7_EDX_13 COMMON_CPUID_INDEX_7
#define index_cpu_SERIALIZE COMMON_CPUID_INDEX_7
@@ -695,7 +695,7 @@ extern const struct cpu_features *__x86_get_cpu_features (unsigned int)
#define reg_AVX512_VP2INTERSECT edx
#define reg_INDEX_7_EDX_9 edx
#define reg_MD_CLEAR edx
-#define reg_INDEX_7_EDX_11 edx
+#define reg_RTM_ALWAYS_ABORT edx
#define reg_INDEX_7_EDX_12 edx
#define reg_INDEX_7_EDX_13 edx
#define reg_SERIALIZE edx
diff --git a/sysdeps/x86/tst-cpu-features-supports.c b/sysdeps/x86/tst-cpu-features-supports.c
index 287cf01f..8100a319 100644
--- a/sysdeps/x86/tst-cpu-features-supports.c
+++ b/sysdeps/x86/tst-cpu-features-supports.c
@@ -152,7 +152,7 @@ do_test (int argc, char **argv)
fails += CHECK_SUPPORTS (rdpid, RDPID);
fails += CHECK_SUPPORTS (rdrnd, RDRAND);
fails += CHECK_SUPPORTS (rdseed, RDSEED);
- fails += CHECK_SUPPORTS (rtm, RTM);
+ fails += CHECK_CPU_SUPPORTS (rtm, RTM);
fails += CHECK_SUPPORTS (serialize, SERIALIZE);
fails += CHECK_SUPPORTS (sha, SHA);
fails += CHECK_CPU_SUPPORTS (shstk, SHSTK);
diff --git a/sysdeps/x86/tst-get-cpu-features.c b/sysdeps/x86/tst-get-cpu-features.c
index 2763deb6..0717e5d8 100644
--- a/sysdeps/x86/tst-get-cpu-features.c
+++ b/sysdeps/x86/tst-get-cpu-features.c
@@ -183,6 +183,7 @@ do_test (void)
CHECK_CPU_FEATURE (UINTR);
CHECK_CPU_FEATURE (AVX512_VP2INTERSECT);
CHECK_CPU_FEATURE (MD_CLEAR);
+ CHECK_CPU_FEATURE (RTM_ALWAYS_ABORT);
CHECK_CPU_FEATURE (SERIALIZE);
CHECK_CPU_FEATURE (HYBRID);
CHECK_CPU_FEATURE (TSXLDTRK);
@@ -344,6 +345,7 @@ do_test (void)
CHECK_CPU_FEATURE_USABLE (FSRM);
CHECK_CPU_FEATURE_USABLE (AVX512_VP2INTERSECT);
CHECK_CPU_FEATURE_USABLE (MD_CLEAR);
+ CHECK_CPU_FEATURE_USABLE (RTM_ALWAYS_ABORT);
CHECK_CPU_FEATURE_USABLE (SERIALIZE);
CHECK_CPU_FEATURE_USABLE (HYBRID);
CHECK_CPU_FEATURE_USABLE (TSXLDTRK);
--
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