|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen stable-4.8] x86/feature: Definitions for Indirect Branch Controls
commit da49e518d79ca6c405a244889cab57ac8ed097cb
Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Feb 8 12:49:41 2018 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 8 12:49:41 2018 +0100
x86/feature: Definitions for Indirect Branch Controls
Contemporary processors are gaining Indirect Branch Controls via microcode
updates. Intel are introducing one bit to indicate IBRS and IBPB support,
and
a second bit for STIBP. AMD are introducing IBPB only, so enumerate it
with a
separate bit.
Furthermore, depending on compiler and microcode availability, we may want
to
run Xen with IBRS set, or clear.
To use these facilities, we synthesise separate IBRS and IBPB bits for
internal use. A lot of infrastructure is required before these features are
safe to offer to guests.
This is part of XSA-254.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
master commit: 0d703a701cc4bc47773986b2796eebd28b1439b5
master date: 2018-01-16 17:45:50 +0000
---
tools/libxc/xc_cpuid_x86.c | 8 ++++++--
tools/libxl/libxl_cpuid.c | 3 +++
tools/misc/xen-cpuid.c | 16 +++++++++++++++-
xen/arch/x86/cpu/common.c | 2 +-
xen/arch/x86/spec_ctrl.c | 17 +++++++++++++++++
xen/include/asm-x86/cpufeature.h | 3 +++
xen/include/asm-x86/msr-index.h | 8 ++++++++
xen/include/public/arch-x86/cpufeatureset.h | 5 +++++
xen/tools/gen-cpuid.py | 5 +++++
9 files changed, 63 insertions(+), 4 deletions(-)
diff --git a/tools/libxc/xc_cpuid_x86.c b/tools/libxc/xc_cpuid_x86.c
index 2ad9aeb..2779925 100644
--- a/tools/libxc/xc_cpuid_x86.c
+++ b/tools/libxc/xc_cpuid_x86.c
@@ -547,13 +547,15 @@ static void xc_cpuid_hvm_policy(xc_interface *xch,
{
regs[1] = info->featureset[featureword_of(X86_FEATURE_FSGSBASE)];
regs[2] =
info->featureset[featureword_of(X86_FEATURE_PREFETCHWT1)];
+ regs[3] = info->featureset[featureword_of(X86_FEATURE_IBRSB)];
}
else
{
regs[1] = 0;
regs[2] = 0;
+ regs[3] = 0;
}
- regs[0] = regs[3] = 0;
+ regs[0] = 0;
break;
case 0x0000000d:
@@ -638,13 +640,15 @@ static void xc_cpuid_pv_policy(xc_interface *xch,
{
regs[1] = info->featureset[featureword_of(X86_FEATURE_FSGSBASE)];
regs[2] =
info->featureset[featureword_of(X86_FEATURE_PREFETCHWT1)];
+ regs[3] = info->featureset[featureword_of(X86_FEATURE_IBRSB)];
}
else
{
regs[1] = 0;
regs[2] = 0;
+ regs[3] = 0;
}
- regs[0] = regs[3] = 0;
+ regs[0] = 0;
break;
case 0x0000000d:
diff --git a/tools/libxl/libxl_cpuid.c b/tools/libxl/libxl_cpuid.c
index 24591e2..8292654 100644
--- a/tools/libxl/libxl_cpuid.c
+++ b/tools/libxl/libxl_cpuid.c
@@ -158,6 +158,8 @@ int libxl_cpuid_parse_config(libxl_cpuid_policy_list
*cpuid, const char* str)
{"de", 0x00000001, NA, CPUID_REG_EDX, 2, 1},
{"vme", 0x00000001, NA, CPUID_REG_EDX, 1, 1},
{"fpu", 0x00000001, NA, CPUID_REG_EDX, 0, 1},
+ {"ibrsb", 0x00000007, 0, CPUID_REG_EDX, 26, 1},
+ {"stibp", 0x00000007, 0, CPUID_REG_EDX, 27, 1},
{"topoext", 0x80000001, NA, CPUID_REG_ECX, 22, 1},
{"tbm", 0x80000001, NA, CPUID_REG_ECX, 21, 1},
{"nodeid", 0x80000001, NA, CPUID_REG_ECX, 19, 1},
@@ -187,6 +189,7 @@ int libxl_cpuid_parse_config(libxl_cpuid_policy_list
*cpuid, const char* str)
{"nx", 0x80000001, NA, CPUID_REG_EDX, 20, 1},
{"syscall", 0x80000001, NA, CPUID_REG_EDX, 11, 1},
{"procpkg", 0x00000004, 0, CPUID_REG_EAX, 26, 6},
+ {"ibpb", 0x80000008, NA, CPUID_REG_EBX, 12, 1},
{"apicidsize", 0x80000008, NA, CPUID_REG_ECX, 12, 4},
{"nc", 0x80000008, NA, CPUID_REG_ECX, 0, 8},
{"svm_npt", 0x8000000a, NA, CPUID_REG_EDX, 0, 1},
diff --git a/tools/misc/xen-cpuid.c b/tools/misc/xen-cpuid.c
index 44991f6..0981366 100644
--- a/tools/misc/xen-cpuid.c
+++ b/tools/misc/xen-cpuid.c
@@ -140,7 +140,20 @@ static const char *str_e8b[32] =
{
[ 0] = "clzero",
- [1 ... 31] = "REZ",
+ [1 ... 11] = "REZ",
+
+ [12] = "ibpb",
+
+ [13 ... 31] = "REZ",
+};
+
+static const char *str_7d0[32] =
+{
+ [0 ... 25] = "REZ",
+
+ [26] = "ibrsb", [27] = "stibp",
+
+ [28 ... 31] = "REZ",
};
static struct {
@@ -158,6 +171,7 @@ static struct {
{ "0x00000007:0.ecx", "7c0", str_7c0 },
{ "0x80000007.edx", "e7d", str_e7d },
{ "0x80000008.ebx", "e8b", str_e8b },
+ { "0x00000007:0.edx", "7d0", str_7d0 },
};
#define COL_ALIGN "18"
diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index 3e48882..948b0a9 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -350,7 +350,7 @@ static void generic_identify(struct cpuinfo_x86 *c)
cpuid_count(0x00000007, 0, &tmp,
&c->x86_capability[cpufeat_word(X86_FEATURE_FSGSBASE)],
&c->x86_capability[cpufeat_word(X86_FEATURE_PKU)],
- &tmp);
+
&c->x86_capability[cpufeat_word(X86_FEATURE_IBRSB)]);
}
/*
diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
index d601c02..89e7287 100644
--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -67,8 +67,25 @@ custom_param("bti", parse_bti);
static void __init print_details(enum ind_thunk thunk)
{
+ unsigned int _7d0 = 0, e8b = 0, tmp;
+
+ /* Collect diagnostics about available mitigations. */
+ if ( boot_cpu_data.cpuid_level >= 7 )
+ cpuid_count(7, 0, &tmp, &tmp, &tmp, &_7d0);
+ if ( boot_cpu_data.extended_cpuid_level >= 0x80000008 )
+ cpuid(0x80000008, &tmp, &e8b, &tmp, &tmp);
+
printk(XENLOG_DEBUG "Speculative mitigation facilities:\n");
+ /* Hardware features which pertain to speculative mitigations. */
+ if ( (_7d0 & (cpufeat_mask(X86_FEATURE_IBRSB) |
+ cpufeat_mask(X86_FEATURE_STIBP))) ||
+ (e8b & cpufeat_mask(X86_FEATURE_IBPB)) )
+ printk(XENLOG_DEBUG " Hardware features:%s%s%s\n",
+ (_7d0 & cpufeat_mask(X86_FEATURE_IBRSB)) ? " IBRS/IBPB" : "",
+ (_7d0 & cpufeat_mask(X86_FEATURE_STIBP)) ? " STIBP" : "",
+ (e8b & cpufeat_mask(X86_FEATURE_IBPB)) ? " IBPB" : "");
+
/* Compiled-in support which pertains to BTI mitigations. */
if ( IS_ENABLED(CONFIG_INDIRECT_THUNK) )
printk(XENLOG_DEBUG " Compiled-in support: INDIRECT_THUNK\n");
diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
index 4dbcf86..dc3a335 100644
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -24,6 +24,9 @@ XEN_CPUFEATURE(MSR_MISC_FEATURES, (FSCAPINTS+0)*32+13) /*
MISC_FEATURES_ENABLES
XEN_CPUFEATURE(LFENCE_DISPATCH, (FSCAPINTS+0)*32+14) /* lfence set as Dispatch
Serialising */
XEN_CPUFEATURE(IND_THUNK_LFENCE,(FSCAPINTS+0)*32+15) /* Use IND_THUNK_LFENCE */
XEN_CPUFEATURE(IND_THUNK_JMP, (FSCAPINTS+0)*32+16) /* Use IND_THUNK_JMP */
+XEN_CPUFEATURE(XEN_IBPB, (FSCAPINTS+0)*32+17) /* IBRSB || IBPB */
+XEN_CPUFEATURE(XEN_IBRS_SET, (FSCAPINTS+0)*32+18) /* IBRSB && IRBS set in
Xen */
+XEN_CPUFEATURE(XEN_IBRS_CLEAR, (FSCAPINTS+0)*32+19) /* IBRSB && IBRS clear in
Xen */
#define NCAPINTS (FSCAPINTS + 1) /* N 32-bit words worth of info */
diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h
index c45d0cd..fc5bf79 100644
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -31,6 +31,14 @@
#define EFER_LMSLE (1<<_EFER_LMSLE)
#define EFER_FFXSE (1<<_EFER_FFXSE)
+/* Speculation Controls. */
+#define MSR_SPEC_CTRL 0x00000048
+#define SPEC_CTRL_IBRS (_AC(1, ULL) << 0)
+#define SPEC_CTRL_STIBP (_AC(1, ULL) << 1)
+
+#define MSR_PRED_CMD 0x00000049
+#define PRED_CMD_IBPB (_AC(1, ULL) << 0)
+
/* Intel MSRs. Some also available on other CPUs */
#define MSR_IA32_PERFCTR0 0x000000c1
#define MSR_IA32_A_PERFCTR0 0x000004c1
diff --git a/xen/include/public/arch-x86/cpufeatureset.h
b/xen/include/public/arch-x86/cpufeatureset.h
index 9320c9e..a6040b2 100644
--- a/xen/include/public/arch-x86/cpufeatureset.h
+++ b/xen/include/public/arch-x86/cpufeatureset.h
@@ -233,6 +233,11 @@ XEN_CPUFEATURE(EFRO, 7*32+10) /* APERF/MPERF
Read Only interface */
/* AMD-defined CPU features, CPUID level 0x80000008.ebx, word 8 */
XEN_CPUFEATURE(CLZERO, 8*32+ 0) /*A CLZERO instruction */
+XEN_CPUFEATURE(IBPB, 8*32+12) /* IBPB support only (no IBRS, used
by AMD) */
+
+/* Intel-defined CPU features, CPUID level 0x00000007:0.edx, word 9 */
+XEN_CPUFEATURE(IBRSB, 9*32+26) /* IBRS and IBPB support (used by
Intel) */
+XEN_CPUFEATURE(STIBP, 9*32+27) /* STIBP */
#endif /* XEN_CPUFEATURE */
diff --git a/xen/tools/gen-cpuid.py b/xen/tools/gen-cpuid.py
index 005cad9..9b2cb6f 100755
--- a/xen/tools/gen-cpuid.py
+++ b/xen/tools/gen-cpuid.py
@@ -254,6 +254,11 @@ def crunch_numbers(state):
# are built on top of AVX512F
AVX512F: [AVX512DQ, AVX512IFMA, AVX512PF, AVX512ER, AVX512CD,
AVX512BW, AVX512VL, AVX512VBMI],
+
+ # Single Thread Indirect Branch Predictors enumerates a new bit in the
+ # MSR enumerated by Indirect Branch Restricted Speculation/Indirect
+ # Branch Prediction Barrier enumeration.
+ IBRSB: [STIBP],
}
deep_features = tuple(sorted(deps.keys()))
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.8
_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/xen-changelog
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |