[SRU Xenial 1/2] x86/cpuid: Provide get_scattered_cpuid_leaf()
Stefan Bader
stefan.bader at canonical.com
Wed Jan 17 14:31:30 UTC 2018
From: He Chen <he.chen at linux.intel.com>
CVE-2017-5715
CVE-2017-5753
Sparse populated CPUID leafs are collected in a software provided leaf to
avoid bloat of the x86_capability array, but there is no way to rebuild the
real leafs (e.g. for KVM CPUID enumeration) other than rereading the CPUID
leaf from the CPU. While this is possible it is problematic as it does not
take software disabled features into account. If a feature is disabled on
the host it should not be exposed to a guest either.
Add get_scattered_cpuid_leaf() which rebuilds the leaf from the scattered
cpuid table information and the active CPU features.
[ tglx: Rewrote changelog ]
Signed-off-by: He Chen <he.chen at linux.intel.com>
Reviewed-by: Borislav Petkov <bp at suse.de>
Cc: Luwei Kang <luwei.kang at intel.com>
Cc: kvm at vger.kernel.org
Cc: Radim Krčmář <rkrcmar at redhat.com>
Cc: Piotr Luc <Piotr.Luc at intel.com>
Cc: Borislav Petkov <bp at alien8.de>
Cc: Paolo Bonzini <pbonzini at redhat.com>
Link: http://lkml.kernel.org/r/1478856336-9388-3-git-send-email-he.chen@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
(backported from commit 47bdf3378d62a627cfb8a54e1180c08d67078b61)
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
arch/x86/include/asm/processor.h | 3 ++
arch/x86/kernel/cpu/scattered.c | 86 +++++++++++++++++++++++++---------------
2 files changed, 58 insertions(+), 31 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 9325709..7769a0d 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -180,6 +180,9 @@ extern void identify_secondary_cpu(struct cpuinfo_x86 *);
extern void print_cpu_info(struct cpuinfo_x86 *);
void print_cpu_msr(struct cpuinfo_x86 *);
extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
+extern u32 get_scattered_cpuid_leaf(unsigned int level,
+ unsigned int sub_leaf,
+ u8 reg);
extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);
extern void init_amd_cacheinfo(struct cpuinfo_x86 *c);
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index 417a37f..38cd046 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -24,43 +24,44 @@ enum cpuid_regs {
CR_EBX
};
+/* Please keep the leaf sorted by cpuid_bit.level for faster search. */
+static const struct cpuid_bit cpuid_bits[] = {
+ { X86_FEATURE_DTHERM, CR_EAX, 0, 0x00000006, 0 },
+ { X86_FEATURE_APERFMPERF, CR_ECX, 0, 0x00000006, 0 },
+ { X86_FEATURE_IDA, CR_EAX, 1, 0x00000006, 0 },
+ { X86_FEATURE_ARAT, CR_EAX, 2, 0x00000006, 0 },
+ { X86_FEATURE_EPB, CR_ECX, 3, 0x00000006, 0 },
+ { X86_FEATURE_PLN, CR_EAX, 4, 0x00000006, 0 },
+ { X86_FEATURE_PTS, CR_EAX, 6, 0x00000006, 0 },
+ { X86_FEATURE_HWP, CR_EAX, 7, 0x00000006, 0 },
+ { X86_FEATURE_HWP_NOTIFY, CR_EAX, 8, 0x00000006, 0 },
+ { X86_FEATURE_HWP_ACT_WINDOW, CR_EAX, 9, 0x00000006, 0 },
+ { X86_FEATURE_HWP_EPP, CR_EAX,10, 0x00000006, 0 },
+ { X86_FEATURE_HWP_PKG_REQ, CR_EAX,11, 0x00000006, 0 },
+ { X86_FEATURE_INTEL_PT, CR_EBX,25, 0x00000007, 0 },
+ { X86_FEATURE_SPEC_CTRL, CR_EDX,26, 0x00000007, 0 },
+ { X86_FEATURE_HW_PSTATE, CR_EDX, 7, 0x80000007, 0 },
+ { X86_FEATURE_CPB, CR_EDX, 9, 0x80000007, 0 },
+ { X86_FEATURE_PROC_FEEDBACK, CR_EDX,11, 0x80000007, 0 },
+ { X86_FEATURE_NPT, CR_EDX, 0, 0x8000000a, 0 },
+ { X86_FEATURE_LBRV, CR_EDX, 1, 0x8000000a, 0 },
+ { X86_FEATURE_SVML, CR_EDX, 2, 0x8000000a, 0 },
+ { X86_FEATURE_NRIPS, CR_EDX, 3, 0x8000000a, 0 },
+ { X86_FEATURE_TSCRATEMSR, CR_EDX, 4, 0x8000000a, 0 },
+ { X86_FEATURE_VMCBCLEAN, CR_EDX, 5, 0x8000000a, 0 },
+ { X86_FEATURE_FLUSHBYASID, CR_EDX, 6, 0x8000000a, 0 },
+ { X86_FEATURE_DECODEASSISTS, CR_EDX, 7, 0x8000000a, 0 },
+ { X86_FEATURE_PAUSEFILTER, CR_EDX,10, 0x8000000a, 0 },
+ { X86_FEATURE_PFTHRESHOLD, CR_EDX,12, 0x8000000a, 0 },
+ { 0, 0, 0, 0, 0 }
+};
+
void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
{
u32 max_level;
u32 regs[4];
const struct cpuid_bit *cb;
- static const struct cpuid_bit cpuid_bits[] = {
- { X86_FEATURE_DTHERM, CR_EAX, 0, 0x00000006, 0 },
- { X86_FEATURE_IDA, CR_EAX, 1, 0x00000006, 0 },
- { X86_FEATURE_ARAT, CR_EAX, 2, 0x00000006, 0 },
- { X86_FEATURE_PLN, CR_EAX, 4, 0x00000006, 0 },
- { X86_FEATURE_PTS, CR_EAX, 6, 0x00000006, 0 },
- { X86_FEATURE_HWP, CR_EAX, 7, 0x00000006, 0 },
- { X86_FEATURE_HWP_NOTIFY, CR_EAX, 8, 0x00000006, 0 },
- { X86_FEATURE_HWP_ACT_WINDOW, CR_EAX, 9, 0x00000006, 0 },
- { X86_FEATURE_HWP_EPP, CR_EAX,10, 0x00000006, 0 },
- { X86_FEATURE_HWP_PKG_REQ, CR_EAX,11, 0x00000006, 0 },
- { X86_FEATURE_INTEL_PT, CR_EBX,25, 0x00000007, 0 },
- { X86_FEATURE_SPEC_CTRL, CR_EDX,26, 0x00000007, 0 },
- { X86_FEATURE_APERFMPERF, CR_ECX, 0, 0x00000006, 0 },
- { X86_FEATURE_EPB, CR_ECX, 3, 0x00000006, 0 },
- { X86_FEATURE_HW_PSTATE, CR_EDX, 7, 0x80000007, 0 },
- { X86_FEATURE_CPB, CR_EDX, 9, 0x80000007, 0 },
- { X86_FEATURE_PROC_FEEDBACK, CR_EDX,11, 0x80000007, 0 },
- { X86_FEATURE_NPT, CR_EDX, 0, 0x8000000a, 0 },
- { X86_FEATURE_LBRV, CR_EDX, 1, 0x8000000a, 0 },
- { X86_FEATURE_SVML, CR_EDX, 2, 0x8000000a, 0 },
- { X86_FEATURE_NRIPS, CR_EDX, 3, 0x8000000a, 0 },
- { X86_FEATURE_TSCRATEMSR, CR_EDX, 4, 0x8000000a, 0 },
- { X86_FEATURE_VMCBCLEAN, CR_EDX, 5, 0x8000000a, 0 },
- { X86_FEATURE_FLUSHBYASID, CR_EDX, 6, 0x8000000a, 0 },
- { X86_FEATURE_DECODEASSISTS, CR_EDX, 7, 0x8000000a, 0 },
- { X86_FEATURE_PAUSEFILTER, CR_EDX,10, 0x8000000a, 0 },
- { X86_FEATURE_PFTHRESHOLD, CR_EDX,12, 0x8000000a, 0 },
- { 0, 0, 0, 0, 0 }
- };
-
for (cb = cpuid_bits; cb->feature; cb++) {
/* Verify that the level is valid */
@@ -76,3 +77,26 @@ void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
set_cpu_cap(c, cb->feature);
}
}
+
+u32 get_scattered_cpuid_leaf(unsigned int level, unsigned int sub_leaf, u8 reg)
+{
+ const struct cpuid_bit *cb;
+ u32 cpuid_val = 0;
+
+ for (cb = cpuid_bits; cb->feature; cb++) {
+
+ if (level > cb->level)
+ continue;
+
+ if (level < cb->level)
+ break;
+
+ if (reg == cb->reg && sub_leaf == cb->sub_leaf) {
+ if (cpu_has(&boot_cpu_data, cb->feature))
+ cpuid_val |= BIT(cb->bit);
+ }
+ }
+
+ return cpuid_val;
+}
+EXPORT_SYMBOL_GPL(get_scattered_cpuid_leaf);
--
2.7.4
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