From d95f7053350059e05f4515a04da5528e50b60121 Mon Sep 17 00:00:00 2001 From: He Chen Date: Fri, 11 Nov 2016 17:25:35 +0800 Subject: [PATCH 052/131] x86/cpuid: Provide get_scattered_cpuid_leaf() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CVE-2017-5715 (Spectre v2 retpoline) 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 Reviewed-by: Borislav Petkov Cc: Luwei Kang Cc: kvm@vger.kernel.org Cc: Radim Krčmář Cc: Piotr Luc Cc: Borislav Petkov Cc: Paolo Bonzini Link: http://lkml.kernel.org/r/1478856336-9388-3-git-send-email-he.chen@linux.intel.com Signed-off-by: Thomas Gleixner [adjusted for longer list compared to initial commit] (backported from commit 47bdf3378d62a627cfb8a54e1180c08d67078b61) Signed-off-by: Stefan Bader Signed-off-by: Andy Whitcroft --- arch/x86/include/asm/processor.h | 2 ++ arch/x86/kernel/cpu/scattered.c | 74 ++++++++++++++++++++++++++-------------- 2 files changed, 51 insertions(+), 25 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 2a0d8e21f0c7..94e201e1bb86 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -171,6 +171,8 @@ 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 b6f794aa1693..d9bc713badca 100644 --- a/arch/x86/kernel/cpu/scattered.c +++ b/arch/x86/kernel/cpu/scattered.c @@ -24,37 +24,38 @@ 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_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_APERFMPERF, CR_ECX, 0, 0x00000006, 0 }, + { X86_FEATURE_EPB, CR_ECX, 3, 0x00000006, 0 }, + { X86_FEATURE_XSAVEOPT, CR_EAX, 0, 0x0000000d, 1 }, + { 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_APERFMPERF, CR_ECX, 0, 0x00000006, 0 }, - { X86_FEATURE_EPB, CR_ECX, 3, 0x00000006, 0 }, - { X86_FEATURE_XSAVEOPT, CR_EAX, 0, 0x0000000d, 1 }, - { 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 */ @@ -70,3 +71,26 @@ 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); -- 2.15.1