415de44076
Currently, Linux probes for X86_BUG_NULL_SEL unconditionally which makes it unsafe to migrate in a virtualised environment as the properties across the migration pool might differ. To be specific, the case which goes wrong is: 1. Zen1 (or earlier) and Zen2 (or later) in a migration pool 2. Linux boots on Zen2, probes and finds the absence of X86_BUG_NULL_SEL 3. Linux is then migrated to Zen1 Linux is now running on a X86_BUG_NULL_SEL-impacted CPU while believing that the bug is fixed. The only way to address the problem is to fully trust the "no longer affected" CPUID bit when virtualised, because in the above case it would be clear deliberately to indicate the fact "you might migrate to somewhere which has this behaviour". Zen3 adds the NullSelectorClearsBase CPUID bit to indicate that loading a NULL segment selector zeroes the base and limit fields, as well as just attributes. Zen2 also has this behaviour but doesn't have the NSCB bit. [ bp: Minor touchups. ] Signed-off-by: Jane Malalane <jane.malalane@citrix.com> Signed-off-by: Borislav Petkov <bp@suse.de> CC: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20211021104744.24126-1-jane.malalane@citrix.com
88 lines
2.5 KiB
C
88 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef ARCH_X86_CPU_H
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#define ARCH_X86_CPU_H
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/* attempt to consolidate cpu attributes */
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struct cpu_dev {
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const char *c_vendor;
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/* some have two possibilities for cpuid string */
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const char *c_ident[2];
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void (*c_early_init)(struct cpuinfo_x86 *);
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void (*c_bsp_init)(struct cpuinfo_x86 *);
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void (*c_init)(struct cpuinfo_x86 *);
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void (*c_identify)(struct cpuinfo_x86 *);
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void (*c_detect_tlb)(struct cpuinfo_x86 *);
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int c_x86_vendor;
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#ifdef CONFIG_X86_32
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/* Optional vendor specific routine to obtain the cache size. */
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unsigned int (*legacy_cache_size)(struct cpuinfo_x86 *,
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unsigned int);
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/* Family/stepping-based lookup table for model names. */
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struct legacy_cpu_model_info {
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int family;
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const char *model_names[16];
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} legacy_models[5];
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#endif
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};
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struct _tlb_table {
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unsigned char descriptor;
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char tlb_type;
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unsigned int entries;
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/* unsigned int ways; */
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char info[128];
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};
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#define cpu_dev_register(cpu_devX) \
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static const struct cpu_dev *const __cpu_dev_##cpu_devX __used \
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__section(".x86_cpu_dev.init") = \
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&cpu_devX;
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extern const struct cpu_dev *const __x86_cpu_dev_start[],
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*const __x86_cpu_dev_end[];
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#ifdef CONFIG_CPU_SUP_INTEL
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enum tsx_ctrl_states {
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TSX_CTRL_ENABLE,
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TSX_CTRL_DISABLE,
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TSX_CTRL_RTM_ALWAYS_ABORT,
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TSX_CTRL_NOT_SUPPORTED,
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};
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extern __ro_after_init enum tsx_ctrl_states tsx_ctrl_state;
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extern void __init tsx_init(void);
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extern void tsx_enable(void);
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extern void tsx_disable(void);
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extern void tsx_clear_cpuid(void);
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#else
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static inline void tsx_init(void) { }
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#endif /* CONFIG_CPU_SUP_INTEL */
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extern void get_cpu_cap(struct cpuinfo_x86 *c);
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extern void get_cpu_address_sizes(struct cpuinfo_x86 *c);
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extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
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extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
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extern void init_intel_cacheinfo(struct cpuinfo_x86 *c);
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extern void init_amd_cacheinfo(struct cpuinfo_x86 *c);
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extern void init_hygon_cacheinfo(struct cpuinfo_x86 *c);
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extern void detect_num_cpu_cores(struct cpuinfo_x86 *c);
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extern int detect_extended_topology_early(struct cpuinfo_x86 *c);
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extern int detect_extended_topology(struct cpuinfo_x86 *c);
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extern int detect_ht_early(struct cpuinfo_x86 *c);
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extern void detect_ht(struct cpuinfo_x86 *c);
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extern void check_null_seg_clears_base(struct cpuinfo_x86 *c);
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unsigned int aperfmperf_get_khz(int cpu);
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extern void x86_spec_ctrl_setup_ap(void);
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extern void update_srbds_msr(void);
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extern u64 x86_read_arch_cap_msr(void);
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#endif /* ARCH_X86_CPU_H */
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