cpuid-deps.c

  1/* Declare dependencies between CPUIDs */
  2#include <linux/kernel.h>
  3#include <linux/init.h>
  4#include <linux/module.h>
  5#include <asm/cpufeature.h>
  6
  7struct cpuid_dep {
  8	unsigned int	feature;
  9	unsigned int	depends;
 10};
 11
 12/*
 13 * Table of CPUID features that depend on others.
 14 *
 15 * This only includes dependencies that can be usefully disabled, not
 16 * features part of the base set (like FPU).
 17 *
 18 * Note this all is not __init / __initdata because it can be
 19 * called from cpu hotplug. It shouldn't do anything in this case,
 20 * but it's difficult to tell that to the init reference checker.
 21 */
 22static const struct cpuid_dep cpuid_deps[] = {
 23	{ X86_FEATURE_FXSR,			X86_FEATURE_FPU	      },
 24	{ X86_FEATURE_XSAVEOPT,			X86_FEATURE_XSAVE     },
 25	{ X86_FEATURE_XSAVEC,			X86_FEATURE_XSAVE     },
 26	{ X86_FEATURE_XSAVES,			X86_FEATURE_XSAVE     },
 27	{ X86_FEATURE_AVX,			X86_FEATURE_XSAVE     },
 28	{ X86_FEATURE_PKU,			X86_FEATURE_XSAVE     },
 29	{ X86_FEATURE_MPX,			X86_FEATURE_XSAVE     },
 30	{ X86_FEATURE_XGETBV1,			X86_FEATURE_XSAVE     },
 31	{ X86_FEATURE_APX,			X86_FEATURE_XSAVE     },
 32	{ X86_FEATURE_CMOV,			X86_FEATURE_FXSR      },
 33	{ X86_FEATURE_MMX,			X86_FEATURE_FXSR      },
 34	{ X86_FEATURE_MMXEXT,			X86_FEATURE_MMX       },
 35	{ X86_FEATURE_FXSR_OPT,			X86_FEATURE_FXSR      },
 36	{ X86_FEATURE_XSAVE,			X86_FEATURE_FXSR      },
 37	{ X86_FEATURE_XMM,			X86_FEATURE_FXSR      },
 38	{ X86_FEATURE_XMM2,			X86_FEATURE_XMM       },
 39	{ X86_FEATURE_XMM3,			X86_FEATURE_XMM2      },
 40	{ X86_FEATURE_XMM4_1,			X86_FEATURE_XMM2      },
 41	{ X86_FEATURE_XMM4_2,			X86_FEATURE_XMM2      },
 42	{ X86_FEATURE_XMM3,			X86_FEATURE_XMM2      },
 43	{ X86_FEATURE_PCLMULQDQ,		X86_FEATURE_XMM2      },
 44	{ X86_FEATURE_SSSE3,			X86_FEATURE_XMM2,     },
 45	{ X86_FEATURE_F16C,			X86_FEATURE_XMM2,     },
 46	{ X86_FEATURE_AES,			X86_FEATURE_XMM2      },
 47	{ X86_FEATURE_SHA_NI,			X86_FEATURE_XMM2      },
 48	{ X86_FEATURE_GFNI,			X86_FEATURE_XMM2      },
 49	{ X86_FEATURE_AVX_VNNI,			X86_FEATURE_AVX       },
 50	{ X86_FEATURE_FMA,			X86_FEATURE_AVX       },
 51	{ X86_FEATURE_VAES,			X86_FEATURE_AVX       },
 52	{ X86_FEATURE_VPCLMULQDQ,		X86_FEATURE_AVX       },
 53	{ X86_FEATURE_AVX2,			X86_FEATURE_AVX,      },
 54	{ X86_FEATURE_AVX512F,			X86_FEATURE_AVX,      },
 55	{ X86_FEATURE_AVX512IFMA,		X86_FEATURE_AVX512F   },
 56	{ X86_FEATURE_AVX512PF,			X86_FEATURE_AVX512F   },
 57	{ X86_FEATURE_AVX512ER,			X86_FEATURE_AVX512F   },
 58	{ X86_FEATURE_AVX512CD,			X86_FEATURE_AVX512F   },
 59	{ X86_FEATURE_AVX512DQ,			X86_FEATURE_AVX512F   },
 60	{ X86_FEATURE_AVX512BW,			X86_FEATURE_AVX512F   },
 61	{ X86_FEATURE_AVX512VL,			X86_FEATURE_AVX512F   },
 62	{ X86_FEATURE_AVX512VBMI,		X86_FEATURE_AVX512F   },
 63	{ X86_FEATURE_AVX512_VBMI2,		X86_FEATURE_AVX512VL  },
 64	{ X86_FEATURE_AVX512_VNNI,		X86_FEATURE_AVX512VL  },
 65	{ X86_FEATURE_AVX512_BITALG,		X86_FEATURE_AVX512VL  },
 66	{ X86_FEATURE_AVX512_4VNNIW,		X86_FEATURE_AVX512F   },
 67	{ X86_FEATURE_AVX512_4FMAPS,		X86_FEATURE_AVX512F   },
 68	{ X86_FEATURE_AVX512_VPOPCNTDQ,		X86_FEATURE_AVX512F   },
 69	{ X86_FEATURE_AVX512_VP2INTERSECT,	X86_FEATURE_AVX512VL  },
 70	{ X86_FEATURE_CQM_OCCUP_LLC,		X86_FEATURE_CQM_LLC   },
 71	{ X86_FEATURE_CQM_MBM_TOTAL,		X86_FEATURE_CQM_LLC   },
 72	{ X86_FEATURE_CQM_MBM_LOCAL,		X86_FEATURE_CQM_LLC   },
 73	{ X86_FEATURE_BMEC,			X86_FEATURE_CQM_MBM_TOTAL   },
 74	{ X86_FEATURE_BMEC,			X86_FEATURE_CQM_MBM_LOCAL   },
 75	{ X86_FEATURE_SDCIAE,			X86_FEATURE_CAT_L3    },
 76	{ X86_FEATURE_AVX512_BF16,		X86_FEATURE_AVX512VL  },
 77	{ X86_FEATURE_AVX512_FP16,		X86_FEATURE_AVX512BW  },
 78	{ X86_FEATURE_ENQCMD,			X86_FEATURE_XSAVES    },
 79	{ X86_FEATURE_PER_THREAD_MBA,		X86_FEATURE_MBA       },
 80	{ X86_FEATURE_SGX_LC,			X86_FEATURE_SGX	      },
 81	{ X86_FEATURE_SGX1,			X86_FEATURE_SGX       },
 82	{ X86_FEATURE_SGX2,			X86_FEATURE_SGX1      },
 83	{ X86_FEATURE_SGX_EUPDATESVN,		X86_FEATURE_SGX1      },
 84	{ X86_FEATURE_SGX_EDECCSSA,		X86_FEATURE_SGX1      },
 85	{ X86_FEATURE_XFD,			X86_FEATURE_XSAVES    },
 86	{ X86_FEATURE_XFD,			X86_FEATURE_XGETBV1   },
 87	{ X86_FEATURE_AMX_TILE,			X86_FEATURE_XFD       },
 88	{ X86_FEATURE_AMX_FP16,			X86_FEATURE_AMX_TILE  },
 89	{ X86_FEATURE_AMX_BF16,			X86_FEATURE_AMX_TILE  },
 90	{ X86_FEATURE_AMX_INT8,			X86_FEATURE_AMX_TILE  },
 91	{ X86_FEATURE_SHSTK,			X86_FEATURE_XSAVES    },
 92	{ X86_FEATURE_FRED,			X86_FEATURE_LKGS      },
 93	{ X86_FEATURE_SPEC_CTRL_SSBD,		X86_FEATURE_SPEC_CTRL },
 94	{ X86_FEATURE_LASS,			X86_FEATURE_SMAP      },
 95	{}
 96};
 97
 98static inline void clear_feature(struct cpuinfo_x86 *c, unsigned int feature)
 99{
100	/*
101	 * Note: This could use the non atomic __*_bit() variants, but the
102	 * rest of the cpufeature code uses atomics as well, so keep it for
103	 * consistency. Cleanup all of it separately.
104	 */
105	if (!c) {
106		clear_cpu_cap(&boot_cpu_data, feature);
107		set_bit(feature, (unsigned long *)cpu_caps_cleared);
108	} else {
109		clear_bit(feature, (unsigned long *)c->x86_capability);
110	}
111}
112
113/* Take the capabilities and the BUG bits into account */
114#define MAX_FEATURE_BITS ((NCAPINTS + NBUGINTS) * sizeof(u32) * 8)
115
116static void do_clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int feature)
117{
118	DECLARE_BITMAP(disable, MAX_FEATURE_BITS);
119	const struct cpuid_dep *d;
120	bool changed;
121
122	if (WARN_ON(feature >= MAX_FEATURE_BITS))
123		return;
124
125	if (boot_cpu_has(feature))
126		WARN_ON(alternatives_patched);
127
128	clear_feature(c, feature);
129
130	/* Collect all features to disable, handling dependencies */
131	memset(disable, 0, sizeof(disable));
132	__set_bit(feature, disable);
133
134	/* Loop until we get a stable state. */
135	do {
136		changed = false;
137		for (d = cpuid_deps; d->feature; d++) {
138			if (!test_bit(d->depends, disable))
139				continue;
140			if (__test_and_set_bit(d->feature, disable))
141				continue;
142
143			changed = true;
144			clear_feature(c, d->feature);
145		}
146	} while (changed);
147}
148
149void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int feature)
150{
151	do_clear_cpu_cap(c, feature);
152}
153
154void setup_clear_cpu_cap(unsigned int feature)
155{
156	do_clear_cpu_cap(NULL, feature);
157}
158
159/*
160 * Return the feature "name" if available, otherwise return
161 * the X86_FEATURE_* numerals to make it easier to identify
162 * the feature.
163 */
164static const char *x86_feature_name(unsigned int feature, char *buf)
165{
166	if (x86_cap_flags[feature])
167		return x86_cap_flags[feature];
168
169	snprintf(buf, 16, "%d*32+%2d", feature / 32, feature % 32);
170
171	return buf;
172}
173
174void check_cpufeature_deps(struct cpuinfo_x86 *c)
175{
176	char feature_buf[16], depends_buf[16];
177	const struct cpuid_dep *d;
178
179	for (d = cpuid_deps; d->feature; d++) {
180		if (cpu_has(c, d->feature) && !cpu_has(c, d->depends)) {
181			/*
182			 * Only warn about the first unmet dependency on the
183			 * first CPU where it is encountered to avoid spamming
184			 * the kernel log.
185			 */
186			pr_warn_once("x86 CPU feature dependency check failure: CPU%d has '%s' enabled but '%s' disabled. Kernel might be fine, but no guarantees.\n",
187				     smp_processor_id(),
188				     x86_feature_name(d->feature, feature_buf),
189				     x86_feature_name(d->depends, depends_buf));
190		}
191	}
192}