Quelle  cpuid-deps.c   Sprache: C

/* Declare dependencies between CPUIDs */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <asm/cpufeature.h>

struct cpuid_dep {
 unsigned int feature;
 unsigned int depends;
};

/*
 * Table of CPUID features that depend on others.
 *
 * This only includes dependencies that can be usefully disabled, not
 * features part of the base set (like FPU).
 *
 * Note this all is not __init / __initdata because it can be
 * called from cpu hotplug. It shouldn't do anything in this case,
 * but it's difficult to tell that to the init reference checker.
 */
static const struct cpuid_dep cpuid_deps[] = {
 { X86_FEATURE_FXSR,   X86_FEATURE_FPU       },
 { X86_FEATURE_XSAVEOPT,   X86_FEATURE_XSAVE     },
 { X86_FEATURE_XSAVEC,   X86_FEATURE_XSAVE     },
 { X86_FEATURE_XSAVES,   X86_FEATURE_XSAVE     },
 { X86_FEATURE_AVX,   X86_FEATURE_XSAVE     },
 { X86_FEATURE_PKU,   X86_FEATURE_XSAVE     },
 { X86_FEATURE_MPX,   X86_FEATURE_XSAVE     },
 { X86_FEATURE_XGETBV1,   X86_FEATURE_XSAVE     },
 { X86_FEATURE_APX,   X86_FEATURE_XSAVE     },
 { X86_FEATURE_CMOV,   X86_FEATURE_FXSR      },
 { X86_FEATURE_MMX,   X86_FEATURE_FXSR      },
 { X86_FEATURE_MMXEXT,   X86_FEATURE_MMX       },
 { X86_FEATURE_FXSR_OPT,   X86_FEATURE_FXSR      },
 { X86_FEATURE_XSAVE,   X86_FEATURE_FXSR      },
 { X86_FEATURE_XMM,   X86_FEATURE_FXSR      },
 { X86_FEATURE_XMM2,   X86_FEATURE_XMM       },
 { X86_FEATURE_XMM3,   X86_FEATURE_XMM2      },
 { X86_FEATURE_XMM4_1,   X86_FEATURE_XMM2      },
 { X86_FEATURE_XMM4_2,   X86_FEATURE_XMM2      },
 { X86_FEATURE_XMM3,   X86_FEATURE_XMM2      },
 { X86_FEATURE_PCLMULQDQ,  X86_FEATURE_XMM2      },
 { X86_FEATURE_SSSE3,   X86_FEATURE_XMM2,     },
 { X86_FEATURE_F16C,   X86_FEATURE_XMM2,     },
 { X86_FEATURE_AES,   X86_FEATURE_XMM2      },
 { X86_FEATURE_SHA_NI,   X86_FEATURE_XMM2      },
 { X86_FEATURE_GFNI,   X86_FEATURE_XMM2      },
 { X86_FEATURE_AVX_VNNI,   X86_FEATURE_AVX       },
 { X86_FEATURE_FMA,   X86_FEATURE_AVX       },
 { X86_FEATURE_VAES,   X86_FEATURE_AVX       },
 { X86_FEATURE_VPCLMULQDQ,  X86_FEATURE_AVX       },
 { X86_FEATURE_AVX2,   X86_FEATURE_AVX,      },
 { X86_FEATURE_AVX512F,   X86_FEATURE_AVX,      },
 { X86_FEATURE_AVX512IFMA,  X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512PF,   X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512ER,   X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512CD,   X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512DQ,   X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512BW,   X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512VL,   X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512VBMI,  X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512_VBMI2,  X86_FEATURE_AVX512VL  },
 { X86_FEATURE_AVX512_VNNI,  X86_FEATURE_AVX512VL  },
 { X86_FEATURE_AVX512_BITALG,  X86_FEATURE_AVX512VL  },
 { X86_FEATURE_AVX512_4VNNIW,  X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512_4FMAPS,  X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512_VPOPCNTDQ,  X86_FEATURE_AVX512F   },
 { X86_FEATURE_AVX512_VP2INTERSECT, X86_FEATURE_AVX512VL  },
 { X86_FEATURE_CQM_OCCUP_LLC,  X86_FEATURE_CQM_LLC   },
 { X86_FEATURE_CQM_MBM_TOTAL,  X86_FEATURE_CQM_LLC   },
 { X86_FEATURE_CQM_MBM_LOCAL,  X86_FEATURE_CQM_LLC   },
 { X86_FEATURE_BMEC,   X86_FEATURE_CQM_MBM_TOTAL   },
 { X86_FEATURE_BMEC,   X86_FEATURE_CQM_MBM_LOCAL   },
 { X86_FEATURE_AVX512_BF16,  X86_FEATURE_AVX512VL  },
 { X86_FEATURE_AVX512_FP16,  X86_FEATURE_AVX512BW  },
 { X86_FEATURE_ENQCMD,   X86_FEATURE_XSAVES    },
 { X86_FEATURE_PER_THREAD_MBA,  X86_FEATURE_MBA       },
 { X86_FEATURE_SGX_LC,   X86_FEATURE_SGX       },
 { X86_FEATURE_SGX1,   X86_FEATURE_SGX       },
 { X86_FEATURE_SGX2,   X86_FEATURE_SGX1      },
 { X86_FEATURE_SGX_EDECCSSA,  X86_FEATURE_SGX1      },
 { X86_FEATURE_XFD,   X86_FEATURE_XSAVES    },
 { X86_FEATURE_XFD,   X86_FEATURE_XGETBV1   },
 { X86_FEATURE_AMX_TILE,   X86_FEATURE_XFD       },
 { X86_FEATURE_AMX_FP16,   X86_FEATURE_AMX_TILE  },
 { X86_FEATURE_AMX_BF16,   X86_FEATURE_AMX_TILE  },
 { X86_FEATURE_AMX_INT8,   X86_FEATURE_AMX_TILE  },
 { X86_FEATURE_SHSTK,   X86_FEATURE_XSAVES    },
 { X86_FEATURE_FRED,   X86_FEATURE_LKGS      },
 { X86_FEATURE_SPEC_CTRL_SSBD,  X86_FEATURE_SPEC_CTRL },
 {}
};

static inline void clear_feature(struct cpuinfo_x86 *c, unsigned int feature)
{
 /*
 * Note: This could use the non atomic __*_bit() variants, but the
 * rest of the cpufeature code uses atomics as well, so keep it for
 * consistency. Cleanup all of it separately.
 */
 if (!c) {
  clear_cpu_cap(&boot_cpu_data, feature);
  set_bit(feature, (unsigned long *)cpu_caps_cleared);
 } else {
  clear_bit(feature, (unsigned long *)c->x86_capability);
 }
}

/* Take the capabilities and the BUG bits into account */
#define MAX_FEATURE_BITS ((NCAPINTS + NBUGINTS) * sizeof(u32) * 8)

static void do_clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int feature)
{
 DECLARE_BITMAP(disable, MAX_FEATURE_BITS);
 const struct cpuid_dep *d;
 bool changed;

 if (WARN_ON(feature >= MAX_FEATURE_BITS))
  return;

 if (boot_cpu_has(feature))
  WARN_ON(alternatives_patched);

 clear_feature(c, feature);

 /* Collect all features to disable, handling dependencies */
 memset(disable, 0, sizeof(disable));
 __set_bit(feature, disable);

 /* Loop until we get a stable state. */
 do {
  changed = false;
  for (d = cpuid_deps; d->feature; d++) {
   if (!test_bit(d->depends, disable))
    continue;
   if (__test_and_set_bit(d->feature, disable))
    continue;

   changed = true;
   clear_feature(c, d->feature);
  }
 } while (changed);
}

void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int feature)
{
 do_clear_cpu_cap(c, feature);
}

void setup_clear_cpu_cap(unsigned int feature)
{
 do_clear_cpu_cap(NULL, feature);
}

/*
 * Return the feature "name" if available, otherwise return
 * the X86_FEATURE_* numerals to make it easier to identify
 * the feature.
 */
static const char *x86_feature_name(unsigned int feature, char *buf)
{
 if (x86_cap_flags[feature])
  return x86_cap_flags[feature];

 snprintf(buf, 16, "%d*32+%2d", feature / 32, feature % 32);

 return buf;
}

void check_cpufeature_deps(struct cpuinfo_x86 *c)
{
 char feature_buf[16], depends_buf[16];
 const struct cpuid_dep *d;

 for (d = cpuid_deps; d->feature; d++) {
  if (cpu_has(c, d->feature) && !cpu_has(c, d->depends)) {
   /*
 * Only warn about the first unmet dependency on the
 * first CPU where it is encountered to avoid spamming
 * the kernel log.
 */
   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",
         smp_processor_id(),
         x86_feature_name(d->feature, feature_buf),
         x86_feature_name(d->depends, depends_buf));
  }
 }
}