162784854SIngo Molnar /* 262784854SIngo Molnar * xsave/xrstor support. 362784854SIngo Molnar * 462784854SIngo Molnar * Author: Suresh Siddha <suresh.b.siddha@intel.com> 562784854SIngo Molnar */ 662784854SIngo Molnar #include <linux/compat.h> 762784854SIngo Molnar #include <linux/cpu.h> 859a36d16SIngo Molnar 962784854SIngo Molnar #include <asm/fpu/api.h> 1062784854SIngo Molnar #include <asm/fpu/internal.h> 11fcbc99c4SIngo Molnar #include <asm/fpu/signal.h> 1259a36d16SIngo Molnar #include <asm/fpu/regset.h> 13b992c660SIngo Molnar 1462784854SIngo Molnar #include <asm/tlbflush.h> 1562784854SIngo Molnar 165b073430SIngo Molnar static const char *xfeature_names[] = 175b073430SIngo Molnar { 185b073430SIngo Molnar "x87 floating point registers" , 195b073430SIngo Molnar "SSE registers" , 205b073430SIngo Molnar "AVX registers" , 215b073430SIngo Molnar "MPX bounds registers" , 225b073430SIngo Molnar "MPX CSR" , 235b073430SIngo Molnar "AVX-512 opmask" , 245b073430SIngo Molnar "AVX-512 Hi256" , 255b073430SIngo Molnar "AVX-512 ZMM_Hi256" , 265b073430SIngo Molnar "unknown xstate feature" , 275b073430SIngo Molnar }; 285b073430SIngo Molnar 2962784854SIngo Molnar /* 3062784854SIngo Molnar * Mask of xstate features supported by the CPU and the kernel: 3162784854SIngo Molnar */ 325b073430SIngo Molnar u64 xfeatures_mask __read_mostly; 3362784854SIngo Molnar 3462784854SIngo Molnar static unsigned int xstate_offsets[XFEATURES_NR_MAX], xstate_sizes[XFEATURES_NR_MAX]; 3562784854SIngo Molnar static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8]; 3662784854SIngo Molnar 3762784854SIngo Molnar /* The number of supported xfeatures in xfeatures_mask: */ 3862784854SIngo Molnar static unsigned int xfeatures_nr; 3962784854SIngo Molnar 4062784854SIngo Molnar /* 415b073430SIngo Molnar * Return whether the system supports a given xfeature. 425b073430SIngo Molnar * 435b073430SIngo Molnar * Also return the name of the (most advanced) feature that the caller requested: 445b073430SIngo Molnar */ 455b073430SIngo Molnar int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name) 465b073430SIngo Molnar { 475b073430SIngo Molnar u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask; 485b073430SIngo Molnar 495b073430SIngo Molnar if (unlikely(feature_name)) { 505b073430SIngo Molnar long xfeature_idx, max_idx; 515b073430SIngo Molnar u64 xfeatures_print; 525b073430SIngo Molnar /* 535b073430SIngo Molnar * So we use FLS here to be able to print the most advanced 545b073430SIngo Molnar * feature that was requested but is missing. So if a driver 555b073430SIngo Molnar * asks about "XSTATE_SSE | XSTATE_YMM" we'll print the 565b073430SIngo Molnar * missing AVX feature - this is the most informative message 575b073430SIngo Molnar * to users: 585b073430SIngo Molnar */ 595b073430SIngo Molnar if (xfeatures_missing) 605b073430SIngo Molnar xfeatures_print = xfeatures_missing; 615b073430SIngo Molnar else 625b073430SIngo Molnar xfeatures_print = xfeatures_needed; 635b073430SIngo Molnar 645b073430SIngo Molnar xfeature_idx = fls64(xfeatures_print)-1; 655b073430SIngo Molnar max_idx = ARRAY_SIZE(xfeature_names)-1; 665b073430SIngo Molnar xfeature_idx = min(xfeature_idx, max_idx); 675b073430SIngo Molnar 685b073430SIngo Molnar *feature_name = xfeature_names[xfeature_idx]; 695b073430SIngo Molnar } 705b073430SIngo Molnar 715b073430SIngo Molnar if (xfeatures_missing) 725b073430SIngo Molnar return 0; 735b073430SIngo Molnar 745b073430SIngo Molnar return 1; 755b073430SIngo Molnar } 765b073430SIngo Molnar EXPORT_SYMBOL_GPL(cpu_has_xfeatures); 775b073430SIngo Molnar 785b073430SIngo Molnar /* 7962784854SIngo Molnar * When executing XSAVEOPT (optimized XSAVE), if a processor implementation 8062784854SIngo Molnar * detects that an FPU state component is still (or is again) in its 8162784854SIngo Molnar * initialized state, it may clear the corresponding bit in the header.xfeatures 8262784854SIngo Molnar * field, and can skip the writeout of registers to the corresponding memory layout. 8362784854SIngo Molnar * 8462784854SIngo Molnar * This means that when the bit is zero, the state component might still contain 8562784854SIngo Molnar * some previous - non-initialized register state. 8662784854SIngo Molnar * 8762784854SIngo Molnar * Before writing xstate information to user-space we sanitize those components, 8862784854SIngo Molnar * to always ensure that the memory layout of a feature will be in the init state 8962784854SIngo Molnar * if the corresponding header bit is zero. This is to ensure that user-space doesn't 9062784854SIngo Molnar * see some stale state in the memory layout during signal handling, debugging etc. 9162784854SIngo Molnar */ 9236e49e7fSIngo Molnar void fpstate_sanitize_xstate(struct fpu *fpu) 9362784854SIngo Molnar { 9436e49e7fSIngo Molnar struct i387_fxsave_struct *fx = &fpu->state.fxsave; 9562784854SIngo Molnar int feature_bit; 9662784854SIngo Molnar u64 xfeatures; 9762784854SIngo Molnar 981ac91a76SIngo Molnar if (!use_xsaveopt()) 9962784854SIngo Molnar return; 10062784854SIngo Molnar 10136e49e7fSIngo Molnar xfeatures = fpu->state.xsave.header.xfeatures; 10262784854SIngo Molnar 10362784854SIngo Molnar /* 10462784854SIngo Molnar * None of the feature bits are in init state. So nothing else 10562784854SIngo Molnar * to do for us, as the memory layout is up to date. 10662784854SIngo Molnar */ 10762784854SIngo Molnar if ((xfeatures & xfeatures_mask) == xfeatures_mask) 10862784854SIngo Molnar return; 10962784854SIngo Molnar 11062784854SIngo Molnar /* 11162784854SIngo Molnar * FP is in init state 11262784854SIngo Molnar */ 11362784854SIngo Molnar if (!(xfeatures & XSTATE_FP)) { 11462784854SIngo Molnar fx->cwd = 0x37f; 11562784854SIngo Molnar fx->swd = 0; 11662784854SIngo Molnar fx->twd = 0; 11762784854SIngo Molnar fx->fop = 0; 11862784854SIngo Molnar fx->rip = 0; 11962784854SIngo Molnar fx->rdp = 0; 12062784854SIngo Molnar memset(&fx->st_space[0], 0, 128); 12162784854SIngo Molnar } 12262784854SIngo Molnar 12362784854SIngo Molnar /* 12462784854SIngo Molnar * SSE is in init state 12562784854SIngo Molnar */ 12662784854SIngo Molnar if (!(xfeatures & XSTATE_SSE)) 12762784854SIngo Molnar memset(&fx->xmm_space[0], 0, 256); 12862784854SIngo Molnar 12962784854SIngo Molnar /* 13062784854SIngo Molnar * First two features are FPU and SSE, which above we handled 13162784854SIngo Molnar * in a special way already: 13262784854SIngo Molnar */ 13362784854SIngo Molnar feature_bit = 0x2; 13462784854SIngo Molnar xfeatures = (xfeatures_mask & ~xfeatures) >> 2; 13562784854SIngo Molnar 13662784854SIngo Molnar /* 13762784854SIngo Molnar * Update all the remaining memory layouts according to their 13862784854SIngo Molnar * standard xstate layout, if their header bit is in the init 13962784854SIngo Molnar * state: 14062784854SIngo Molnar */ 14162784854SIngo Molnar while (xfeatures) { 14262784854SIngo Molnar if (xfeatures & 0x1) { 14362784854SIngo Molnar int offset = xstate_offsets[feature_bit]; 14462784854SIngo Molnar int size = xstate_sizes[feature_bit]; 14562784854SIngo Molnar 14662784854SIngo Molnar memcpy((void *)fx + offset, 1476f575023SIngo Molnar (void *)&init_fpstate.xsave + offset, 14862784854SIngo Molnar size); 14962784854SIngo Molnar } 15062784854SIngo Molnar 15162784854SIngo Molnar xfeatures >>= 1; 15262784854SIngo Molnar feature_bit++; 15362784854SIngo Molnar } 15462784854SIngo Molnar } 15562784854SIngo Molnar 15662784854SIngo Molnar /* 15762784854SIngo Molnar * Enable the extended processor state save/restore feature. 15862784854SIngo Molnar * Called once per CPU onlining. 15962784854SIngo Molnar */ 16062784854SIngo Molnar void fpu__init_cpu_xstate(void) 16162784854SIngo Molnar { 16262784854SIngo Molnar if (!cpu_has_xsave || !xfeatures_mask) 16362784854SIngo Molnar return; 16462784854SIngo Molnar 16562784854SIngo Molnar cr4_set_bits(X86_CR4_OSXSAVE); 16662784854SIngo Molnar xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask); 16762784854SIngo Molnar } 16862784854SIngo Molnar 16962784854SIngo Molnar /* 17062784854SIngo Molnar * Record the offsets and sizes of different state managed by the xsave 17162784854SIngo Molnar * memory layout. 17262784854SIngo Molnar */ 17362784854SIngo Molnar static void __init setup_xstate_features(void) 17462784854SIngo Molnar { 17562784854SIngo Molnar int eax, ebx, ecx, edx, leaf = 0x2; 17662784854SIngo Molnar 17762784854SIngo Molnar xfeatures_nr = fls64(xfeatures_mask); 17862784854SIngo Molnar 17962784854SIngo Molnar do { 18062784854SIngo Molnar cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx); 18162784854SIngo Molnar 18262784854SIngo Molnar if (eax == 0) 18362784854SIngo Molnar break; 18462784854SIngo Molnar 18562784854SIngo Molnar xstate_offsets[leaf] = ebx; 18662784854SIngo Molnar xstate_sizes[leaf] = eax; 18762784854SIngo Molnar 18862784854SIngo Molnar leaf++; 18962784854SIngo Molnar } while (1); 19062784854SIngo Molnar } 19162784854SIngo Molnar 19233588b52SIngo Molnar static void print_xstate_feature(u64 xstate_mask) 19362784854SIngo Molnar { 19433588b52SIngo Molnar const char *feature_name; 19562784854SIngo Molnar 19633588b52SIngo Molnar if (cpu_has_xfeatures(xstate_mask, &feature_name)) 19733588b52SIngo Molnar pr_info("x86/fpu: Supporting XSAVE feature 0x%02Lx: '%s'\n", xstate_mask, feature_name); 19862784854SIngo Molnar } 19962784854SIngo Molnar 20062784854SIngo Molnar /* 20162784854SIngo Molnar * Print out all the supported xstate features: 20262784854SIngo Molnar */ 20362784854SIngo Molnar static void print_xstate_features(void) 20462784854SIngo Molnar { 20533588b52SIngo Molnar print_xstate_feature(XSTATE_FP); 20633588b52SIngo Molnar print_xstate_feature(XSTATE_SSE); 20733588b52SIngo Molnar print_xstate_feature(XSTATE_YMM); 20833588b52SIngo Molnar print_xstate_feature(XSTATE_BNDREGS); 20933588b52SIngo Molnar print_xstate_feature(XSTATE_BNDCSR); 21033588b52SIngo Molnar print_xstate_feature(XSTATE_OPMASK); 21133588b52SIngo Molnar print_xstate_feature(XSTATE_ZMM_Hi256); 21233588b52SIngo Molnar print_xstate_feature(XSTATE_Hi16_ZMM); 21362784854SIngo Molnar } 21462784854SIngo Molnar 21562784854SIngo Molnar /* 21662784854SIngo Molnar * This function sets up offsets and sizes of all extended states in 21762784854SIngo Molnar * xsave area. This supports both standard format and compacted format 21862784854SIngo Molnar * of the xsave aread. 21962784854SIngo Molnar * 22062784854SIngo Molnar * Input: void 22162784854SIngo Molnar * Output: void 22262784854SIngo Molnar */ 22362784854SIngo Molnar void setup_xstate_comp(void) 22462784854SIngo Molnar { 22562784854SIngo Molnar unsigned int xstate_comp_sizes[sizeof(xfeatures_mask)*8]; 22662784854SIngo Molnar int i; 22762784854SIngo Molnar 22862784854SIngo Molnar /* 22962784854SIngo Molnar * The FP xstates and SSE xstates are legacy states. They are always 23062784854SIngo Molnar * in the fixed offsets in the xsave area in either compacted form 23162784854SIngo Molnar * or standard form. 23262784854SIngo Molnar */ 23362784854SIngo Molnar xstate_comp_offsets[0] = 0; 23462784854SIngo Molnar xstate_comp_offsets[1] = offsetof(struct i387_fxsave_struct, xmm_space); 23562784854SIngo Molnar 23662784854SIngo Molnar if (!cpu_has_xsaves) { 23762784854SIngo Molnar for (i = 2; i < xfeatures_nr; i++) { 23862784854SIngo Molnar if (test_bit(i, (unsigned long *)&xfeatures_mask)) { 23962784854SIngo Molnar xstate_comp_offsets[i] = xstate_offsets[i]; 24062784854SIngo Molnar xstate_comp_sizes[i] = xstate_sizes[i]; 24162784854SIngo Molnar } 24262784854SIngo Molnar } 24362784854SIngo Molnar return; 24462784854SIngo Molnar } 24562784854SIngo Molnar 24662784854SIngo Molnar xstate_comp_offsets[2] = FXSAVE_SIZE + XSAVE_HDR_SIZE; 24762784854SIngo Molnar 24862784854SIngo Molnar for (i = 2; i < xfeatures_nr; i++) { 24962784854SIngo Molnar if (test_bit(i, (unsigned long *)&xfeatures_mask)) 25062784854SIngo Molnar xstate_comp_sizes[i] = xstate_sizes[i]; 25162784854SIngo Molnar else 25262784854SIngo Molnar xstate_comp_sizes[i] = 0; 25362784854SIngo Molnar 25462784854SIngo Molnar if (i > 2) 25562784854SIngo Molnar xstate_comp_offsets[i] = xstate_comp_offsets[i-1] 25662784854SIngo Molnar + xstate_comp_sizes[i-1]; 25762784854SIngo Molnar 25862784854SIngo Molnar } 25962784854SIngo Molnar } 26062784854SIngo Molnar 26162784854SIngo Molnar /* 26262784854SIngo Molnar * setup the xstate image representing the init state 26362784854SIngo Molnar */ 26462784854SIngo Molnar static void setup_init_fpu_buf(void) 26562784854SIngo Molnar { 26662784854SIngo Molnar if (!cpu_has_xsave) 26762784854SIngo Molnar return; 26862784854SIngo Molnar 26962784854SIngo Molnar setup_xstate_features(); 27062784854SIngo Molnar print_xstate_features(); 27162784854SIngo Molnar 27262784854SIngo Molnar if (cpu_has_xsaves) { 2736f575023SIngo Molnar init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask; 2746f575023SIngo Molnar init_fpstate.xsave.header.xfeatures = xfeatures_mask; 27562784854SIngo Molnar } 27662784854SIngo Molnar 27762784854SIngo Molnar /* 27862784854SIngo Molnar * Init all the features state with header_bv being 0x0 27962784854SIngo Molnar */ 280c6813144SIngo Molnar copy_kernel_to_xregs_booting(&init_fpstate.xsave, -1); 28162784854SIngo Molnar 28262784854SIngo Molnar /* 28362784854SIngo Molnar * Dump the init state again. This is to identify the init state 28462784854SIngo Molnar * of any feature which is not represented by all zero's. 28562784854SIngo Molnar */ 286c6813144SIngo Molnar copy_xregs_to_kernel_booting(&init_fpstate.xsave); 28762784854SIngo Molnar } 28862784854SIngo Molnar 28962784854SIngo Molnar /* 29062784854SIngo Molnar * Calculate total size of enabled xstates in XCR0/xfeatures_mask. 29162784854SIngo Molnar */ 29262784854SIngo Molnar static void __init init_xstate_size(void) 29362784854SIngo Molnar { 29462784854SIngo Molnar unsigned int eax, ebx, ecx, edx; 29562784854SIngo Molnar int i; 29662784854SIngo Molnar 29762784854SIngo Molnar if (!cpu_has_xsaves) { 29862784854SIngo Molnar cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); 29962784854SIngo Molnar xstate_size = ebx; 30062784854SIngo Molnar return; 30162784854SIngo Molnar } 30262784854SIngo Molnar 30362784854SIngo Molnar xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE; 30462784854SIngo Molnar for (i = 2; i < 64; i++) { 30562784854SIngo Molnar if (test_bit(i, (unsigned long *)&xfeatures_mask)) { 30662784854SIngo Molnar cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx); 30762784854SIngo Molnar xstate_size += eax; 30862784854SIngo Molnar } 30962784854SIngo Molnar } 31062784854SIngo Molnar } 31162784854SIngo Molnar 31262784854SIngo Molnar /* 31362784854SIngo Molnar * Enable and initialize the xsave feature. 31462784854SIngo Molnar * Called once per system bootup. 31562784854SIngo Molnar * 31662784854SIngo Molnar * ( Not marked __init because of false positive section warnings. ) 31762784854SIngo Molnar */ 31862784854SIngo Molnar void fpu__init_system_xstate(void) 31962784854SIngo Molnar { 32062784854SIngo Molnar unsigned int eax, ebx, ecx, edx; 32162784854SIngo Molnar 32262784854SIngo Molnar if (!cpu_has_xsave) { 32362784854SIngo Molnar pr_info("x86/fpu: Legacy x87 FPU detected.\n"); 32462784854SIngo Molnar return; 32562784854SIngo Molnar } 32662784854SIngo Molnar 32762784854SIngo Molnar if (boot_cpu_data.cpuid_level < XSTATE_CPUID) { 32862784854SIngo Molnar WARN(1, "x86/fpu: XSTATE_CPUID missing!\n"); 32962784854SIngo Molnar return; 33062784854SIngo Molnar } 33162784854SIngo Molnar 33262784854SIngo Molnar cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); 33362784854SIngo Molnar xfeatures_mask = eax + ((u64)edx << 32); 33462784854SIngo Molnar 33562784854SIngo Molnar if ((xfeatures_mask & XSTATE_FPSSE) != XSTATE_FPSSE) { 33662784854SIngo Molnar pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n", xfeatures_mask); 33762784854SIngo Molnar BUG(); 33862784854SIngo Molnar } 33962784854SIngo Molnar 34062784854SIngo Molnar /* 34162784854SIngo Molnar * Support only the state known to OS. 34262784854SIngo Molnar */ 34362784854SIngo Molnar xfeatures_mask = xfeatures_mask & XCNTXT_MASK; 34462784854SIngo Molnar 34562784854SIngo Molnar /* Enable xstate instructions to be able to continue with initialization: */ 34662784854SIngo Molnar fpu__init_cpu_xstate(); 34762784854SIngo Molnar 34862784854SIngo Molnar /* 34962784854SIngo Molnar * Recompute the context size for enabled features 35062784854SIngo Molnar */ 35162784854SIngo Molnar init_xstate_size(); 35262784854SIngo Molnar 35362784854SIngo Molnar update_regset_xstate_info(xstate_size, xfeatures_mask); 354b992c660SIngo Molnar fpu__init_prepare_fx_sw_frame(); 35562784854SIngo Molnar setup_init_fpu_buf(); 35662784854SIngo Molnar 35762784854SIngo Molnar pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is 0x%x bytes, using '%s' format.\n", 35862784854SIngo Molnar xfeatures_mask, 35962784854SIngo Molnar xstate_size, 36062784854SIngo Molnar cpu_has_xsaves ? "compacted" : "standard"); 36162784854SIngo Molnar } 36262784854SIngo Molnar 36362784854SIngo Molnar /* 36462784854SIngo Molnar * Restore minimal FPU state after suspend: 36562784854SIngo Molnar */ 36662784854SIngo Molnar void fpu__resume_cpu(void) 36762784854SIngo Molnar { 36862784854SIngo Molnar /* 36962784854SIngo Molnar * Restore XCR0 on xsave capable CPUs: 37062784854SIngo Molnar */ 37162784854SIngo Molnar if (cpu_has_xsave) 37262784854SIngo Molnar xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask); 37362784854SIngo Molnar } 37462784854SIngo Molnar 37562784854SIngo Molnar /* 37662784854SIngo Molnar * Given the xsave area and a state inside, this function returns the 37762784854SIngo Molnar * address of the state. 37862784854SIngo Molnar * 37962784854SIngo Molnar * This is the API that is called to get xstate address in either 38062784854SIngo Molnar * standard format or compacted format of xsave area. 38162784854SIngo Molnar * 38262784854SIngo Molnar * Inputs: 38362784854SIngo Molnar * xsave: base address of the xsave area; 38462784854SIngo Molnar * xstate: state which is defined in xsave.h (e.g. XSTATE_FP, XSTATE_SSE, 38562784854SIngo Molnar * etc.) 38662784854SIngo Molnar * Output: 38762784854SIngo Molnar * address of the state in the xsave area. 38862784854SIngo Molnar */ 38962784854SIngo Molnar void *get_xsave_addr(struct xsave_struct *xsave, int xstate) 39062784854SIngo Molnar { 39162784854SIngo Molnar int feature = fls64(xstate) - 1; 39262784854SIngo Molnar if (!test_bit(feature, (unsigned long *)&xfeatures_mask)) 39362784854SIngo Molnar return NULL; 39462784854SIngo Molnar 39562784854SIngo Molnar return (void *)xsave + xstate_comp_offsets[feature]; 39662784854SIngo Molnar } 39762784854SIngo Molnar EXPORT_SYMBOL_GPL(get_xsave_addr); 398