1 // SPDX-License-Identifier: GPL-2.0-only
3 * xsave/xrstor support.
7 #include <linux/bitops.h>
8 #include <linux/compat.h>
10 #include <linux/mman.h>
11 #include <linux/nospec.h>
12 #include <linux/pkeys.h>
13 #include <linux/seq_file.h>
14 #include <linux/proc_fs.h>
15 #include <linux/vmalloc.h>
17 #include <asm/fpu/api.h>
18 #include <asm/fpu/regset.h>
19 #include <asm/fpu/signal.h>
20 #include <asm/fpu/xcr.h>
22 #include <asm/tlbflush.h>
23 #include <asm/prctl.h>
31 #define for_each_extended_xfeature(bit, mask) \
32 (bit) = FIRST_EXTENDED_XFEATURE; \
33 for_each_set_bit_from(bit, (unsigned long *)&(mask), 8 * sizeof(mask))
36 * Although we spell it out in here, the Processor Trace
37 * xfeature is completely unused. We use other mechanisms
38 * to save/restore PT state in Linux.
40 static const char *xfeature_names[] =
42 "x87 floating point registers",
45 "MPX bounds registers",
50 "Processor Trace (unused)",
51 "Protection Keys User registers",
53 "Control-flow User registers",
54 "Control-flow Kernel registers (unused)",
55 "unknown xstate feature",
56 "unknown xstate feature",
57 "unknown xstate feature",
58 "unknown xstate feature",
61 "unknown xstate feature",
64 static unsigned short xsave_cpuid_features[] __initdata = {
65 [XFEATURE_FP] = X86_FEATURE_FPU,
66 [XFEATURE_SSE] = X86_FEATURE_XMM,
67 [XFEATURE_YMM] = X86_FEATURE_AVX,
68 [XFEATURE_BNDREGS] = X86_FEATURE_MPX,
69 [XFEATURE_BNDCSR] = X86_FEATURE_MPX,
70 [XFEATURE_OPMASK] = X86_FEATURE_AVX512F,
71 [XFEATURE_ZMM_Hi256] = X86_FEATURE_AVX512F,
72 [XFEATURE_Hi16_ZMM] = X86_FEATURE_AVX512F,
73 [XFEATURE_PT_UNIMPLEMENTED_SO_FAR] = X86_FEATURE_INTEL_PT,
74 [XFEATURE_PKRU] = X86_FEATURE_OSPKE,
75 [XFEATURE_PASID] = X86_FEATURE_ENQCMD,
76 [XFEATURE_CET_USER] = X86_FEATURE_SHSTK,
77 [XFEATURE_XTILE_CFG] = X86_FEATURE_AMX_TILE,
78 [XFEATURE_XTILE_DATA] = X86_FEATURE_AMX_TILE,
81 static unsigned int xstate_offsets[XFEATURE_MAX] __ro_after_init =
82 { [ 0 ... XFEATURE_MAX - 1] = -1};
83 static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init =
84 { [ 0 ... XFEATURE_MAX - 1] = -1};
85 static unsigned int xstate_flags[XFEATURE_MAX] __ro_after_init;
87 #define XSTATE_FLAG_SUPERVISOR BIT(0)
88 #define XSTATE_FLAG_ALIGNED64 BIT(1)
91 * Return whether the system supports a given xfeature.
93 * Also return the name of the (most advanced) feature that the caller requested:
95 int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
97 u64 xfeatures_missing = xfeatures_needed & ~fpu_kernel_cfg.max_features;
99 if (unlikely(feature_name)) {
100 long xfeature_idx, max_idx;
103 * So we use FLS here to be able to print the most advanced
104 * feature that was requested but is missing. So if a driver
105 * asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the
106 * missing AVX feature - this is the most informative message
109 if (xfeatures_missing)
110 xfeatures_print = xfeatures_missing;
112 xfeatures_print = xfeatures_needed;
114 xfeature_idx = fls64(xfeatures_print)-1;
115 max_idx = ARRAY_SIZE(xfeature_names)-1;
116 xfeature_idx = min(xfeature_idx, max_idx);
118 *feature_name = xfeature_names[xfeature_idx];
121 if (xfeatures_missing)
126 EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
128 static bool xfeature_is_aligned64(int xfeature_nr)
130 return xstate_flags[xfeature_nr] & XSTATE_FLAG_ALIGNED64;
133 static bool xfeature_is_supervisor(int xfeature_nr)
135 return xstate_flags[xfeature_nr] & XSTATE_FLAG_SUPERVISOR;
138 static unsigned int xfeature_get_offset(u64 xcomp_bv, int xfeature)
140 unsigned int offs, i;
143 * Non-compacted format and legacy features use the cached fixed
146 if (!cpu_feature_enabled(X86_FEATURE_XCOMPACTED) ||
147 xfeature <= XFEATURE_SSE)
148 return xstate_offsets[xfeature];
151 * Compacted format offsets depend on the actual content of the
152 * compacted xsave area which is determined by the xcomp_bv header
155 offs = FXSAVE_SIZE + XSAVE_HDR_SIZE;
156 for_each_extended_xfeature(i, xcomp_bv) {
157 if (xfeature_is_aligned64(i))
158 offs = ALIGN(offs, 64);
161 offs += xstate_sizes[i];
167 * Enable the extended processor state save/restore feature.
168 * Called once per CPU onlining.
170 void fpu__init_cpu_xstate(void)
172 if (!boot_cpu_has(X86_FEATURE_XSAVE) || !fpu_kernel_cfg.max_features)
175 cr4_set_bits(X86_CR4_OSXSAVE);
178 * Must happen after CR4 setup and before xsetbv() to allow KVM
179 * lazy passthrough. Write independent of the dynamic state static
180 * key as that does not work on the boot CPU. This also ensures
181 * that any stale state is wiped out from XFD.
183 if (cpu_feature_enabled(X86_FEATURE_XFD))
184 wrmsrl(MSR_IA32_XFD, init_fpstate.xfd);
187 * XCR_XFEATURE_ENABLED_MASK (aka. XCR0) sets user features
188 * managed by XSAVE{C, OPT, S} and XRSTOR{S}. Only XSAVE user
189 * states can be set here.
191 xsetbv(XCR_XFEATURE_ENABLED_MASK, fpu_user_cfg.max_features);
194 * MSR_IA32_XSS sets supervisor states managed by XSAVES.
196 if (boot_cpu_has(X86_FEATURE_XSAVES)) {
197 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() |
198 xfeatures_mask_independent());
202 static bool xfeature_enabled(enum xfeature xfeature)
204 return fpu_kernel_cfg.max_features & BIT_ULL(xfeature);
208 * Record the offsets and sizes of various xstates contained
209 * in the XSAVE state memory layout.
211 static void __init setup_xstate_cache(void)
213 u32 eax, ebx, ecx, edx, i;
214 /* start at the beginning of the "extended state" */
215 unsigned int last_good_offset = offsetof(struct xregs_state,
216 extended_state_area);
218 * The FP xstates and SSE xstates are legacy states. They are always
219 * in the fixed offsets in the xsave area in either compacted form
222 xstate_offsets[XFEATURE_FP] = 0;
223 xstate_sizes[XFEATURE_FP] = offsetof(struct fxregs_state,
226 xstate_offsets[XFEATURE_SSE] = xstate_sizes[XFEATURE_FP];
227 xstate_sizes[XFEATURE_SSE] = sizeof_field(struct fxregs_state,
230 for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
231 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
233 xstate_sizes[i] = eax;
234 xstate_flags[i] = ecx;
237 * If an xfeature is supervisor state, the offset in EBX is
238 * invalid, leave it to -1.
240 if (xfeature_is_supervisor(i))
243 xstate_offsets[i] = ebx;
246 * In our xstate size checks, we assume that the highest-numbered
247 * xstate feature has the highest offset in the buffer. Ensure
250 WARN_ONCE(last_good_offset > xstate_offsets[i],
251 "x86/fpu: misordered xstate at %d\n", last_good_offset);
253 last_good_offset = xstate_offsets[i];
257 static void __init print_xstate_feature(u64 xstate_mask)
259 const char *feature_name;
261 if (cpu_has_xfeatures(xstate_mask, &feature_name))
262 pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name);
266 * Print out all the supported xstate features:
268 static void __init print_xstate_features(void)
270 print_xstate_feature(XFEATURE_MASK_FP);
271 print_xstate_feature(XFEATURE_MASK_SSE);
272 print_xstate_feature(XFEATURE_MASK_YMM);
273 print_xstate_feature(XFEATURE_MASK_BNDREGS);
274 print_xstate_feature(XFEATURE_MASK_BNDCSR);
275 print_xstate_feature(XFEATURE_MASK_OPMASK);
276 print_xstate_feature(XFEATURE_MASK_ZMM_Hi256);
277 print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
278 print_xstate_feature(XFEATURE_MASK_PKRU);
279 print_xstate_feature(XFEATURE_MASK_PASID);
280 print_xstate_feature(XFEATURE_MASK_CET_USER);
281 print_xstate_feature(XFEATURE_MASK_XTILE_CFG);
282 print_xstate_feature(XFEATURE_MASK_XTILE_DATA);
286 * This check is important because it is easy to get XSTATE_*
287 * confused with XSTATE_BIT_*.
289 #define CHECK_XFEATURE(nr) do { \
290 WARN_ON(nr < FIRST_EXTENDED_XFEATURE); \
291 WARN_ON(nr >= XFEATURE_MAX); \
295 * Print out xstate component offsets and sizes
297 static void __init print_xstate_offset_size(void)
301 for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
302 pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
303 i, xfeature_get_offset(fpu_kernel_cfg.max_features, i),
309 * This function is called only during boot time when x86 caps are not set
310 * up and alternative can not be used yet.
312 static __init void os_xrstor_booting(struct xregs_state *xstate)
314 u64 mask = fpu_kernel_cfg.max_features & XFEATURE_MASK_FPSTATE;
316 u32 hmask = mask >> 32;
319 if (cpu_feature_enabled(X86_FEATURE_XSAVES))
320 XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
322 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
325 * We should never fault when copying from a kernel buffer, and the FPU
326 * state we set at boot time should be valid.
332 * All supported features have either init state all zeros or are
333 * handled in setup_init_fpu() individually. This is an explicit
334 * feature list and does not use XFEATURE_MASK*SUPPORTED to catch
335 * newly added supported features at build time and make people
336 * actually look at the init state for the new feature.
338 #define XFEATURES_INIT_FPSTATE_HANDLED \
339 (XFEATURE_MASK_FP | \
340 XFEATURE_MASK_SSE | \
341 XFEATURE_MASK_YMM | \
342 XFEATURE_MASK_OPMASK | \
343 XFEATURE_MASK_ZMM_Hi256 | \
344 XFEATURE_MASK_Hi16_ZMM | \
345 XFEATURE_MASK_PKRU | \
346 XFEATURE_MASK_BNDREGS | \
347 XFEATURE_MASK_BNDCSR | \
348 XFEATURE_MASK_PASID | \
349 XFEATURE_MASK_CET_USER | \
353 * setup the xstate image representing the init state
355 static void __init setup_init_fpu_buf(void)
357 BUILD_BUG_ON((XFEATURE_MASK_USER_SUPPORTED |
358 XFEATURE_MASK_SUPERVISOR_SUPPORTED) !=
359 XFEATURES_INIT_FPSTATE_HANDLED);
361 if (!boot_cpu_has(X86_FEATURE_XSAVE))
364 print_xstate_features();
366 xstate_init_xcomp_bv(&init_fpstate.regs.xsave, init_fpstate.xfeatures);
369 * Init all the features state with header.xfeatures being 0x0
371 os_xrstor_booting(&init_fpstate.regs.xsave);
374 * All components are now in init state. Read the state back so
375 * that init_fpstate contains all non-zero init state. This only
376 * works with XSAVE, but not with XSAVEOPT and XSAVEC/S because
377 * those use the init optimization which skips writing data for
378 * components in init state.
380 * XSAVE could be used, but that would require to reshuffle the
381 * data when XSAVEC/S is available because XSAVEC/S uses xstate
382 * compaction. But doing so is a pointless exercise because most
383 * components have an all zeros init state except for the legacy
384 * ones (FP and SSE). Those can be saved with FXSAVE into the
385 * legacy area. Adding new features requires to ensure that init
386 * state is all zeroes or if not to add the necessary handling
389 fxsave(&init_fpstate.regs.fxsave);
392 int xfeature_size(int xfeature_nr)
394 u32 eax, ebx, ecx, edx;
396 CHECK_XFEATURE(xfeature_nr);
397 cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
401 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
402 static int validate_user_xstate_header(const struct xstate_header *hdr,
403 struct fpstate *fpstate)
405 /* No unknown or supervisor features may be set */
406 if (hdr->xfeatures & ~fpstate->user_xfeatures)
409 /* Userspace must use the uncompacted format */
414 * If 'reserved' is shrunken to add a new field, make sure to validate
415 * that new field here!
417 BUILD_BUG_ON(sizeof(hdr->reserved) != 48);
419 /* No reserved bits may be set */
420 if (memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved)))
426 static void __init __xstate_dump_leaves(void)
429 u32 eax, ebx, ecx, edx;
430 static int should_dump = 1;
436 * Dump out a few leaves past the ones that we support
437 * just in case there are some goodies up there
439 for (i = 0; i < XFEATURE_MAX + 10; i++) {
440 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
441 pr_warn("CPUID[%02x, %02x]: eax=%08x ebx=%08x ecx=%08x edx=%08x\n",
442 XSTATE_CPUID, i, eax, ebx, ecx, edx);
446 #define XSTATE_WARN_ON(x, fmt, ...) do { \
447 if (WARN_ONCE(x, "XSAVE consistency problem: " fmt, ##__VA_ARGS__)) { \
448 __xstate_dump_leaves(); \
452 #define XCHECK_SZ(sz, nr, __struct) ({ \
453 if (WARN_ONCE(sz != sizeof(__struct), \
454 "[%s]: struct is %zu bytes, cpu state %d bytes\n", \
455 xfeature_names[nr], sizeof(__struct), sz)) { \
456 __xstate_dump_leaves(); \
463 * check_xtile_data_against_struct - Check tile data state size.
465 * Calculate the state size by multiplying the single tile size which is
466 * recorded in a C struct, and the number of tiles that the CPU informs.
467 * Compare the provided size with the calculation.
469 * @size: The tile data state size
471 * Returns: 0 on success, -EINVAL on mismatch.
473 static int __init check_xtile_data_against_struct(int size)
475 u32 max_palid, palid, state_size;
476 u32 eax, ebx, ecx, edx;
480 * Check the maximum palette id:
481 * eax: the highest numbered palette subleaf.
483 cpuid_count(TILE_CPUID, 0, &max_palid, &ebx, &ecx, &edx);
486 * Cross-check each tile size and find the maximum number of
489 for (palid = 1, max_tile = 0; palid <= max_palid; palid++) {
493 * Check the tile size info:
494 * eax[31:16]: bytes per title
495 * ebx[31:16]: the max names (or max number of tiles)
497 cpuid_count(TILE_CPUID, palid, &eax, &ebx, &edx, &edx);
498 tile_size = eax >> 16;
501 if (tile_size != sizeof(struct xtile_data)) {
502 pr_err("%s: struct is %zu bytes, cpu xtile %d bytes\n",
503 __stringify(XFEATURE_XTILE_DATA),
504 sizeof(struct xtile_data), tile_size);
505 __xstate_dump_leaves();
513 state_size = sizeof(struct xtile_data) * max_tile;
514 if (size != state_size) {
515 pr_err("%s: calculated size is %u bytes, cpu state %d bytes\n",
516 __stringify(XFEATURE_XTILE_DATA), state_size, size);
517 __xstate_dump_leaves();
524 * We have a C struct for each 'xstate'. We need to ensure
525 * that our software representation matches what the CPU
526 * tells us about the state's size.
528 static bool __init check_xstate_against_struct(int nr)
531 * Ask the CPU for the size of the state.
533 int sz = xfeature_size(nr);
536 * Match each CPU state with the corresponding software
540 case XFEATURE_YMM: return XCHECK_SZ(sz, nr, struct ymmh_struct);
541 case XFEATURE_BNDREGS: return XCHECK_SZ(sz, nr, struct mpx_bndreg_state);
542 case XFEATURE_BNDCSR: return XCHECK_SZ(sz, nr, struct mpx_bndcsr_state);
543 case XFEATURE_OPMASK: return XCHECK_SZ(sz, nr, struct avx_512_opmask_state);
544 case XFEATURE_ZMM_Hi256: return XCHECK_SZ(sz, nr, struct avx_512_zmm_uppers_state);
545 case XFEATURE_Hi16_ZMM: return XCHECK_SZ(sz, nr, struct avx_512_hi16_state);
546 case XFEATURE_PKRU: return XCHECK_SZ(sz, nr, struct pkru_state);
547 case XFEATURE_PASID: return XCHECK_SZ(sz, nr, struct ia32_pasid_state);
548 case XFEATURE_XTILE_CFG: return XCHECK_SZ(sz, nr, struct xtile_cfg);
549 case XFEATURE_CET_USER: return XCHECK_SZ(sz, nr, struct cet_user_state);
550 case XFEATURE_XTILE_DATA: check_xtile_data_against_struct(sz); return true;
552 XSTATE_WARN_ON(1, "No structure for xstate: %d\n", nr);
559 static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted)
561 unsigned int topmost = fls64(xfeatures) - 1;
562 unsigned int offset = xstate_offsets[topmost];
564 if (topmost <= XFEATURE_SSE)
565 return sizeof(struct xregs_state);
568 offset = xfeature_get_offset(xfeatures, topmost);
569 return offset + xstate_sizes[topmost];
573 * This essentially double-checks what the cpu told us about
574 * how large the XSAVE buffer needs to be. We are recalculating
577 * Independent XSAVE features allocate their own buffers and are not
578 * covered by these checks. Only the size of the buffer for task->fpu
581 static bool __init paranoid_xstate_size_valid(unsigned int kernel_size)
583 bool compacted = cpu_feature_enabled(X86_FEATURE_XCOMPACTED);
584 bool xsaves = cpu_feature_enabled(X86_FEATURE_XSAVES);
585 unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
588 for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
589 if (!check_xstate_against_struct(i))
592 * Supervisor state components can be managed only by
595 if (!xsaves && xfeature_is_supervisor(i)) {
596 XSTATE_WARN_ON(1, "Got supervisor feature %d, but XSAVES not advertised\n", i);
600 size = xstate_calculate_size(fpu_kernel_cfg.max_features, compacted);
601 XSTATE_WARN_ON(size != kernel_size,
602 "size %u != kernel_size %u\n", size, kernel_size);
603 return size == kernel_size;
607 * Get total size of enabled xstates in XCR0 | IA32_XSS.
609 * Note the SDM's wording here. "sub-function 0" only enumerates
610 * the size of the *user* states. If we use it to size a buffer
611 * that we use 'XSAVES' on, we could potentially overflow the
612 * buffer because 'XSAVES' saves system states too.
614 * This also takes compaction into account. So this works for
617 static unsigned int __init get_compacted_size(void)
619 unsigned int eax, ebx, ecx, edx;
621 * - CPUID function 0DH, sub-function 1:
622 * EBX enumerates the size (in bytes) required by
623 * the XSAVES instruction for an XSAVE area
624 * containing all the state components
625 * corresponding to bits currently set in
628 * When XSAVES is not available but XSAVEC is (virt), then there
629 * are no supervisor states, but XSAVEC still uses compacted
632 cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
637 * Get the total size of the enabled xstates without the independent supervisor
640 static unsigned int __init get_xsave_compacted_size(void)
642 u64 mask = xfeatures_mask_independent();
646 return get_compacted_size();
648 /* Disable independent features. */
649 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor());
652 * Ask the hardware what size is required of the buffer.
653 * This is the size required for the task->fpu buffer.
655 size = get_compacted_size();
657 /* Re-enable independent features so XSAVES will work on them again. */
658 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() | mask);
663 static unsigned int __init get_xsave_size_user(void)
665 unsigned int eax, ebx, ecx, edx;
667 * - CPUID function 0DH, sub-function 0:
668 * EBX enumerates the size (in bytes) required by
669 * the XSAVE instruction for an XSAVE area
670 * containing all the *user* state components
671 * corresponding to bits currently set in XCR0.
673 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
677 static int __init init_xstate_size(void)
679 /* Recompute the context size for enabled features: */
680 unsigned int user_size, kernel_size, kernel_default_size;
681 bool compacted = cpu_feature_enabled(X86_FEATURE_XCOMPACTED);
683 /* Uncompacted user space size */
684 user_size = get_xsave_size_user();
687 * XSAVES kernel size includes supervisor states and uses compacted
688 * format. XSAVEC uses compacted format, but does not save
691 * XSAVE[OPT] do not support supervisor states so kernel and user
695 kernel_size = get_xsave_compacted_size();
697 kernel_size = user_size;
699 kernel_default_size =
700 xstate_calculate_size(fpu_kernel_cfg.default_features, compacted);
702 if (!paranoid_xstate_size_valid(kernel_size))
705 fpu_kernel_cfg.max_size = kernel_size;
706 fpu_user_cfg.max_size = user_size;
708 fpu_kernel_cfg.default_size = kernel_default_size;
709 fpu_user_cfg.default_size =
710 xstate_calculate_size(fpu_user_cfg.default_features, false);
716 * We enabled the XSAVE hardware, but something went wrong and
717 * we can not use it. Disable it.
719 static void __init fpu__init_disable_system_xstate(unsigned int legacy_size)
721 fpu_kernel_cfg.max_features = 0;
722 cr4_clear_bits(X86_CR4_OSXSAVE);
723 setup_clear_cpu_cap(X86_FEATURE_XSAVE);
725 /* Restore the legacy size.*/
726 fpu_kernel_cfg.max_size = legacy_size;
727 fpu_kernel_cfg.default_size = legacy_size;
728 fpu_user_cfg.max_size = legacy_size;
729 fpu_user_cfg.default_size = legacy_size;
732 * Prevent enabling the static branch which enables writes to the
735 init_fpstate.xfd = 0;
737 fpstate_reset(¤t->thread.fpu);
741 * Enable and initialize the xsave feature.
742 * Called once per system bootup.
744 void __init fpu__init_system_xstate(unsigned int legacy_size)
746 unsigned int eax, ebx, ecx, edx;
751 if (!boot_cpu_has(X86_FEATURE_FPU)) {
752 pr_info("x86/fpu: No FPU detected\n");
756 if (!boot_cpu_has(X86_FEATURE_XSAVE)) {
757 pr_info("x86/fpu: x87 FPU will use %s\n",
758 boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE");
762 if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
768 * Find user xstates supported by the processor.
770 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
771 fpu_kernel_cfg.max_features = eax + ((u64)edx << 32);
774 * Find supervisor xstates supported by the processor.
776 cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
777 fpu_kernel_cfg.max_features |= ecx + ((u64)edx << 32);
779 if ((fpu_kernel_cfg.max_features & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
781 * This indicates that something really unexpected happened
782 * with the enumeration. Disable XSAVE and try to continue
783 * booting without it. This is too early to BUG().
785 pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n",
786 fpu_kernel_cfg.max_features);
791 * Clear XSAVE features that are disabled in the normal CPUID.
793 for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
794 unsigned short cid = xsave_cpuid_features[i];
796 /* Careful: X86_FEATURE_FPU is 0! */
797 if ((i != XFEATURE_FP && !cid) || !boot_cpu_has(cid))
798 fpu_kernel_cfg.max_features &= ~BIT_ULL(i);
801 if (!cpu_feature_enabled(X86_FEATURE_XFD))
802 fpu_kernel_cfg.max_features &= ~XFEATURE_MASK_USER_DYNAMIC;
804 if (!cpu_feature_enabled(X86_FEATURE_XSAVES))
805 fpu_kernel_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED;
807 fpu_kernel_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED |
808 XFEATURE_MASK_SUPERVISOR_SUPPORTED;
810 fpu_user_cfg.max_features = fpu_kernel_cfg.max_features;
811 fpu_user_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED;
813 /* Clean out dynamic features from default */
814 fpu_kernel_cfg.default_features = fpu_kernel_cfg.max_features;
815 fpu_kernel_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC;
817 fpu_user_cfg.default_features = fpu_user_cfg.max_features;
818 fpu_user_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC;
820 /* Store it for paranoia check at the end */
821 xfeatures = fpu_kernel_cfg.max_features;
824 * Initialize the default XFD state in initfp_state and enable the
825 * dynamic sizing mechanism if dynamic states are available. The
826 * static key cannot be enabled here because this runs before
827 * jump_label_init(). This is delayed to an initcall.
829 init_fpstate.xfd = fpu_user_cfg.max_features & XFEATURE_MASK_USER_DYNAMIC;
831 /* Set up compaction feature bit */
832 if (cpu_feature_enabled(X86_FEATURE_XSAVEC) ||
833 cpu_feature_enabled(X86_FEATURE_XSAVES))
834 setup_force_cpu_cap(X86_FEATURE_XCOMPACTED);
836 /* Enable xstate instructions to be able to continue with initialization: */
837 fpu__init_cpu_xstate();
839 /* Cache size, offset and flags for initialization */
840 setup_xstate_cache();
842 err = init_xstate_size();
846 /* Reset the state for the current task */
847 fpstate_reset(¤t->thread.fpu);
850 * Update info used for ptrace frames; use standard-format size and no
851 * supervisor xstates:
853 update_regset_xstate_info(fpu_user_cfg.max_size,
854 fpu_user_cfg.max_features);
857 * init_fpstate excludes dynamic states as they are large but init
860 init_fpstate.size = fpu_kernel_cfg.default_size;
861 init_fpstate.xfeatures = fpu_kernel_cfg.default_features;
863 if (init_fpstate.size > sizeof(init_fpstate.regs)) {
864 pr_warn("x86/fpu: init_fpstate buffer too small (%zu < %d), disabling XSAVE\n",
865 sizeof(init_fpstate.regs), init_fpstate.size);
869 setup_init_fpu_buf();
872 * Paranoia check whether something in the setup modified the
875 if (xfeatures != fpu_kernel_cfg.max_features) {
876 pr_err("x86/fpu: xfeatures modified from 0x%016llx to 0x%016llx during init, disabling XSAVE\n",
877 xfeatures, fpu_kernel_cfg.max_features);
882 * CPU capabilities initialization runs before FPU init. So
883 * X86_FEATURE_OSXSAVE is not set. Now that XSAVE is completely
884 * functional, set the feature bit so depending code works.
886 setup_force_cpu_cap(X86_FEATURE_OSXSAVE);
888 print_xstate_offset_size();
889 pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
890 fpu_kernel_cfg.max_features,
891 fpu_kernel_cfg.max_size,
892 boot_cpu_has(X86_FEATURE_XCOMPACTED) ? "compacted" : "standard");
896 /* something went wrong, try to boot without any XSAVE support */
897 fpu__init_disable_system_xstate(legacy_size);
901 * Restore minimal FPU state after suspend:
903 void fpu__resume_cpu(void)
906 * Restore XCR0 on xsave capable CPUs:
908 if (cpu_feature_enabled(X86_FEATURE_XSAVE))
909 xsetbv(XCR_XFEATURE_ENABLED_MASK, fpu_user_cfg.max_features);
912 * Restore IA32_XSS. The same CPUID bit enumerates support
913 * of XSAVES and MSR_IA32_XSS.
915 if (cpu_feature_enabled(X86_FEATURE_XSAVES)) {
916 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() |
917 xfeatures_mask_independent());
920 if (fpu_state_size_dynamic())
921 wrmsrl(MSR_IA32_XFD, current->thread.fpu.fpstate->xfd);
925 * Given an xstate feature nr, calculate where in the xsave
926 * buffer the state is. Callers should ensure that the buffer
929 static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
931 u64 xcomp_bv = xsave->header.xcomp_bv;
933 if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr)))
936 if (cpu_feature_enabled(X86_FEATURE_XCOMPACTED)) {
937 if (WARN_ON_ONCE(!(xcomp_bv & BIT_ULL(xfeature_nr))))
941 return (void *)xsave + xfeature_get_offset(xcomp_bv, xfeature_nr);
945 * Given the xsave area and a state inside, this function returns the
946 * address of the state.
948 * This is the API that is called to get xstate address in either
949 * standard format or compacted format of xsave area.
951 * Note that if there is no data for the field in the xsave buffer
952 * this will return NULL.
955 * xstate: the thread's storage area for all FPU data
956 * xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
957 * XFEATURE_SSE, etc...)
959 * address of the state in the xsave area, or NULL if the
960 * field is not present in the xsave buffer.
962 void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
965 * Do we even *have* xsave state?
967 if (!boot_cpu_has(X86_FEATURE_XSAVE))
971 * We should not ever be requesting features that we
974 if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr)))
978 * This assumes the last 'xsave*' instruction to
979 * have requested that 'xfeature_nr' be saved.
980 * If it did not, we might be seeing and old value
981 * of the field in the buffer.
983 * This can happen because the last 'xsave' did not
984 * request that this feature be saved (unlikely)
985 * or because the "init optimization" caused it
988 if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr)))
991 return __raw_xsave_addr(xsave, xfeature_nr);
994 #ifdef CONFIG_ARCH_HAS_PKEYS
997 * This will go out and modify PKRU register to set the access
998 * rights for @pkey to @init_val.
1000 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
1001 unsigned long init_val)
1003 u32 old_pkru, new_pkru_bits = 0;
1007 * This check implies XSAVE support. OSPKE only gets
1008 * set if we enable XSAVE and we enable PKU in XCR0.
1010 if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
1014 * This code should only be called with valid 'pkey'
1015 * values originating from in-kernel users. Complain
1016 * if a bad value is observed.
1018 if (WARN_ON_ONCE(pkey >= arch_max_pkey()))
1021 /* Set the bits we need in PKRU: */
1022 if (init_val & PKEY_DISABLE_ACCESS)
1023 new_pkru_bits |= PKRU_AD_BIT;
1024 if (init_val & PKEY_DISABLE_WRITE)
1025 new_pkru_bits |= PKRU_WD_BIT;
1027 /* Shift the bits in to the correct place in PKRU for pkey: */
1028 pkey_shift = pkey * PKRU_BITS_PER_PKEY;
1029 new_pkru_bits <<= pkey_shift;
1031 /* Get old PKRU and mask off any old bits in place: */
1032 old_pkru = read_pkru();
1033 old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift);
1035 /* Write old part along with new part: */
1036 write_pkru(old_pkru | new_pkru_bits);
1040 #endif /* ! CONFIG_ARCH_HAS_PKEYS */
1042 static void copy_feature(bool from_xstate, struct membuf *to, void *xstate,
1043 void *init_xstate, unsigned int size)
1045 membuf_write(to, from_xstate ? xstate : init_xstate, size);
1049 * __copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
1050 * @to: membuf descriptor
1051 * @fpstate: The fpstate buffer from which to copy
1052 * @xfeatures: The mask of xfeatures to save (XSAVE mode only)
1053 * @pkru_val: The PKRU value to store in the PKRU component
1054 * @copy_mode: The requested copy mode
1056 * Converts from kernel XSAVE or XSAVES compacted format to UABI conforming
1057 * format, i.e. from the kernel internal hardware dependent storage format
1058 * to the requested @mode. UABI XSTATE is always uncompacted!
1060 * It supports partial copy but @to.pos always starts from zero.
1062 void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
1063 u64 xfeatures, u32 pkru_val,
1064 enum xstate_copy_mode copy_mode)
1066 const unsigned int off_mxcsr = offsetof(struct fxregs_state, mxcsr);
1067 struct xregs_state *xinit = &init_fpstate.regs.xsave;
1068 struct xregs_state *xsave = &fpstate->regs.xsave;
1069 struct xstate_header header;
1070 unsigned int zerofrom;
1074 memset(&header, 0, sizeof(header));
1075 header.xfeatures = xsave->header.xfeatures;
1077 /* Mask out the feature bits depending on copy mode */
1078 switch (copy_mode) {
1079 case XSTATE_COPY_FP:
1080 header.xfeatures &= XFEATURE_MASK_FP;
1083 case XSTATE_COPY_FX:
1084 header.xfeatures &= XFEATURE_MASK_FP | XFEATURE_MASK_SSE;
1087 case XSTATE_COPY_XSAVE:
1088 header.xfeatures &= fpstate->user_xfeatures & xfeatures;
1092 /* Copy FP state up to MXCSR */
1093 copy_feature(header.xfeatures & XFEATURE_MASK_FP, &to, &xsave->i387,
1094 &xinit->i387, off_mxcsr);
1096 /* Copy MXCSR when SSE or YMM are set in the feature mask */
1097 copy_feature(header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM),
1098 &to, &xsave->i387.mxcsr, &xinit->i387.mxcsr,
1099 MXCSR_AND_FLAGS_SIZE);
1101 /* Copy the remaining FP state */
1102 copy_feature(header.xfeatures & XFEATURE_MASK_FP,
1103 &to, &xsave->i387.st_space, &xinit->i387.st_space,
1104 sizeof(xsave->i387.st_space));
1106 /* Copy the SSE state - shared with YMM, but independently managed */
1107 copy_feature(header.xfeatures & XFEATURE_MASK_SSE,
1108 &to, &xsave->i387.xmm_space, &xinit->i387.xmm_space,
1109 sizeof(xsave->i387.xmm_space));
1111 if (copy_mode != XSTATE_COPY_XSAVE)
1114 /* Zero the padding area */
1115 membuf_zero(&to, sizeof(xsave->i387.padding));
1117 /* Copy xsave->i387.sw_reserved */
1118 membuf_write(&to, xstate_fx_sw_bytes, sizeof(xsave->i387.sw_reserved));
1120 /* Copy the user space relevant state of @xsave->header */
1121 membuf_write(&to, &header, sizeof(header));
1123 zerofrom = offsetof(struct xregs_state, extended_state_area);
1126 * This 'mask' indicates which states to copy from fpstate.
1127 * Those extended states that are not present in fpstate are
1128 * either disabled or initialized:
1130 * In non-compacted format, disabled features still occupy
1131 * state space but there is no state to copy from in the
1132 * compacted init_fpstate. The gap tracking will zero these
1135 * The extended features have an all zeroes init state. Thus,
1136 * remove them from 'mask' to zero those features in the user
1137 * buffer instead of retrieving them from init_fpstate.
1139 mask = header.xfeatures;
1141 for_each_extended_xfeature(i, mask) {
1143 * If there was a feature or alignment gap, zero the space
1144 * in the destination buffer.
1146 if (zerofrom < xstate_offsets[i])
1147 membuf_zero(&to, xstate_offsets[i] - zerofrom);
1149 if (i == XFEATURE_PKRU) {
1150 struct pkru_state pkru = {0};
1152 * PKRU is not necessarily up to date in the
1153 * XSAVE buffer. Use the provided value.
1155 pkru.pkru = pkru_val;
1156 membuf_write(&to, &pkru, sizeof(pkru));
1159 __raw_xsave_addr(xsave, i),
1163 * Keep track of the last copied state in the non-compacted
1164 * target buffer for gap zeroing.
1166 zerofrom = xstate_offsets[i] + xstate_sizes[i];
1171 membuf_zero(&to, to.left);
1175 * copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
1176 * @to: membuf descriptor
1177 * @tsk: The task from which to copy the saved xstate
1178 * @copy_mode: The requested copy mode
1180 * Converts from kernel XSAVE or XSAVES compacted format to UABI conforming
1181 * format, i.e. from the kernel internal hardware dependent storage format
1182 * to the requested @mode. UABI XSTATE is always uncompacted!
1184 * It supports partial copy but @to.pos always starts from zero.
1186 void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
1187 enum xstate_copy_mode copy_mode)
1189 __copy_xstate_to_uabi_buf(to, tsk->thread.fpu.fpstate,
1190 tsk->thread.fpu.fpstate->user_xfeatures,
1191 tsk->thread.pkru, copy_mode);
1194 static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size,
1195 const void *kbuf, const void __user *ubuf)
1198 memcpy(dst, kbuf + offset, size);
1200 if (copy_from_user(dst, ubuf + offset, size))
1208 * copy_uabi_to_xstate - Copy a UABI format buffer to the kernel xstate
1209 * @fpstate: The fpstate buffer to copy to
1210 * @kbuf: The UABI format buffer, if it comes from the kernel
1211 * @ubuf: The UABI format buffer, if it comes from userspace
1212 * @pkru: The location to write the PKRU value to
1214 * Converts from the UABI format into the kernel internal hardware
1217 * This function ultimately has three different callers with distinct PKRU
1219 * 1. When called from sigreturn the PKRU register will be restored from
1220 * @fpstate via an XRSTOR. Correctly copying the UABI format buffer to
1221 * @fpstate is sufficient to cover this case, but the caller will also
1222 * pass a pointer to the thread_struct's pkru field in @pkru and updating
1224 * 2. When called from ptrace the PKRU register will be restored from the
1225 * thread_struct's pkru field. A pointer to that is passed in @pkru.
1226 * The kernel will restore it manually, so the XRSTOR behavior that resets
1227 * the PKRU register to the hardware init value (0) if the corresponding
1228 * xfeatures bit is not set is emulated here.
1229 * 3. When called from KVM the PKRU register will be restored from the vcpu's
1230 * pkru field. A pointer to that is passed in @pkru. KVM hasn't used
1231 * XRSTOR and hasn't had the PKRU resetting behavior described above. To
1232 * preserve that KVM behavior, it passes NULL for @pkru if the xfeatures
1235 static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf,
1236 const void __user *ubuf, u32 *pkru)
1238 struct xregs_state *xsave = &fpstate->regs.xsave;
1239 unsigned int offset, size;
1240 struct xstate_header hdr;
1244 offset = offsetof(struct xregs_state, header);
1245 if (copy_from_buffer(&hdr, offset, sizeof(hdr), kbuf, ubuf))
1248 if (validate_user_xstate_header(&hdr, fpstate))
1251 /* Validate MXCSR when any of the related features is in use */
1252 mask = XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM;
1253 if (hdr.xfeatures & mask) {
1256 offset = offsetof(struct fxregs_state, mxcsr);
1257 if (copy_from_buffer(mxcsr, offset, sizeof(mxcsr), kbuf, ubuf))
1260 /* Reserved bits in MXCSR must be zero. */
1261 if (mxcsr[0] & ~mxcsr_feature_mask)
1264 /* SSE and YMM require MXCSR even when FP is not in use. */
1265 if (!(hdr.xfeatures & XFEATURE_MASK_FP)) {
1266 xsave->i387.mxcsr = mxcsr[0];
1267 xsave->i387.mxcsr_mask = mxcsr[1];
1271 for (i = 0; i < XFEATURE_MAX; i++) {
1274 if (hdr.xfeatures & mask) {
1275 void *dst = __raw_xsave_addr(xsave, i);
1277 offset = xstate_offsets[i];
1278 size = xstate_sizes[i];
1280 if (copy_from_buffer(dst, offset, size, kbuf, ubuf))
1285 if (hdr.xfeatures & XFEATURE_MASK_PKRU) {
1286 struct pkru_state *xpkru;
1288 xpkru = __raw_xsave_addr(xsave, XFEATURE_PKRU);
1289 *pkru = xpkru->pkru;
1292 * KVM may pass NULL here to indicate that it does not need
1300 * The state that came in from userspace was user-state only.
1301 * Mask all the user states out of 'xfeatures':
1303 xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL;
1306 * Add back in the features that came in from userspace:
1308 xsave->header.xfeatures |= hdr.xfeatures;
1314 * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S]
1315 * format and copy to the target thread. Used by ptrace and KVM.
1317 int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru)
1319 return copy_uabi_to_xstate(fpstate, kbuf, NULL, pkru);
1323 * Convert from a sigreturn standard-format user-space buffer to kernel
1324 * XSAVE[S] format and copy to the target thread. This is called from the
1325 * sigreturn() and rt_sigreturn() system calls.
1327 int copy_sigframe_from_user_to_xstate(struct task_struct *tsk,
1328 const void __user *ubuf)
1330 return copy_uabi_to_xstate(tsk->thread.fpu.fpstate, NULL, ubuf, &tsk->thread.pkru);
1333 static bool validate_independent_components(u64 mask)
1337 if (WARN_ON_FPU(!cpu_feature_enabled(X86_FEATURE_XSAVES)))
1340 xchk = ~xfeatures_mask_independent();
1342 if (WARN_ON_ONCE(!mask || mask & xchk))
1349 * xsaves - Save selected components to a kernel xstate buffer
1350 * @xstate: Pointer to the buffer
1351 * @mask: Feature mask to select the components to save
1353 * The @xstate buffer must be 64 byte aligned and correctly initialized as
1354 * XSAVES does not write the full xstate header. Before first use the
1355 * buffer should be zeroed otherwise a consecutive XRSTORS from that buffer
1358 * The feature mask must be a subset of the independent features.
1360 void xsaves(struct xregs_state *xstate, u64 mask)
1364 if (!validate_independent_components(mask))
1367 XSTATE_OP(XSAVES, xstate, (u32)mask, (u32)(mask >> 32), err);
1372 * xrstors - Restore selected components from a kernel xstate buffer
1373 * @xstate: Pointer to the buffer
1374 * @mask: Feature mask to select the components to restore
1376 * The @xstate buffer must be 64 byte aligned and correctly initialized
1377 * otherwise XRSTORS from that buffer can #GP.
1379 * Proper usage is to restore the state which was saved with
1380 * xsaves() into @xstate.
1382 * The feature mask must be a subset of the independent features.
1384 void xrstors(struct xregs_state *xstate, u64 mask)
1388 if (!validate_independent_components(mask))
1391 XSTATE_OP(XRSTORS, xstate, (u32)mask, (u32)(mask >> 32), err);
1395 #if IS_ENABLED(CONFIG_KVM)
1396 void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature)
1398 void *addr = get_xsave_addr(&fps->regs.xsave, xfeature);
1401 memset(addr, 0, xstate_sizes[xfeature]);
1403 EXPORT_SYMBOL_GPL(fpstate_clear_xstate_component);
1406 #ifdef CONFIG_X86_64
1408 #ifdef CONFIG_X86_DEBUG_FPU
1410 * Ensure that a subsequent XSAVE* or XRSTOR* instruction with RFBM=@mask
1411 * can safely operate on the @fpstate buffer.
1413 static bool xstate_op_valid(struct fpstate *fpstate, u64 mask, bool rstor)
1415 u64 xfd = __this_cpu_read(xfd_state);
1417 if (fpstate->xfd == xfd)
1421 * The XFD MSR does not match fpstate->xfd. That's invalid when
1422 * the passed in fpstate is current's fpstate.
1424 if (fpstate->xfd == current->thread.fpu.fpstate->xfd)
1428 * XRSTOR(S) from init_fpstate are always correct as it will just
1429 * bring all components into init state and not read from the
1430 * buffer. XSAVE(S) raises #PF after init.
1432 if (fpstate == &init_fpstate)
1436 * XSAVE(S): clone(), fpu_swap_kvm_fpu()
1437 * XRSTORS(S): fpu_swap_kvm_fpu()
1441 * No XSAVE/XRSTOR instructions (except XSAVE itself) touch
1442 * the buffer area for XFD-disabled state components.
1447 * Remove features which are valid in fpstate. They
1448 * have space allocated in fpstate.
1450 mask &= ~fpstate->xfeatures;
1453 * Any remaining state components in 'mask' might be written
1454 * by XSAVE/XRSTOR. Fail validation it found.
1459 void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor)
1461 WARN_ON_ONCE(!xstate_op_valid(fpstate, mask, rstor));
1463 #endif /* CONFIG_X86_DEBUG_FPU */
1465 static int __init xfd_update_static_branch(void)
1468 * If init_fpstate.xfd has bits set then dynamic features are
1469 * available and the dynamic sizing must be enabled.
1471 if (init_fpstate.xfd)
1472 static_branch_enable(&__fpu_state_size_dynamic);
1475 arch_initcall(xfd_update_static_branch)
1477 void fpstate_free(struct fpu *fpu)
1479 if (fpu->fpstate && fpu->fpstate != &fpu->__fpstate)
1480 vfree(fpu->fpstate);
1484 * fpstate_realloc - Reallocate struct fpstate for the requested new features
1486 * @xfeatures: A bitmap of xstate features which extend the enabled features
1488 * @ksize: The required size for the kernel buffer
1489 * @usize: The required size for user space buffers
1490 * @guest_fpu: Pointer to a guest FPU container. NULL for host allocations
1492 * Note vs. vmalloc(): If the task with a vzalloc()-allocated buffer
1493 * terminates quickly, vfree()-induced IPIs may be a concern, but tasks
1494 * with large states are likely to live longer.
1496 * Returns: 0 on success, -ENOMEM on allocation error.
1498 static int fpstate_realloc(u64 xfeatures, unsigned int ksize,
1499 unsigned int usize, struct fpu_guest *guest_fpu)
1501 struct fpu *fpu = ¤t->thread.fpu;
1502 struct fpstate *curfps, *newfps = NULL;
1503 unsigned int fpsize;
1506 fpsize = ksize + ALIGN(offsetof(struct fpstate, regs), 64);
1508 newfps = vzalloc(fpsize);
1511 newfps->size = ksize;
1512 newfps->user_size = usize;
1513 newfps->is_valloc = true;
1516 * When a guest FPU is supplied, use @guest_fpu->fpstate
1517 * as reference independent whether it is in use or not.
1519 curfps = guest_fpu ? guest_fpu->fpstate : fpu->fpstate;
1521 /* Determine whether @curfps is the active fpstate */
1522 in_use = fpu->fpstate == curfps;
1525 newfps->is_guest = true;
1526 newfps->is_confidential = curfps->is_confidential;
1527 newfps->in_use = curfps->in_use;
1528 guest_fpu->xfeatures |= xfeatures;
1529 guest_fpu->uabi_size = usize;
1534 * If @curfps is in use, ensure that the current state is in the
1535 * registers before swapping fpstate as that might invalidate it
1536 * due to layout changes.
1538 if (in_use && test_thread_flag(TIF_NEED_FPU_LOAD))
1539 fpregs_restore_userregs();
1541 newfps->xfeatures = curfps->xfeatures | xfeatures;
1542 newfps->user_xfeatures = curfps->user_xfeatures | xfeatures;
1543 newfps->xfd = curfps->xfd & ~xfeatures;
1545 /* Do the final updates within the locked region */
1546 xstate_init_xcomp_bv(&newfps->regs.xsave, newfps->xfeatures);
1549 guest_fpu->fpstate = newfps;
1550 /* If curfps is active, update the FPU fpstate pointer */
1552 fpu->fpstate = newfps;
1554 fpu->fpstate = newfps;
1558 xfd_update_state(fpu->fpstate);
1561 /* Only free valloc'ed state */
1562 if (curfps && curfps->is_valloc)
1568 static int validate_sigaltstack(unsigned int usize)
1570 struct task_struct *thread, *leader = current->group_leader;
1571 unsigned long framesize = get_sigframe_size();
1573 lockdep_assert_held(¤t->sighand->siglock);
1575 /* get_sigframe_size() is based on fpu_user_cfg.max_size */
1576 framesize -= fpu_user_cfg.max_size;
1578 for_each_thread(leader, thread) {
1579 if (thread->sas_ss_size && thread->sas_ss_size < framesize)
1585 static int __xstate_request_perm(u64 permitted, u64 requested, bool guest)
1588 * This deliberately does not exclude !XSAVES as we still might
1589 * decide to optionally context switch XCR0 or talk the silicon
1590 * vendors into extending XFD for the pre AMX states, especially
1593 bool compacted = cpu_feature_enabled(X86_FEATURE_XCOMPACTED);
1594 struct fpu *fpu = ¤t->group_leader->thread.fpu;
1595 struct fpu_state_perm *perm;
1596 unsigned int ksize, usize;
1600 /* Check whether fully enabled */
1601 if ((permitted & requested) == requested)
1604 /* Calculate the resulting kernel state size */
1605 mask = permitted | requested;
1606 /* Take supervisor states into account on the host */
1608 mask |= xfeatures_mask_supervisor();
1609 ksize = xstate_calculate_size(mask, compacted);
1611 /* Calculate the resulting user state size */
1612 mask &= XFEATURE_MASK_USER_SUPPORTED;
1613 usize = xstate_calculate_size(mask, false);
1616 ret = validate_sigaltstack(usize);
1621 perm = guest ? &fpu->guest_perm : &fpu->perm;
1622 /* Pairs with the READ_ONCE() in xstate_get_group_perm() */
1623 WRITE_ONCE(perm->__state_perm, mask);
1624 /* Protected by sighand lock */
1625 perm->__state_size = ksize;
1626 perm->__user_state_size = usize;
1631 * Permissions array to map facilities with more than one component
1633 static const u64 xstate_prctl_req[XFEATURE_MAX] = {
1634 [XFEATURE_XTILE_DATA] = XFEATURE_MASK_XTILE_DATA,
1637 static int xstate_request_perm(unsigned long idx, bool guest)
1639 u64 permitted, requested;
1642 if (idx >= XFEATURE_MAX)
1646 * Look up the facility mask which can require more than
1647 * one xstate component.
1649 idx = array_index_nospec(idx, ARRAY_SIZE(xstate_prctl_req));
1650 requested = xstate_prctl_req[idx];
1654 if ((fpu_user_cfg.max_features & requested) != requested)
1657 /* Lockless quick check */
1658 permitted = xstate_get_group_perm(guest);
1659 if ((permitted & requested) == requested)
1662 /* Protect against concurrent modifications */
1663 spin_lock_irq(¤t->sighand->siglock);
1664 permitted = xstate_get_group_perm(guest);
1666 /* First vCPU allocation locks the permissions. */
1667 if (guest && (permitted & FPU_GUEST_PERM_LOCKED))
1670 ret = __xstate_request_perm(permitted, requested, guest);
1671 spin_unlock_irq(¤t->sighand->siglock);
1675 int __xfd_enable_feature(u64 xfd_err, struct fpu_guest *guest_fpu)
1677 u64 xfd_event = xfd_err & XFEATURE_MASK_USER_DYNAMIC;
1678 struct fpu_state_perm *perm;
1679 unsigned int ksize, usize;
1684 pr_err_once("XFD: Invalid xfd error: %016llx\n", xfd_err);
1688 /* Protect against concurrent modifications */
1689 spin_lock_irq(¤t->sighand->siglock);
1691 /* If not permitted let it die */
1692 if ((xstate_get_group_perm(!!guest_fpu) & xfd_event) != xfd_event) {
1693 spin_unlock_irq(¤t->sighand->siglock);
1697 fpu = ¤t->group_leader->thread.fpu;
1698 perm = guest_fpu ? &fpu->guest_perm : &fpu->perm;
1699 ksize = perm->__state_size;
1700 usize = perm->__user_state_size;
1703 * The feature is permitted. State size is sufficient. Dropping
1704 * the lock is safe here even if more features are added from
1705 * another task, the retrieved buffer sizes are valid for the
1706 * currently requested feature(s).
1708 spin_unlock_irq(¤t->sighand->siglock);
1711 * Try to allocate a new fpstate. If that fails there is no way
1714 if (fpstate_realloc(xfd_event, ksize, usize, guest_fpu))
1719 int xfd_enable_feature(u64 xfd_err)
1721 return __xfd_enable_feature(xfd_err, NULL);
1724 #else /* CONFIG_X86_64 */
1725 static inline int xstate_request_perm(unsigned long idx, bool guest)
1729 #endif /* !CONFIG_X86_64 */
1731 u64 xstate_get_guest_group_perm(void)
1733 return xstate_get_group_perm(true);
1735 EXPORT_SYMBOL_GPL(xstate_get_guest_group_perm);
1738 * fpu_xstate_prctl - xstate permission operations
1739 * @option: A subfunction of arch_prctl()
1740 * @arg2: option argument
1741 * Return: 0 if successful; otherwise, an error code
1745 * ARCH_GET_XCOMP_SUPP: Pointer to user space u64 to store the info
1746 * ARCH_GET_XCOMP_PERM: Pointer to user space u64 to store the info
1747 * ARCH_REQ_XCOMP_PERM: Facility number requested
1749 * For facilities which require more than one XSTATE component, the request
1750 * must be the highest state component number related to that facility,
1751 * e.g. for AMX which requires XFEATURE_XTILE_CFG(17) and
1752 * XFEATURE_XTILE_DATA(18) this would be XFEATURE_XTILE_DATA(18).
1754 long fpu_xstate_prctl(int option, unsigned long arg2)
1756 u64 __user *uptr = (u64 __user *)arg2;
1757 u64 permitted, supported;
1758 unsigned long idx = arg2;
1762 case ARCH_GET_XCOMP_SUPP:
1763 supported = fpu_user_cfg.max_features | fpu_user_cfg.legacy_features;
1764 return put_user(supported, uptr);
1766 case ARCH_GET_XCOMP_PERM:
1768 * Lockless snapshot as it can also change right after the
1769 * dropping the lock.
1771 permitted = xstate_get_host_group_perm();
1772 permitted &= XFEATURE_MASK_USER_SUPPORTED;
1773 return put_user(permitted, uptr);
1775 case ARCH_GET_XCOMP_GUEST_PERM:
1776 permitted = xstate_get_guest_group_perm();
1777 permitted &= XFEATURE_MASK_USER_SUPPORTED;
1778 return put_user(permitted, uptr);
1780 case ARCH_REQ_XCOMP_GUEST_PERM:
1784 case ARCH_REQ_XCOMP_PERM:
1785 if (!IS_ENABLED(CONFIG_X86_64))
1788 return xstate_request_perm(idx, guest);
1795 #ifdef CONFIG_PROC_PID_ARCH_STATUS
1797 * Report the amount of time elapsed in millisecond since last AVX512
1800 static void avx512_status(struct seq_file *m, struct task_struct *task)
1802 unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
1807 * Report -1 if no AVX512 usage
1811 delta = (long)(jiffies - timestamp);
1813 * Cap to LONG_MAX if time difference > LONG_MAX
1817 delta = jiffies_to_msecs(delta);
1820 seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
1825 * Report architecture specific information
1827 int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
1828 struct pid *pid, struct task_struct *task)
1831 * Report AVX512 state if the processor and build option supported.
1833 if (cpu_feature_enabled(X86_FEATURE_AVX512F))
1834 avx512_status(m, task);
1838 #endif /* CONFIG_PROC_PID_ARCH_STATUS */