1 // SPDX-License-Identifier: GPL-2.0-only
3 * xsave/xrstor support.
5 * Author: Suresh Siddha <suresh.b.siddha@intel.com>
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 "unknown xstate feature" ,
54 "unknown xstate feature" ,
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_PKU,
75 [XFEATURE_PASID] = X86_FEATURE_ENQCMD,
76 [XFEATURE_XTILE_CFG] = X86_FEATURE_AMX_TILE,
77 [XFEATURE_XTILE_DATA] = X86_FEATURE_AMX_TILE,
80 static unsigned int xstate_offsets[XFEATURE_MAX] __ro_after_init =
81 { [ 0 ... XFEATURE_MAX - 1] = -1};
82 static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init =
83 { [ 0 ... XFEATURE_MAX - 1] = -1};
84 static unsigned int xstate_flags[XFEATURE_MAX] __ro_after_init;
86 #define XSTATE_FLAG_SUPERVISOR BIT(0)
87 #define XSTATE_FLAG_ALIGNED64 BIT(1)
90 * Return whether the system supports a given xfeature.
92 * Also return the name of the (most advanced) feature that the caller requested:
94 int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
96 u64 xfeatures_missing = xfeatures_needed & ~fpu_kernel_cfg.max_features;
98 if (unlikely(feature_name)) {
99 long xfeature_idx, max_idx;
102 * So we use FLS here to be able to print the most advanced
103 * feature that was requested but is missing. So if a driver
104 * asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the
105 * missing AVX feature - this is the most informative message
108 if (xfeatures_missing)
109 xfeatures_print = xfeatures_missing;
111 xfeatures_print = xfeatures_needed;
113 xfeature_idx = fls64(xfeatures_print)-1;
114 max_idx = ARRAY_SIZE(xfeature_names)-1;
115 xfeature_idx = min(xfeature_idx, max_idx);
117 *feature_name = xfeature_names[xfeature_idx];
120 if (xfeatures_missing)
125 EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
127 static bool xfeature_is_aligned64(int xfeature_nr)
129 return xstate_flags[xfeature_nr] & XSTATE_FLAG_ALIGNED64;
132 static bool xfeature_is_supervisor(int xfeature_nr)
134 return xstate_flags[xfeature_nr] & XSTATE_FLAG_SUPERVISOR;
137 static unsigned int xfeature_get_offset(u64 xcomp_bv, int xfeature)
139 unsigned int offs, i;
142 * Non-compacted format and legacy features use the cached fixed
145 if (!cpu_feature_enabled(X86_FEATURE_XCOMPACTED) ||
146 xfeature <= XFEATURE_SSE)
147 return xstate_offsets[xfeature];
150 * Compacted format offsets depend on the actual content of the
151 * compacted xsave area which is determined by the xcomp_bv header
154 offs = FXSAVE_SIZE + XSAVE_HDR_SIZE;
155 for_each_extended_xfeature(i, xcomp_bv) {
156 if (xfeature_is_aligned64(i))
157 offs = ALIGN(offs, 64);
160 offs += xstate_sizes[i];
166 * Enable the extended processor state save/restore feature.
167 * Called once per CPU onlining.
169 void fpu__init_cpu_xstate(void)
171 if (!boot_cpu_has(X86_FEATURE_XSAVE) || !fpu_kernel_cfg.max_features)
174 cr4_set_bits(X86_CR4_OSXSAVE);
177 * Must happen after CR4 setup and before xsetbv() to allow KVM
178 * lazy passthrough. Write independent of the dynamic state static
179 * key as that does not work on the boot CPU. This also ensures
180 * that any stale state is wiped out from XFD.
182 if (cpu_feature_enabled(X86_FEATURE_XFD))
183 wrmsrl(MSR_IA32_XFD, init_fpstate.xfd);
186 * XCR_XFEATURE_ENABLED_MASK (aka. XCR0) sets user features
187 * managed by XSAVE{C, OPT, S} and XRSTOR{S}. Only XSAVE user
188 * states can be set here.
190 xsetbv(XCR_XFEATURE_ENABLED_MASK, fpu_user_cfg.max_features);
193 * MSR_IA32_XSS sets supervisor states managed by XSAVES.
195 if (boot_cpu_has(X86_FEATURE_XSAVES)) {
196 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() |
197 xfeatures_mask_independent());
201 static bool xfeature_enabled(enum xfeature xfeature)
203 return fpu_kernel_cfg.max_features & BIT_ULL(xfeature);
207 * Record the offsets and sizes of various xstates contained
208 * in the XSAVE state memory layout.
210 static void __init setup_xstate_cache(void)
212 u32 eax, ebx, ecx, edx, i;
213 /* start at the beginning of the "extended state" */
214 unsigned int last_good_offset = offsetof(struct xregs_state,
215 extended_state_area);
217 * The FP xstates and SSE xstates are legacy states. They are always
218 * in the fixed offsets in the xsave area in either compacted form
221 xstate_offsets[XFEATURE_FP] = 0;
222 xstate_sizes[XFEATURE_FP] = offsetof(struct fxregs_state,
225 xstate_offsets[XFEATURE_SSE] = xstate_sizes[XFEATURE_FP];
226 xstate_sizes[XFEATURE_SSE] = sizeof_field(struct fxregs_state,
229 for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
230 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
232 xstate_sizes[i] = eax;
233 xstate_flags[i] = ecx;
236 * If an xfeature is supervisor state, the offset in EBX is
237 * invalid, leave it to -1.
239 if (xfeature_is_supervisor(i))
242 xstate_offsets[i] = ebx;
245 * In our xstate size checks, we assume that the highest-numbered
246 * xstate feature has the highest offset in the buffer. Ensure
249 WARN_ONCE(last_good_offset > xstate_offsets[i],
250 "x86/fpu: misordered xstate at %d\n", last_good_offset);
252 last_good_offset = xstate_offsets[i];
256 static void __init print_xstate_feature(u64 xstate_mask)
258 const char *feature_name;
260 if (cpu_has_xfeatures(xstate_mask, &feature_name))
261 pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name);
265 * Print out all the supported xstate features:
267 static void __init print_xstate_features(void)
269 print_xstate_feature(XFEATURE_MASK_FP);
270 print_xstate_feature(XFEATURE_MASK_SSE);
271 print_xstate_feature(XFEATURE_MASK_YMM);
272 print_xstate_feature(XFEATURE_MASK_BNDREGS);
273 print_xstate_feature(XFEATURE_MASK_BNDCSR);
274 print_xstate_feature(XFEATURE_MASK_OPMASK);
275 print_xstate_feature(XFEATURE_MASK_ZMM_Hi256);
276 print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
277 print_xstate_feature(XFEATURE_MASK_PKRU);
278 print_xstate_feature(XFEATURE_MASK_PASID);
279 print_xstate_feature(XFEATURE_MASK_XTILE_CFG);
280 print_xstate_feature(XFEATURE_MASK_XTILE_DATA);
284 * This check is important because it is easy to get XSTATE_*
285 * confused with XSTATE_BIT_*.
287 #define CHECK_XFEATURE(nr) do { \
288 WARN_ON(nr < FIRST_EXTENDED_XFEATURE); \
289 WARN_ON(nr >= XFEATURE_MAX); \
293 * Print out xstate component offsets and sizes
295 static void __init print_xstate_offset_size(void)
299 for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
300 pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
301 i, xfeature_get_offset(fpu_kernel_cfg.max_features, i),
307 * This function is called only during boot time when x86 caps are not set
308 * up and alternative can not be used yet.
310 static __init void os_xrstor_booting(struct xregs_state *xstate)
312 u64 mask = fpu_kernel_cfg.max_features & XFEATURE_MASK_FPSTATE;
314 u32 hmask = mask >> 32;
317 if (cpu_feature_enabled(X86_FEATURE_XSAVES))
318 XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
320 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
323 * We should never fault when copying from a kernel buffer, and the FPU
324 * state we set at boot time should be valid.
330 * All supported features have either init state all zeros or are
331 * handled in setup_init_fpu() individually. This is an explicit
332 * feature list and does not use XFEATURE_MASK*SUPPORTED to catch
333 * newly added supported features at build time and make people
334 * actually look at the init state for the new feature.
336 #define XFEATURES_INIT_FPSTATE_HANDLED \
337 (XFEATURE_MASK_FP | \
338 XFEATURE_MASK_SSE | \
339 XFEATURE_MASK_YMM | \
340 XFEATURE_MASK_OPMASK | \
341 XFEATURE_MASK_ZMM_Hi256 | \
342 XFEATURE_MASK_Hi16_ZMM | \
343 XFEATURE_MASK_PKRU | \
344 XFEATURE_MASK_BNDREGS | \
345 XFEATURE_MASK_BNDCSR | \
346 XFEATURE_MASK_PASID | \
350 * setup the xstate image representing the init state
352 static void __init setup_init_fpu_buf(void)
354 BUILD_BUG_ON((XFEATURE_MASK_USER_SUPPORTED |
355 XFEATURE_MASK_SUPERVISOR_SUPPORTED) !=
356 XFEATURES_INIT_FPSTATE_HANDLED);
358 if (!boot_cpu_has(X86_FEATURE_XSAVE))
361 print_xstate_features();
363 xstate_init_xcomp_bv(&init_fpstate.regs.xsave, init_fpstate.xfeatures);
366 * Init all the features state with header.xfeatures being 0x0
368 os_xrstor_booting(&init_fpstate.regs.xsave);
371 * All components are now in init state. Read the state back so
372 * that init_fpstate contains all non-zero init state. This only
373 * works with XSAVE, but not with XSAVEOPT and XSAVEC/S because
374 * those use the init optimization which skips writing data for
375 * components in init state.
377 * XSAVE could be used, but that would require to reshuffle the
378 * data when XSAVEC/S is available because XSAVEC/S uses xstate
379 * compaction. But doing so is a pointless exercise because most
380 * components have an all zeros init state except for the legacy
381 * ones (FP and SSE). Those can be saved with FXSAVE into the
382 * legacy area. Adding new features requires to ensure that init
383 * state is all zeroes or if not to add the necessary handling
386 fxsave(&init_fpstate.regs.fxsave);
389 int xfeature_size(int xfeature_nr)
391 u32 eax, ebx, ecx, edx;
393 CHECK_XFEATURE(xfeature_nr);
394 cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
398 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
399 static int validate_user_xstate_header(const struct xstate_header *hdr,
400 struct fpstate *fpstate)
402 /* No unknown or supervisor features may be set */
403 if (hdr->xfeatures & ~fpstate->user_xfeatures)
406 /* Userspace must use the uncompacted format */
411 * If 'reserved' is shrunken to add a new field, make sure to validate
412 * that new field here!
414 BUILD_BUG_ON(sizeof(hdr->reserved) != 48);
416 /* No reserved bits may be set */
417 if (memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved)))
423 static void __init __xstate_dump_leaves(void)
426 u32 eax, ebx, ecx, edx;
427 static int should_dump = 1;
433 * Dump out a few leaves past the ones that we support
434 * just in case there are some goodies up there
436 for (i = 0; i < XFEATURE_MAX + 10; i++) {
437 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
438 pr_warn("CPUID[%02x, %02x]: eax=%08x ebx=%08x ecx=%08x edx=%08x\n",
439 XSTATE_CPUID, i, eax, ebx, ecx, edx);
443 #define XSTATE_WARN_ON(x, fmt, ...) do { \
444 if (WARN_ONCE(x, "XSAVE consistency problem: " fmt, ##__VA_ARGS__)) { \
445 __xstate_dump_leaves(); \
449 #define XCHECK_SZ(sz, nr, nr_macro, __struct) do { \
450 if ((nr == nr_macro) && \
451 WARN_ONCE(sz != sizeof(__struct), \
452 "%s: struct is %zu bytes, cpu state %d bytes\n", \
453 __stringify(nr_macro), sizeof(__struct), sz)) { \
454 __xstate_dump_leaves(); \
459 * check_xtile_data_against_struct - Check tile data state size.
461 * Calculate the state size by multiplying the single tile size which is
462 * recorded in a C struct, and the number of tiles that the CPU informs.
463 * Compare the provided size with the calculation.
465 * @size: The tile data state size
467 * Returns: 0 on success, -EINVAL on mismatch.
469 static int __init check_xtile_data_against_struct(int size)
471 u32 max_palid, palid, state_size;
472 u32 eax, ebx, ecx, edx;
476 * Check the maximum palette id:
477 * eax: the highest numbered palette subleaf.
479 cpuid_count(TILE_CPUID, 0, &max_palid, &ebx, &ecx, &edx);
482 * Cross-check each tile size and find the maximum number of
485 for (palid = 1, max_tile = 0; palid <= max_palid; palid++) {
489 * Check the tile size info:
490 * eax[31:16]: bytes per title
491 * ebx[31:16]: the max names (or max number of tiles)
493 cpuid_count(TILE_CPUID, palid, &eax, &ebx, &edx, &edx);
494 tile_size = eax >> 16;
497 if (tile_size != sizeof(struct xtile_data)) {
498 pr_err("%s: struct is %zu bytes, cpu xtile %d bytes\n",
499 __stringify(XFEATURE_XTILE_DATA),
500 sizeof(struct xtile_data), tile_size);
501 __xstate_dump_leaves();
509 state_size = sizeof(struct xtile_data) * max_tile;
510 if (size != state_size) {
511 pr_err("%s: calculated size is %u bytes, cpu state %d bytes\n",
512 __stringify(XFEATURE_XTILE_DATA), state_size, size);
513 __xstate_dump_leaves();
520 * We have a C struct for each 'xstate'. We need to ensure
521 * that our software representation matches what the CPU
522 * tells us about the state's size.
524 static bool __init check_xstate_against_struct(int nr)
527 * Ask the CPU for the size of the state.
529 int sz = xfeature_size(nr);
531 * Match each CPU state with the corresponding software
534 XCHECK_SZ(sz, nr, XFEATURE_YMM, struct ymmh_struct);
535 XCHECK_SZ(sz, nr, XFEATURE_BNDREGS, struct mpx_bndreg_state);
536 XCHECK_SZ(sz, nr, XFEATURE_BNDCSR, struct mpx_bndcsr_state);
537 XCHECK_SZ(sz, nr, XFEATURE_OPMASK, struct avx_512_opmask_state);
538 XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state);
539 XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM, struct avx_512_hi16_state);
540 XCHECK_SZ(sz, nr, XFEATURE_PKRU, struct pkru_state);
541 XCHECK_SZ(sz, nr, XFEATURE_PASID, struct ia32_pasid_state);
542 XCHECK_SZ(sz, nr, XFEATURE_XTILE_CFG, struct xtile_cfg);
544 /* The tile data size varies between implementations. */
545 if (nr == XFEATURE_XTILE_DATA)
546 check_xtile_data_against_struct(sz);
549 * Make *SURE* to add any feature numbers in below if
550 * there are "holes" in the xsave state component
553 if ((nr < XFEATURE_YMM) ||
554 (nr >= XFEATURE_MAX) ||
555 (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) ||
556 ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_RSRVD_COMP_16))) {
557 XSTATE_WARN_ON(1, "No structure for xstate: %d\n", nr);
563 static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted)
565 unsigned int topmost = fls64(xfeatures) - 1;
566 unsigned int offset = xstate_offsets[topmost];
568 if (topmost <= XFEATURE_SSE)
569 return sizeof(struct xregs_state);
572 offset = xfeature_get_offset(xfeatures, topmost);
573 return offset + xstate_sizes[topmost];
577 * This essentially double-checks what the cpu told us about
578 * how large the XSAVE buffer needs to be. We are recalculating
581 * Independent XSAVE features allocate their own buffers and are not
582 * covered by these checks. Only the size of the buffer for task->fpu
585 static bool __init paranoid_xstate_size_valid(unsigned int kernel_size)
587 bool compacted = cpu_feature_enabled(X86_FEATURE_XCOMPACTED);
588 bool xsaves = cpu_feature_enabled(X86_FEATURE_XSAVES);
589 unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
592 for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
593 if (!check_xstate_against_struct(i))
596 * Supervisor state components can be managed only by
599 if (!xsaves && xfeature_is_supervisor(i)) {
600 XSTATE_WARN_ON(1, "Got supervisor feature %d, but XSAVES not advertised\n", i);
604 size = xstate_calculate_size(fpu_kernel_cfg.max_features, compacted);
605 XSTATE_WARN_ON(size != kernel_size,
606 "size %u != kernel_size %u\n", size, kernel_size);
607 return size == kernel_size;
611 * Get total size of enabled xstates in XCR0 | IA32_XSS.
613 * Note the SDM's wording here. "sub-function 0" only enumerates
614 * the size of the *user* states. If we use it to size a buffer
615 * that we use 'XSAVES' on, we could potentially overflow the
616 * buffer because 'XSAVES' saves system states too.
618 * This also takes compaction into account. So this works for
621 static unsigned int __init get_compacted_size(void)
623 unsigned int eax, ebx, ecx, edx;
625 * - CPUID function 0DH, sub-function 1:
626 * EBX enumerates the size (in bytes) required by
627 * the XSAVES instruction for an XSAVE area
628 * containing all the state components
629 * corresponding to bits currently set in
632 * When XSAVES is not available but XSAVEC is (virt), then there
633 * are no supervisor states, but XSAVEC still uses compacted
636 cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
641 * Get the total size of the enabled xstates without the independent supervisor
644 static unsigned int __init get_xsave_compacted_size(void)
646 u64 mask = xfeatures_mask_independent();
650 return get_compacted_size();
652 /* Disable independent features. */
653 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor());
656 * Ask the hardware what size is required of the buffer.
657 * This is the size required for the task->fpu buffer.
659 size = get_compacted_size();
661 /* Re-enable independent features so XSAVES will work on them again. */
662 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() | mask);
667 static unsigned int __init get_xsave_size_user(void)
669 unsigned int eax, ebx, ecx, edx;
671 * - CPUID function 0DH, sub-function 0:
672 * EBX enumerates the size (in bytes) required by
673 * the XSAVE instruction for an XSAVE area
674 * containing all the *user* state components
675 * corresponding to bits currently set in XCR0.
677 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
681 static int __init init_xstate_size(void)
683 /* Recompute the context size for enabled features: */
684 unsigned int user_size, kernel_size, kernel_default_size;
685 bool compacted = cpu_feature_enabled(X86_FEATURE_XCOMPACTED);
687 /* Uncompacted user space size */
688 user_size = get_xsave_size_user();
691 * XSAVES kernel size includes supervisor states and uses compacted
692 * format. XSAVEC uses compacted format, but does not save
695 * XSAVE[OPT] do not support supervisor states so kernel and user
699 kernel_size = get_xsave_compacted_size();
701 kernel_size = user_size;
703 kernel_default_size =
704 xstate_calculate_size(fpu_kernel_cfg.default_features, compacted);
706 if (!paranoid_xstate_size_valid(kernel_size))
709 fpu_kernel_cfg.max_size = kernel_size;
710 fpu_user_cfg.max_size = user_size;
712 fpu_kernel_cfg.default_size = kernel_default_size;
713 fpu_user_cfg.default_size =
714 xstate_calculate_size(fpu_user_cfg.default_features, false);
720 * We enabled the XSAVE hardware, but something went wrong and
721 * we can not use it. Disable it.
723 static void __init fpu__init_disable_system_xstate(unsigned int legacy_size)
725 fpu_kernel_cfg.max_features = 0;
726 cr4_clear_bits(X86_CR4_OSXSAVE);
727 setup_clear_cpu_cap(X86_FEATURE_XSAVE);
729 /* Restore the legacy size.*/
730 fpu_kernel_cfg.max_size = legacy_size;
731 fpu_kernel_cfg.default_size = legacy_size;
732 fpu_user_cfg.max_size = legacy_size;
733 fpu_user_cfg.default_size = legacy_size;
736 * Prevent enabling the static branch which enables writes to the
739 init_fpstate.xfd = 0;
741 fpstate_reset(¤t->thread.fpu);
745 * Enable and initialize the xsave feature.
746 * Called once per system bootup.
748 void __init fpu__init_system_xstate(unsigned int legacy_size)
750 unsigned int eax, ebx, ecx, edx;
755 if (!boot_cpu_has(X86_FEATURE_FPU)) {
756 pr_info("x86/fpu: No FPU detected\n");
760 if (!boot_cpu_has(X86_FEATURE_XSAVE)) {
761 pr_info("x86/fpu: x87 FPU will use %s\n",
762 boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE");
766 if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
772 * Find user xstates supported by the processor.
774 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
775 fpu_kernel_cfg.max_features = eax + ((u64)edx << 32);
778 * Find supervisor xstates supported by the processor.
780 cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
781 fpu_kernel_cfg.max_features |= ecx + ((u64)edx << 32);
783 if ((fpu_kernel_cfg.max_features & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
785 * This indicates that something really unexpected happened
786 * with the enumeration. Disable XSAVE and try to continue
787 * booting without it. This is too early to BUG().
789 pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n",
790 fpu_kernel_cfg.max_features);
795 * Clear XSAVE features that are disabled in the normal CPUID.
797 for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
798 unsigned short cid = xsave_cpuid_features[i];
800 /* Careful: X86_FEATURE_FPU is 0! */
801 if ((i != XFEATURE_FP && !cid) || !boot_cpu_has(cid))
802 fpu_kernel_cfg.max_features &= ~BIT_ULL(i);
805 if (!cpu_feature_enabled(X86_FEATURE_XFD))
806 fpu_kernel_cfg.max_features &= ~XFEATURE_MASK_USER_DYNAMIC;
808 if (!cpu_feature_enabled(X86_FEATURE_XSAVES))
809 fpu_kernel_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED;
811 fpu_kernel_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED |
812 XFEATURE_MASK_SUPERVISOR_SUPPORTED;
814 fpu_user_cfg.max_features = fpu_kernel_cfg.max_features;
815 fpu_user_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED;
817 /* Clean out dynamic features from default */
818 fpu_kernel_cfg.default_features = fpu_kernel_cfg.max_features;
819 fpu_kernel_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC;
821 fpu_user_cfg.default_features = fpu_user_cfg.max_features;
822 fpu_user_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC;
824 /* Store it for paranoia check at the end */
825 xfeatures = fpu_kernel_cfg.max_features;
828 * Initialize the default XFD state in initfp_state and enable the
829 * dynamic sizing mechanism if dynamic states are available. The
830 * static key cannot be enabled here because this runs before
831 * jump_label_init(). This is delayed to an initcall.
833 init_fpstate.xfd = fpu_user_cfg.max_features & XFEATURE_MASK_USER_DYNAMIC;
835 /* Set up compaction feature bit */
836 if (cpu_feature_enabled(X86_FEATURE_XSAVEC) ||
837 cpu_feature_enabled(X86_FEATURE_XSAVES))
838 setup_force_cpu_cap(X86_FEATURE_XCOMPACTED);
840 /* Enable xstate instructions to be able to continue with initialization: */
841 fpu__init_cpu_xstate();
843 /* Cache size, offset and flags for initialization */
844 setup_xstate_cache();
846 err = init_xstate_size();
850 /* Reset the state for the current task */
851 fpstate_reset(¤t->thread.fpu);
854 * Update info used for ptrace frames; use standard-format size and no
855 * supervisor xstates:
857 update_regset_xstate_info(fpu_user_cfg.max_size,
858 fpu_user_cfg.max_features);
861 * init_fpstate excludes dynamic states as they are large but init
864 init_fpstate.size = fpu_kernel_cfg.default_size;
865 init_fpstate.xfeatures = fpu_kernel_cfg.default_features;
867 if (init_fpstate.size > sizeof(init_fpstate.regs)) {
868 pr_warn("x86/fpu: init_fpstate buffer too small (%zu < %d), disabling XSAVE\n",
869 sizeof(init_fpstate.regs), init_fpstate.size);
873 setup_init_fpu_buf();
876 * Paranoia check whether something in the setup modified the
879 if (xfeatures != fpu_kernel_cfg.max_features) {
880 pr_err("x86/fpu: xfeatures modified from 0x%016llx to 0x%016llx during init, disabling XSAVE\n",
881 xfeatures, fpu_kernel_cfg.max_features);
886 * CPU capabilities initialization runs before FPU init. So
887 * X86_FEATURE_OSXSAVE is not set. Now that XSAVE is completely
888 * functional, set the feature bit so depending code works.
890 setup_force_cpu_cap(X86_FEATURE_OSXSAVE);
892 print_xstate_offset_size();
893 pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
894 fpu_kernel_cfg.max_features,
895 fpu_kernel_cfg.max_size,
896 boot_cpu_has(X86_FEATURE_XCOMPACTED) ? "compacted" : "standard");
900 /* something went wrong, try to boot without any XSAVE support */
901 fpu__init_disable_system_xstate(legacy_size);
905 * Restore minimal FPU state after suspend:
907 void fpu__resume_cpu(void)
910 * Restore XCR0 on xsave capable CPUs:
912 if (cpu_feature_enabled(X86_FEATURE_XSAVE))
913 xsetbv(XCR_XFEATURE_ENABLED_MASK, fpu_user_cfg.max_features);
916 * Restore IA32_XSS. The same CPUID bit enumerates support
917 * of XSAVES and MSR_IA32_XSS.
919 if (cpu_feature_enabled(X86_FEATURE_XSAVES)) {
920 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() |
921 xfeatures_mask_independent());
924 if (fpu_state_size_dynamic())
925 wrmsrl(MSR_IA32_XFD, current->thread.fpu.fpstate->xfd);
929 * Given an xstate feature nr, calculate where in the xsave
930 * buffer the state is. Callers should ensure that the buffer
933 static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
935 u64 xcomp_bv = xsave->header.xcomp_bv;
937 if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr)))
940 if (cpu_feature_enabled(X86_FEATURE_XCOMPACTED)) {
941 if (WARN_ON_ONCE(!(xcomp_bv & BIT_ULL(xfeature_nr))))
945 return (void *)xsave + xfeature_get_offset(xcomp_bv, xfeature_nr);
949 * Given the xsave area and a state inside, this function returns the
950 * address of the state.
952 * This is the API that is called to get xstate address in either
953 * standard format or compacted format of xsave area.
955 * Note that if there is no data for the field in the xsave buffer
956 * this will return NULL.
959 * xstate: the thread's storage area for all FPU data
960 * xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
961 * XFEATURE_SSE, etc...)
963 * address of the state in the xsave area, or NULL if the
964 * field is not present in the xsave buffer.
966 void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
969 * Do we even *have* xsave state?
971 if (!boot_cpu_has(X86_FEATURE_XSAVE))
975 * We should not ever be requesting features that we
978 if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr)))
982 * This assumes the last 'xsave*' instruction to
983 * have requested that 'xfeature_nr' be saved.
984 * If it did not, we might be seeing and old value
985 * of the field in the buffer.
987 * This can happen because the last 'xsave' did not
988 * request that this feature be saved (unlikely)
989 * or because the "init optimization" caused it
992 if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr)))
995 return __raw_xsave_addr(xsave, xfeature_nr);
998 #ifdef CONFIG_ARCH_HAS_PKEYS
1001 * This will go out and modify PKRU register to set the access
1002 * rights for @pkey to @init_val.
1004 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
1005 unsigned long init_val)
1007 u32 old_pkru, new_pkru_bits = 0;
1011 * This check implies XSAVE support. OSPKE only gets
1012 * set if we enable XSAVE and we enable PKU in XCR0.
1014 if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
1018 * This code should only be called with valid 'pkey'
1019 * values originating from in-kernel users. Complain
1020 * if a bad value is observed.
1022 if (WARN_ON_ONCE(pkey >= arch_max_pkey()))
1025 /* Set the bits we need in PKRU: */
1026 if (init_val & PKEY_DISABLE_ACCESS)
1027 new_pkru_bits |= PKRU_AD_BIT;
1028 if (init_val & PKEY_DISABLE_WRITE)
1029 new_pkru_bits |= PKRU_WD_BIT;
1031 /* Shift the bits in to the correct place in PKRU for pkey: */
1032 pkey_shift = pkey * PKRU_BITS_PER_PKEY;
1033 new_pkru_bits <<= pkey_shift;
1035 /* Get old PKRU and mask off any old bits in place: */
1036 old_pkru = read_pkru();
1037 old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift);
1039 /* Write old part along with new part: */
1040 write_pkru(old_pkru | new_pkru_bits);
1044 #endif /* ! CONFIG_ARCH_HAS_PKEYS */
1046 static void copy_feature(bool from_xstate, struct membuf *to, void *xstate,
1047 void *init_xstate, unsigned int size)
1049 membuf_write(to, from_xstate ? xstate : init_xstate, size);
1053 * __copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
1054 * @to: membuf descriptor
1055 * @fpstate: The fpstate buffer from which to copy
1056 * @pkru_val: The PKRU value to store in the PKRU component
1057 * @copy_mode: The requested copy mode
1059 * Converts from kernel XSAVE or XSAVES compacted format to UABI conforming
1060 * format, i.e. from the kernel internal hardware dependent storage format
1061 * to the requested @mode. UABI XSTATE is always uncompacted!
1063 * It supports partial copy but @to.pos always starts from zero.
1065 void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
1066 u32 pkru_val, enum xstate_copy_mode copy_mode)
1068 const unsigned int off_mxcsr = offsetof(struct fxregs_state, mxcsr);
1069 struct xregs_state *xinit = &init_fpstate.regs.xsave;
1070 struct xregs_state *xsave = &fpstate->regs.xsave;
1071 struct xstate_header header;
1072 unsigned int zerofrom;
1076 memset(&header, 0, sizeof(header));
1077 header.xfeatures = xsave->header.xfeatures;
1079 /* Mask out the feature bits depending on copy mode */
1080 switch (copy_mode) {
1081 case XSTATE_COPY_FP:
1082 header.xfeatures &= XFEATURE_MASK_FP;
1085 case XSTATE_COPY_FX:
1086 header.xfeatures &= XFEATURE_MASK_FP | XFEATURE_MASK_SSE;
1089 case XSTATE_COPY_XSAVE:
1090 header.xfeatures &= fpstate->user_xfeatures;
1094 /* Copy FP state up to MXCSR */
1095 copy_feature(header.xfeatures & XFEATURE_MASK_FP, &to, &xsave->i387,
1096 &xinit->i387, off_mxcsr);
1098 /* Copy MXCSR when SSE or YMM are set in the feature mask */
1099 copy_feature(header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM),
1100 &to, &xsave->i387.mxcsr, &xinit->i387.mxcsr,
1101 MXCSR_AND_FLAGS_SIZE);
1103 /* Copy the remaining FP state */
1104 copy_feature(header.xfeatures & XFEATURE_MASK_FP,
1105 &to, &xsave->i387.st_space, &xinit->i387.st_space,
1106 sizeof(xsave->i387.st_space));
1108 /* Copy the SSE state - shared with YMM, but independently managed */
1109 copy_feature(header.xfeatures & XFEATURE_MASK_SSE,
1110 &to, &xsave->i387.xmm_space, &xinit->i387.xmm_space,
1111 sizeof(xsave->i387.xmm_space));
1113 if (copy_mode != XSTATE_COPY_XSAVE)
1116 /* Zero the padding area */
1117 membuf_zero(&to, sizeof(xsave->i387.padding));
1119 /* Copy xsave->i387.sw_reserved */
1120 membuf_write(&to, xstate_fx_sw_bytes, sizeof(xsave->i387.sw_reserved));
1122 /* Copy the user space relevant state of @xsave->header */
1123 membuf_write(&to, &header, sizeof(header));
1125 zerofrom = offsetof(struct xregs_state, extended_state_area);
1128 * This 'mask' indicates which states to copy from fpstate.
1129 * Those extended states that are not present in fpstate are
1130 * either disabled or initialized:
1132 * In non-compacted format, disabled features still occupy
1133 * state space but there is no state to copy from in the
1134 * compacted init_fpstate. The gap tracking will zero these
1137 * The extended features have an all zeroes init state. Thus,
1138 * remove them from 'mask' to zero those features in the user
1139 * buffer instead of retrieving them from init_fpstate.
1141 mask = header.xfeatures;
1143 for_each_extended_xfeature(i, mask) {
1145 * If there was a feature or alignment gap, zero the space
1146 * in the destination buffer.
1148 if (zerofrom < xstate_offsets[i])
1149 membuf_zero(&to, xstate_offsets[i] - zerofrom);
1151 if (i == XFEATURE_PKRU) {
1152 struct pkru_state pkru = {0};
1154 * PKRU is not necessarily up to date in the
1155 * XSAVE buffer. Use the provided value.
1157 pkru.pkru = pkru_val;
1158 membuf_write(&to, &pkru, sizeof(pkru));
1161 __raw_xsave_addr(xsave, i),
1165 * Keep track of the last copied state in the non-compacted
1166 * target buffer for gap zeroing.
1168 zerofrom = xstate_offsets[i] + xstate_sizes[i];
1173 membuf_zero(&to, to.left);
1177 * copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
1178 * @to: membuf descriptor
1179 * @tsk: The task from which to copy the saved xstate
1180 * @copy_mode: The requested copy mode
1182 * Converts from kernel XSAVE or XSAVES compacted format to UABI conforming
1183 * format, i.e. from the kernel internal hardware dependent storage format
1184 * to the requested @mode. UABI XSTATE is always uncompacted!
1186 * It supports partial copy but @to.pos always starts from zero.
1188 void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
1189 enum xstate_copy_mode copy_mode)
1191 __copy_xstate_to_uabi_buf(to, tsk->thread.fpu.fpstate,
1192 tsk->thread.pkru, copy_mode);
1195 static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size,
1196 const void *kbuf, const void __user *ubuf)
1199 memcpy(dst, kbuf + offset, size);
1201 if (copy_from_user(dst, ubuf + offset, size))
1209 * copy_uabi_to_xstate - Copy a UABI format buffer to the kernel xstate
1210 * @fpstate: The fpstate buffer to copy to
1211 * @kbuf: The UABI format buffer, if it comes from the kernel
1212 * @ubuf: The UABI format buffer, if it comes from userspace
1213 * @pkru: The location to write the PKRU value to
1215 * Converts from the UABI format into the kernel internal hardware
1218 * This function ultimately has three different callers with distinct PKRU
1220 * 1. When called from sigreturn the PKRU register will be restored from
1221 * @fpstate via an XRSTOR. Correctly copying the UABI format buffer to
1222 * @fpstate is sufficient to cover this case, but the caller will also
1223 * pass a pointer to the thread_struct's pkru field in @pkru and updating
1225 * 2. When called from ptrace the PKRU register will be restored from the
1226 * thread_struct's pkru field. A pointer to that is passed in @pkru.
1227 * The kernel will restore it manually, so the XRSTOR behavior that resets
1228 * the PKRU register to the hardware init value (0) if the corresponding
1229 * xfeatures bit is not set is emulated here.
1230 * 3. When called from KVM the PKRU register will be restored from the vcpu's
1231 * pkru field. A pointer to that is passed in @pkru. KVM hasn't used
1232 * XRSTOR and hasn't had the PKRU resetting behavior described above. To
1233 * preserve that KVM behavior, it passes NULL for @pkru if the xfeatures
1236 static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf,
1237 const void __user *ubuf, u32 *pkru)
1239 struct xregs_state *xsave = &fpstate->regs.xsave;
1240 unsigned int offset, size;
1241 struct xstate_header hdr;
1245 offset = offsetof(struct xregs_state, header);
1246 if (copy_from_buffer(&hdr, offset, sizeof(hdr), kbuf, ubuf))
1249 if (validate_user_xstate_header(&hdr, fpstate))
1252 /* Validate MXCSR when any of the related features is in use */
1253 mask = XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM;
1254 if (hdr.xfeatures & mask) {
1257 offset = offsetof(struct fxregs_state, mxcsr);
1258 if (copy_from_buffer(mxcsr, offset, sizeof(mxcsr), kbuf, ubuf))
1261 /* Reserved bits in MXCSR must be zero. */
1262 if (mxcsr[0] & ~mxcsr_feature_mask)
1265 /* SSE and YMM require MXCSR even when FP is not in use. */
1266 if (!(hdr.xfeatures & XFEATURE_MASK_FP)) {
1267 xsave->i387.mxcsr = mxcsr[0];
1268 xsave->i387.mxcsr_mask = mxcsr[1];
1272 for (i = 0; i < XFEATURE_MAX; i++) {
1275 if (hdr.xfeatures & mask) {
1276 void *dst = __raw_xsave_addr(xsave, i);
1278 offset = xstate_offsets[i];
1279 size = xstate_sizes[i];
1281 if (copy_from_buffer(dst, offset, size, kbuf, ubuf))
1286 if (hdr.xfeatures & XFEATURE_MASK_PKRU) {
1287 struct pkru_state *xpkru;
1289 xpkru = __raw_xsave_addr(xsave, XFEATURE_PKRU);
1290 *pkru = xpkru->pkru;
1293 * KVM may pass NULL here to indicate that it does not need
1301 * The state that came in from userspace was user-state only.
1302 * Mask all the user states out of 'xfeatures':
1304 xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL;
1307 * Add back in the features that came in from userspace:
1309 xsave->header.xfeatures |= hdr.xfeatures;
1315 * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S]
1316 * format and copy to the target thread. Used by ptrace and KVM.
1318 int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru)
1320 return copy_uabi_to_xstate(fpstate, kbuf, NULL, pkru);
1324 * Convert from a sigreturn standard-format user-space buffer to kernel
1325 * XSAVE[S] format and copy to the target thread. This is called from the
1326 * sigreturn() and rt_sigreturn() system calls.
1328 int copy_sigframe_from_user_to_xstate(struct task_struct *tsk,
1329 const void __user *ubuf)
1331 return copy_uabi_to_xstate(tsk->thread.fpu.fpstate, NULL, ubuf, &tsk->thread.pkru);
1334 static bool validate_independent_components(u64 mask)
1338 if (WARN_ON_FPU(!cpu_feature_enabled(X86_FEATURE_XSAVES)))
1341 xchk = ~xfeatures_mask_independent();
1343 if (WARN_ON_ONCE(!mask || mask & xchk))
1350 * xsaves - Save selected components to a kernel xstate buffer
1351 * @xstate: Pointer to the buffer
1352 * @mask: Feature mask to select the components to save
1354 * The @xstate buffer must be 64 byte aligned and correctly initialized as
1355 * XSAVES does not write the full xstate header. Before first use the
1356 * buffer should be zeroed otherwise a consecutive XRSTORS from that buffer
1359 * The feature mask must be a subset of the independent features.
1361 void xsaves(struct xregs_state *xstate, u64 mask)
1365 if (!validate_independent_components(mask))
1368 XSTATE_OP(XSAVES, xstate, (u32)mask, (u32)(mask >> 32), err);
1373 * xrstors - Restore selected components from a kernel xstate buffer
1374 * @xstate: Pointer to the buffer
1375 * @mask: Feature mask to select the components to restore
1377 * The @xstate buffer must be 64 byte aligned and correctly initialized
1378 * otherwise XRSTORS from that buffer can #GP.
1380 * Proper usage is to restore the state which was saved with
1381 * xsaves() into @xstate.
1383 * The feature mask must be a subset of the independent features.
1385 void xrstors(struct xregs_state *xstate, u64 mask)
1389 if (!validate_independent_components(mask))
1392 XSTATE_OP(XRSTORS, xstate, (u32)mask, (u32)(mask >> 32), err);
1396 #if IS_ENABLED(CONFIG_KVM)
1397 void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature)
1399 void *addr = get_xsave_addr(&fps->regs.xsave, xfeature);
1402 memset(addr, 0, xstate_sizes[xfeature]);
1404 EXPORT_SYMBOL_GPL(fpstate_clear_xstate_component);
1407 #ifdef CONFIG_X86_64
1409 #ifdef CONFIG_X86_DEBUG_FPU
1411 * Ensure that a subsequent XSAVE* or XRSTOR* instruction with RFBM=@mask
1412 * can safely operate on the @fpstate buffer.
1414 static bool xstate_op_valid(struct fpstate *fpstate, u64 mask, bool rstor)
1416 u64 xfd = __this_cpu_read(xfd_state);
1418 if (fpstate->xfd == xfd)
1422 * The XFD MSR does not match fpstate->xfd. That's invalid when
1423 * the passed in fpstate is current's fpstate.
1425 if (fpstate->xfd == current->thread.fpu.fpstate->xfd)
1429 * XRSTOR(S) from init_fpstate are always correct as it will just
1430 * bring all components into init state and not read from the
1431 * buffer. XSAVE(S) raises #PF after init.
1433 if (fpstate == &init_fpstate)
1437 * XSAVE(S): clone(), fpu_swap_kvm_fpu()
1438 * XRSTORS(S): fpu_swap_kvm_fpu()
1442 * No XSAVE/XRSTOR instructions (except XSAVE itself) touch
1443 * the buffer area for XFD-disabled state components.
1448 * Remove features which are valid in fpstate. They
1449 * have space allocated in fpstate.
1451 mask &= ~fpstate->xfeatures;
1454 * Any remaining state components in 'mask' might be written
1455 * by XSAVE/XRSTOR. Fail validation it found.
1460 void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor)
1462 WARN_ON_ONCE(!xstate_op_valid(fpstate, mask, rstor));
1464 #endif /* CONFIG_X86_DEBUG_FPU */
1466 static int __init xfd_update_static_branch(void)
1469 * If init_fpstate.xfd has bits set then dynamic features are
1470 * available and the dynamic sizing must be enabled.
1472 if (init_fpstate.xfd)
1473 static_branch_enable(&__fpu_state_size_dynamic);
1476 arch_initcall(xfd_update_static_branch)
1478 void fpstate_free(struct fpu *fpu)
1480 if (fpu->fpstate && fpu->fpstate != &fpu->__fpstate)
1481 vfree(fpu->fpstate);
1485 * fpstate_realloc - Reallocate struct fpstate for the requested new features
1487 * @xfeatures: A bitmap of xstate features which extend the enabled features
1489 * @ksize: The required size for the kernel buffer
1490 * @usize: The required size for user space buffers
1491 * @guest_fpu: Pointer to a guest FPU container. NULL for host allocations
1493 * Note vs. vmalloc(): If the task with a vzalloc()-allocated buffer
1494 * terminates quickly, vfree()-induced IPIs may be a concern, but tasks
1495 * with large states are likely to live longer.
1497 * Returns: 0 on success, -ENOMEM on allocation error.
1499 static int fpstate_realloc(u64 xfeatures, unsigned int ksize,
1500 unsigned int usize, struct fpu_guest *guest_fpu)
1502 struct fpu *fpu = ¤t->thread.fpu;
1503 struct fpstate *curfps, *newfps = NULL;
1504 unsigned int fpsize;
1507 fpsize = ksize + ALIGN(offsetof(struct fpstate, regs), 64);
1509 newfps = vzalloc(fpsize);
1512 newfps->size = ksize;
1513 newfps->user_size = usize;
1514 newfps->is_valloc = true;
1517 * When a guest FPU is supplied, use @guest_fpu->fpstate
1518 * as reference independent whether it is in use or not.
1520 curfps = guest_fpu ? guest_fpu->fpstate : fpu->fpstate;
1522 /* Determine whether @curfps is the active fpstate */
1523 in_use = fpu->fpstate == curfps;
1526 newfps->is_guest = true;
1527 newfps->is_confidential = curfps->is_confidential;
1528 newfps->in_use = curfps->in_use;
1529 guest_fpu->xfeatures |= xfeatures;
1530 guest_fpu->uabi_size = usize;
1535 * If @curfps is in use, ensure that the current state is in the
1536 * registers before swapping fpstate as that might invalidate it
1537 * due to layout changes.
1539 if (in_use && test_thread_flag(TIF_NEED_FPU_LOAD))
1540 fpregs_restore_userregs();
1542 newfps->xfeatures = curfps->xfeatures | xfeatures;
1545 newfps->user_xfeatures = curfps->user_xfeatures | xfeatures;
1547 newfps->xfd = curfps->xfd & ~xfeatures;
1549 /* Do the final updates within the locked region */
1550 xstate_init_xcomp_bv(&newfps->regs.xsave, newfps->xfeatures);
1553 guest_fpu->fpstate = newfps;
1554 /* If curfps is active, update the FPU fpstate pointer */
1556 fpu->fpstate = newfps;
1558 fpu->fpstate = newfps;
1562 xfd_update_state(fpu->fpstate);
1565 /* Only free valloc'ed state */
1566 if (curfps && curfps->is_valloc)
1572 static int validate_sigaltstack(unsigned int usize)
1574 struct task_struct *thread, *leader = current->group_leader;
1575 unsigned long framesize = get_sigframe_size();
1577 lockdep_assert_held(¤t->sighand->siglock);
1579 /* get_sigframe_size() is based on fpu_user_cfg.max_size */
1580 framesize -= fpu_user_cfg.max_size;
1582 for_each_thread(leader, thread) {
1583 if (thread->sas_ss_size && thread->sas_ss_size < framesize)
1589 static int __xstate_request_perm(u64 permitted, u64 requested, bool guest)
1592 * This deliberately does not exclude !XSAVES as we still might
1593 * decide to optionally context switch XCR0 or talk the silicon
1594 * vendors into extending XFD for the pre AMX states, especially
1597 bool compacted = cpu_feature_enabled(X86_FEATURE_XCOMPACTED);
1598 struct fpu *fpu = ¤t->group_leader->thread.fpu;
1599 struct fpu_state_perm *perm;
1600 unsigned int ksize, usize;
1604 /* Check whether fully enabled */
1605 if ((permitted & requested) == requested)
1608 /* Calculate the resulting kernel state size */
1609 mask = permitted | requested;
1610 /* Take supervisor states into account on the host */
1612 mask |= xfeatures_mask_supervisor();
1613 ksize = xstate_calculate_size(mask, compacted);
1615 /* Calculate the resulting user state size */
1616 mask &= XFEATURE_MASK_USER_SUPPORTED;
1617 usize = xstate_calculate_size(mask, false);
1620 ret = validate_sigaltstack(usize);
1625 perm = guest ? &fpu->guest_perm : &fpu->perm;
1626 /* Pairs with the READ_ONCE() in xstate_get_group_perm() */
1627 WRITE_ONCE(perm->__state_perm, mask);
1628 /* Protected by sighand lock */
1629 perm->__state_size = ksize;
1630 perm->__user_state_size = usize;
1635 * Permissions array to map facilities with more than one component
1637 static const u64 xstate_prctl_req[XFEATURE_MAX] = {
1638 [XFEATURE_XTILE_DATA] = XFEATURE_MASK_XTILE_DATA,
1641 static int xstate_request_perm(unsigned long idx, bool guest)
1643 u64 permitted, requested;
1646 if (idx >= XFEATURE_MAX)
1650 * Look up the facility mask which can require more than
1651 * one xstate component.
1653 idx = array_index_nospec(idx, ARRAY_SIZE(xstate_prctl_req));
1654 requested = xstate_prctl_req[idx];
1658 if ((fpu_user_cfg.max_features & requested) != requested)
1661 /* Lockless quick check */
1662 permitted = xstate_get_group_perm(guest);
1663 if ((permitted & requested) == requested)
1666 /* Protect against concurrent modifications */
1667 spin_lock_irq(¤t->sighand->siglock);
1668 permitted = xstate_get_group_perm(guest);
1670 /* First vCPU allocation locks the permissions. */
1671 if (guest && (permitted & FPU_GUEST_PERM_LOCKED))
1674 ret = __xstate_request_perm(permitted, requested, guest);
1675 spin_unlock_irq(¤t->sighand->siglock);
1679 int __xfd_enable_feature(u64 xfd_err, struct fpu_guest *guest_fpu)
1681 u64 xfd_event = xfd_err & XFEATURE_MASK_USER_DYNAMIC;
1682 struct fpu_state_perm *perm;
1683 unsigned int ksize, usize;
1688 pr_err_once("XFD: Invalid xfd error: %016llx\n", xfd_err);
1692 /* Protect against concurrent modifications */
1693 spin_lock_irq(¤t->sighand->siglock);
1695 /* If not permitted let it die */
1696 if ((xstate_get_group_perm(!!guest_fpu) & xfd_event) != xfd_event) {
1697 spin_unlock_irq(¤t->sighand->siglock);
1701 fpu = ¤t->group_leader->thread.fpu;
1702 perm = guest_fpu ? &fpu->guest_perm : &fpu->perm;
1703 ksize = perm->__state_size;
1704 usize = perm->__user_state_size;
1707 * The feature is permitted. State size is sufficient. Dropping
1708 * the lock is safe here even if more features are added from
1709 * another task, the retrieved buffer sizes are valid for the
1710 * currently requested feature(s).
1712 spin_unlock_irq(¤t->sighand->siglock);
1715 * Try to allocate a new fpstate. If that fails there is no way
1718 if (fpstate_realloc(xfd_event, ksize, usize, guest_fpu))
1723 int xfd_enable_feature(u64 xfd_err)
1725 return __xfd_enable_feature(xfd_err, NULL);
1728 #else /* CONFIG_X86_64 */
1729 static inline int xstate_request_perm(unsigned long idx, bool guest)
1733 #endif /* !CONFIG_X86_64 */
1735 u64 xstate_get_guest_group_perm(void)
1737 return xstate_get_group_perm(true);
1739 EXPORT_SYMBOL_GPL(xstate_get_guest_group_perm);
1742 * fpu_xstate_prctl - xstate permission operations
1743 * @tsk: Redundant pointer to current
1744 * @option: A subfunction of arch_prctl()
1745 * @arg2: option argument
1746 * Return: 0 if successful; otherwise, an error code
1750 * ARCH_GET_XCOMP_SUPP: Pointer to user space u64 to store the info
1751 * ARCH_GET_XCOMP_PERM: Pointer to user space u64 to store the info
1752 * ARCH_REQ_XCOMP_PERM: Facility number requested
1754 * For facilities which require more than one XSTATE component, the request
1755 * must be the highest state component number related to that facility,
1756 * e.g. for AMX which requires XFEATURE_XTILE_CFG(17) and
1757 * XFEATURE_XTILE_DATA(18) this would be XFEATURE_XTILE_DATA(18).
1759 long fpu_xstate_prctl(int option, unsigned long arg2)
1761 u64 __user *uptr = (u64 __user *)arg2;
1762 u64 permitted, supported;
1763 unsigned long idx = arg2;
1767 case ARCH_GET_XCOMP_SUPP:
1768 supported = fpu_user_cfg.max_features | fpu_user_cfg.legacy_features;
1769 return put_user(supported, uptr);
1771 case ARCH_GET_XCOMP_PERM:
1773 * Lockless snapshot as it can also change right after the
1774 * dropping the lock.
1776 permitted = xstate_get_host_group_perm();
1777 permitted &= XFEATURE_MASK_USER_SUPPORTED;
1778 return put_user(permitted, uptr);
1780 case ARCH_GET_XCOMP_GUEST_PERM:
1781 permitted = xstate_get_guest_group_perm();
1782 permitted &= XFEATURE_MASK_USER_SUPPORTED;
1783 return put_user(permitted, uptr);
1785 case ARCH_REQ_XCOMP_GUEST_PERM:
1789 case ARCH_REQ_XCOMP_PERM:
1790 if (!IS_ENABLED(CONFIG_X86_64))
1793 return xstate_request_perm(idx, guest);
1800 #ifdef CONFIG_PROC_PID_ARCH_STATUS
1802 * Report the amount of time elapsed in millisecond since last AVX512
1805 static void avx512_status(struct seq_file *m, struct task_struct *task)
1807 unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
1812 * Report -1 if no AVX512 usage
1816 delta = (long)(jiffies - timestamp);
1818 * Cap to LONG_MAX if time difference > LONG_MAX
1822 delta = jiffies_to_msecs(delta);
1825 seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
1830 * Report architecture specific information
1832 int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
1833 struct pid *pid, struct task_struct *task)
1836 * Report AVX512 state if the processor and build option supported.
1838 if (cpu_feature_enabled(X86_FEATURE_AVX512F))
1839 avx512_status(m, task);
1843 #endif /* CONFIG_PROC_PID_ARCH_STATUS */