1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (C) 1994 Linus Torvalds 4 * 5 * Pentium III FXSR, SSE support 6 * General FPU state handling cleanups 7 * Gareth Hughes <gareth@valinux.com>, May 2000 8 * x86-64 work by Andi Kleen 2002 9 */ 10 11 #ifndef _ASM_X86_FPU_API_H 12 #define _ASM_X86_FPU_API_H 13 #include <linux/bottom_half.h> 14 15 #include <asm/fpu/types.h> 16 17 /* 18 * Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It 19 * disables preemption so be careful if you intend to use it for long periods 20 * of time. 21 * If you intend to use the FPU in irq/softirq you need to check first with 22 * irq_fpu_usable() if it is possible. 23 */ 24 25 /* Kernel FPU states to initialize in kernel_fpu_begin_mask() */ 26 #define KFPU_387 _BITUL(0) /* 387 state will be initialized */ 27 #define KFPU_MXCSR _BITUL(1) /* MXCSR will be initialized */ 28 29 extern void kernel_fpu_begin_mask(unsigned int kfpu_mask); 30 extern void kernel_fpu_end(void); 31 extern bool irq_fpu_usable(void); 32 extern void fpregs_mark_activate(void); 33 34 /* Code that is unaware of kernel_fpu_begin_mask() can use this */ 35 static inline void kernel_fpu_begin(void) 36 { 37 #ifdef CONFIG_X86_64 38 /* 39 * Any 64-bit code that uses 387 instructions must explicitly request 40 * KFPU_387. 41 */ 42 kernel_fpu_begin_mask(KFPU_MXCSR); 43 #else 44 /* 45 * 32-bit kernel code may use 387 operations as well as SSE2, etc, 46 * as long as it checks that the CPU has the required capability. 47 */ 48 kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR); 49 #endif 50 } 51 52 /* 53 * Use fpregs_lock() while editing CPU's FPU registers or fpu->fpstate. 54 * A context switch will (and softirq might) save CPU's FPU registers to 55 * fpu->fpstate.regs and set TIF_NEED_FPU_LOAD leaving CPU's FPU registers in 56 * a random state. 57 * 58 * local_bh_disable() protects against both preemption and soft interrupts 59 * on !RT kernels. 60 * 61 * On RT kernels local_bh_disable() is not sufficient because it only 62 * serializes soft interrupt related sections via a local lock, but stays 63 * preemptible. Disabling preemption is the right choice here as bottom 64 * half processing is always in thread context on RT kernels so it 65 * implicitly prevents bottom half processing as well. 66 * 67 * Disabling preemption also serializes against kernel_fpu_begin(). 68 */ 69 static inline void fpregs_lock(void) 70 { 71 if (!IS_ENABLED(CONFIG_PREEMPT_RT)) 72 local_bh_disable(); 73 else 74 preempt_disable(); 75 } 76 77 static inline void fpregs_unlock(void) 78 { 79 if (!IS_ENABLED(CONFIG_PREEMPT_RT)) 80 local_bh_enable(); 81 else 82 preempt_enable(); 83 } 84 85 /* 86 * FPU state gets lazily restored before returning to userspace. So when in the 87 * kernel, the valid FPU state may be kept in the buffer. This function will force 88 * restore all the fpu state to the registers early if needed, and lock them from 89 * being automatically saved/restored. Then FPU state can be modified safely in the 90 * registers, before unlocking with fpregs_unlock(). 91 */ 92 void fpregs_lock_and_load(void); 93 94 #ifdef CONFIG_X86_DEBUG_FPU 95 extern void fpregs_assert_state_consistent(void); 96 #else 97 static inline void fpregs_assert_state_consistent(void) { } 98 #endif 99 100 /* 101 * Load the task FPU state before returning to userspace. 102 */ 103 extern void switch_fpu_return(void); 104 105 /* 106 * Query the presence of one or more xfeatures. Works on any legacy CPU as well. 107 * 108 * If 'feature_name' is set then put a human-readable description of 109 * the feature there as well - this can be used to print error (or success) 110 * messages. 111 */ 112 extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name); 113 114 /* Trap handling */ 115 extern int fpu__exception_code(struct fpu *fpu, int trap_nr); 116 extern void fpu_sync_fpstate(struct fpu *fpu); 117 extern void fpu_reset_from_exception_fixup(void); 118 119 /* Boot, hotplug and resume */ 120 extern void fpu__init_cpu(void); 121 extern void fpu__init_system(void); 122 extern void fpu__init_check_bugs(void); 123 extern void fpu__resume_cpu(void); 124 125 #ifdef CONFIG_MATH_EMULATION 126 extern void fpstate_init_soft(struct swregs_state *soft); 127 #else 128 static inline void fpstate_init_soft(struct swregs_state *soft) {} 129 #endif 130 131 /* State tracking */ 132 DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx); 133 134 /* Process cleanup */ 135 #ifdef CONFIG_X86_64 136 extern void fpstate_free(struct fpu *fpu); 137 #else 138 static inline void fpstate_free(struct fpu *fpu) { } 139 #endif 140 141 /* fpstate-related functions which are exported to KVM */ 142 extern void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature); 143 144 extern u64 xstate_get_guest_group_perm(void); 145 146 /* KVM specific functions */ 147 extern bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu); 148 extern void fpu_free_guest_fpstate(struct fpu_guest *gfpu); 149 extern int fpu_swap_kvm_fpstate(struct fpu_guest *gfpu, bool enter_guest); 150 extern int fpu_enable_guest_xfd_features(struct fpu_guest *guest_fpu, u64 xfeatures); 151 152 #ifdef CONFIG_X86_64 153 extern void fpu_update_guest_xfd(struct fpu_guest *guest_fpu, u64 xfd); 154 extern void fpu_sync_guest_vmexit_xfd_state(void); 155 #else 156 static inline void fpu_update_guest_xfd(struct fpu_guest *guest_fpu, u64 xfd) { } 157 static inline void fpu_sync_guest_vmexit_xfd_state(void) { } 158 #endif 159 160 extern void fpu_copy_guest_fpstate_to_uabi(struct fpu_guest *gfpu, void *buf, unsigned int size, u32 pkru); 161 extern int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf, u64 xcr0, u32 *vpkru); 162 163 static inline void fpstate_set_confidential(struct fpu_guest *gfpu) 164 { 165 gfpu->fpstate->is_confidential = true; 166 } 167 168 static inline bool fpstate_is_confidential(struct fpu_guest *gfpu) 169 { 170 return gfpu->fpstate->is_confidential; 171 } 172 173 /* prctl */ 174 extern long fpu_xstate_prctl(int option, unsigned long arg2); 175 176 extern void fpu_idle_fpregs(void); 177 178 #endif /* _ASM_X86_FPU_API_H */ 179