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 and softirq processing, so be careful if you intend to
20 * use it for long periods of time. Kernel-mode FPU cannot be used in all
21 * contexts -- see irq_fpu_usable() for details.
22 */
23
24 /* Kernel FPU states to initialize in kernel_fpu_begin_mask() */
25 #define KFPU_387 _BITUL(0) /* 387 state will be initialized */
26 #define KFPU_MXCSR _BITUL(1) /* MXCSR will be initialized */
27
28 extern void kernel_fpu_begin_mask(unsigned int kfpu_mask);
29 extern void kernel_fpu_end(void);
30 extern bool irq_fpu_usable(void);
31 extern void fpregs_mark_activate(void);
32
33 /* Code that is unaware of kernel_fpu_begin_mask() can use this */
kernel_fpu_begin(void)34 static inline void kernel_fpu_begin(void)
35 {
36 #ifdef CONFIG_X86_64
37 /*
38 * Any 64-bit code that uses 387 instructions must explicitly request
39 * KFPU_387.
40 */
41 kernel_fpu_begin_mask(KFPU_MXCSR);
42 #else
43 /*
44 * 32-bit kernel code may use 387 operations as well as SSE2, etc,
45 * as long as it checks that the CPU has the required capability.
46 */
47 kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR);
48 #endif
49 }
50
51 /*
52 * Use fpregs_lock() while editing CPU's FPU registers or fpu->fpstate, or while
53 * using the FPU in kernel mode. A context switch will (and softirq might) save
54 * CPU's FPU registers to fpu->fpstate.regs and set TIF_NEED_FPU_LOAD leaving
55 * CPU's FPU registers in a random state.
56 *
57 * local_bh_disable() protects against both preemption and soft interrupts
58 * on !RT kernels.
59 *
60 * On RT kernels local_bh_disable() is not sufficient because it only
61 * serializes soft interrupt related sections via a local lock, but stays
62 * preemptible. Disabling preemption is the right choice here as bottom
63 * half processing is always in thread context on RT kernels so it
64 * implicitly prevents bottom half processing as well.
65 */
fpregs_lock(void)66 static inline void fpregs_lock(void)
67 {
68 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
69 local_bh_disable();
70 else
71 preempt_disable();
72 }
73
fpregs_unlock(void)74 static inline void fpregs_unlock(void)
75 {
76 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
77 local_bh_enable();
78 else
79 preempt_enable();
80 }
81
82 /*
83 * FPU state gets lazily restored before returning to userspace. So when in the
84 * kernel, the valid FPU state may be kept in the buffer. This function will force
85 * restore all the fpu state to the registers early if needed, and lock them from
86 * being automatically saved/restored. Then FPU state can be modified safely in the
87 * registers, before unlocking with fpregs_unlock().
88 */
89 void fpregs_lock_and_load(void);
90
91 #ifdef CONFIG_X86_DEBUG_FPU
92 extern void fpregs_assert_state_consistent(void);
93 #else
fpregs_assert_state_consistent(void)94 static inline void fpregs_assert_state_consistent(void) { }
95 #endif
96
97 /*
98 * Load the task FPU state before returning to userspace.
99 */
100 extern void switch_fpu_return(void);
101
102 /*
103 * Query the presence of one or more xfeatures. Works on any legacy CPU as well.
104 *
105 * If 'feature_name' is set then put a human-readable description of
106 * the feature there as well - this can be used to print error (or success)
107 * messages.
108 */
109 extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name);
110
111 /* Trap handling */
112 extern int fpu__exception_code(struct fpu *fpu, int trap_nr);
113 extern void fpu_sync_fpstate(struct fpu *fpu);
114 extern void fpu_reset_from_exception_fixup(void);
115
116 /* Boot, hotplug and resume */
117 extern void fpu__init_cpu(void);
118 extern void fpu__init_system(void);
119 extern void fpu__init_check_bugs(void);
120 extern void fpu__resume_cpu(void);
121
122 #ifdef CONFIG_MATH_EMULATION
123 extern void fpstate_init_soft(struct swregs_state *soft);
124 #else
fpstate_init_soft(struct swregs_state * soft)125 static inline void fpstate_init_soft(struct swregs_state *soft) {}
126 #endif
127
128 /* State tracking */
129 DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);
130
131 /* Process cleanup */
132 #ifdef CONFIG_X86_64
133 extern void fpstate_free(struct fpu *fpu);
134 #else
fpstate_free(struct fpu * fpu)135 static inline void fpstate_free(struct fpu *fpu) { }
136 #endif
137
138 /* fpstate-related functions which are exported to KVM */
139 extern void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature);
140
141 extern u64 xstate_get_guest_group_perm(void);
142
143 extern void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
144
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
fpu_update_guest_xfd(struct fpu_guest * guest_fpu,u64 xfd)156 static inline void fpu_update_guest_xfd(struct fpu_guest *guest_fpu, u64 xfd) { }
fpu_sync_guest_vmexit_xfd_state(void)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,
161 unsigned int size, u64 xfeatures, u32 pkru);
162 extern int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf, u64 xcr0, u32 *vpkru);
163
fpstate_set_confidential(struct fpu_guest * gfpu)164 static inline void fpstate_set_confidential(struct fpu_guest *gfpu)
165 {
166 gfpu->fpstate->is_confidential = true;
167 }
168
fpstate_is_confidential(struct fpu_guest * gfpu)169 static inline bool fpstate_is_confidential(struct fpu_guest *gfpu)
170 {
171 return gfpu->fpstate->is_confidential;
172 }
173
174 /* prctl */
175 extern long fpu_xstate_prctl(int option, unsigned long arg2);
176
177 extern void fpu_idle_fpregs(void);
178
179 #endif /* _ASM_X86_FPU_API_H */
180