1 files changed, 170 insertions, 0 deletions
diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
new file mode 100644
index 000000000..e829fa4c6
--- /dev/null
+++ b/arch/x86/include/asm/fpu/api.h
@@ -0,0 +1,170 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 1994 Linus Torvalds
+ *
+ * Pentium III FXSR, SSE support
+ * General FPU state handling cleanups
+ *	Gareth Hughes <gareth@valinux.com>, May 2000
+ * x86-64 work by Andi Kleen 2002
+ */
+
+#ifndef _ASM_X86_FPU_API_H
+#define _ASM_X86_FPU_API_H
+#include <linux/bottom_half.h>
+
+#include <asm/fpu/types.h>
+
+/*
+ * Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It
+ * disables preemption so be careful if you intend to use it for long periods
+ * of time.
+ * If you intend to use the FPU in irq/softirq you need to check first with
+ * irq_fpu_usable() if it is possible.
+ */
+
+/* Kernel FPU states to initialize in kernel_fpu_begin_mask() */
+#define KFPU_387	_BITUL(0)	/* 387 state will be initialized */
+#define KFPU_MXCSR	_BITUL(1)	/* MXCSR will be initialized */
+
+extern void kernel_fpu_begin_mask(unsigned int kfpu_mask);
+extern void kernel_fpu_end(void);
+extern bool irq_fpu_usable(void);
+extern void fpregs_mark_activate(void);
+
+/* Code that is unaware of kernel_fpu_begin_mask() can use this */
+static inline void kernel_fpu_begin(void)
+{
+#ifdef CONFIG_X86_64
+	/*
+	 * Any 64-bit code that uses 387 instructions must explicitly request
+	 * KFPU_387.
+	 */
+	kernel_fpu_begin_mask(KFPU_MXCSR);
+#else
+	/*
+	 * 32-bit kernel code may use 387 operations as well as SSE2, etc,
+	 * as long as it checks that the CPU has the required capability.
+	 */
+	kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR);
+#endif
+}
+
+/*
+ * Use fpregs_lock() while editing CPU's FPU registers or fpu->fpstate.
+ * A context switch will (and softirq might) save CPU's FPU registers to
+ * fpu->fpstate.regs and set TIF_NEED_FPU_LOAD leaving CPU's FPU registers in
+ * a random state.
+ *
+ * local_bh_disable() protects against both preemption and soft interrupts
+ * on !RT kernels.
+ *
+ * On RT kernels local_bh_disable() is not sufficient because it only
+ * serializes soft interrupt related sections via a local lock, but stays
+ * preemptible. Disabling preemption is the right choice here as bottom
+ * half processing is always in thread context on RT kernels so it
+ * implicitly prevents bottom half processing as well.
+ *
+ * Disabling preemption also serializes against kernel_fpu_begin().
+ */
+static inline void fpregs_lock(void)
+{
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_bh_disable();
+	else
+		preempt_disable();
+}
+
+static inline void fpregs_unlock(void)
+{
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_bh_enable();
+	else
+		preempt_enable();
+}
+
+#ifdef CONFIG_X86_DEBUG_FPU
+extern void fpregs_assert_state_consistent(void);
+#else
+static inline void fpregs_assert_state_consistent(void) { }
+#endif
+
+/*
+ * Load the task FPU state before returning to userspace.
+ */
+extern void switch_fpu_return(void);
+
+/*
+ * Query the presence of one or more xfeatures. Works on any legacy CPU as well.
+ *
+ * If 'feature_name' is set then put a human-readable description of
+ * the feature there as well - this can be used to print error (or success)
+ * messages.
+ */
+extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name);
+
+/* Trap handling */
+extern int  fpu__exception_code(struct fpu *fpu, int trap_nr);
+extern void fpu_sync_fpstate(struct fpu *fpu);
+extern void fpu_reset_from_exception_fixup(void);
+
+/* Boot, hotplug and resume */
+extern void fpu__init_cpu(void);
+extern void fpu__init_system(void);
+extern void fpu__init_check_bugs(void);
+extern void fpu__resume_cpu(void);
+
+#ifdef CONFIG_MATH_EMULATION
+extern void fpstate_init_soft(struct swregs_state *soft);
+#else
+static inline void fpstate_init_soft(struct swregs_state *soft) {}
+#endif
+
+/* State tracking */
+DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);
+
+/* Process cleanup */
+#ifdef CONFIG_X86_64
+extern void fpstate_free(struct fpu *fpu);
+#else
+static inline void fpstate_free(struct fpu *fpu) { }
+#endif
+
+/* fpstate-related functions which are exported to KVM */
+extern void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature);
+
+extern u64 xstate_get_guest_group_perm(void);
+
+/* KVM specific functions */
+extern bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu);
+extern void fpu_free_guest_fpstate(struct fpu_guest *gfpu);
+extern int fpu_swap_kvm_fpstate(struct fpu_guest *gfpu, bool enter_guest);
+extern int fpu_enable_guest_xfd_features(struct fpu_guest *guest_fpu, u64 xfeatures);
+
+#ifdef CONFIG_X86_64
+extern void fpu_update_guest_xfd(struct fpu_guest *guest_fpu, u64 xfd);
+extern void fpu_sync_guest_vmexit_xfd_state(void);
+#else
+static inline void fpu_update_guest_xfd(struct fpu_guest *guest_fpu, u64 xfd) { }
+static inline void fpu_sync_guest_vmexit_xfd_state(void) { }
+#endif
+
+extern void fpu_copy_guest_fpstate_to_uabi(struct fpu_guest *gfpu, void *buf,
+					   unsigned int size, u64 xfeatures, u32 pkru);
+extern int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf, u64 xcr0, u32 *vpkru);
+
+static inline void fpstate_set_confidential(struct fpu_guest *gfpu)
+{
+	gfpu->fpstate->is_confidential = true;
+}
+
+static inline bool fpstate_is_confidential(struct fpu_guest *gfpu)
+{
+	return gfpu->fpstate->is_confidential;
+}
+
+/* prctl */
+extern long fpu_xstate_prctl(int option, unsigned long arg2);
+
+extern void fpu_idle_fpregs(void);
+
+#endif /* _ASM_X86_FPU_API_H */