Commit 079ec41b authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/fpu: Provide a proper function for ex_handler_fprestore() 



To make upcoming changes for support of dynamically enabled features
simpler, provide a proper function for the exception handler which removes
exposure of FPU internals.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011540.053515012@linutronix.de
parent b56d2795

arch/x86/include/asm/fpu/api.h

+1 −3
Original line number Diff line number Diff line
@@ -113,6 +113,7 @@ static inline void update_pasid(void) { } 
/* 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);
@@ -129,9 +130,6 @@ static inline void fpstate_init_soft(struct swregs_state *soft) {} 
/* State tracking */

DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);



/* fpstate */

extern union fpregs_state init_fpstate;



/* fpstate-related functions which are exported to KVM */

extern void fpu_init_fpstate_user(struct fpu *fpu);

arch/x86/kernel/fpu/core.c

+5 −0
Original line number Diff line number Diff line
@@ -155,6 +155,11 @@ void restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask) 
	}

}



void fpu_reset_from_exception_fixup(void)

{

	restore_fpregs_from_fpstate(&init_fpstate, xfeatures_mask_fpstate());

}



#if IS_ENABLED(CONFIG_KVM)

void fpu_swap_kvm_fpu(struct fpu *save, struct fpu *rstor, u64 restore_mask)

{

arch/x86/kernel/fpu/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -2,6 +2,8 @@ 
#ifndef __X86_KERNEL_FPU_INTERNAL_H

#define __X86_KERNEL_FPU_INTERNAL_H



extern union fpregs_state init_fpstate;



/* CPU feature check wrappers */

static __always_inline __pure bool use_xsave(void)

{

arch/x86/mm/extable.c

+2 −3
Original line number Diff line number Diff line
@@ -4,8 +4,7 @@ 
#include <linux/sched/debug.h>

#include <xen/xen.h>



#include <asm/fpu/signal.h>

#include <asm/fpu/xstate.h>

#include <asm/fpu/api.h>

#include <asm/sev.h>

#include <asm/traps.h>

#include <asm/kdebug.h>
@@ -48,7 +47,7 @@ static bool ex_handler_fprestore(const struct exception_table_entry *fixup, 
	WARN_ONCE(1, "Bad FPU state detected at %pB, reinitializing FPU registers.",

		  (void *)instruction_pointer(regs));



	restore_fpregs_from_fpstate(&init_fpstate, xfeatures_mask_fpstate());

	fpu_reset_from_exception_fixup();

	return true;

}