Commit 126fe040 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/fpu: Cleanup xstate xcomp_bv initialization 



No point in having this duplicated all over the place with needlessly
different defines.

Provide a proper initialization function which initializes user buffers
properly and make KVM use it.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011538.897664678@linutronix.de
parent 509e7a30

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

+3 −1
Original line number Diff line number Diff line
@@ -80,7 +80,9 @@ static __always_inline __pure bool use_fxsr(void) 


extern union fpregs_state init_fpstate;



extern void fpstate_init(union fpregs_state *state);

extern void fpstate_init_user(union fpregs_state *state);

extern void fpu_init_fpstate_user(struct fpu *fpu);



#ifdef CONFIG_MATH_EMULATION

extern void fpstate_init_soft(struct swregs_state *soft);

#else

arch/x86/kernel/fpu/core.c

+19 −16
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ 
#include <linux/hardirq.h>

#include <linux/pkeys.h>



#include "xstate.h"



#define CREATE_TRACE_POINTS

#include <asm/trace/fpu.h>
@@ -203,15 +205,6 @@ void fpu_sync_fpstate(struct fpu *fpu) 
	fpregs_unlock();

}



static inline void fpstate_init_xstate(struct xregs_state *xsave)

{

	/*

	 * XRSTORS requires these bits set in xcomp_bv, or it will

	 * trigger #GP:

	 */

	xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask_all;

}



static inline unsigned int init_fpstate_copy_size(void)

{

	if (!use_xsave())
@@ -238,23 +231,33 @@ static inline void fpstate_init_fstate(struct fregs_state *fp) 
	fp->fos = 0xffff0000u;

}



void fpstate_init(union fpregs_state *state)

/*

 * Used in two places:

 * 1) Early boot to setup init_fpstate for non XSAVE systems

 * 2) fpu_init_fpstate_user() which is invoked from KVM

 */

void fpstate_init_user(union fpregs_state *state)

{

	if (!static_cpu_has(X86_FEATURE_FPU)) {

	if (!cpu_feature_enabled(X86_FEATURE_FPU)) {

		fpstate_init_soft(&state->soft);

		return;

	}



	memset(state, 0, fpu_kernel_xstate_size);

	xstate_init_xcomp_bv(&state->xsave, xfeatures_mask_uabi());



	if (static_cpu_has(X86_FEATURE_XSAVES))

		fpstate_init_xstate(&state->xsave);

	if (static_cpu_has(X86_FEATURE_FXSR))

	if (cpu_feature_enabled(X86_FEATURE_FXSR))

		fpstate_init_fxstate(&state->fxsave);

	else

		fpstate_init_fstate(&state->fsave);

}

EXPORT_SYMBOL_GPL(fpstate_init);



#if IS_ENABLED(CONFIG_KVM)

void fpu_init_fpstate_user(struct fpu *fpu)

{

	fpstate_init_user(&fpu->state);

}

EXPORT_SYMBOL_GPL(fpu_init_fpstate_user);

#endif



/* Clone current's FPU state on fork */

int fpu_clone(struct task_struct *dst)

arch/x86/kernel/fpu/init.c

+3 −3
Original line number Diff line number Diff line
@@ -121,10 +121,10 @@ static void __init fpu__init_system_mxcsr(void) 
static void __init fpu__init_system_generic(void)

{

	/*

	 * Set up the legacy init FPU context. (xstate init might overwrite this

	 * with a more modern format, if the CPU supports it.)

	 * Set up the legacy init FPU context. Will be updated when the

	 * CPU supports XSAVE[S].

	 */

	fpstate_init(&init_fpstate);

	fpstate_init_user(&init_fpstate);



	fpu__init_system_mxcsr();

}

arch/x86/kernel/fpu/xstate.c

+3 −5
Original line number Diff line number Diff line
@@ -15,10 +15,10 @@ 
#include <asm/fpu/internal.h>

#include <asm/fpu/signal.h>

#include <asm/fpu/regset.h>

#include <asm/fpu/xstate.h>



#include <asm/tlbflush.h>

#include <asm/cpufeature.h>



#include "xstate.h"



/*

 * Although we spell it out in here, the Processor Trace
@@ -389,9 +389,7 @@ static void __init setup_init_fpu_buf(void) 
	setup_xstate_features();

	print_xstate_features();



	if (boot_cpu_has(X86_FEATURE_XSAVES))

		init_fpstate.xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT |

						     xfeatures_mask_all;

	xstate_init_xcomp_bv(&init_fpstate.xsave, xfeatures_mask_all);



	/*

	 * Init all the features state with header.xfeatures being 0x0

arch/x86/kernel/fpu/xstate.h

0 → 100644
+18 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef __X86_KERNEL_FPU_XSTATE_H

#define __X86_KERNEL_FPU_XSTATE_H



#include <asm/cpufeature.h>

#include <asm/fpu/xstate.h>



static inline void xstate_init_xcomp_bv(struct xregs_state *xsave, u64 mask)

{

	/*

	 * XRSTORS requires these bits set in xcomp_bv, or it will

	 * trigger #GP:

	 */

	if (cpu_feature_enabled(X86_FEATURE_XSAVES))

		xsave->header.xcomp_bv = mask | XCOMP_BV_COMPACTED_FORMAT;

}



#endif