s390/fpu: always enable the vector facility if it is available

If the kernel detects that the s390 hardware supports the vector
facility, it is enabled by default at an early stage.  To force
it off, use the novx kernel parameter.  Note that there is a small
time window, where the vector facility is enabled before it is
forced to be off.

With enabling the vector facility by default, the FPU save and
restore functions can be improved.  They do not longer require
to manage expensive control register updates to enable or disable
the vector enablement control for particular processes.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 2 insertions, 12 deletions

diff --git a/arch/s390/include/asm/fpu-internal.h b/arch/s390/include/asm/fpu-internal.h
index 55dc2c0..cd79a33 100644
--- a/arch/s390/include/asm/fpu-internal.h
+++ b/arch/s390/include/asm/fpu-internal.h
@@ -8,10 +8,6 @@
 #ifndef _ASM_S390_FPU_INTERNAL_H
 #define _ASM_S390_FPU_INTERNAL_H
 
-#define FPU_USE_VX		1	/* Vector extension is active */
-
-#ifndef __ASSEMBLY__
-
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <asm/linkage.h>
@@ -20,7 +16,6 @@
 
 struct fpu {
 	__u32 fpc;			/* Floating-point control */
-	__u32 flags;
 	union {
 		void *regs;
 		freg_t *fprs;		/* Floating-point register save area */
@@ -30,9 +25,6 @@ struct fpu {
 
 void save_fpu_regs(void);
 
-#define is_vx_fpu(fpu) (!!((fpu)->flags & FPU_USE_VX))
-#define is_vx_task(tsk) (!!((tsk)->thread.fpu.flags & FPU_USE_VX))
-
 /* VX array structure for address operand constraints in inline assemblies */
 struct vx_array { __vector128 _[__NUM_VXRS]; };
 
@@ -89,7 +81,7 @@ static inline void convert_fp_to_vx(__vector128 *vxrs, freg_t *fprs)
 static inline void fpregs_store(_s390_fp_regs *fpregs, struct fpu *fpu)
 {
 	fpregs->pad = 0;
-	if (is_vx_fpu(fpu))
+	if (MACHINE_HAS_VX)
 		convert_vx_to_fp((freg_t *)&fpregs->fprs, fpu->vxrs);
 	else
 		memcpy((freg_t *)&fpregs->fprs, fpu->fprs,
@@ -98,13 +90,11 @@ static inline void fpregs_store(_s390_fp_regs *fpregs, struct fpu *fpu)
 
 static inline void fpregs_load(_s390_fp_regs *fpregs, struct fpu *fpu)
 {
-	if (is_vx_fpu(fpu))
+	if (MACHINE_HAS_VX)
 		convert_fp_to_vx(fpu->vxrs, (freg_t *)&fpregs->fprs);
 	else
 		memcpy(fpu->fprs, (freg_t *)&fpregs->fprs,
 		       sizeof(fpregs->fprs));
 }
 
-#endif
-
 #endif /* _ASM_S390_FPU_INTERNAL_H */