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x86/fpu: Add XFD state to fpstate

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Add storage for XFD register state to struct fpstate. This will be used to
store the XFD MSR state. This will be used for switching the XFD MSR when
FPU content is restored.

Add a per-CPU variable to cache the current MSR value so the MSR has only
to be written when the values are different.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-15-chang.seok.bae@intel.com
This commit is contained in:
Chang S. Bae 2021-10-21 15:55:18 -07:00 committed by Borislav Petkov
parent dae1bd5838
commit 8bf26758ca
3 changed files with 9 additions and 0 deletions
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3
arch/x86/include/asm/fpu/types.h
View File

@ -322,6 +322,9 @@ struct fpstate {
/* @user_xfeatures: xfeatures valid in UABI buffers */
u64 user_xfeatures;
/* @xfd: xfeatures disabled to trap userspace use. */
u64 xfd;
/* @is_valloc: Indicator for dynamically allocated state */
unsigned int is_valloc : 1;

2
arch/x86/kernel/fpu/core.c
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@ -27,6 +27,7 @@
#ifdef CONFIG_X86_64
DEFINE_STATIC_KEY_FALSE(__fpu_state_size_dynamic);
DEFINE_PER_CPU(u64, xfd_state);
#endif
/* The FPU state configuration data for kernel and user space */
@ -409,6 +410,7 @@ static void __fpstate_reset(struct fpstate *fpstate)
fpstate->user_size = fpu_user_cfg.default_size;
fpstate->xfeatures = fpu_kernel_cfg.default_features;
fpstate->user_xfeatures = fpu_user_cfg.default_features;
fpstate->xfd = init_fpstate.xfd;
}
void fpstate_reset(struct fpu *fpu)

4
arch/x86/kernel/fpu/xstate.h
View File

@ -5,6 +5,10 @@
#include <asm/cpufeature.h>
#include <asm/fpu/xstate.h>
#ifdef CONFIG_X86_64
DECLARE_PER_CPU(u64, xfd_state);
#endif
static inline void xstate_init_xcomp_bv(struct xregs_state *xsave, u64 mask)
{
/*