diff options
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index b0f6e9a0cf2e..987a07bc668b 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -835,6 +835,12 @@ static void __init fpu__init_disable_system_xstate(unsigned int legacy_size) fpu_user_cfg.max_size = legacy_size; fpu_user_cfg.default_size = legacy_size; + /* + * Prevent enabling the static branch which enables writes to the + * XFD MSR. + */ + init_fpstate.xfd = 0; + fpstate_reset(¤t->thread.fpu); } @@ -918,6 +924,14 @@ void __init fpu__init_system_xstate(unsigned int legacy_size) /* Store it for paranoia check at the end */ xfeatures = fpu_kernel_cfg.max_features; + /* + * Initialize the default XFD state in initfp_state and enable the + * dynamic sizing mechanism if dynamic states are available. The + * static key cannot be enabled here because this runs before + * jump_label_init(). This is delayed to an initcall. + */ + init_fpstate.xfd = fpu_user_cfg.max_features & XFEATURE_MASK_USER_DYNAMIC; + /* Enable xstate instructions to be able to continue with initialization: */ fpu__init_cpu_xstate(); err = init_xstate_size(); @@ -1466,9 +1480,21 @@ void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) } #endif /* CONFIG_X86_DEBUG_FPU */ +static int __init xfd_update_static_branch(void) +{ + /* + * If init_fpstate.xfd has bits set then dynamic features are + * available and the dynamic sizing must be enabled. + */ + if (init_fpstate.xfd) + static_branch_enable(&__fpu_state_size_dynamic); + return 0; +} +arch_initcall(xfd_update_static_branch) + void fpstate_free(struct fpu *fpu) { - if (fpu->fpstate || fpu->fpstate != &fpu->__fpstate) + if (fpu->fpstate && fpu->fpstate != &fpu->__fpstate) vfree(fpu->fpstate); } |