diff options
Diffstat (limited to 'arch/x86/kernel/fpu/core.c')
| -rw-r--r-- | arch/x86/kernel/fpu/core.c | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index b5f5b08b84d7..12ca174891dc 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -156,6 +156,23 @@ void restore_fpregs_from_fpstate(struct fpstate *fpstate, u64 mask) if (use_xsave()) { /* + * Dynamically enabled features are enabled in XCR0, but + * usage requires also that the corresponding bits in XFD + * are cleared. If the bits are set then using a related + * instruction will raise #NM. This allows to do the + * allocation of the larger FPU buffer lazy from #NM or if + * the task has no permission to kill it which would happen + * via #UD if the feature is disabled in XCR0. + * + * XFD state is following the same life time rules as + * XSTATE and to restore state correctly XFD has to be + * updated before XRSTORS otherwise the component would + * stay in or go into init state even if the bits are set + * in fpstate::regs::xsave::xfeatures. + */ + xfd_update_state(fpstate); + + /* * Restoring state always needs to modify all features * which are in @mask even if the current task cannot use * extended features. @@ -241,8 +258,17 @@ int fpu_swap_kvm_fpstate(struct fpu_guest *guest_fpu, bool enter_guest) cur_fps = fpu->fpstate; - if (!cur_fps->is_confidential) + if (!cur_fps->is_confidential) { + /* Includes XFD update */ restore_fpregs_from_fpstate(cur_fps, XFEATURE_MASK_FPSTATE); + } else { + /* + * XSTATE is restored by firmware from encrypted + * memory. Make sure XFD state is correct while + * running with guest fpstate + */ + xfd_update_state(cur_fps); + } fpregs_mark_activate(); fpregs_unlock(); |