diff options
| author | Chang S. Bae <chang.seok.bae@intel.com> | 2021-10-21 15:55:20 -0700 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-10-26 10:53:02 +0200 |
| commit | 672365477ae8afca5a1cca98c1deb733235e4525 (patch) | |
| tree | 9e41b4eb5c5a3dff90c0ceb443f071035bcc0d4a /arch/x86/kernel/fpu/xstate.h | |
| parent | 5529acf47ec31ece0815f69d43f5e6a1e485a0f3 (diff) | |
x86/fpu: Update XFD state where required
The IA32_XFD_MSR allows to arm #NM traps for XSTATE components which are
enabled in XCR0. The register has to be restored before the tasks XSTATE is
restored. The life time rules are the same as for FPU state.
XFD is updated on return to userspace only when the FPU state of the task
is not up to date in the registers. It's updated before the XRSTORS so
that eventually enabled dynamic features are restored as well and not
brought into init state.
Also in signal handling for restoring FPU state from user space the
correctness of the XFD state has to be ensured.
Add it to CPU initialization and resume as well.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-17-chang.seok.bae@intel.com
Diffstat (limited to 'arch/x86/kernel/fpu/xstate.h')
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.h | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h index 29024244965b..e18210dff88c 100644 --- a/arch/x86/kernel/fpu/xstate.h +++ b/arch/x86/kernel/fpu/xstate.h @@ -136,6 +136,22 @@ extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor); static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { } #endif +#ifdef CONFIG_X86_64 +static inline void xfd_update_state(struct fpstate *fpstate) +{ + if (fpu_state_size_dynamic()) { + u64 xfd = fpstate->xfd; + + if (__this_cpu_read(xfd_state) != xfd) { + wrmsrl(MSR_IA32_XFD, xfd); + __this_cpu_write(xfd_state, xfd); + } + } +} +#else +static inline void xfd_update_state(struct fpstate *fpstate) { } +#endif + /* * Save processor xstate to xsave area. * @@ -247,7 +263,8 @@ static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask) u32 hmask = mask >> 32; int err; - /* Must enforce XFD update here */ + /* Ensure that XFD is up to date */ + xfd_update_state(fpstate); if (cpu_feature_enabled(X86_FEATURE_XSAVES)) XSTATE_OP(XRSTORS, xstate, lmask, hmask, err); |