From 672365477ae8afca5a1cca98c1deb733235e4525 Mon Sep 17 00:00:00 2001 From: "Chang S. Bae" Date: Thu, 21 Oct 2021 15:55:20 -0700 Subject: 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 Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20211021225527.10184-17-chang.seok.bae@intel.com --- arch/x86/kernel/fpu/signal.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/kernel/fpu/signal.c') diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 16fdecd02341..cc977da6e128 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -282,6 +282,8 @@ static bool restore_fpregs_from_user(void __user *buf, u64 xrestore, retry: fpregs_lock(); + /* Ensure that XFD is up to date */ + xfd_update_state(fpu->fpstate); pagefault_disable(); ret = __restore_fpregs_from_user(buf, fpu->fpstate->user_xfeatures, xrestore, fx_only); -- cgit v1.2.3