Sebastian Andrzej Siewior 0b455673e7 x86/fpu: Deactivate FPU state after failure during state load ... [ Upstream commit bbc55341b9 ] In __fpu__restore_sig(), fpu_fpregs_owner_ctx needs to be reset if the FPU state was not fully restored. Otherwise the following may happen (on the same CPU): Task A Task B fpu_fpregs_owner_ctx *active* A.fpu __fpu__restore_sig() ctx switch load B.fpu *active* B.fpu fpregs_lock() copy_user_to_fpregs_zeroing() copy_kernel_to_xregs() *modify* copy_user_to_xregs() *fails* fpregs_unlock() ctx switch skip loading B.fpu, *active* B.fpu In the success case, fpu_fpregs_owner_ctx is set to the current task. In the failure case, the FPU state might have been modified by loading the init state. In this case, fpu_fpregs_owner_ctx needs to be reset in order to ensure that the FPU state of the following task is loaded from saved state (and not skipped because it was the previous state). Reset fpu_fpregs_owner_ctx after a failure during restore occurred, to ensure that the FPU state for the next task is always loaded. The problem was debugged-by Yu-cheng Yu <yu-cheng.yu@intel.com>. [ bp: Massage commit message. ] Fixes: 5f409e20b7 ("x86/fpu: Defer FPU state load until return to userspace") Reported-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20191220195906.plk6kpmsrikvbcfn@linutronix.de Signed-off-by: Sasha Levin <sashal@kernel.org>		2020-02-24 08:36:26 +01:00
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Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
bugs.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
core.c	x86/fpu: Remove the fpu__save() export	2019-06-17 12:21:26 +02:00
init.c	x86/fpu: Inline fpu__xstate_clear_all_cpu_caps()	2019-07-07 12:01:47 +02:00
regset.c	x86/fpu: Remove fpu->initialized	2019-04-10 15:42:40 +02:00
signal.c	x86/fpu: Deactivate FPU state after failure during state load	2020-02-24 08:36:26 +01:00
xstate.c	Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2019-07-08 17:28:57 -07:00