Commit-ID: bef8b6da95229f780a0a7f63e23124058bfad6d3 Gitweb: http://git.kernel.org/tip/bef8b6da95229f780a0a7f63e23124058bfad6d3 Author: Andy Lutomirski <luto@xxxxxxxxxx> AuthorDate: Mon, 31 Oct 2016 15:18:47 -0700 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Tue, 1 Nov 2016 07:47:54 +0100 x86/fpu: Handle #NM without FPU emulation as an error Don't use CR0.TS. Make it an error rather than making nonsensical changes to the FPU state. (The cond_local_irq_enable() appears to have been pointless, too.) Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: kvm list <kvm@xxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/f1ee6bf73ed1025fccaab321ba43d0594245f927.1477951965.git.luto@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/kernel/traps.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index bd4e3d4..bf0c6d0 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -853,6 +853,8 @@ do_spurious_interrupt_bug(struct pt_regs *regs, long error_code) dotraplinkage void do_device_not_available(struct pt_regs *regs, long error_code) { + unsigned long cr0; + RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); #ifdef CONFIG_MATH_EMULATION @@ -866,10 +868,20 @@ do_device_not_available(struct pt_regs *regs, long error_code) return; } #endif - fpu__restore(¤t->thread.fpu); /* interrupts still off */ -#ifdef CONFIG_X86_32 - cond_local_irq_enable(regs); -#endif + + /* This should not happen. */ + cr0 = read_cr0(); + if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) { + /* Try to fix it up and carry on. */ + write_cr0(cr0 & ~X86_CR0_TS); + } else { + /* + * Something terrible happened, and we're better off trying + * to kill the task than getting stuck in a never-ending + * loop of #NM faults. + */ + die("unexpected #NM exception", regs, error_code); + } } NOKPROBE_SYMBOL(do_device_not_available); -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
