diff options
| author | Andy Lutomirski | 2016-10-31 15:18:46 -0700 |
|---|---|---|
| committer | Ingo Molnar | 2016-11-01 07:47:54 +0100 |
| commit | cd95ea81f25608c403052d0508ee5c9b32e2bc7d (patch) | |
| tree | b5901aa76a2882cf4e722faa33b430945455d1dc /arch/x86/lguest | |
| parent | 04ac88abaf758bd76edcc3be5549003a017e7963 (diff) | |
x86/fpu, lguest: Remove CR0.TS support
Now that Linux never sets CR0.TS, lguest doesn't need to support it.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm list <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/8a7bf2c11231c082258fd67705d0f275639b8475.1477951965.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/lguest')
| -rw-r--r-- | arch/x86/lguest/boot.c | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index 25da5bc8d83d..d74afcdbc580 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -497,27 +497,24 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx, * a whole series of functions like read_cr0() and write_cr0(). * * We start with cr0. cr0 allows you to turn on and off all kinds of basic - * features, but Linux only really cares about one: the horrifically-named Task - * Switched (TS) bit at bit 3 (ie. 8) + * features, but the only cr0 bit that Linux ever used at runtime was the + * horrifically-named Task Switched (TS) bit at bit 3 (ie. 8) * * What does the TS bit do? Well, it causes the CPU to trap (interrupt 7) if * the floating point unit is used. Which allows us to restore FPU state - * lazily after a task switch, and Linux uses that gratefully, but wouldn't a - * name like "FPUTRAP bit" be a little less cryptic? + * lazily after a task switch if we wanted to, but wouldn't a name like + * "FPUTRAP bit" be a little less cryptic? * - * We store cr0 locally because the Host never changes it. The Guest sometimes - * wants to read it and we'd prefer not to bother the Host unnecessarily. + * Fortunately, Linux keeps it simple and doesn't use TS, so we can ignore + * cr0. */ -static unsigned long current_cr0; static void lguest_write_cr0(unsigned long val) { - lazy_hcall1(LHCALL_TS, val & X86_CR0_TS); - current_cr0 = val; } static unsigned long lguest_read_cr0(void) { - return current_cr0; + return 0; } /* |