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>
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@ -9,7 +9,6 @@
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#define LHCALL_FLUSH_TLB 5
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#define LHCALL_FLUSH_TLB 5
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#define LHCALL_LOAD_IDT_ENTRY 6
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#define LHCALL_LOAD_IDT_ENTRY 6
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#define LHCALL_SET_STACK 7
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#define LHCALL_SET_STACK 7
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#define LHCALL_TS 8
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#define LHCALL_SET_CLOCKEVENT 9
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#define LHCALL_SET_CLOCKEVENT 9
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#define LHCALL_HALT 10
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#define LHCALL_HALT 10
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#define LHCALL_SET_PMD 13
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#define LHCALL_SET_PMD 13
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@ -497,27 +497,24 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx,
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* a whole series of functions like read_cr0() and write_cr0().
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* a whole series of functions like read_cr0() and write_cr0().
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*
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*
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* We start with cr0. cr0 allows you to turn on and off all kinds of basic
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* We start with cr0. cr0 allows you to turn on and off all kinds of basic
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* features, but Linux only really cares about one: the horrifically-named Task
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* features, but the only cr0 bit that Linux ever used at runtime was the
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* Switched (TS) bit at bit 3 (ie. 8)
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* horrifically-named Task Switched (TS) bit at bit 3 (ie. 8)
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*
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*
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* What does the TS bit do? Well, it causes the CPU to trap (interrupt 7) if
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* What does the TS bit do? Well, it causes the CPU to trap (interrupt 7) if
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* the floating point unit is used. Which allows us to restore FPU state
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* the floating point unit is used. Which allows us to restore FPU state
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* lazily after a task switch, and Linux uses that gratefully, but wouldn't a
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* lazily after a task switch if we wanted to, but wouldn't a name like
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* name like "FPUTRAP bit" be a little less cryptic?
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* "FPUTRAP bit" be a little less cryptic?
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*
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*
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* We store cr0 locally because the Host never changes it. The Guest sometimes
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* Fortunately, Linux keeps it simple and doesn't use TS, so we can ignore
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* wants to read it and we'd prefer not to bother the Host unnecessarily.
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* cr0.
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*/
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*/
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static unsigned long current_cr0;
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static void lguest_write_cr0(unsigned long val)
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static void lguest_write_cr0(unsigned long val)
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{
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{
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lazy_hcall1(LHCALL_TS, val & X86_CR0_TS);
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current_cr0 = val;
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}
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}
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static unsigned long lguest_read_cr0(void)
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static unsigned long lguest_read_cr0(void)
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{
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{
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return current_cr0;
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return 0;
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}
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}
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/*
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/*
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@ -109,10 +109,6 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
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case LHCALL_SET_CLOCKEVENT:
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case LHCALL_SET_CLOCKEVENT:
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guest_set_clockevent(cpu, args->arg1);
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guest_set_clockevent(cpu, args->arg1);
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break;
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break;
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case LHCALL_TS:
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/* This sets the TS flag, as we saw used in run_guest(). */
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cpu->ts = args->arg1;
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break;
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case LHCALL_HALT:
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case LHCALL_HALT:
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/* Similarly, this sets the halted flag for run_guest(). */
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/* Similarly, this sets the halted flag for run_guest(). */
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cpu->halted = 1;
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cpu->halted = 1;
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@ -43,7 +43,6 @@ struct lg_cpu {
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struct mm_struct *mm; /* == tsk->mm, but that becomes NULL on exit */
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struct mm_struct *mm; /* == tsk->mm, but that becomes NULL on exit */
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u32 cr2;
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u32 cr2;
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int ts;
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u32 esp1;
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u32 esp1;
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u16 ss1;
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u16 ss1;
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@ -246,14 +246,6 @@ unsigned long *lguest_arch_regptr(struct lg_cpu *cpu, size_t reg_off, bool any)
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*/
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*/
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void lguest_arch_run_guest(struct lg_cpu *cpu)
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void lguest_arch_run_guest(struct lg_cpu *cpu)
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{
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{
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/*
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* Remember the awfully-named TS bit? If the Guest has asked to set it
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* we set it now, so we can trap and pass that trap to the Guest if it
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* uses the FPU.
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*/
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if (cpu->ts && fpregs_active())
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stts();
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/*
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/*
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* SYSENTER is an optimized way of doing system calls. We can't allow
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* SYSENTER is an optimized way of doing system calls. We can't allow
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* it because it always jumps to privilege level 0. A normal Guest
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* it because it always jumps to privilege level 0. A normal Guest
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@ -282,10 +274,6 @@ void lguest_arch_run_guest(struct lg_cpu *cpu)
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if (boot_cpu_has(X86_FEATURE_SEP))
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if (boot_cpu_has(X86_FEATURE_SEP))
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wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
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wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
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/* Clear the host TS bit if it was set above. */
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if (cpu->ts && fpregs_active())
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clts();
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/*
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/*
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* If the Guest page faulted, then the cr2 register will tell us the
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* If the Guest page faulted, then the cr2 register will tell us the
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* bad virtual address. We have to grab this now, because once we
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* bad virtual address. We have to grab this now, because once we
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@ -421,12 +409,7 @@ void lguest_arch_handle_trap(struct lg_cpu *cpu)
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kill_guest(cpu, "Writing cr2");
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kill_guest(cpu, "Writing cr2");
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break;
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break;
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case 7: /* We've intercepted a Device Not Available fault. */
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case 7: /* We've intercepted a Device Not Available fault. */
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/*
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/* No special handling is needed here. */
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* If the Guest doesn't want to know, we already restored the
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* Floating Point Unit, so we just continue without telling it.
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*/
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if (!cpu->ts)
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return;
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break;
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break;
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case 32 ... 255:
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case 32 ... 255:
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/* This might be a syscall. */
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/* This might be a syscall. */
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