x86/fpu, kvm: Remove host CR0.TS manipulation

Now that x86 always uses eager FPU switching on the host, there's no
need for KVM to manipulate the host's CR0.TS.

This should be both simpler and faster.

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/b212064922537c05d0c81d931fc4dbe769127ce7.1477951965.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cf1b16dbc98a90d4035a480362a549f299faf55f..531c446331903072b49033dc4cdf86c5889b341c 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2144,12 +2144,6 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx)
 #endif
        if (vmx->host_state.msr_host_bndcfgs)
                wrmsrl(MSR_IA32_BNDCFGS, vmx->host_state.msr_host_bndcfgs);
-       /*
-        * If the FPU is not active (through the host task or
-        * the guest vcpu), then restore the cr0.TS bit.
-        */
-       if (!fpregs_active() && !vmx->vcpu.guest_fpu_loaded)
-               stts();
        load_gdt(this_cpu_ptr(&host_gdt));
 }
 
@@ -4871,9 +4865,11 @@ static void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
        u32 low32, high32;
        unsigned long tmpl;
        struct desc_ptr dt;
-       unsigned long cr4;
+       unsigned long cr0, cr4;
 
-       vmcs_writel(HOST_CR0, read_cr0() & ~X86_CR0_TS);  /* 22.2.3 */
+       cr0 = read_cr0();
+       WARN_ON(cr0 & X86_CR0_TS);
+       vmcs_writel(HOST_CR0, cr0);  /* 22.2.3 */
        vmcs_writel(HOST_CR3, read_cr3());  /* 22.2.3  FIXME: shadow tables */
 
        /* Save the most likely value for this task's CR4 in the VMCS. */

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7f9fa2d8f4e4745ea78fb13c5d1858439ff05c7d..cfe6a75b5358bfe4c5826941258b2212cb9919f5 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5060,11 +5060,6 @@ static void emulator_get_fpu(struct x86_emulate_ctxt *ctxt)
 {
        preempt_disable();
        kvm_load_guest_fpu(emul_to_vcpu(ctxt));
-       /*
-        * CR0.TS may reference the host fpu state, not the guest fpu state,
-        * so it may be clear at this point.
-        */
-       clts();
 }
 
 static void emulator_put_fpu(struct x86_emulate_ctxt *ctxt)