x86/fpu, kvm: Remove host CR0.TS manipulation (04ac88ab) · Commits · 戴 / test

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>

arch/x86/kvm/vmx.c

+4 −8

Original line number	Diff line number	Diff line
		@@ -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. */

arch/x86/kvm/x86.c

+0 −5

Original line number	Diff line number	Diff line
		@@ -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)

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