KVM: x86: Remove unneeded kvm_vcpu variable, guest_xcr0_loaded (78958563) · Commits · 戴 / test

The kvm_vcpu variable, guest_xcr0_loaded, is a waste of an 'int' and a conditional branch. VMX and SVM are the only users, and both unconditionally pair kvm_load_guest_xcr0() with kvm_put_guest_xcr0() making this check unnecessary. Without this variable, the predicates in kvm_load_guest_xcr0 and kvm_put_guest_xcr0 should match. Suggested-by:

Sean Christopherson <sean.j.christopherson@intel.com> Reviewed-by:

Jim Mattson <jmattson@google.com> Signed-off-by:

Aaron Lewis <aaronlewis@google.com> Change-Id: I7b1eb9b62969d7bbb2850f27e42f863421641b23 Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

+5 −11

Original line number	Diff line number	Diff line
		@@ -811,22 +811,16 @@ EXPORT_SYMBOL_GPL(kvm_lmsw);
		void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu)
		{
		if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
		!vcpu->guest_xcr0_loaded) {
		/* kvm_set_xcr() also depends on this */
		if (vcpu->arch.xcr0 != host_xcr0)
		vcpu->arch.xcr0 != host_xcr0)
		xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0);
		vcpu->guest_xcr0_loaded = 1;
		}
		}
		EXPORT_SYMBOL_GPL(kvm_load_guest_xcr0);

		void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
		{
		if (vcpu->guest_xcr0_loaded) {
		if (vcpu->arch.xcr0 != host_xcr0)
		if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
		vcpu->arch.xcr0 != host_xcr0)
		xsetbv(XCR_XFEATURE_ENABLED_MASK, host_xcr0);
		vcpu->guest_xcr0_loaded = 0;
		}
		}
		EXPORT_SYMBOL_GPL(kvm_put_guest_xcr0);

include/linux/kvm_host.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -278,7 +278,6 @@ struct kvm_vcpu {
		struct mutex mutex;
		struct kvm_run *run;

		int guest_xcr0_loaded;
		struct swait_queue_head wq;
		struct pid __rcu *pid;
		int sigset_active;

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