Commit 9c1c3fac authored Aug 24, 2012 by Suresh Siddha Committed by H. Peter Anvin Sep 18, 2012

x86, kvm: use kernel_fpu_begin/end() in kvm_load/put_guest_fpu()



kvm's guest fpu save/restore should be wrapped around
kernel_fpu_begin/end(). This will avoid for example taking a DNA
in kvm_load_guest_fpu() when it tries to load the fpu immediately
after doing unlazy_fpu() on the host side.

More importantly this will prevent the host process fpu from being
corrupted.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-4-git-send-email-suresh.b.siddha@intel.com


Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

parent 377ffbcc

arch/x86/kvm/x86.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -5972,7 +5972,7 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
		*/
		kvm_put_guest_xcr0(vcpu);
		vcpu->guest_fpu_loaded = 1;
		unlazy_fpu(current);
		kernel_fpu_begin();
		fpu_restore_checking(&vcpu->arch.guest_fpu);
		trace_kvm_fpu(1);
		}
		@@ -5986,6 +5986,7 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)

		vcpu->guest_fpu_loaded = 0;
		fpu_save_init(&vcpu->arch.guest_fpu);
		kernel_fpu_end();
		++vcpu->stat.fpu_reload;
		kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
		trace_kvm_fpu(0);

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