Commit da38f438 authored Jul 06, 2010 by Avi Kivity

KVM: VMX: Fix host MSR_KERNEL_GS_BASE corruption



enter_lmode() and exit_lmode() modify the guest's EFER.LMA before calling
vmx_set_efer().  However, the latter function depends on the value of EFER.LMA
to determine whether MSR_KERNEL_GS_BASE needs reloading, via
vmx_load_host_state().  With EFER.LMA changing under its feet, it took the
wrong choice and corrupted userspace's %gs.

This causes 32-on-64 host userspace to fault.

Fix not touching EFER.LMA; instead ask vmx_set_efer() to change it.

Signed-off-by: Avi Kivity <avi@redhat.com>

parent 815c4163

arch/x86/kvm/vmx.c

+2 −5

Original line number	Diff line number	Diff line
		@@ -1744,18 +1744,15 @@ static void enter_lmode(struct kvm_vcpu *vcpu)
		(guest_tr_ar & ~AR_TYPE_MASK)
		\| AR_TYPE_BUSY_64_TSS);
		}
		vcpu->arch.efer \|= EFER_LMA;
		vmx_set_efer(vcpu, vcpu->arch.efer);
		vmx_set_efer(vcpu, vcpu->arch.efer \| EFER_LMA);
		}

		static void exit_lmode(struct kvm_vcpu *vcpu)
		{
		vcpu->arch.efer &= ~EFER_LMA;

		vmcs_write32(VM_ENTRY_CONTROLS,
		vmcs_read32(VM_ENTRY_CONTROLS)
		& ~VM_ENTRY_IA32E_MODE);
		vmx_set_efer(vcpu, vcpu->arch.efer);
		vmx_set_efer(vcpu, vcpu->arch.efer & ~EFER_LMA);
		}

		#endif

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