From: Avi Kivity Date: Tue, 6 Jul 2010 08:30:49 +0000 (+0300) Subject: KVM: VMX: Fix host MSR_KERNEL_GS_BASE corruption X-Git-Tag: firefly_0821_release~9833^2~1417^2~1 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=da38f43859467a8048365b9e1cce99ccbc62b6e2;p=firefly-linux-kernel-4.4.55.git 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 --- diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 859a01a07dbf..ee03679efe78 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -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