On Fri, 21 Feb 2020 08:52:17 -0600 Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> wrote: > Launching VM w/ AVIC disabled together with pass-through device > results in NULL pointer dereference bug with the following call trace. > > RIP: 0010:svm_refresh_apicv_exec_ctrl+0x17e/0x1a0 [kvm_amd] > > Call Trace: > kvm_vcpu_update_apicv+0x44/0x60 [kvm] > kvm_arch_vcpu_ioctl_run+0x3f4/0x1c80 [kvm] > kvm_vcpu_ioctl+0x3d8/0x650 [kvm] > do_vfs_ioctl+0xaa/0x660 > ? tomoyo_file_ioctl+0x19/0x20 > ksys_ioctl+0x67/0x90 > __x64_sys_ioctl+0x1a/0x20 > do_syscall_64+0x57/0x190 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Investigation shows that this is due to the uninitialized usage of > struct vapu_svm.ir_list in the svm_set_pi_irte_mode(), which is > called from svm_refresh_apicv_exec_ctrl(). > > The ir_list is initialized only if AVIC is enabled. So, fixes by > adding a check if AVIC is enabled in the svm_refresh_apicv_exec_ctrl(). > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=206579 > Fixes: 8937d762396d ("kvm: x86: svm: Add support to (de)activate posted interrupts.") > Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> > Cc: Alex Williamson <alex.williamson@xxxxxxxxxx> > --- > arch/x86/kvm/svm.c | 3 +++ > 1 file changed, 3 insertions(+) Works for me, thanks Suravee! Tested-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 19035fb..1858455 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -5222,6 +5222,9 @@ static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu) > struct vmcb *vmcb = svm->vmcb; > bool activated = kvm_vcpu_apicv_active(vcpu); > > + if (!avic) > + return; > + > if (activated) { > /** > * During AVIC temporary deactivation, guest could update
