On 21/02/20 16:39, Alex Williamson wrote: > 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 > Thanks to both of you. I'll get it to Linus next Monday. Paolo
