Messages in this thread | | | From | Coleman Dietsch <> | Subject | [PATCH v2 0/2] KVM: x86/xen: Prevent xen timer init when running | Date | Fri, 29 Jul 2022 13:46:38 -0500 |
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This patch series was created to address the following bug found by syzbot WARNING: ODEBUG bug in kvm_xen_vcpu_set_attr.
When running the syzbot reproducer code, the following crash dump occurs:
ODEBUG: init active (active state 0) object type: hrtimer hint: xen_timer_callbac0 RIP: 0010:debug_print_object+0x16e/0x250 lib/debugobjects.c:502 Call Trace: __debug_object_init debug_hrtimer_init debug_init hrtimer_init kvm_xen_init_timer kvm_xen_vcpu_set_attr kvm_arch_vcpu_ioctl kvm_vcpu_ioctl vfs_ioctl
The ODEBUG bug crash appears to be happening when vcpu->arch.xen.timer is already set and kvm_xen_init_timer() is called, which appears to be the result of two separate issues.
The first issue is that kvm_xen_init_timer() is run "every" KVM_XEN_VCPU_ATTR_TYPE_TIMER. This is addressed in patch 1.
The second issue is that the stop xen timer code should be run before changing the IRQ vector. This is addressed in patch 2 with some cleanup.
version 2 changes (mostly feedback from Sean Christopherson) -split patch into 2 patches -fix changelogs to be more descriptive -fix formatting issues -add check for existing xen timer before trying to initialize another one -removed conditional for kvm_xen_stop_timer() so that it always runs -ensure that xen timer is stopped before changing IRQ vector -streamlined switch case KVM_XEN_VCPU_ATTR_TYPE_TIMER a bit
Coleman Dietsch (2): KVM: x86/xen: Initialize Xen timer only once KVM: x86/xen: Stop Xen timer before changing the IRQ vector
arch/x86/kvm/xen.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-)
-- 2.34.1
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