From: Sean Christopherson Date: Thu, 18 Jun 2026 17:43:46 +0000 (-0700) Subject: KVM: VMX: Grab vmcs12 on CR8 interception update iff vCPU is in guest mode X-Git-Tag: v7.2-rc1~30^2~4 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=7ef78d71ca713d8c00f7c34ddcf276c808143f77;p=thirdparty%2Flinux.git KVM: VMX: Grab vmcs12 on CR8 interception update iff vCPU is in guest mode When updating CR8 intercepts, get vmcs12 if and only if the vCPU is in guest mode so that a future change can have update CR8 intercepts during vCPU creation, without running afoul of get_vmcs12()'s lockdep assertion. ------------[ cut here ]------------ debug_locks && !(lock_is_held(&(&vcpu->mutex)->dep_map) || !refcount_read(&vcpu->kvm->users_count)) WARNING: arch/x86/kvm/vmx/nested.h:61 at get_vmcs12 arch/x86/kvm/vmx/nested.h:60 [inline], CPU#0: syz.2.19/5879 WARNING: arch/x86/kvm/vmx/nested.h:61 at vmx_update_cr8_intercept+0x3de/0x4e0 arch/x86/kvm/vmx/vmx.c:6879, CPU#0: syz.2.19/5879 Modules linked in: CPU: 0 UID: 0 PID: 5879 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:get_vmcs12 arch/x86/kvm/vmx/nested.h:60 [inline] RIP: 0010:vmx_update_cr8_intercept+0x3de/0x4e0 arch/x86/kvm/vmx/vmx.c:6879 Call Trace: apic_update_ppr arch/x86/kvm/lapic.c:984 [inline] kvm_lapic_reset+0x1c24/0x2980 arch/x86/kvm/lapic.c:3023 kvm_vcpu_reset+0x44c/0x1bf0 arch/x86/kvm/x86.c:12986 kvm_arch_vcpu_create+0x746/0x8b0 arch/x86/kvm/x86.c:12847 kvm_vm_ioctl_create_vcpu+0x428/0x930 virt/kvm/kvm_main.c:4201 kvm_vm_ioctl+0x893/0xd50 virt/kvm/kvm_main.c:5159 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f No functional change intended. Reported-by: syzbot ci Closes: https://lore.kernel.org/all/6a2adf3b.3b0a2d4e.8c8d1.0012.GAE@google.com Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-ID: <20260618174347.1981064-2-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index a1a5edb39a7ed..125994ed3db5b 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6872,11 +6872,10 @@ int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) void vmx_update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr) { - struct vmcs12 *vmcs12 = get_vmcs12(vcpu); int tpr_threshold; if (is_guest_mode(vcpu) && - nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW)) + nested_cpu_has(get_vmcs12(vcpu), CPU_BASED_TPR_SHADOW)) return; guard(vmx_vmcs01)(vcpu);