From: Sean Christopherson seanjc@google.com
[ Upstream commit e32b120071ea114efc0b4ddd439547750b85f618 ]
Call kvm_init() only after _all_ setup is complete, as kvm_init() exposes /dev/kvm to userspace and thus allows userspace to create VMs (and call other ioctls). E.g. KVM will encounter a NULL pointer when attempting to add a vCPU to the per-CPU loaded_vmcss_on_cpu list if userspace is able to create a VM before vmx_init() configures said list.
BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP CPU: 6 PID: 1143 Comm: stable Not tainted 6.0.0-rc7+ #988 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:vmx_vcpu_load_vmcs+0x68/0x230 [kvm_intel] <TASK> vmx_vcpu_load+0x16/0x60 [kvm_intel] kvm_arch_vcpu_load+0x32/0x1f0 [kvm] vcpu_load+0x2f/0x40 [kvm] kvm_arch_vcpu_create+0x231/0x310 [kvm] kvm_vm_ioctl+0x79f/0xe10 [kvm] ? handle_mm_fault+0xb1/0x220 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f5a6b05743b </TASK> Modules linked in: vhost_net vhost vhost_iotlb tap kvm_intel(+) kvm irqbypass
Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20221130230934.1014142-15-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/vmx/vmx.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 81a23ae4f872b..bc868958e91fe 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -8456,19 +8456,23 @@ static void vmx_cleanup_l1d_flush(void) l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; }
-static void vmx_exit(void) +static void __vmx_exit(void) { + allow_smaller_maxphyaddr = false; + #ifdef CONFIG_KEXEC_CORE RCU_INIT_POINTER(crash_vmclear_loaded_vmcss, NULL); synchronize_rcu(); #endif + vmx_cleanup_l1d_flush(); +}
+static void vmx_exit(void) +{ kvm_exit(); kvm_x86_vendor_exit();
- vmx_cleanup_l1d_flush(); - - allow_smaller_maxphyaddr = false; + __vmx_exit(); } module_exit(vmx_exit);
@@ -8513,11 +8517,6 @@ static int __init vmx_init(void) if (r) return r;
- r = kvm_init(&vmx_init_ops, sizeof(struct vcpu_vmx), - __alignof__(struct vcpu_vmx), THIS_MODULE); - if (r) - goto err_kvm_init; - /* * Must be called after common x86 init so enable_ept is properly set * up. Hand the parameter mitigation value in which was stored in @@ -8551,11 +8550,20 @@ static int __init vmx_init(void) if (!enable_ept) allow_smaller_maxphyaddr = true;
+ /* + * Common KVM initialization _must_ come last, after this, /dev/kvm is + * exposed to userspace! + */ + r = kvm_init(&vmx_init_ops, sizeof(struct vcpu_vmx), + __alignof__(struct vcpu_vmx), THIS_MODULE); + if (r) + goto err_kvm_init; + return 0;
-err_l1d_flush: - vmx_exit(); err_kvm_init: + __vmx_exit(); +err_l1d_flush: kvm_x86_vendor_exit(); return r; }