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Wed, 02 Nov 2022 16:19:34 -0700 (PDT) Date: Wed, 2 Nov 2022 23:18:39 +0000 In-Reply-To: <20221102231911.3107438-1-seanjc@google.com> Mime-Version: 1.0 References: <20221102231911.3107438-1-seanjc@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221102231911.3107438-13-seanjc@google.com> Subject: [PATCH 12/44] KVM: VMX: Do _all_ initialization before exposing /dev/kvm to userspace From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Sean Christopherson , Vitaly Kuznetsov Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Cc: kvm@vger.kernel.org, David Hildenbrand , Atish Patra , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-s390@vger.kernel.org, Chao Gao , Suzuki K Poulose , Yuan Yao , kvmarm@lists.linux.dev, Thomas Gleixner , Alexandru Elisei , linux-arm-kernel@lists.infradead.org, Isaku Yamahata , Fabiano Rosas , linux-mips@vger.kernel.org, Oliver Upton , James Morse , kvm-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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] 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 Modules linked in: vhost_net vhost vhost_iotlb tap kvm_intel(+) kvm irqbypass Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/vmx.c | 38 +++++++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 15 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 118d9b29b339..6adb60485839 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -8493,21 +8493,25 @@ 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 - - kvm_exit(); - kvm_x86_vendor_exit(); - - hv_cleanup_evmcs(); - vmx_cleanup_l1d_flush(); +} - allow_smaller_maxphyaddr = false; +static void vmx_exit(void) +{ + kvm_exit(); + kvm_x86_vendor_exit(); + + __vmx_exit(); + + hv_cleanup_evmcs(); } module_exit(vmx_exit); @@ -8521,11 +8525,6 @@ static int __init vmx_init(void) if (r) goto err_x86_init; - 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 @@ -8559,11 +8558,20 @@ 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(); err_x86_init: hv_cleanup_evmcs(); -- 2.38.1.431.g37b22c650d-goog