FAILED: patch "[PATCH] KVM: VMX: Do _all_ initialization before exposing /dev/kvm to" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x e32b120071ea114efc0b4ddd439547750b85f618
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '[email protected]' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

e32b120071ea ("KVM: VMX: Do _all_ initialization before exposing /dev/kvm to userspace") 4f8396b96a9f ("KVM: x86: Move guts of kvm_arch_init() to standalone helper") da66de44b01e ("KVM: VMX: Don't bother disabling eVMCS static key on module exit") 2916b70fc342 ("KVM: VMX: Reset eVMCS controls in VP assist page during hardware disabling") 94bda2f4cd86 ("KVM: x86: Reject loading KVM if host.PAT[0] != WB") fdc298da8661 ("KVM: x86: Move kvm_ops_static_call_update() to x86.c") 5e17b2ee45b9 ("kvm: x86: Require const tsc for RT")
925088781eed ("KVM: x86: Fix pointer mistmatch warning when patching RET0 static calls") 5be2226f417d ("KVM: x86: allow defining return-0 static calls")
abb6d479e226 ("KVM: x86: make several APIC virtualization callbacks optional") dd2319c61888 ("KVM: x86: warn on incorrectly NULL members of kvm_x86_ops") e4fc23bad813 ("KVM: x86: remove KVM_X86_OP_NULL and mark optional kvm_x86_ops") 8a2897853c53 ("KVM: x86: return 1 unconditionally for availability of KVM_CAP_VAPIC") db6e7adf8de9 ("KVM: SVM: Rename AVIC helpers to use "avic" prefix instead of "svm"") 4e71cad31c62 ("Merge remote-tracking branch 'kvm/master' into HEAD")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e32b120071ea114efc0b4ddd439547750b85f618 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <[email protected]>
Date: Wed, 30 Nov 2022 23:08:58 +0000
Subject: [PATCH] KVM: VMX: Do _all_ initialization before exposing /dev/kvm to
userspace

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

Message-Id: <[email protected]>

index 1e2eab6bda16..e0e3f2c1f681 100644
@@ -8564,19 +8564,23 @@ 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);
 

@@ -8594,11 +8598,6 @@ 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

@@ -8632,11 +8631,20 @@ 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;
 }