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

by gregkh＠linuxfoundation.org

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 <stable(a)vger.kernel.org>. 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 '<stable(a)vger.kernel.org>' --in-reply-to '167811895112883(a)kroah.com' --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 <seanjc(a)google.com> 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 Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-15-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 1e2eab6bda16..e0e3f2c1f681 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -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; }

2 years, 8 months

1
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FAILED: patch "[PATCH] KVM: VMX: Do _all_ initialization before exposing /dev/kvm to" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-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 <stable(a)vger.kernel.org>. 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-5.10.y git checkout FETCH_HEAD git cherry-pick -x e32b120071ea114efc0b4ddd439547750b85f618 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '1678118950130149(a)kroah.com' --subject-prefix 'PATCH 5.10.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 <seanjc(a)google.com> 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 Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-15-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 1e2eab6bda16..e0e3f2c1f681 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -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; }

2 years, 8 months

1
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FAILED: patch "[PATCH] KVM: VMX: Do _all_ initialization before exposing /dev/kvm to" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-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 <stable(a)vger.kernel.org>. 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-5.15.y git checkout FETCH_HEAD git cherry-pick -x e32b120071ea114efc0b4ddd439547750b85f618 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '167811894915491(a)kroah.com' --subject-prefix 'PATCH 5.15.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 <seanjc(a)google.com> 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 Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-15-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 1e2eab6bda16..e0e3f2c1f681 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -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; }

2 years, 8 months

1
0
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FAILED: patch "[PATCH] KVM: VMX: Do _all_ initialization before exposing /dev/kvm to" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-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 <stable(a)vger.kernel.org>. 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-6.1.y git checkout FETCH_HEAD git cherry-pick -x e32b120071ea114efc0b4ddd439547750b85f618 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '1678118948184196(a)kroah.com' --subject-prefix 'PATCH 6.1.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") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From e32b120071ea114efc0b4ddd439547750b85f618 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> 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 Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-15-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 1e2eab6bda16..e0e3f2c1f681 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -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; }

2 years, 8 months

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0 0

FAILED: patch "[PATCH] KVM: VMX: Do _all_ initialization before exposing /dev/kvm to" failed to apply to 6.2-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.2-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 <stable(a)vger.kernel.org>. 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-6.2.y git checkout FETCH_HEAD git cherry-pick -x e32b120071ea114efc0b4ddd439547750b85f618 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '167811894610616(a)kroah.com' --subject-prefix 'PATCH 6.2.y' HEAD^.. Possible dependencies: e32b120071ea ("KVM: VMX: Do _all_ initialization before exposing /dev/kvm to userspace") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From e32b120071ea114efc0b4ddd439547750b85f618 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> 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 Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-15-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 1e2eab6bda16..e0e3f2c1f681 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -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; }

2 years, 8 months

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FAILED: patch "[PATCH] KVM: Register /dev/kvm as the _very_ last thing during" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-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 <stable(a)vger.kernel.org>. 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-4.19.y git checkout FETCH_HEAD git cherry-pick -x 2b01281273738bf2d6551da48d65db2df3f28998 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '16781189338715(a)kroah.com' --subject-prefix 'PATCH 4.19.y' HEAD^.. Possible dependencies: 2b0128127373 ("KVM: Register /dev/kvm as the _very_ last thing during initialization") baff59ccdc65 ("KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except()") ae0946cd3601 ("KVM: Optimize kvm_make_vcpus_request_mask() a bit") 0bbc2ca8515f ("KVM: KVM: Use cpumask_available() to check for NULL cpumask when kicking vCPUs") 85b640450ddc ("KVM: Clean up benign vcpu->cpu data races when kicking vCPUs") e649b3f0188f ("KVM: x86: Fix APIC page invalidation race") 54163a346d4a ("KVM: Introduce kvm_make_all_cpus_request_except()") db5a95ec166f ("KVM: x86: remove set but not used variable 'called'") 7ee30bc132c6 ("KVM: x86: deliver KVM IOAPIC scan request to target vCPUs") dfcd66604c1c ("mm/mmu_notifier: convert user range->blockable to helper function") a3e0d41c2b1f ("mm/hmm: improve driver API to work and wait over a range") 73231612dc7c ("mm/hmm: improve and rename hmm_vma_fault() to hmm_range_fault()") 25f23a0c7127 ("mm/hmm: improve and rename hmm_vma_get_pfns() to hmm_range_snapshot()") 9f454612f602 ("mm/hmm: do not erase snapshot when a range is invalidated") 704f3f2cf63c ("mm/hmm: use reference counting for HMM struct") 484d9a844d0d ("drm/i915/userptr: Avoid struct_mutex recursion for mmu_invalidate_range_start") ac46d4f3c432 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2") 5d6527a784f7 ("mm/mmu_notifier: use structure for invalidate_range_start/end callback") ec131b2d7fa6 ("mm/hmm: invalidate device page table at start of invalidation") 44532d4c591c ("mm/hmm: use a structure for update callback parameters") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2b01281273738bf2d6551da48d65db2df3f28998 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Wed, 30 Nov 2022 23:08:45 +0000 Subject: [PATCH] KVM: Register /dev/kvm as the _very_ last thing during initialization Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-2-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 13e88297f999..28a1a02f5228 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5988,12 +5988,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -6002,11 +5996,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -6032,8 +6039,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache);

2 years, 8 months

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FAILED: patch "[PATCH] KVM: Register /dev/kvm as the _very_ last thing during" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-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 <stable(a)vger.kernel.org>. 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-4.14.y git checkout FETCH_HEAD git cherry-pick -x 2b01281273738bf2d6551da48d65db2df3f28998 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '167811893352(a)kroah.com' --subject-prefix 'PATCH 4.14.y' HEAD^.. Possible dependencies: 2b0128127373 ("KVM: Register /dev/kvm as the _very_ last thing during initialization") baff59ccdc65 ("KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except()") ae0946cd3601 ("KVM: Optimize kvm_make_vcpus_request_mask() a bit") 0bbc2ca8515f ("KVM: KVM: Use cpumask_available() to check for NULL cpumask when kicking vCPUs") 85b640450ddc ("KVM: Clean up benign vcpu->cpu data races when kicking vCPUs") e649b3f0188f ("KVM: x86: Fix APIC page invalidation race") 54163a346d4a ("KVM: Introduce kvm_make_all_cpus_request_except()") db5a95ec166f ("KVM: x86: remove set but not used variable 'called'") 7ee30bc132c6 ("KVM: x86: deliver KVM IOAPIC scan request to target vCPUs") dfcd66604c1c ("mm/mmu_notifier: convert user range->blockable to helper function") a3e0d41c2b1f ("mm/hmm: improve driver API to work and wait over a range") 73231612dc7c ("mm/hmm: improve and rename hmm_vma_fault() to hmm_range_fault()") 25f23a0c7127 ("mm/hmm: improve and rename hmm_vma_get_pfns() to hmm_range_snapshot()") 9f454612f602 ("mm/hmm: do not erase snapshot when a range is invalidated") 704f3f2cf63c ("mm/hmm: use reference counting for HMM struct") 484d9a844d0d ("drm/i915/userptr: Avoid struct_mutex recursion for mmu_invalidate_range_start") ac46d4f3c432 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2") 5d6527a784f7 ("mm/mmu_notifier: use structure for invalidate_range_start/end callback") ec131b2d7fa6 ("mm/hmm: invalidate device page table at start of invalidation") 44532d4c591c ("mm/hmm: use a structure for update callback parameters") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2b01281273738bf2d6551da48d65db2df3f28998 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Wed, 30 Nov 2022 23:08:45 +0000 Subject: [PATCH] KVM: Register /dev/kvm as the _very_ last thing during initialization Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-2-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 13e88297f999..28a1a02f5228 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5988,12 +5988,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -6002,11 +5996,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -6032,8 +6039,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache);

2 years, 8 months

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FAILED: patch "[PATCH] KVM: Register /dev/kvm as the _very_ last thing during" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

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 <stable(a)vger.kernel.org>. 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 2b01281273738bf2d6551da48d65db2df3f28998 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '1678118932196(a)kroah.com' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: 2b0128127373 ("KVM: Register /dev/kvm as the _very_ last thing during initialization") baff59ccdc65 ("KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except()") ae0946cd3601 ("KVM: Optimize kvm_make_vcpus_request_mask() a bit") 0bbc2ca8515f ("KVM: KVM: Use cpumask_available() to check for NULL cpumask when kicking vCPUs") 85b640450ddc ("KVM: Clean up benign vcpu->cpu data races when kicking vCPUs") e649b3f0188f ("KVM: x86: Fix APIC page invalidation race") 54163a346d4a ("KVM: Introduce kvm_make_all_cpus_request_except()") db5a95ec166f ("KVM: x86: remove set but not used variable 'called'") 7ee30bc132c6 ("KVM: x86: deliver KVM IOAPIC scan request to target vCPUs") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2b01281273738bf2d6551da48d65db2df3f28998 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Wed, 30 Nov 2022 23:08:45 +0000 Subject: [PATCH] KVM: Register /dev/kvm as the _very_ last thing during initialization Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-2-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 13e88297f999..28a1a02f5228 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5988,12 +5988,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -6002,11 +5996,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -6032,8 +6039,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache);

2 years, 8 months

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FAILED: patch "[PATCH] KVM: Register /dev/kvm as the _very_ last thing during" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-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 <stable(a)vger.kernel.org>. 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-5.10.y git checkout FETCH_HEAD git cherry-pick -x 2b01281273738bf2d6551da48d65db2df3f28998 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '167811893117738(a)kroah.com' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: 2b0128127373 ("KVM: Register /dev/kvm as the _very_ last thing during initialization") baff59ccdc65 ("KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except()") ae0946cd3601 ("KVM: Optimize kvm_make_vcpus_request_mask() a bit") 0bbc2ca8515f ("KVM: KVM: Use cpumask_available() to check for NULL cpumask when kicking vCPUs") 85b640450ddc ("KVM: Clean up benign vcpu->cpu data races when kicking vCPUs") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2b01281273738bf2d6551da48d65db2df3f28998 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Wed, 30 Nov 2022 23:08:45 +0000 Subject: [PATCH] KVM: Register /dev/kvm as the _very_ last thing during initialization Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-2-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 13e88297f999..28a1a02f5228 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5988,12 +5988,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -6002,11 +5996,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -6032,8 +6039,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache);

2 years, 8 months

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FAILED: patch "[PATCH] KVM: Register /dev/kvm as the _very_ last thing during" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-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 <stable(a)vger.kernel.org>. 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-5.15.y git checkout FETCH_HEAD git cherry-pick -x 2b01281273738bf2d6551da48d65db2df3f28998 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '1678118930227127(a)kroah.com' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: 2b0128127373 ("KVM: Register /dev/kvm as the _very_ last thing during initialization") baff59ccdc65 ("KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except()") ae0946cd3601 ("KVM: Optimize kvm_make_vcpus_request_mask() a bit") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2b01281273738bf2d6551da48d65db2df3f28998 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Wed, 30 Nov 2022 23:08:45 +0000 Subject: [PATCH] KVM: Register /dev/kvm as the _very_ last thing during initialization Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20221130230934.1014142-2-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 13e88297f999..28a1a02f5228 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5988,12 +5988,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -6002,11 +5996,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -6032,8 +6039,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache);

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