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Message-ID: <20221102231911.3107438-13-seanjc@google.com>
Date: Wed, 2 Nov 2022 23:18:39 +0000
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>,
Huacai Chen <chenhuacai@...nel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
Anup Patel <anup@...infault.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Matthew Rosato <mjrosato@...ux.ibm.com>,
Eric Farman <farman@...ux.ibm.com>,
Sean Christopherson <seanjc@...gle.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: James Morse <james.morse@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Oliver Upton <oliver.upton@...ux.dev>,
Atish Patra <atishp@...shpatra.org>,
David Hildenbrand <david@...hat.com>, kvm@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
kvmarm@...ts.cs.columbia.edu, linux-mips@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org,
linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
linux-kernel@...r.kernel.org,
Isaku Yamahata <isaku.yamahata@...el.com>,
Fabiano Rosas <farosas@...ux.ibm.com>,
Michael Ellerman <mpe@...erman.id.au>,
Chao Gao <chao.gao@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Yuan Yao <yuan.yao@...el.com>
Subject: [PATCH 12/44] 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@...r.kernel.org
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
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
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