| Message ID | 1511388240-3163-1-git-send-email-wanpeng.li@hotmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 22/11/2017 23:04, Wanpeng Li wrote: > From: Wanpeng Li <wanpeng.li@hotmail.com> > > Reported by syzkaller: > > ------------[ cut here ]------------ > WARNING: CPU: 5 PID: 2939 at arch/x86/kvm/vmx.c:3844 free_loaded_vmcs+0x77/0x80 [kvm_intel] > CPU: 5 PID: 2939 Comm: repro Not tainted 4.14.0+ #26 > RIP: 0010:free_loaded_vmcs+0x77/0x80 [kvm_intel] > Call Trace: > vmx_free_vcpu+0xda/0x130 [kvm_intel] > kvm_arch_destroy_vm+0x192/0x290 [kvm] > kvm_put_kvm+0x262/0x560 [kvm] > kvm_vm_release+0x2c/0x30 [kvm] > __fput+0x190/0x370 > task_work_run+0xa1/0xd0 > do_exit+0x4d2/0x13e0 > do_group_exit+0x89/0x140 > get_signal+0x318/0xb80 > do_signal+0x8c/0xb40 > exit_to_usermode_loop+0xe4/0x140 > syscall_return_slowpath+0x206/0x230 > entry_SYSCALL_64_fastpath+0x98/0x9a > > The syzkaller testcase will execute VMXON/VMLAUCH instructions, so the > vmx->nested stuff is populated, it will also issue KVM_SMI ioctl. However, > the testcase is just a simple c program and not be lauched by something > like seabios which implements smi_handler. Commit 05cade71cf (KVM: nSVM: > fix SMI injection in guest mode) gets out of guest mode and set nested.vmxon > to false for the duration of SMM according to SDM 34.14.1 "leave VMX > operation" upon entering SMM. We can't alloc/free the vmx->nested stuff > each time when entering/exiting SMM since it will induce more overhead. So > the function vmx_pre_enter_smm() marks nested.vmxon false even if vmx->nested > stuff is still populated. What it expected is em_rsm() can mark nested.vmxon > to be true again. However, the smi_handler/rsm will not execute since there > is no something like seabios in this scenario. The function free_nested() > fails to free the vmx->nested stuff since the vmx->nested.vmxon is false > which results in the above warning. > > This patch fixes it by also considering the no SMI handler case, luckily > vmx->nested.smm.vmxon is marked according to the value of vmx->nested.vmxon > in vmx_pre_enter_smm(), we can take advantage of it and free vmx->nested > stuff when L1 goes down. > > Reported-by: Dmitry Vyukov <dvyukov@google.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Reviewed-by: Liran Alon <liran.alon@oracle.com> > Fixes: 05cade71cf (KVM: nSVM: fix SMI injection in guest mode) > Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> > --- > v1 -> v2: > * also clear nested.smm.vmxon flag > > arch/x86/kvm/vmx.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index e1f4e29..a62e1af 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -7373,10 +7373,11 @@ static inline void nested_release_vmcs12(struct vcpu_vmx *vmx) > */ > static void free_nested(struct vcpu_vmx *vmx) > { > - if (!vmx->nested.vmxon) > + if (!vmx->nested.vmxon && !vmx->nested.smm.vmxon) > return; > > vmx->nested.vmxon = false; > + vmx->nested.smm.vmxon = false; > free_vpid(vmx->nested.vpid02); > vmx->nested.posted_intr_nv = -1; > vmx->nested.current_vmptr = -1ull; > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
On 22/11/2017 23:04, Wanpeng Li wrote: > From: Wanpeng Li <wanpeng.li@hotmail.com> > > Reported by syzkaller: > > ------------[ cut here ]------------ > WARNING: CPU: 5 PID: 2939 at arch/x86/kvm/vmx.c:3844 free_loaded_vmcs+0x77/0x80 [kvm_intel] > CPU: 5 PID: 2939 Comm: repro Not tainted 4.14.0+ #26 > RIP: 0010:free_loaded_vmcs+0x77/0x80 [kvm_intel] > Call Trace: > vmx_free_vcpu+0xda/0x130 [kvm_intel] > kvm_arch_destroy_vm+0x192/0x290 [kvm] > kvm_put_kvm+0x262/0x560 [kvm] > kvm_vm_release+0x2c/0x30 [kvm] > __fput+0x190/0x370 > task_work_run+0xa1/0xd0 > do_exit+0x4d2/0x13e0 > do_group_exit+0x89/0x140 > get_signal+0x318/0xb80 > do_signal+0x8c/0xb40 > exit_to_usermode_loop+0xe4/0x140 > syscall_return_slowpath+0x206/0x230 > entry_SYSCALL_64_fastpath+0x98/0x9a > > The syzkaller testcase will execute VMXON/VMLAUCH instructions, so the > vmx->nested stuff is populated, it will also issue KVM_SMI ioctl. However, > the testcase is just a simple c program and not be lauched by something > like seabios which implements smi_handler. Commit 05cade71cf (KVM: nSVM: > fix SMI injection in guest mode) gets out of guest mode and set nested.vmxon > to false for the duration of SMM according to SDM 34.14.1 "leave VMX > operation" upon entering SMM. We can't alloc/free the vmx->nested stuff > each time when entering/exiting SMM since it will induce more overhead. So > the function vmx_pre_enter_smm() marks nested.vmxon false even if vmx->nested > stuff is still populated. What it expected is em_rsm() can mark nested.vmxon > to be true again. However, the smi_handler/rsm will not execute since there > is no something like seabios in this scenario. The function free_nested() > fails to free the vmx->nested stuff since the vmx->nested.vmxon is false > which results in the above warning. > > This patch fixes it by also considering the no SMI handler case, luckily > vmx->nested.smm.vmxon is marked according to the value of vmx->nested.vmxon > in vmx_pre_enter_smm(), we can take advantage of it and free vmx->nested > stuff when L1 goes down. > > Reported-by: Dmitry Vyukov <dvyukov@google.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Reviewed-by: Liran Alon <liran.alon@oracle.com> > Fixes: 05cade71cf (KVM: nSVM: fix SMI injection in guest mode) > Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> > --- > v1 -> v2: > * also clear nested.smm.vmxon flag > > arch/x86/kvm/vmx.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index e1f4e29..a62e1af 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -7373,10 +7373,11 @@ static inline void nested_release_vmcs12(struct vcpu_vmx *vmx) > */ > static void free_nested(struct vcpu_vmx *vmx) > { > - if (!vmx->nested.vmxon) > + if (!vmx->nested.vmxon && !vmx->nested.smm.vmxon) > return; > > vmx->nested.vmxon = false; > + vmx->nested.smm.vmxon = false; > free_vpid(vmx->nested.vpid02); > vmx->nested.posted_intr_nv = -1; > vmx->nested.current_vmptr = -1ull; > Queued, thanks. Paolo
On Wed, Nov 22, 2017 at 11:04 PM, Wanpeng Li <kernellwp@gmail.com> wrote: > From: Wanpeng Li <wanpeng.li@hotmail.com> > > Reported by syzkaller: > > ------------[ cut here ]------------ > WARNING: CPU: 5 PID: 2939 at arch/x86/kvm/vmx.c:3844 free_loaded_vmcs+0x77/0x80 [kvm_intel] > CPU: 5 PID: 2939 Comm: repro Not tainted 4.14.0+ #26 > RIP: 0010:free_loaded_vmcs+0x77/0x80 [kvm_intel] > Call Trace: > vmx_free_vcpu+0xda/0x130 [kvm_intel] > kvm_arch_destroy_vm+0x192/0x290 [kvm] > kvm_put_kvm+0x262/0x560 [kvm] > kvm_vm_release+0x2c/0x30 [kvm] > __fput+0x190/0x370 > task_work_run+0xa1/0xd0 > do_exit+0x4d2/0x13e0 > do_group_exit+0x89/0x140 > get_signal+0x318/0xb80 > do_signal+0x8c/0xb40 > exit_to_usermode_loop+0xe4/0x140 > syscall_return_slowpath+0x206/0x230 > entry_SYSCALL_64_fastpath+0x98/0x9a > > The syzkaller testcase will execute VMXON/VMLAUCH instructions, so the > vmx->nested stuff is populated, it will also issue KVM_SMI ioctl. However, > the testcase is just a simple c program and not be lauched by something > like seabios which implements smi_handler. Commit 05cade71cf (KVM: nSVM: > fix SMI injection in guest mode) gets out of guest mode and set nested.vmxon Just a nit, this should be 72e9cbdb43 (KVM: nVMX: fix SMI injection in guest mode) > to false for the duration of SMM according to SDM 34.14.1 "leave VMX > operation" upon entering SMM. We can't alloc/free the vmx->nested stuff > each time when entering/exiting SMM since it will induce more overhead. So > the function vmx_pre_enter_smm() marks nested.vmxon false even if vmx->nested > stuff is still populated. What it expected is em_rsm() can mark nested.vmxon > to be true again. However, the smi_handler/rsm will not execute since there > is no something like seabios in this scenario. The function free_nested() > fails to free the vmx->nested stuff since the vmx->nested.vmxon is false > which results in the above warning. > > This patch fixes it by also considering the no SMI handler case, luckily > vmx->nested.smm.vmxon is marked according to the value of vmx->nested.vmxon > in vmx_pre_enter_smm(), we can take advantage of it and free vmx->nested > stuff when L1 goes down. > > Reported-by: Dmitry Vyukov <dvyukov@google.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Reviewed-by: Liran Alon <liran.alon@oracle.com> > Fixes: 05cade71cf (KVM: nSVM: fix SMI injection in guest mode) Same here. > Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> > --- > v1 -> v2: > * also clear nested.smm.vmxon flag > > arch/x86/kvm/vmx.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index e1f4e29..a62e1af 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -7373,10 +7373,11 @@ static inline void nested_release_vmcs12(struct vcpu_vmx *vmx) > */ > static void free_nested(struct vcpu_vmx *vmx) > { > - if (!vmx->nested.vmxon) > + if (!vmx->nested.vmxon && !vmx->nested.smm.vmxon) > return; > > vmx->nested.vmxon = false; > + vmx->nested.smm.vmxon = false; > free_vpid(vmx->nested.vpid02); > vmx->nested.posted_intr_nv = -1; > vmx->nested.current_vmptr = -1ull; Thank you! Ladi
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index e1f4e29..a62e1af 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -7373,10 +7373,11 @@ static inline void nested_release_vmcs12(struct vcpu_vmx *vmx) */ static void free_nested(struct vcpu_vmx *vmx) { - if (!vmx->nested.vmxon) + if (!vmx->nested.vmxon && !vmx->nested.smm.vmxon) return; vmx->nested.vmxon = false; + vmx->nested.smm.vmxon = false; free_vpid(vmx->nested.vpid02); vmx->nested.posted_intr_nv = -1; vmx->nested.current_vmptr = -1ull;