Re: [PATCH] KVM: nVMX: Reset nested_run_pending if the CPU is going to be reset

[Dmitry Vyukov]

On Sat, Mar 4, 2017 at 5:03 AM, Wanpeng Li  wrote:
> Reported by syzkaller:
>
> WARNING: CPU: 1 PID: 27742 at arch/x86/kvm/vmx.c:11029
> nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
> CPU: 1 PID: 27742 Comm: a.out Not tainted 4.10.0+ #229
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 
> 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:15 [inline]
>  dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
>  panic+0x1fb/0x412 kernel/panic.c:179
>  __warn+0x1c4/0x1e0 kernel/panic.c:540
>  warn_slowpath_null+0x2c/0x40 kernel/panic.c:583
>  nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
>  vmx_leave_nested arch/x86/kvm/vmx.c:11136 [inline]
>  vmx_set_msr+0x1565/0x1910 arch/x86/kvm/vmx.c:3324
>  kvm_set_msr+0xd4/0x170 arch/x86/kvm/x86.c:1099
>  do_set_msr+0x11e/0x190 arch/x86/kvm/x86.c:1128
>  __msr_io arch/x86/kvm/x86.c:2577 [inline]
>  msr_io+0x24b/0x450 arch/x86/kvm/x86.c:2614
>  kvm_arch_vcpu_ioctl+0x35b/0x46a0 arch/x86/kvm/x86.c:3497
>  kvm_vcpu_ioctl+0x232/0x1120 
> arch/x86/kvm/../../../virt/kvm/kvm_main.c:2721
>  vfs_ioctl fs/ioctl.c:43 [inline]
>  do_vfs_ioctl+0x1bf/0x1790 fs/ioctl.c:683
>  SYSC_ioctl fs/ioctl.c:698 [inline]
>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689
>  entry_SYSCALL_64_fastpath+0x1f/0xc2
>
> The syzkaller folks reported a nested_run_pending warning during userspace 
> clear VMX
> capability which is exposed to L1 before.
>
> The warning gets thrown while doing
>
> (*(uint32_t*)0x20aecfe8 = (uint32_t)0x1);
> (*(uint32_t*)0x20aecfec = (uint32_t)0x0);
> (*(uint32_t*)0x20aecff0 = (uint32_t)0x3a);
> (*(uint32_t*)0x20aecff4 = (uint32_t)0x0);
> (*(uint64_t*)0x20aecff8 = (uint64_t)0x0);
> r[29] = syscall(__NR_ioctl, r[4], 0x4008ae89ul,
> 0x20aecfe8ul, 0, 0, 0, 0, 0, 0);
>
> i.e. KVM_SET_MSR ioctl with
>
> struct kvm_msrs {
> .nmsrs = 1,
> .pad = 0,
> .entries = {
> {.index = MSR_IA32_FEATURE_CONTROL,
> .reserved = 0,
> .data = 0}
> }
> }
>
> The VMLANCH/VMRESUME emulation should be stopped since the CPU is going to 
> reset here.
> This patch resets the nested_run_pending since the CPU is going to be reset 
> hence there
> should be nothing pending.

Applied on bots. Thanks!

> Reported-by: Dmitry Vyukov 
> Suggested-by: Radim Krčmář 
> Cc: Paolo Bonzini 
> Cc: Radim Krčmář 
> Cc: Dmitry Vyukov 
> Signed-off-by: Wanpeng Li 
> ---
>  arch/x86/kvm/vmx.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 283aa86..b4a757369 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3310,8 +3310,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct 
> msr_data *msr_info)
>  FEATURE_CONTROL_LOCKED && !msr_info->host_initiated))
> return 1;
> vmx->msr_ia32_feature_control = data;
> -   if (msr_info->host_initiated && data == 0)
> +   if (msr_info->host_initiated && data == 0) {
> +   vmx->nested.nested_run_pending = 0;
> vmx_leave_nested(vcpu);
> +   }
> break;
> case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
> if (!msr_info->host_initiated)
> --
> 2.7.4
>

Re: [PATCH] KVM: nVMX: Reset nested_run_pending if the CPU is going to be reset

[Dmitry Vyukov]

On Sat, Mar 4, 2017 at 5:03 AM, Wanpeng Li  wrote:
> Reported by syzkaller:
>
> WARNING: CPU: 1 PID: 27742 at arch/x86/kvm/vmx.c:11029
> nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
> CPU: 1 PID: 27742 Comm: a.out Not tainted 4.10.0+ #229
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 
> 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:15 [inline]
>  dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
>  panic+0x1fb/0x412 kernel/panic.c:179
>  __warn+0x1c4/0x1e0 kernel/panic.c:540
>  warn_slowpath_null+0x2c/0x40 kernel/panic.c:583
>  nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
>  vmx_leave_nested arch/x86/kvm/vmx.c:11136 [inline]
>  vmx_set_msr+0x1565/0x1910 arch/x86/kvm/vmx.c:3324
>  kvm_set_msr+0xd4/0x170 arch/x86/kvm/x86.c:1099
>  do_set_msr+0x11e/0x190 arch/x86/kvm/x86.c:1128
>  __msr_io arch/x86/kvm/x86.c:2577 [inline]
>  msr_io+0x24b/0x450 arch/x86/kvm/x86.c:2614
>  kvm_arch_vcpu_ioctl+0x35b/0x46a0 arch/x86/kvm/x86.c:3497
>  kvm_vcpu_ioctl+0x232/0x1120 
> arch/x86/kvm/../../../virt/kvm/kvm_main.c:2721
>  vfs_ioctl fs/ioctl.c:43 [inline]
>  do_vfs_ioctl+0x1bf/0x1790 fs/ioctl.c:683
>  SYSC_ioctl fs/ioctl.c:698 [inline]
>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689
>  entry_SYSCALL_64_fastpath+0x1f/0xc2
>
> The syzkaller folks reported a nested_run_pending warning during userspace 
> clear VMX
> capability which is exposed to L1 before.
>
> The warning gets thrown while doing
>
> (*(uint32_t*)0x20aecfe8 = (uint32_t)0x1);
> (*(uint32_t*)0x20aecfec = (uint32_t)0x0);
> (*(uint32_t*)0x20aecff0 = (uint32_t)0x3a);
> (*(uint32_t*)0x20aecff4 = (uint32_t)0x0);
> (*(uint64_t*)0x20aecff8 = (uint64_t)0x0);
> r[29] = syscall(__NR_ioctl, r[4], 0x4008ae89ul,
> 0x20aecfe8ul, 0, 0, 0, 0, 0, 0);
>
> i.e. KVM_SET_MSR ioctl with
>
> struct kvm_msrs {
> .nmsrs = 1,
> .pad = 0,
> .entries = {
> {.index = MSR_IA32_FEATURE_CONTROL,
> .reserved = 0,
> .data = 0}
> }
> }
>
> The VMLANCH/VMRESUME emulation should be stopped since the CPU is going to 
> reset here.
> This patch resets the nested_run_pending since the CPU is going to be reset 
> hence there
> should be nothing pending.

Applied on bots. Thanks!

> Reported-by: Dmitry Vyukov 
> Suggested-by: Radim Krčmář 
> Cc: Paolo Bonzini 
> Cc: Radim Krčmář 
> Cc: Dmitry Vyukov 
> Signed-off-by: Wanpeng Li 
> ---
>  arch/x86/kvm/vmx.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 283aa86..b4a757369 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3310,8 +3310,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct 
> msr_data *msr_info)
>  FEATURE_CONTROL_LOCKED && !msr_info->host_initiated))
> return 1;
> vmx->msr_ia32_feature_control = data;
> -   if (msr_info->host_initiated && data == 0)
> +   if (msr_info->host_initiated && data == 0) {
> +   vmx->nested.nested_run_pending = 0;
> vmx_leave_nested(vcpu);
> +   }
> break;
> case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
> if (!msr_info->host_initiated)
> --
> 2.7.4
>

[PATCH] KVM: nVMX: Reset nested_run_pending if the CPU is going to be reset

[Wanpeng Li]

Reported by syzkaller:

WARNING: CPU: 1 PID: 27742 at arch/x86/kvm/vmx.c:11029
nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
CPU: 1 PID: 27742 Comm: a.out Not tainted 4.10.0+ #229
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 
01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:15 [inline]
 dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
 panic+0x1fb/0x412 kernel/panic.c:179
 __warn+0x1c4/0x1e0 kernel/panic.c:540
 warn_slowpath_null+0x2c/0x40 kernel/panic.c:583
 nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
 vmx_leave_nested arch/x86/kvm/vmx.c:11136 [inline]
 vmx_set_msr+0x1565/0x1910 arch/x86/kvm/vmx.c:3324
 kvm_set_msr+0xd4/0x170 arch/x86/kvm/x86.c:1099
 do_set_msr+0x11e/0x190 arch/x86/kvm/x86.c:1128
 __msr_io arch/x86/kvm/x86.c:2577 [inline]
 msr_io+0x24b/0x450 arch/x86/kvm/x86.c:2614
 kvm_arch_vcpu_ioctl+0x35b/0x46a0 arch/x86/kvm/x86.c:3497
 kvm_vcpu_ioctl+0x232/0x1120 
arch/x86/kvm/../../../virt/kvm/kvm_main.c:2721
 vfs_ioctl fs/ioctl.c:43 [inline]
 do_vfs_ioctl+0x1bf/0x1790 fs/ioctl.c:683
 SYSC_ioctl fs/ioctl.c:698 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689
 entry_SYSCALL_64_fastpath+0x1f/0xc2

The syzkaller folks reported a nested_run_pending warning during userspace 
clear VMX 
capability which is exposed to L1 before. 

The warning gets thrown while doing

(*(uint32_t*)0x20aecfe8 = (uint32_t)0x1);
(*(uint32_t*)0x20aecfec = (uint32_t)0x0);
(*(uint32_t*)0x20aecff0 = (uint32_t)0x3a);
(*(uint32_t*)0x20aecff4 = (uint32_t)0x0);
(*(uint64_t*)0x20aecff8 = (uint64_t)0x0);
r[29] = syscall(__NR_ioctl, r[4], 0x4008ae89ul,
0x20aecfe8ul, 0, 0, 0, 0, 0, 0);

i.e. KVM_SET_MSR ioctl with

struct kvm_msrs {
.nmsrs = 1,
.pad = 0,
.entries = {
{.index = MSR_IA32_FEATURE_CONTROL,
.reserved = 0,
.data = 0}
}
}

The VMLANCH/VMRESUME emulation should be stopped since the CPU is going to 
reset here. 
This patch resets the nested_run_pending since the CPU is going to be reset 
hence there 
should be nothing pending.

Reported-by: Dmitry Vyukov 
Suggested-by: Radim Krčmář 
Cc: Paolo Bonzini 
Cc: Radim Krčmář 
Cc: Dmitry Vyukov 
Signed-off-by: Wanpeng Li 
---
 arch/x86/kvm/vmx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 283aa86..b4a757369 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3310,8 +3310,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct 
msr_data *msr_info)
 FEATURE_CONTROL_LOCKED && !msr_info->host_initiated))
return 1;
vmx->msr_ia32_feature_control = data;
-   if (msr_info->host_initiated && data == 0)
+   if (msr_info->host_initiated && data == 0) {
+   vmx->nested.nested_run_pending = 0;
vmx_leave_nested(vcpu);
+   }
break;
case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
if (!msr_info->host_initiated)
-- 
2.7.4

[PATCH] KVM: nVMX: Reset nested_run_pending if the CPU is going to be reset

[Wanpeng Li]

Reported by syzkaller:

WARNING: CPU: 1 PID: 27742 at arch/x86/kvm/vmx.c:11029
nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
CPU: 1 PID: 27742 Comm: a.out Not tainted 4.10.0+ #229
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 
01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:15 [inline]
 dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
 panic+0x1fb/0x412 kernel/panic.c:179
 __warn+0x1c4/0x1e0 kernel/panic.c:540
 warn_slowpath_null+0x2c/0x40 kernel/panic.c:583
 nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
 vmx_leave_nested arch/x86/kvm/vmx.c:11136 [inline]
 vmx_set_msr+0x1565/0x1910 arch/x86/kvm/vmx.c:3324
 kvm_set_msr+0xd4/0x170 arch/x86/kvm/x86.c:1099
 do_set_msr+0x11e/0x190 arch/x86/kvm/x86.c:1128
 __msr_io arch/x86/kvm/x86.c:2577 [inline]
 msr_io+0x24b/0x450 arch/x86/kvm/x86.c:2614
 kvm_arch_vcpu_ioctl+0x35b/0x46a0 arch/x86/kvm/x86.c:3497
 kvm_vcpu_ioctl+0x232/0x1120 
arch/x86/kvm/../../../virt/kvm/kvm_main.c:2721
 vfs_ioctl fs/ioctl.c:43 [inline]
 do_vfs_ioctl+0x1bf/0x1790 fs/ioctl.c:683
 SYSC_ioctl fs/ioctl.c:698 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689
 entry_SYSCALL_64_fastpath+0x1f/0xc2

The syzkaller folks reported a nested_run_pending warning during userspace 
clear VMX 
capability which is exposed to L1 before. 

The warning gets thrown while doing

(*(uint32_t*)0x20aecfe8 = (uint32_t)0x1);
(*(uint32_t*)0x20aecfec = (uint32_t)0x0);
(*(uint32_t*)0x20aecff0 = (uint32_t)0x3a);
(*(uint32_t*)0x20aecff4 = (uint32_t)0x0);
(*(uint64_t*)0x20aecff8 = (uint64_t)0x0);
r[29] = syscall(__NR_ioctl, r[4], 0x4008ae89ul,
0x20aecfe8ul, 0, 0, 0, 0, 0, 0);

i.e. KVM_SET_MSR ioctl with

struct kvm_msrs {
.nmsrs = 1,
.pad = 0,
.entries = {
{.index = MSR_IA32_FEATURE_CONTROL,
.reserved = 0,
.data = 0}
}
}

The VMLANCH/VMRESUME emulation should be stopped since the CPU is going to 
reset here. 
This patch resets the nested_run_pending since the CPU is going to be reset 
hence there 
should be nothing pending.

Reported-by: Dmitry Vyukov 
Suggested-by: Radim Krčmář 
Cc: Paolo Bonzini 
Cc: Radim Krčmář 
Cc: Dmitry Vyukov 
Signed-off-by: Wanpeng Li 
---
 arch/x86/kvm/vmx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 283aa86..b4a757369 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3310,8 +3310,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct 
msr_data *msr_info)
 FEATURE_CONTROL_LOCKED && !msr_info->host_initiated))
return 1;
vmx->msr_ia32_feature_control = data;
-   if (msr_info->host_initiated && data == 0)
+   if (msr_info->host_initiated && data == 0) {
+   vmx->nested.nested_run_pending = 0;
vmx_leave_nested(vcpu);
+   }
break;
case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
if (!msr_info->host_initiated)
-- 
2.7.4