diff mbox

[3/3] KVM: nVMX: Fix vmptrld fail and vmwrite error when L1 goes down

Message ID 1405573011-41330-3-git-send-email-wanpeng.li@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Wanpeng Li July 17, 2014, 4:56 a.m. UTC 
This bug can be trigger by L1 goes down directly w/ enable_shadow_vmcs.

[ 6413.158950] kvm: vmptrld           (null)/780000000000 failed
[ 6413.158954] vmwrite error: reg 401e value 4 (err 1)
[ 6413.158957] CPU: 0 PID: 4840 Comm: qemu-system-x86 Tainted: G           OE 3.16.0kvm+ #2
[ 6413.158958] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05 12/05/2013
[ 6413.158959]  0000000000000003 ffff880210c9fb58 ffffffff81741de9 ffff8800d7433f80
[ 6413.158960]  ffff880210c9fb68 ffffffffa059fa08 ffff880210c9fb78 ffffffffa05938bf
[ 6413.158962]  ffff880210c9fba8 ffffffffa059a97f ffff8800d7433f80 0000000000000003
[ 6413.158963] Call Trace:
[ 6413.158968]  [<ffffffff81741de9>] dump_stack+0x45/0x56
[ 6413.158972]  [<ffffffffa059fa08>] vmwrite_error+0x2c/0x2e [kvm_intel]
[ 6413.158974]  [<ffffffffa05938bf>] vmcs_writel+0x1f/0x30 [kvm_intel]
[ 6413.158976]  [<ffffffffa059a97f>] free_nested.part.73+0x5f/0x170 [kvm_intel]
[ 6413.158978]  [<ffffffffa059ab13>] vmx_free_vcpu+0x33/0x70 [kvm_intel]
[ 6413.158991]  [<ffffffffa0360324>] kvm_arch_vcpu_free+0x44/0x50 [kvm]
[ 6413.158998]  [<ffffffffa0360f92>] kvm_arch_destroy_vm+0xf2/0x1f0 [kvm]

Commit 26a865 (KVM: VMX: fix use after free of vmx->loaded_vmcs) fix the use 
after free bug by move free_loaded_vmcs() before free_nested(), however, this 
lead to free loaded_vmcs->vmcs premature and vmptrld load a NULL pointer during 
sync shadow vmcs to vmcs12. In addition, vmwrite which used to disable shadow 
vmcs and reset VMCS_LINK_POINTER failed since there is no valid current-VMCS.
This patch fix it by skipping sync shadow vmcs and reset vmcs field for L1 
destroy since they will be reinitialized after L1 recreate.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
---
 arch/x86/kvm/vmx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Paolo Bonzini July 17, 2014, 8:56 a.m. UTC | #1 
Il 17/07/2014 06:56, Wanpeng Li ha scritto:
> This bug can be trigger by L1 goes down directly w/ enable_shadow_vmcs.
>
> [ 6413.158950] kvm: vmptrld           (null)/780000000000 failed
> [ 6413.158954] vmwrite error: reg 401e value 4 (err 1)
> [ 6413.158957] CPU: 0 PID: 4840 Comm: qemu-system-x86 Tainted: G           OE 3.16.0kvm+ #2
> [ 6413.158958] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05 12/05/2013
> [ 6413.158959]  0000000000000003 ffff880210c9fb58 ffffffff81741de9 ffff8800d7433f80
> [ 6413.158960]  ffff880210c9fb68 ffffffffa059fa08 ffff880210c9fb78 ffffffffa05938bf
> [ 6413.158962]  ffff880210c9fba8 ffffffffa059a97f ffff8800d7433f80 0000000000000003
> [ 6413.158963] Call Trace:
> [ 6413.158968]  [<ffffffff81741de9>] dump_stack+0x45/0x56
> [ 6413.158972]  [<ffffffffa059fa08>] vmwrite_error+0x2c/0x2e [kvm_intel]
> [ 6413.158974]  [<ffffffffa05938bf>] vmcs_writel+0x1f/0x30 [kvm_intel]
> [ 6413.158976]  [<ffffffffa059a97f>] free_nested.part.73+0x5f/0x170 [kvm_intel]
> [ 6413.158978]  [<ffffffffa059ab13>] vmx_free_vcpu+0x33/0x70 [kvm_intel]
> [ 6413.158991]  [<ffffffffa0360324>] kvm_arch_vcpu_free+0x44/0x50 [kvm]
> [ 6413.158998]  [<ffffffffa0360f92>] kvm_arch_destroy_vm+0xf2/0x1f0 [kvm]
>
> Commit 26a865 (KVM: VMX: fix use after free of vmx->loaded_vmcs) fix the use
> after free bug by move free_loaded_vmcs() before free_nested(), however, this
> lead to free loaded_vmcs->vmcs premature and vmptrld load a NULL pointer during
> sync shadow vmcs to vmcs12. In addition, vmwrite which used to disable shadow
> vmcs and reset VMCS_LINK_POINTER failed since there is no valid current-VMCS.
> This patch fix it by skipping sync shadow vmcs and reset vmcs field for L1
> destroy since they will be reinitialized after L1 recreate.
>
> Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
> ---
>  arch/x86/kvm/vmx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index fbce89e..2b28da7 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6113,9 +6113,9 @@ static void free_nested(struct vcpu_vmx *vmx)
>  		return;
>  	vmx->nested.vmxon = false;
>  	if (vmx->nested.current_vmptr != -1ull) {
> -		nested_release_vmcs12(vmx);
>  		vmx->nested.current_vmptr = -1ull;
>  		vmx->nested.current_vmcs12 = NULL;
> +		nested_release_vmcs12(vmx);
>  	}
>  	if (enable_shadow_vmcs)
>  		free_vmcs(vmx->nested.current_shadow_vmcs);
>

This looks good, I'll apply it to kvm/master.

Paolo
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Paolo Bonzini July 17, 2014, 9:04 a.m. UTC | #2 
Il 17/07/2014 10:56, Paolo Bonzini ha scritto:
> Il 17/07/2014 06:56, Wanpeng Li ha scritto:
>> This bug can be trigger by L1 goes down directly w/ enable_shadow_vmcs.
>>
>> [ 6413.158950] kvm: vmptrld           (null)/780000000000 failed
>> [ 6413.158954] vmwrite error: reg 401e value 4 (err 1)
>> [ 6413.158957] CPU: 0 PID: 4840 Comm: qemu-system-x86 Tainted:
>> G           OE 3.16.0kvm+ #2
>> [ 6413.158958] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05
>> 12/05/2013
>> [ 6413.158959]  0000000000000003 ffff880210c9fb58 ffffffff81741de9
>> ffff8800d7433f80
>> [ 6413.158960]  ffff880210c9fb68 ffffffffa059fa08 ffff880210c9fb78
>> ffffffffa05938bf
>> [ 6413.158962]  ffff880210c9fba8 ffffffffa059a97f ffff8800d7433f80
>> 0000000000000003
>> [ 6413.158963] Call Trace:
>> [ 6413.158968]  [<ffffffff81741de9>] dump_stack+0x45/0x56
>> [ 6413.158972]  [<ffffffffa059fa08>] vmwrite_error+0x2c/0x2e [kvm_intel]
>> [ 6413.158974]  [<ffffffffa05938bf>] vmcs_writel+0x1f/0x30 [kvm_intel]
>> [ 6413.158976]  [<ffffffffa059a97f>] free_nested.part.73+0x5f/0x170
>> [kvm_intel]
>> [ 6413.158978]  [<ffffffffa059ab13>] vmx_free_vcpu+0x33/0x70 [kvm_intel]
>> [ 6413.158991]  [<ffffffffa0360324>] kvm_arch_vcpu_free+0x44/0x50 [kvm]
>> [ 6413.158998]  [<ffffffffa0360f92>] kvm_arch_destroy_vm+0xf2/0x1f0 [kvm]
>>
>> Commit 26a865 (KVM: VMX: fix use after free of vmx->loaded_vmcs) fix
>> the use
>> after free bug by move free_loaded_vmcs() before free_nested(),
>> however, this
>> lead to free loaded_vmcs->vmcs premature and vmptrld load a NULL
>> pointer during
>> sync shadow vmcs to vmcs12. In addition, vmwrite which used to disable
>> shadow
>> vmcs and reset VMCS_LINK_POINTER failed since there is no valid
>> current-VMCS.
>> This patch fix it by skipping sync shadow vmcs and reset vmcs field
>> for L1
>> destroy since they will be reinitialized after L1 recreate.
>>
>> Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
>> ---
>>  arch/x86/kvm/vmx.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index fbce89e..2b28da7 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -6113,9 +6113,9 @@ static void free_nested(struct vcpu_vmx *vmx)
>>          return;
>>      vmx->nested.vmxon = false;
>>      if (vmx->nested.current_vmptr != -1ull) {
>> -        nested_release_vmcs12(vmx);
>>          vmx->nested.current_vmptr = -1ull;
>>          vmx->nested.current_vmcs12 = NULL;
>> +        nested_release_vmcs12(vmx);
>>      }
>>      if (enable_shadow_vmcs)
>>          free_vmcs(vmx->nested.current_shadow_vmcs);
>>
>
> This looks good, I'll apply it to kvm/master.

Hmm, on second thought the lifetimes of the VMCSes are a total mess. 
Let me look more at this.

Paolo

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diff mbox

Patch

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index fbce89e..2b28da7 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6113,9 +6113,9 @@  static void free_nested(struct vcpu_vmx *vmx)
 		return;
 	vmx->nested.vmxon = false;
 	if (vmx->nested.current_vmptr != -1ull) {
-		nested_release_vmcs12(vmx);
 		vmx->nested.current_vmptr = -1ull;
 		vmx->nested.current_vmcs12 = NULL;
+		nested_release_vmcs12(vmx);
 	}
 	if (enable_shadow_vmcs)
 		free_vmcs(vmx->nested.current_shadow_vmcs);