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* Re: [PATCH] KVM: nVMX: fix comments of handle_vmon()
  2021-09-08 17:17 [PATCH] KVM: nVMX: fix comments of handle_vmon() Yu Zhang
@ 2021-09-08  9:55 ` Vitaly Kuznetsov
  2021-09-08 13:01   ` Yu Zhang
  2021-09-21 17:50 ` Paolo Bonzini
  1 sibling, 1 reply; 6+ messages in thread
From: Vitaly Kuznetsov @ 2021-09-08  9:55 UTC (permalink / raw)
  To: Yu Zhang, seanjc, pbonzini; +Cc: kvm, linux-kernel, wanpengli, jmattson, joro

Yu Zhang <yu.c.zhang@linux.intel.com> writes:

> "VMXON pointer" is saved in vmx->nested.vmxon_ptr since
> commit 3573e22cfeca ("KVM: nVMX: additional checks on
> vmxon region"). Also, handle_vmptrld() & handle_vmclear()
> now have logic to check the VMCS pointer against the VMXON
> pointer.
>
> So just remove the obsolete comments of handle_vmon().
>
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index bc6327950657..90f34f12f883 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -4862,14 +4862,7 @@ static int enter_vmx_operation(struct kvm_vcpu *vcpu)
>  	return -ENOMEM;
>  }
>  
> -/*
> - * Emulate the VMXON instruction.
> - * Currently, we just remember that VMX is active, and do not save or even
> - * inspect the argument to VMXON (the so-called "VMXON pointer") because we
> - * do not currently need to store anything in that guest-allocated memory
> - * region. Consequently, VMCLEAR and VMPTRLD also do not verify that the their
> - * argument is different from the VMXON pointer (which the spec says they do).
> - */
> +/* Emulate the VMXON instruction. */
>  static int handle_vmon(struct kvm_vcpu *vcpu)
>  {
>  	int ret;

Indeed,

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

On a slightly related note: we don't seem to reset
'vmx->nested.vmxon_ptr' upon VMXOFF emulation; this is not a problem per
se as we never access it when !vmx->nested.vmxon but I'd still suggest
we do something like

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index bc6327950657..8beb41d02d21 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -290,6 +290,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
 
        vmx->nested.vmxon = false;
        vmx->nested.smm.vmxon = false;
+       vmx->nested.vmxon_ptr = -1ull;
        free_vpid(vmx->nested.vpid02);
        vmx->nested.posted_intr_nv = -1;
        vmx->nested.current_vmptr = -1ull;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d7c5257eb5c0..2214e6bd4713 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6884,6 +6884,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
 
        vcpu_setup_sgx_lepubkeyhash(vcpu);
 
+       vmx->nested.vmxon_ptr = -1ull;
        vmx->nested.posted_intr_nv = -1;
        vmx->nested.current_vmptr = -1ull;
        vmx->nested.hv_evmcs_vmptr = EVMPTR_INVALID;

to avoid issues in the future.

-- 
Vitaly


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: nVMX: fix comments of handle_vmon()
  2021-09-08  9:55 ` Vitaly Kuznetsov
@ 2021-09-08 13:01   ` Yu Zhang
  2021-09-08 13:42     ` Vitaly Kuznetsov
  0 siblings, 1 reply; 6+ messages in thread
From: Yu Zhang @ 2021-09-08 13:01 UTC (permalink / raw)
  To: Vitaly Kuznetsov
  Cc: seanjc, pbonzini, kvm, linux-kernel, wanpengli, jmattson, joro

On Wed, Sep 08, 2021 at 11:55:59AM +0200, Vitaly Kuznetsov wrote:
> Indeed,
> 
> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> 
> On a slightly related note: we don't seem to reset
> 'vmx->nested.vmxon_ptr' upon VMXOFF emulation; this is not a problem per
> se as we never access it when !vmx->nested.vmxon but I'd still suggest
> we do something like
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index bc6327950657..8beb41d02d21 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -290,6 +290,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
>  
>         vmx->nested.vmxon = false;
>         vmx->nested.smm.vmxon = false;
> +       vmx->nested.vmxon_ptr = -1ull;
>         free_vpid(vmx->nested.vpid02);
>         vmx->nested.posted_intr_nv = -1;
>         vmx->nested.current_vmptr = -1ull;
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index d7c5257eb5c0..2214e6bd4713 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6884,6 +6884,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
>  
>         vcpu_setup_sgx_lepubkeyhash(vcpu);
>  
> +       vmx->nested.vmxon_ptr = -1ull;
>         vmx->nested.posted_intr_nv = -1;
>         vmx->nested.current_vmptr = -1ull;
>         vmx->nested.hv_evmcs_vmptr = EVMPTR_INVALID;
> 
> to avoid issues in the future.
> 
Thanks, Vitaly. And above suggestion sounds reasonable to me. :)

I can add this in V2 later, if no one objects. 

B.R.
Yu

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: nVMX: fix comments of handle_vmon()
  2021-09-08 13:01   ` Yu Zhang
@ 2021-09-08 13:42     ` Vitaly Kuznetsov
  2021-09-09  5:13       ` Yu Zhang
  0 siblings, 1 reply; 6+ messages in thread
From: Vitaly Kuznetsov @ 2021-09-08 13:42 UTC (permalink / raw)
  To: Yu Zhang; +Cc: seanjc, pbonzini, kvm, linux-kernel, wanpengli, jmattson, joro

Yu Zhang <yu.c.zhang@linux.intel.com> writes:

> On Wed, Sep 08, 2021 at 11:55:59AM +0200, Vitaly Kuznetsov wrote:
>> Indeed,
>> 
>> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> 
>> On a slightly related note: we don't seem to reset
>> 'vmx->nested.vmxon_ptr' upon VMXOFF emulation; this is not a problem per
>> se as we never access it when !vmx->nested.vmxon but I'd still suggest
>> we do something like
>> 
>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> index bc6327950657..8beb41d02d21 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -290,6 +290,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
>>  
>>         vmx->nested.vmxon = false;
>>         vmx->nested.smm.vmxon = false;
>> +       vmx->nested.vmxon_ptr = -1ull;
>>         free_vpid(vmx->nested.vpid02);
>>         vmx->nested.posted_intr_nv = -1;
>>         vmx->nested.current_vmptr = -1ull;
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index d7c5257eb5c0..2214e6bd4713 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -6884,6 +6884,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
>>  
>>         vcpu_setup_sgx_lepubkeyhash(vcpu);
>>  
>> +       vmx->nested.vmxon_ptr = -1ull;
>>         vmx->nested.posted_intr_nv = -1;
>>         vmx->nested.current_vmptr = -1ull;
>>         vmx->nested.hv_evmcs_vmptr = EVMPTR_INVALID;
>> 
>> to avoid issues in the future.
>> 
> Thanks, Vitaly. And above suggestion sounds reasonable to me. :)
>
> I can add this in V2 later, if no one objects. 
>

Sure, this is rather a separate patch. Thanks!

-- 
Vitaly


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] KVM: nVMX: fix comments of handle_vmon()
@ 2021-09-08 17:17 Yu Zhang
  2021-09-08  9:55 ` Vitaly Kuznetsov
  2021-09-21 17:50 ` Paolo Bonzini
  0 siblings, 2 replies; 6+ messages in thread
From: Yu Zhang @ 2021-09-08 17:17 UTC (permalink / raw)
  To: seanjc, pbonzini; +Cc: kvm, linux-kernel, vkuznets, wanpengli, jmattson, joro

"VMXON pointer" is saved in vmx->nested.vmxon_ptr since
commit 3573e22cfeca ("KVM: nVMX: additional checks on
vmxon region"). Also, handle_vmptrld() & handle_vmclear()
now have logic to check the VMCS pointer against the VMXON
pointer.

So just remove the obsolete comments of handle_vmon().

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
---
 arch/x86/kvm/vmx/nested.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index bc6327950657..90f34f12f883 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4862,14 +4862,7 @@ static int enter_vmx_operation(struct kvm_vcpu *vcpu)
 	return -ENOMEM;
 }
 
-/*
- * Emulate the VMXON instruction.
- * Currently, we just remember that VMX is active, and do not save or even
- * inspect the argument to VMXON (the so-called "VMXON pointer") because we
- * do not currently need to store anything in that guest-allocated memory
- * region. Consequently, VMCLEAR and VMPTRLD also do not verify that the their
- * argument is different from the VMXON pointer (which the spec says they do).
- */
+/* Emulate the VMXON instruction. */
 static int handle_vmon(struct kvm_vcpu *vcpu)
 {
 	int ret;
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: nVMX: fix comments of handle_vmon()
  2021-09-08 13:42     ` Vitaly Kuznetsov
@ 2021-09-09  5:13       ` Yu Zhang
  0 siblings, 0 replies; 6+ messages in thread
From: Yu Zhang @ 2021-09-09  5:13 UTC (permalink / raw)
  To: Vitaly Kuznetsov, Paolo Bonzini
  Cc: seanjc, kvm, linux-kernel, wanpengli, jmattson, joro

On Wed, Sep 08, 2021 at 03:42:13PM +0200, Vitaly Kuznetsov wrote:
> 
> Sure, this is rather a separate patch. Thanks!

Oh, right. Just sent out a seperate patch. :)

@Paolo Any comment on this one? Thanks!

B.R.
Yu

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: nVMX: fix comments of handle_vmon()
  2021-09-08 17:17 [PATCH] KVM: nVMX: fix comments of handle_vmon() Yu Zhang
  2021-09-08  9:55 ` Vitaly Kuznetsov
@ 2021-09-21 17:50 ` Paolo Bonzini
  1 sibling, 0 replies; 6+ messages in thread
From: Paolo Bonzini @ 2021-09-21 17:50 UTC (permalink / raw)
  To: Yu Zhang, seanjc; +Cc: kvm, linux-kernel, vkuznets, wanpengli, jmattson, joro

On 08/09/21 19:17, Yu Zhang wrote:
> "VMXON pointer" is saved in vmx->nested.vmxon_ptr since
> commit 3573e22cfeca ("KVM: nVMX: additional checks on
> vmxon region"). Also, handle_vmptrld() & handle_vmclear()
> now have logic to check the VMCS pointer against the VMXON
> pointer.
> 
> So just remove the obsolete comments of handle_vmon().
> 
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> ---
>   arch/x86/kvm/vmx/nested.c | 9 +--------
>   1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index bc6327950657..90f34f12f883 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -4862,14 +4862,7 @@ static int enter_vmx_operation(struct kvm_vcpu *vcpu)
>   	return -ENOMEM;
>   }
>   
> -/*
> - * Emulate the VMXON instruction.
> - * Currently, we just remember that VMX is active, and do not save or even
> - * inspect the argument to VMXON (the so-called "VMXON pointer") because we
> - * do not currently need to store anything in that guest-allocated memory
> - * region. Consequently, VMCLEAR and VMPTRLD also do not verify that the their
> - * argument is different from the VMXON pointer (which the spec says they do).
> - */
> +/* Emulate the VMXON instruction. */
>   static int handle_vmon(struct kvm_vcpu *vcpu)
>   {
>   	int ret;
> 

Queued, thanks.

Paolo


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-09-21 17:50 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-08 17:17 [PATCH] KVM: nVMX: fix comments of handle_vmon() Yu Zhang
2021-09-08  9:55 ` Vitaly Kuznetsov
2021-09-08 13:01   ` Yu Zhang
2021-09-08 13:42     ` Vitaly Kuznetsov
2021-09-09  5:13       ` Yu Zhang
2021-09-21 17:50 ` Paolo Bonzini

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