Re: [PATCH] KVM: nVMX: Reset vmxon_ptr upon VMXOFF emulation.

Re: [PATCH] KVM: nVMX: Reset vmxon_ptr upon VMXOFF emulation.

[Vitaly Kuznetsov]

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

> From: Vitaly Kuznetsov <vkuznets@redhat.com>
>
> Currently, 'vmx->nested.vmxon_ptr' is not reset upon VMXOFF
> emulation. This is not a problem per se as we never access
> it when !vmx->nested.vmxon. But this should be done to avoid
> any issue in the future.
>
> Also, initialize the vmxon_ptr when vcpu is created.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Thanks but even Suggested-by: would be enough :-)

> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 1 +
>  arch/x86/kvm/vmx/vmx.c    | 1 +
>  2 files changed, 2 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 90f34f12f883..e4260f67caac 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -289,6 +289,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
>  	kvm_clear_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
>  
>  	vmx->nested.vmxon = false;
> +	vmx->nested.vmxon_ptr = -1ull;
>  	vmx->nested.smm.vmxon = false;
>  	free_vpid(vmx->nested.vpid02);
>  	vmx->nested.posted_intr_nv = -1;
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 0c2c0d5ae873..9a3e35c038f2 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6886,6 +6886,7 @@ 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;

-- 
Vitaly

Re: [PATCH] KVM: nVMX: Reset vmxon_ptr upon VMXOFF emulation.

[Yu Zhang]

On Thu, Sep 09, 2021 at 07:19:53AM +0200, Vitaly Kuznetsov wrote:
> 
> Thanks but even Suggested-by: would be enough :-)
> 

I just copied your code. And actually I should be the one to say thanks. :)

B.R.
Yu

[PATCH] KVM: nVMX: Reset vmxon_ptr upon VMXOFF emulation.

[Yu Zhang]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

Currently, 'vmx->nested.vmxon_ptr' is not reset upon VMXOFF
emulation. This is not a problem per se as we never access
it when !vmx->nested.vmxon. But this should be done to avoid
any issue in the future.

Also, initialize the vmxon_ptr when vcpu is created.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
---
 arch/x86/kvm/vmx/nested.c | 1 +
 arch/x86/kvm/vmx/vmx.c    | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 90f34f12f883..e4260f67caac 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -289,6 +289,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
 	kvm_clear_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
 
 	vmx->nested.vmxon = false;
+	vmx->nested.vmxon_ptr = -1ull;
 	vmx->nested.smm.vmxon = false;
 	free_vpid(vmx->nested.vpid02);
 	vmx->nested.posted_intr_nv = -1;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 0c2c0d5ae873..9a3e35c038f2 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6886,6 +6886,7 @@ 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;
-- 
2.17.1

Re: [PATCH] KVM: nVMX: Reset vmxon_ptr upon VMXOFF emulation.

[Sean Christopherson]

On Thu, Sep 09, 2021, Yu Zhang wrote:
> From: Vitaly Kuznetsov <vkuznets@redhat.com>
> 
> Currently, 'vmx->nested.vmxon_ptr' is not reset upon VMXOFF
> emulation. This is not a problem per se as we never access
> it when !vmx->nested.vmxon. But this should be done to avoid
> any issue in the future.
> 
> Also, initialize the vmxon_ptr when vcpu is created.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 1 +
>  arch/x86/kvm/vmx/vmx.c    | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 90f34f12f883..e4260f67caac 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -289,6 +289,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
>  	kvm_clear_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
>  
>  	vmx->nested.vmxon = false;
> +	vmx->nested.vmxon_ptr = -1ull;

Looks like the "-1ull" comes from current_vmptr and friends, but using INVALID_GPA
is more appropriate.  It's the same value, but less arbitrary.  The other usage of
-1ull for guest physical addresses should really be cleaned up, too.

Re: [PATCH] KVM: nVMX: Reset vmxon_ptr upon VMXOFF emulation.

[Yu Zhang]

On Thu, Sep 09, 2021 at 04:20:35PM +0000, Sean Christopherson wrote:
> On Thu, Sep 09, 2021, Yu Zhang wrote:
> > From: Vitaly Kuznetsov <vkuznets@redhat.com>
> > 
> > Currently, 'vmx->nested.vmxon_ptr' is not reset upon VMXOFF
> > emulation. This is not a problem per se as we never access
> > it when !vmx->nested.vmxon. But this should be done to avoid
> > any issue in the future.
> > 
> > Also, initialize the vmxon_ptr when vcpu is created.
> > 
> > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> > ---
> >  arch/x86/kvm/vmx/nested.c | 1 +
> >  arch/x86/kvm/vmx/vmx.c    | 1 +
> >  2 files changed, 2 insertions(+)
> > 
> > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> > index 90f34f12f883..e4260f67caac 100644
> > --- a/arch/x86/kvm/vmx/nested.c
> > +++ b/arch/x86/kvm/vmx/nested.c
> > @@ -289,6 +289,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
> >  	kvm_clear_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
> >  
> >  	vmx->nested.vmxon = false;
> > +	vmx->nested.vmxon_ptr = -1ull;
> 
> Looks like the "-1ull" comes from current_vmptr and friends, but using INVALID_GPA
> is more appropriate.  It's the same value, but less arbitrary.  The other usage of
> -1ull for guest physical addresses should really be cleaned up, too.
> 

Indeed. I guess many "-1ull"s will be replaced in nested.c.

We need another cleanup patch for this cleanup patch, which comes from my
first cleanup patch to just clean some comments.. :-) Anyway, thanks!

B.R.
Yu