Re: [PATCH] KVM/nVMX: Do not validate that posted_intr_desc_addr is page aligned

2018-10-24 Thread Radim Krčmář
2018-10-24 04:01-0700, Sean Christopherson:
> On Sat, Oct 20, 2018 at 11:42:59PM +0200, KarimAllah Ahmed wrote:
> > The spec only requires the posted interrupt descriptor address to be
> > 64-bytes aligned (i.e. bits[0:5] == 0). Using page_address_valid also
> > forces the address to be page aligned.
> > 
> > Only validate that the address does not cross the maximum physical address
> > without enforcing a page alignment.
> > 
> > Cc: Paolo Bonzini 
> > Cc: Radim Krčmář 
> > Cc: Thomas Gleixner 
> > Cc: Ingo Molnar 
> > Cc: Borislav Petkov 
> > Cc: H. Peter Anvin 
> > Cc: x...@kernel.org
> > Cc: k...@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org
> > Fixes: 6de84e581c0 ("nVMX x86: check posted-interrupt descriptor addresss 
> > on vmentry of L2")
> > Signed-off-by: KarimAllah Ahmed 
> > ---
> >  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 30bf860..47962f2 100644
> > --- a/arch/x86/kvm/vmx.c
> > +++ b/arch/x86/kvm/vmx.c
> > @@ -11668,7 +11668,7 @@ static int nested_vmx_check_apicv_controls(struct 
> > kvm_vcpu *vcpu,
> > !nested_exit_intr_ack_set(vcpu) ||
> > (vmcs12->posted_intr_nv & 0xff00) ||
> > (vmcs12->posted_intr_desc_addr & 0x3f) ||
> > -   (!page_address_valid(vcpu, vmcs12->posted_intr_desc_addr
> > +   (vmcs12->posted_intr_desc_addr >> cpuid_maxphyaddr(vcpu)))
> > return -EINVAL;
> 
> Can you update the comment for this code block?  It has a stale blurb
> about "the descriptor address has been already checked in
> nested_get_vmcs12_pages" and it'd be nice to state why bits[5:0] must
> be zero (your changelog is much more helpful than the current comment).
> 
> With that:
> 
> Reviewed-by: Sean Christopherson 

I have just sent a pull request with the stale comment. :(


Re: [PATCH] KVM/nVMX: Do not validate that posted_intr_desc_addr is page aligned

2018-10-24 Thread Sean Christopherson
On Sat, Oct 20, 2018 at 11:42:59PM +0200, KarimAllah Ahmed wrote:
> The spec only requires the posted interrupt descriptor address to be
> 64-bytes aligned (i.e. bits[0:5] == 0). Using page_address_valid also
> forces the address to be page aligned.
> 
> Only validate that the address does not cross the maximum physical address
> without enforcing a page alignment.
> 
> Cc: Paolo Bonzini 
> Cc: Radim Krčmář 
> Cc: Thomas Gleixner 
> Cc: Ingo Molnar 
> Cc: Borislav Petkov 
> Cc: H. Peter Anvin 
> Cc: x...@kernel.org
> Cc: k...@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Fixes: 6de84e581c0 ("nVMX x86: check posted-interrupt descriptor addresss on 
> vmentry of L2")
> Signed-off-by: KarimAllah Ahmed 
> ---
>  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 30bf860..47962f2 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -11668,7 +11668,7 @@ static int nested_vmx_check_apicv_controls(struct 
> kvm_vcpu *vcpu,
>   !nested_exit_intr_ack_set(vcpu) ||
>   (vmcs12->posted_intr_nv & 0xff00) ||
>   (vmcs12->posted_intr_desc_addr & 0x3f) ||
> - (!page_address_valid(vcpu, vmcs12->posted_intr_desc_addr
> + (vmcs12->posted_intr_desc_addr >> cpuid_maxphyaddr(vcpu)))
>   return -EINVAL;

Can you update the comment for this code block?  It has a stale blurb
about "the descriptor address has been already checked in
nested_get_vmcs12_pages" and it'd be nice to state why bits[5:0] must
be zero (your changelog is much more helpful than the current comment).

With that:

Reviewed-by: Sean Christopherson 

>  
>   /* tpr shadow is needed by all apicv features. */
> -- 
> 2.7.4
> 


[PATCH] KVM/nVMX: Do not validate that posted_intr_desc_addr is page aligned

2018-10-20 Thread KarimAllah Ahmed
The spec only requires the posted interrupt descriptor address to be
64-bytes aligned (i.e. bits[0:5] == 0). Using page_address_valid also
forces the address to be page aligned.

Only validate that the address does not cross the maximum physical address
without enforcing a page alignment.

Cc: Paolo Bonzini 
Cc: Radim Krčmář 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: H. Peter Anvin 
Cc: x...@kernel.org
Cc: k...@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Fixes: 6de84e581c0 ("nVMX x86: check posted-interrupt descriptor addresss on 
vmentry of L2")
Signed-off-by: KarimAllah Ahmed 
---
 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 30bf860..47962f2 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11668,7 +11668,7 @@ static int nested_vmx_check_apicv_controls(struct 
kvm_vcpu *vcpu,
!nested_exit_intr_ack_set(vcpu) ||
(vmcs12->posted_intr_nv & 0xff00) ||
(vmcs12->posted_intr_desc_addr & 0x3f) ||
-   (!page_address_valid(vcpu, vmcs12->posted_intr_desc_addr
+   (vmcs12->posted_intr_desc_addr >> cpuid_maxphyaddr(vcpu)))
return -EINVAL;
 
/* tpr shadow is needed by all apicv features. */
-- 
2.7.4