| Message ID | 1540071779-20848-1-git-send-email-karahmed@amazon.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM/nVMX: Do not validate that posted_intr_desc_addr is page aligned | expand |
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 <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Borislav Petkov <bp@alien8.de> > Cc: H. Peter Anvin <hpa@zytor.com> > Cc: x86@kernel.org > Cc: kvm@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 <karahmed@amazon.de> > --- > 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 <sean.j.christopherson@intel.com> > > /* tpr shadow is needed by all apicv features. */ > -- > 2.7.4 >
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 <pbonzini@redhat.com> > > Cc: Radim Krčmář <rkrcmar@redhat.com> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Ingo Molnar <mingo@redhat.com> > > Cc: Borislav Petkov <bp@alien8.de> > > Cc: H. Peter Anvin <hpa@zytor.com> > > Cc: x86@kernel.org > > Cc: kvm@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 <karahmed@amazon.de> > > --- > > 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 <sean.j.christopherson@intel.com> I have just sent a pull request with the stale comment. :(
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. */
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 <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: x86@kernel.org Cc: kvm@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 <karahmed@amazon.de> --- arch/x86/kvm/vmx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)