| Message ID | 20130322191407.GA23681@amt.cnet (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Mar 22, 2013 at 04:14:07PM -0300, Marcelo Tosatti wrote: > > RHEL5 i386 guests register non 32-byte aligned addresses: > > kvm-clock: cpu 1, msr 0:3018aa5, secondary cpu clock > kvm-clock: cpu 2, msr 0:301f8e9, secondary cpu clock > kvm-clock: cpu 3, msr 0:302672d, secondary cpu clock > > Check for an address+len that would cross page boundary > instead. > Ugh. Is there guaranty that it will not register a memory region that crosses page boundary or it is pure luck that this does not happen? > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index f19ac0a..ad36d386 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1952,8 +1952,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > > gpa_offset = data & ~(PAGE_MASK | 1); > > - /* Check that the address is 32-byte aligned. */ > - if (gpa_offset & (sizeof(struct pvclock_vcpu_time_info) - 1)) > + /* Check that address+len does not cross page boundary */ > + if ((gpa_offset + sizeof(struct pvclock_vcpu_time_info) - 1) > + & PAGE_MASK) > break; > > if (kvm_gfn_to_hva_cache_init(vcpu->kvm, -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Mar 22, 2013 at 09:21:00PM +0200, Gleb Natapov wrote: > On Fri, Mar 22, 2013 at 04:14:07PM -0300, Marcelo Tosatti wrote: > > > > RHEL5 i386 guests register non 32-byte aligned addresses: > > > > kvm-clock: cpu 1, msr 0:3018aa5, secondary cpu clock > > kvm-clock: cpu 2, msr 0:301f8e9, secondary cpu clock > > kvm-clock: cpu 3, msr 0:302672d, secondary cpu clock > > > > Check for an address+len that would cross page boundary > > instead. > > > Ugh. Is there guaranty that it will not register a memory region that > crosses page boundary or it is pure luck that this does not happen? Pure build time luck - there is no guarantee that percpu data will not cross page boundary AFAIK. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index f19ac0a..ad36d386 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1952,8 +1952,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) gpa_offset = data & ~(PAGE_MASK | 1); - /* Check that the address is 32-byte aligned. */ - if (gpa_offset & (sizeof(struct pvclock_vcpu_time_info) - 1)) + /* Check that address+len does not cross page boundary */ + if ((gpa_offset + sizeof(struct pvclock_vcpu_time_info) - 1) + & PAGE_MASK) break; if (kvm_gfn_to_hva_cache_init(vcpu->kvm,
RHEL5 i386 guests register non 32-byte aligned addresses: kvm-clock: cpu 1, msr 0:3018aa5, secondary cpu clock kvm-clock: cpu 2, msr 0:301f8e9, secondary cpu clock kvm-clock: cpu 3, msr 0:302672d, secondary cpu clock Check for an address+len that would cross page boundary instead. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html