On Fri, Mar 22, 2013 at 06:19:47PM -0300, Marcelo Tosatti wrote: > > The alignment check is not necessary given that "KVM: x86: Convert > MSR_KVM_SYSTEM_TIME to use gfn_to_hva_cache" (0b79459b482e85cb742) > uses kvm_write_guest which is able to handle data across page > properly. > It uses kvm_write_guest_cached which calls to copy_to_user() directly. While this will not allow to overwrite page that does not belong to qemu process, it is possible to write outside of memory slot. May be we should use kvm_write_guest to do system time updates. > Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index f19ac0a..ec830fa 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1952,10 +1952,6 @@ 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)) > - break; > - > if (kvm_gfn_to_hva_cache_init(vcpu->kvm, > &vcpu->arch.pv_time, data & ~1ULL)) > vcpu->arch.pv_time_enabled = false; -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
