Re: [PATCH 2/2] accel: kvm: Add aligment check for kvm_log_clear_one_slot

[Andrew Jones]

On Tue, Dec 15, 2020 at 12:55:50PM +0100, Andrew Jones wrote:
> On Tue, Dec 15, 2020 at 03:19:48PM +0800, Keqian Zhu wrote:
> > The parameters start and size are transfered from QEMU memory
> > emulation layer. It can promise that they are TARGET_PAGE_SIZE
> > aligned. However, KVM needs they are qemu_real_page_size aligned.
> > 
> > Though no caller breaks this aligned requirement currently, we'd
> > better add an explicit check to avoid future breaking.
> > 
> > Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
> > ---
> >  accel/kvm/kvm-all.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> > index c5e06288eb..3d0e3aa872 100644
> > --- a/accel/kvm/kvm-all.c
> > +++ b/accel/kvm/kvm-all.c
> > @@ -701,6 +701,11 @@ static int kvm_log_clear_one_slot(KVMSlot *mem, int 
> > as_id, uint64_t start,
> >      unsigned long *bmap_clear = NULL, psize = qemu_real_host_page_size;
> >      int ret;
> >  
> > +    /* Make sure start and size are psize aligned */
> > +    if (!QEMU_IS_ALIGNED(start, psize) || !QEMU_IS_ALIGNED(size, psize)) {
> > +        return -EINVAL;
> > +    }
> > +
> >      /*
> >       * We need to extend either the start or the size or both to
> >       * satisfy the KVM interface requirement.  Firstly, do the start
> > -- 
> > 2.23.0
> > 
> >
> 
> It's not clear to me that this function has any restrictions on start
> and size. If it does, then please document those restrictions in the
> function's header and assert rather than return.
>

Also, I see this patch is on its way in

20201215175445.1272776-27-pbonzini@redhat.com/">https://patchwork.ozlabs.org/project/qemu-devel/patch/20201215175445.1272776-27-pbonzini@redhat.com/

Thanks,
drew