Re: KVM: attempt async pf only if address is contained in vma

[Gleb Natapov <gleb@redhat.com>]

On Tue, Oct 19, 2010 at 11:14:48AM -0200, Marcelo Tosatti wrote:
> On Tue, Oct 19, 2010 at 02:17:27PM +0200, Gleb Natapov wrote:
> > On Tue, Oct 19, 2010 at 01:05:22PM +0200, Gleb Natapov wrote:
> > > On Mon, Oct 18, 2010 at 08:24:03PM -0200, Marcelo Tosatti wrote:
> > > > 
> > > > Only attempt async pagefault if address is contained within vma.
> > > > 
> > > > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> > > > 
> > > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > > > index 5d57ec9..a9cfbd2 100644
> > > > --- a/virt/kvm/kvm_main.c
> > > > +++ b/virt/kvm/kvm_main.c
> > > > @@ -996,8 +996,9 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
> > > >  
> > > >  		if (vma == NULL || addr < vma->vm_start ||
> > > >  		    !(vma->vm_flags & VM_PFNMAP)) {
> > > > -			if (async && !(vma->vm_flags & VM_PFNMAP) &&
> > > > -			    (vma->vm_flags & VM_WRITE))
> > > > +			if (async && vma && !(vma->vm_flags & VM_PFNMAP) &&
> > > actually we should check for addr < vma->vm_start here too. find_vma()
> > > is very strange function.
> > > 
> > > What about patch below (only compile tested for now)?
> > > 
> > Works for me.
> 
> Thats much nicer. 
> 
> > > -		vma = find_vma(current->mm, addr);
> > > +		vma = find_vma_intersection(current->mm, addr, addr+1);
> > >  
> > > -		if (vma == NULL || addr < vma->vm_start ||
> > > -		    !(vma->vm_flags & VM_PFNMAP)) {
> > > -			if (async && !(vma->vm_flags & VM_PFNMAP) &&
> > > -			    (vma->vm_flags & VM_WRITE))
> > > +		if (vma == NULL)
> > > +			return get_fault_pfn();
> 
> up_read(mmap_sem)
Oops.

Will resent with fix and all.


--
			Gleb.