Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend
On Wed, 8 Mar 2017, Julien Grall wrote: > Hi Stefano, > > On 08/03/17 00:49, Stefano Stabellini wrote: > > On Tue, 7 Mar 2017, Julien Grall wrote: > > > On 03/06/2017 08:01 PM, Stefano Stabellini wrote: > > > > + if (ring->bytes == NULL) > > > > + goto error; > > > > + for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++) > > > > + ring->intf->ref[i] = > > > > gnttab_grant_foreign_access(dev->otherend_id, > > > > pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);. > > > > > > Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn). > > > > OK > > > > > > > Also, this is not going to work on 64K kernel because you will grant > > > access to > > > noncontiguous memory (e.g 0-4K, 64K-68K,...). > > > > By using virt_to_gfn like you suggested, the loop will correctly iterate > > on a 4K by 4K basis, even on a 64K kernel: > > > > ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO, > > XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT)); > > for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++) > > ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id, > > virt_to_gfn((void*)ring->bytes) + i, 0); > > BTW, the cast (void *) is not necessary. > > > > > where XEN_9PFS_RING_ORDER specifies the order at 4K granularity. Am I > > missing something? > > I think it is fine. You could move virt_to_gfn(...) outside and avoid to do > the translation everytime. All right, thanks.
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend
On Wed, 8 Mar 2017, Julien Grall wrote: > Hi Stefano, > > On 08/03/17 00:49, Stefano Stabellini wrote: > > On Tue, 7 Mar 2017, Julien Grall wrote: > > > On 03/06/2017 08:01 PM, Stefano Stabellini wrote: > > > > + if (ring->bytes == NULL) > > > > + goto error; > > > > + for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++) > > > > + ring->intf->ref[i] = > > > > gnttab_grant_foreign_access(dev->otherend_id, > > > > pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);. > > > > > > Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn). > > > > OK > > > > > > > Also, this is not going to work on 64K kernel because you will grant > > > access to > > > noncontiguous memory (e.g 0-4K, 64K-68K,...). > > > > By using virt_to_gfn like you suggested, the loop will correctly iterate > > on a 4K by 4K basis, even on a 64K kernel: > > > > ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO, > > XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT)); > > for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++) > > ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id, > > virt_to_gfn((void*)ring->bytes) + i, 0); > > BTW, the cast (void *) is not necessary. > > > > > where XEN_9PFS_RING_ORDER specifies the order at 4K granularity. Am I > > missing something? > > I think it is fine. You could move virt_to_gfn(...) outside and avoid to do > the translation everytime. All right, thanks.
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend
Hi Stefano, On 08/03/17 00:49, Stefano Stabellini wrote: On Tue, 7 Mar 2017, Julien Grall wrote: On 03/06/2017 08:01 PM, Stefano Stabellini wrote: + if (ring->bytes == NULL) + goto error; + for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++) + ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id, pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);. Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn). OK Also, this is not going to work on 64K kernel because you will grant access to noncontiguous memory (e.g 0-4K, 64K-68K,...). By using virt_to_gfn like you suggested, the loop will correctly iterate on a 4K by 4K basis, even on a 64K kernel: ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO, XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT)); for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++) ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id, virt_to_gfn((void*)ring->bytes) + i, 0); BTW, the cast (void *) is not necessary. where XEN_9PFS_RING_ORDER specifies the order at 4K granularity. Am I missing something? I think it is fine. You could move virt_to_gfn(...) outside and avoid to do the translation everytime. Cheers, -- Julien Grall
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend
Hi Stefano, On 08/03/17 00:49, Stefano Stabellini wrote: On Tue, 7 Mar 2017, Julien Grall wrote: On 03/06/2017 08:01 PM, Stefano Stabellini wrote: + if (ring->bytes == NULL) + goto error; + for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++) + ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id, pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);. Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn). OK Also, this is not going to work on 64K kernel because you will grant access to noncontiguous memory (e.g 0-4K, 64K-68K,...). By using virt_to_gfn like you suggested, the loop will correctly iterate on a 4K by 4K basis, even on a 64K kernel: ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO, XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT)); for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++) ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id, virt_to_gfn((void*)ring->bytes) + i, 0); BTW, the cast (void *) is not necessary. where XEN_9PFS_RING_ORDER specifies the order at 4K granularity. Am I missing something? I think it is fine. You could move virt_to_gfn(...) outside and avoid to do the translation everytime. Cheers, -- Julien Grall
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend
On Tue, 7 Mar 2017, Julien Grall wrote:
> Hi Stefano,
>
> On 03/06/2017 08:01 PM, Stefano Stabellini wrote:
> > +static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
> > + struct xen_9pfs_dataring *ring)
> > +{
> > + int i;
> > + int ret = -ENOMEM;
> > +
> > + init_waitqueue_head(>wq);
> > + spin_lock_init(>lock);
> > + INIT_WORK(>work, p9_xen_response);
> > +
> > + ring->intf = (struct xen_9pfs_data_intf *) __get_free_page(GFP_KERNEL
> > | __GFP_ZERO);
> > + if (!ring->intf)
> > + goto error;
> > + memset(ring->intf, 0, XEN_PAGE_SIZE);
> > + ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
> > XEN_9PFS_RING_ORDER);
>
> The ring order will be in term of Xen page size and not Linux. So you are
> going to allocate much more memory than expected on 64KB kernel.
I'll fix.
> > + if (ring->bytes == NULL)
> > + goto error;
> > + for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++)
> > + ring->intf->ref[i] =
> > gnttab_grant_foreign_access(dev->otherend_id,
> > pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);.
>
> Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
OK
> Also, this is not going to work on 64K kernel because you will grant access to
> noncontiguous memory (e.g 0-4K, 64K-68K,...).
By using virt_to_gfn like you suggested, the loop will correctly iterate
on a 4K by 4K basis, even on a 64K kernel:
ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT));
for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++)
ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id,
virt_to_gfn((void*)ring->bytes) + i, 0);
where XEN_9PFS_RING_ORDER specifies the order at 4K granularity. Am I
missing something?
> We have various helper to break-down the page for you, see
> gnttab_for_one_grant, gnttab_foreach_grant, gnttab_count_grant,
> xen_for_each_gfn (though this one it is internal to xlate_mmu.c so far)
>
> Please use them to avoid any further.
>
> > + ring->ref = gnttab_grant_foreign_access(dev->otherend_id,
> > pfn_to_gfn(virt_to_pfn((void*)ring->intf)), 0);
>
> Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
Sure
> > + ring->ring.in = ring->bytes;
> > + ring->ring.out = ring->bytes + XEN_9PFS_RING_SIZE;
> > +
> > + ret = xenbus_alloc_evtchn(dev, >evtchn);
> > + if (ret)
> > + goto error;
> > + ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
> > xen_9pfs_front_event_handler,
> > + 0, "xen_9pfs-frontend", ring);
> > + if (ring->irq < 0) {
> > + xenbus_free_evtchn(dev, ring->evtchn);
> > + ret = ring->irq;
> > + goto error;
> > + }
> > return 0;
> > +
> > +error:
> > + if (ring->intf != NULL)
> > + kfree(ring->intf);
> > + if (ring->bytes != NULL)
> > + kfree(ring->bytes);
> > + return ret;
> > }
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend
On Tue, 7 Mar 2017, Julien Grall wrote:
> Hi Stefano,
>
> On 03/06/2017 08:01 PM, Stefano Stabellini wrote:
> > +static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
> > + struct xen_9pfs_dataring *ring)
> > +{
> > + int i;
> > + int ret = -ENOMEM;
> > +
> > + init_waitqueue_head(>wq);
> > + spin_lock_init(>lock);
> > + INIT_WORK(>work, p9_xen_response);
> > +
> > + ring->intf = (struct xen_9pfs_data_intf *) __get_free_page(GFP_KERNEL
> > | __GFP_ZERO);
> > + if (!ring->intf)
> > + goto error;
> > + memset(ring->intf, 0, XEN_PAGE_SIZE);
> > + ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
> > XEN_9PFS_RING_ORDER);
>
> The ring order will be in term of Xen page size and not Linux. So you are
> going to allocate much more memory than expected on 64KB kernel.
I'll fix.
> > + if (ring->bytes == NULL)
> > + goto error;
> > + for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++)
> > + ring->intf->ref[i] =
> > gnttab_grant_foreign_access(dev->otherend_id,
> > pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);.
>
> Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
OK
> Also, this is not going to work on 64K kernel because you will grant access to
> noncontiguous memory (e.g 0-4K, 64K-68K,...).
By using virt_to_gfn like you suggested, the loop will correctly iterate
on a 4K by 4K basis, even on a 64K kernel:
ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT));
for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++)
ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id,
virt_to_gfn((void*)ring->bytes) + i, 0);
where XEN_9PFS_RING_ORDER specifies the order at 4K granularity. Am I
missing something?
> We have various helper to break-down the page for you, see
> gnttab_for_one_grant, gnttab_foreach_grant, gnttab_count_grant,
> xen_for_each_gfn (though this one it is internal to xlate_mmu.c so far)
>
> Please use them to avoid any further.
>
> > + ring->ref = gnttab_grant_foreign_access(dev->otherend_id,
> > pfn_to_gfn(virt_to_pfn((void*)ring->intf)), 0);
>
> Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
Sure
> > + ring->ring.in = ring->bytes;
> > + ring->ring.out = ring->bytes + XEN_9PFS_RING_SIZE;
> > +
> > + ret = xenbus_alloc_evtchn(dev, >evtchn);
> > + if (ret)
> > + goto error;
> > + ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
> > xen_9pfs_front_event_handler,
> > + 0, "xen_9pfs-frontend", ring);
> > + if (ring->irq < 0) {
> > + xenbus_free_evtchn(dev, ring->evtchn);
> > + ret = ring->irq;
> > + goto error;
> > + }
> > return 0;
> > +
> > +error:
> > + if (ring->intf != NULL)
> > + kfree(ring->intf);
> > + if (ring->bytes != NULL)
> > + kfree(ring->bytes);
> > + return ret;
> > }
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend
Hi Stefano,
On 03/06/2017 08:01 PM, Stefano Stabellini wrote:
+static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
+ struct xen_9pfs_dataring *ring)
+{
+ int i;
+ int ret = -ENOMEM;
+
+ init_waitqueue_head(>wq);
+ spin_lock_init(>lock);
+ INIT_WORK(>work, p9_xen_response);
+
+ ring->intf = (struct xen_9pfs_data_intf *) __get_free_page(GFP_KERNEL |
__GFP_ZERO);
+ if (!ring->intf)
+ goto error;
+ memset(ring->intf, 0, XEN_PAGE_SIZE);
+ ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
XEN_9PFS_RING_ORDER);
The ring order will be in term of Xen page size and not Linux. So you
are going to allocate much more memory than expected on 64KB kernel.
+ if (ring->bytes == NULL)
+ goto error;
+ for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++)
+ ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id,
pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);.
Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
Also, this is not going to work on 64K kernel because you will grant
access to noncontiguous memory (e.g 0-4K, 64K-68K,...).
We have various helper to break-down the page for you, see
gnttab_for_one_grant, gnttab_foreach_grant, gnttab_count_grant,
xen_for_each_gfn (though this one it is internal to xlate_mmu.c so far)
Please use them to avoid any further.
+ ring->ref = gnttab_grant_foreign_access(dev->otherend_id,
pfn_to_gfn(virt_to_pfn((void*)ring->intf)), 0);
Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
+ ring->ring.in = ring->bytes;
+ ring->ring.out = ring->bytes + XEN_9PFS_RING_SIZE;
+
+ ret = xenbus_alloc_evtchn(dev, >evtchn);
+ if (ret)
+ goto error;
+ ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
xen_9pfs_front_event_handler,
+ 0, "xen_9pfs-frontend", ring);
+ if (ring->irq < 0) {
+ xenbus_free_evtchn(dev, ring->evtchn);
+ ret = ring->irq;
+ goto error;
+ }
return 0;
+
+error:
+ if (ring->intf != NULL)
+ kfree(ring->intf);
+ if (ring->bytes != NULL)
+ kfree(ring->bytes);
+ return ret;
}
Cheers,
--
Julien Grall
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend
Hi Stefano,
On 03/06/2017 08:01 PM, Stefano Stabellini wrote:
+static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
+ struct xen_9pfs_dataring *ring)
+{
+ int i;
+ int ret = -ENOMEM;
+
+ init_waitqueue_head(>wq);
+ spin_lock_init(>lock);
+ INIT_WORK(>work, p9_xen_response);
+
+ ring->intf = (struct xen_9pfs_data_intf *) __get_free_page(GFP_KERNEL |
__GFP_ZERO);
+ if (!ring->intf)
+ goto error;
+ memset(ring->intf, 0, XEN_PAGE_SIZE);
+ ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
XEN_9PFS_RING_ORDER);
The ring order will be in term of Xen page size and not Linux. So you
are going to allocate much more memory than expected on 64KB kernel.
+ if (ring->bytes == NULL)
+ goto error;
+ for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++)
+ ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id,
pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);.
Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
Also, this is not going to work on 64K kernel because you will grant
access to noncontiguous memory (e.g 0-4K, 64K-68K,...).
We have various helper to break-down the page for you, see
gnttab_for_one_grant, gnttab_foreach_grant, gnttab_count_grant,
xen_for_each_gfn (though this one it is internal to xlate_mmu.c so far)
Please use them to avoid any further.
+ ring->ref = gnttab_grant_foreign_access(dev->otherend_id,
pfn_to_gfn(virt_to_pfn((void*)ring->intf)), 0);
Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
+ ring->ring.in = ring->bytes;
+ ring->ring.out = ring->bytes + XEN_9PFS_RING_SIZE;
+
+ ret = xenbus_alloc_evtchn(dev, >evtchn);
+ if (ret)
+ goto error;
+ ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
xen_9pfs_front_event_handler,
+ 0, "xen_9pfs-frontend", ring);
+ if (ring->irq < 0) {
+ xenbus_free_evtchn(dev, ring->evtchn);
+ ret = ring->irq;
+ goto error;
+ }
return 0;
+
+error:
+ if (ring->intf != NULL)
+ kfree(ring->intf);
+ if (ring->bytes != NULL)
+ kfree(ring->bytes);
+ return ret;
}
Cheers,
--
Julien Grall
