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Groups > linux.kernel > #1594800
| From | Stefano Stabellini <sstabellini@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend |
| Date | 2017-03-08 03:20 +0100 |
| Message-ID | <tizmN-8ev-7@gated-at.bofh.it> (permalink) |
| References | <ti77c-4Of-7@gated-at.bofh.it> <ti7gR-4VX-1@gated-at.bofh.it> <ti7gR-4VX-7@gated-at.bofh.it> <tisv1-3b1-27@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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(&ring->wq);
> > + spin_lock_init(&ring->lock);
> > + INIT_WORK(&ring->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, &ring->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;
> > }
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 0/7] Xen transport for 9pfs frontend driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:10 +0100
[PATCH 1/7] xen: import new ring macros in ring.h Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
[PATCH 7/7] xen/9pfs: build 9pfs Xen transport driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
[PATCH 6/7] xen/9pfs: receive responses Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-07 17:00 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 02:30 +0100
Re: [Xen-devel] [PATCH 6/7] xen/9pfs: receive responses Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2017-03-08 21:20 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 06:30 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 15:40 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 20:30 +0100
[PATCH 2/7] xen: introduce the header file for the Xen 9pfs transport protocol Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
Re: [PATCH 2/7] xen: introduce the header file for the Xen 9pfs transport protocol Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 22:40 +0100
Re: [PATCH 2/7] xen: introduce the header file for the Xen 9pfs transport protocol Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-06 22:50 +0100
Re: [PATCH 2/7] xen: introduce the header file for the Xen 9pfs transport protocol Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-06 23:40 +0100
[PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
Re: [PATCH 4/7] xen/9pfs: connect to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-07 16:10 +0100
Re: [PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 01:30 +0100
Re: [PATCH 4/7] xen/9pfs: connect to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 15:00 +0100
Re: [PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 20:30 +0100
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend Julien Grall <julien.grall@arm.com> - 2017-03-07 20:00 +0100
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 03:20 +0100
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend Julien Grall <julien.grall@arm.com> - 2017-03-08 13:40 +0100
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 20:10 +0100
[PATCH 3/7] xen/9pfs: introduce Xen 9pfs transport driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
[PATCH 5/7] xen/9pfs: send requests to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-07 17:40 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 02:00 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 15:10 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 20:50 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 21:10 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 22:10 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 22:30 +0100
Re: [Xen-devel] [PATCH 1/7] xen: import new ring macros in ring.h Julien Grall <julien.grall@arm.com> - 2017-03-07 20:20 +0100
Re: [Xen-devel] [PATCH 1/7] xen: import new ring macros in ring.h Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 01:30 +0100
Re: [Xen-devel] [PATCH 1/7] xen: import new ring macros in ring.h Julien Grall <julien.grall@arm.com> - 2017-03-08 12:50 +0100
Re: [Xen-devel] [PATCH 0/7] Xen transport for 9pfs frontend driver Roger Pau Monné <roger.pau@citrix.com> - 2017-03-07 17:50 +0100
Re: [Xen-devel] [PATCH 0/7] Xen transport for 9pfs frontend driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-07 19:30 +0100
Re: [Xen-devel] [PATCH 0/7] Xen transport for 9pfs frontend driver Roger Pau Monné <roger.pau@citrix.com> - 2017-03-09 04:10 +0100
Re: [Xen-devel] [PATCH 0/7] Xen transport for 9pfs frontend driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-13 23:40 +0100
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