From: Julien Grall <julien.grall@citrix.com>
To: xen-devel@lists.xenproject.org
Cc: ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com,
linux-kernel@vger.kernel.org,
Julien Grall <julien.grall@citrix.com>,
David Vrabel <david.vrabel@citrix.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 09/20] xen/biomerge: Don't allow biovec's to be merged when Linux is not using 4KB pages
Date: Mon, 7 Sep 2015 16:33:47 +0100 [thread overview]
Message-ID: <1441640038-23615-10-git-send-email-julien.grall__35025.9496983655$1441640199$gmane$org@citrix.com> (raw)
In-Reply-To: <1441640038-23615-1-git-send-email-julien.grall@citrix.com>
On ARM all dma-capable devices on a same platform may not be protected
by an IOMMU. The DMA requests have to use the BFN (i.e MFN on ARM) in
order to use correctly the device.
While the DOM0 memory is allocated in a 1:1 fashion (PFN == MFN), grant
mapping will screw this contiguous mapping.
When Linux is using 64KB page granularitary, the page may be split
accross multiple non-contiguous MFN (Xen is using 4KB page
granularity). Therefore a DMA request will likely fail.
Checking that a 64KB page is using contiguous MFN is tedious. For
now, always says that biovec are not mergeable.
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
There is some ideas to check whether two biovec could be merged
(see [1]) but it's not critical and can be consider as a performance
improvement.
Changes in v4:
- Fix typoes in the subject
- Add Stefano's reviewed-by
Changes in v3:
- Update commit message
- s/mfn/bfn/ base on the new renaming
- Update TODO
Changes in v2:
- Remove the workaround and check if the Linux page granularity
is the same as Xen or not
[1] https://lkml.org/lkml/2015/7/17/418
---
drivers/xen/biomerge.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/xen/biomerge.c b/drivers/xen/biomerge.c
index 8ae2fc90..4da69db 100644
--- a/drivers/xen/biomerge.c
+++ b/drivers/xen/biomerge.c
@@ -6,10 +6,18 @@
bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
const struct bio_vec *vec2)
{
+#if XEN_PAGE_SIZE == PAGE_SIZE
unsigned long bfn1 = pfn_to_bfn(page_to_pfn(vec1->bv_page));
unsigned long bfn2 = pfn_to_bfn(page_to_pfn(vec2->bv_page));
return __BIOVEC_PHYS_MERGEABLE(vec1, vec2) &&
((bfn1 == bfn2) || ((bfn1+1) == bfn2));
+#else
+ /*
+ * XXX: Add support for merging bio_vec when using different page
+ * size in Xen and Linux.
+ */
+ return 0;
+#endif
}
EXPORT_SYMBOL(xen_biovec_phys_mergeable);
--
2.1.4
next prev parent reply other threads:[~2015-09-07 15:35 UTC|newest]
Thread overview: 143+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-07 15:33 [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 01/20] net/xen-netback: xenvif_gop_frag_copy: move GSO check out of the loop Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 02/20] arm/xen: Drop pte_mfn and mfn_pte Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 03/20] xen: Add Xen specific page definition Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 04/20] xen/grant: Introduce helpers to split a page into grant Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 05/20] xen/grant: Add helper gnttab_page_grant_foreign_access_ref_one Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 06/20] block/xen-blkfront: Split blkif_queue_request in 2 Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 07/20] block/xen-blkfront: Store a page rather a pfn in the grant structure Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 08/20] block/xen-blkfront: split get_grant in 2 Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall [this message]
2015-09-07 15:33 ` [PATCH v4 09/20] xen/biomerge: Don't allow biovec's to be merged when Linux is not using 4KB pages Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 10/20] xen/xenbus: Use Xen page definition Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 11/20] tty/hvc: xen: Use xen " Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 12/20] xen/balloon: Don't rely on the page granularity is the same for Xen and Linux Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 16:39 ` Stefano Stabellini
2015-09-07 16:39 ` Stefano Stabellini
2015-09-07 16:39 ` Stefano Stabellini
2015-09-07 15:33 ` [PATCH v4 13/20] xen/events: fifo: Make it running on 64KB granularity Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 14/20] xen/grant-table: " Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 15/20] block/xen-blkfront: Make it running on 64KB page granularity Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 16/20] block/xen-blkback: " Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 17/20] net/xen-netfront: " Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 18/20] net/xen-netback: " Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 16:57 ` Wei Liu
2015-09-07 16:57 ` Wei Liu
2015-09-07 16:57 ` Wei Liu
2015-09-08 11:07 ` [Xen-devel] " Julien Grall
2015-09-08 11:07 ` Julien Grall
2015-09-08 11:09 ` Wei Liu
2015-09-08 11:09 ` [Xen-devel] " Wei Liu
2015-09-08 11:09 ` Wei Liu
2015-09-08 11:07 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 19/20] xen/privcmd: Add support for Linux " Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` [PATCH v4 20/20] arm/xen: Add support for " Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-07 15:33 ` Julien Grall
2015-09-11 19:39 ` [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux Julien Grall
2015-09-11 19:39 ` [Xen-devel] " Julien Grall
2015-09-11 19:39 ` Julien Grall
2015-09-14 8:56 ` Roger Pau Monné
2015-09-14 8:56 ` Roger Pau Monné
2015-09-14 10:40 ` Julien Grall
2015-09-14 10:40 ` Julien Grall
2015-09-14 11:04 ` Roger Pau Monné
2015-09-14 11:04 ` Roger Pau Monné
2015-09-14 11:21 ` Julien Grall
2015-09-14 11:21 ` Julien Grall
2015-09-14 12:08 ` Roger Pau Monné
2015-09-14 12:08 ` Roger Pau Monné
2015-09-14 12:47 ` Julien Grall
2015-09-14 12:47 ` Julien Grall
2015-09-14 14:29 ` Roger Pau Monné
2015-09-14 14:29 ` Roger Pau Monné
2015-09-14 14:29 ` Roger Pau Monné
2015-09-14 14:46 ` Julien Grall
2015-09-14 14:46 ` Julien Grall
2015-09-14 14:46 ` Julien Grall
2015-09-14 14:54 ` Stefano Stabellini
2015-09-14 14:54 ` Stefano Stabellini
2015-09-14 15:23 ` Roger Pau Monné
2015-09-14 15:23 ` Roger Pau Monné
2015-09-14 15:23 ` Roger Pau Monné
2015-09-22 10:59 ` Ian Campbell
2015-09-22 10:59 ` Ian Campbell
2015-10-06 9:28 ` Roger Pau Monné
2015-10-06 9:28 ` Roger Pau Monné
2015-10-06 10:17 ` Ian Campbell
2015-10-06 10:17 ` Ian Campbell
2015-10-06 10:17 ` Ian Campbell
2015-10-06 13:55 ` Stefano Stabellini
2015-10-06 13:55 ` Stefano Stabellini
2015-10-06 13:55 ` Stefano Stabellini
2015-10-06 9:28 ` Roger Pau Monné
2015-09-22 10:59 ` Ian Campbell
2015-09-14 14:54 ` Stefano Stabellini
2015-09-14 12:47 ` Julien Grall
2015-09-18 14:10 ` Julien Grall
2015-09-18 14:10 ` Julien Grall
2015-09-18 14:10 ` Julien Grall
2015-09-14 12:08 ` Roger Pau Monné
2015-09-14 11:21 ` Julien Grall
2015-09-14 11:32 ` Arnd Bergmann
2015-09-14 11:32 ` Arnd Bergmann
2015-09-14 11:32 ` Arnd Bergmann
2015-09-15 13:14 ` David Vrabel
2015-09-15 13:14 ` [Xen-devel] " David Vrabel
2015-09-15 13:14 ` David Vrabel
2015-09-15 13:24 ` Arnd Bergmann
2015-09-15 13:24 ` [Xen-devel] " Arnd Bergmann
2015-09-15 13:24 ` Arnd Bergmann
2015-09-14 11:04 ` Roger Pau Monné
2015-09-14 10:40 ` Julien Grall
2015-09-14 8:56 ` Roger Pau Monné
2015-09-29 16:27 ` David Vrabel
2015-09-29 16:27 ` [Xen-devel] " David Vrabel
2015-09-29 16:27 ` David Vrabel
2015-09-29 16:33 ` Julien Grall
2015-09-29 16:33 ` Julien Grall
2015-09-29 16:36 ` David Vrabel
2015-09-29 16:36 ` [Xen-devel] " David Vrabel
2015-09-29 16:36 ` David Vrabel
2015-09-29 16:33 ` Julien Grall
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