RE: [PATCH 3/3] xen-netback: handle page straddling in xenvif_set_hash_mapping()
From: Paul Durrant <hidden>
Date: 2018-09-03 13:48:05
-----Original Message----- From: Jan Beulich [mailto:JBeulich@suse.com] Sent: 28 August 2018 16:00 To: Paul Durrant <redacted>; Wei Liu <redacted> Cc: davem@davemloft.net; xen-devel <redacted>; netdev@vger.kernel.org Subject: [PATCH 3/3] xen-netback: handle page straddling in xenvif_set_hash_mapping() There's no guarantee that the mapping array doesn't cross a page boundary. Use a second grant copy operation if necessary. Signed-off-by: Jan Beulich <redacted>
Personally I think it would be cleaner to out-of-line the allocation of the mapping table and ensure it is page aligned but this works so... Reviewed-by: Paul Durrant <redacted>
quoted hunk ↗ jump to hunk
--- drivers/net/xen-netback/hash.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-)--- 4.19-rc1-xen-netback-set-hash-mapping.orig/drivers/net/xen-netback/hash.c+++ 4.19-rc1-xen-netback-set-hash-mapping/drivers/net/xen-netback/hash.c@@ -334,28 +334,39 @@ u32 xenvif_set_hash_mapping(struct xenvi u32 off) { u32 *mapping = vif->hash.mapping[!vif->hash.mapping_sel]; - struct gnttab_copy copy_op = { + unsigned int nr = 1; + struct gnttab_copy copy_op[2] = {{ .source.u.ref = gref, .source.domid = vif->domid, .dest.domid = DOMID_SELF, .len = len * sizeof(*mapping), .flags = GNTCOPY_source_gref - }; + }}; if ((off + len < off) || (off + len > vif->hash.size) || len > XEN_PAGE_SIZE / sizeof(*mapping)) return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER; - copy_op.dest.u.gmfn = virt_to_gfn(mapping + off); - copy_op.dest.offset = xen_offset_in_page(mapping + off); + copy_op[0].dest.u.gmfn = virt_to_gfn(mapping + off); + copy_op[0].dest.offset = xen_offset_in_page(mapping + off); + if (copy_op[0].dest.offset + copy_op[0].len > XEN_PAGE_SIZE) { + copy_op[1] = copy_op[0]; + copy_op[1].source.offset = XEN_PAGE_SIZE -copy_op[0].dest.offset; + copy_op[1].dest.u.gmfn = virt_to_gfn(mapping + off + len); + copy_op[1].dest.offset = 0; + copy_op[1].len = copy_op[0].len - copy_op[1].source.offset; + copy_op[0].len = copy_op[1].source.offset; + nr = 2; + } memcpy(mapping, vif->hash.mapping[vif->hash.mapping_sel], vif->hash.size * sizeof(*mapping)); - if (copy_op.len != 0) { - gnttab_batch_copy(©_op, 1); + if (copy_op[0].len != 0) { + gnttab_batch_copy(copy_op, nr); - if (copy_op.status != GNTST_okay) + if (copy_op[0].status != GNTST_okay || + copy_op[nr - 1].status != GNTST_okay) return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER; }