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xen/pciback: Fix conf_space read/write overlap check. 

Current overlap check is evaluating to false a case where a filter
field is fully contained (proper subset) of a r/w request.  This
change applies classical overlap check instead to include all the
scenarios.

More specifically, for (Hilscher GmbH CIFX 50E-DP(M/S)) device driver
the logic is such that the entire confspace is read and written in 4
byte chunks. In this case as an example, CACHE_LINE_SIZE,
LATENCY_TIMER and PCI_BIST are arriving together in one call to
xen_pcibk_config_write() with offset == 0xc and size == 4.  With the
exsisting overlap check the LATENCY_TIMER field (offset == 0xd, length
== 1) is fully contained in the write request and hence is excluded
from write, which is incorrect.

Signed-off-by: Andrey Grodzovsky <andrey2805@gmail.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Jan Beulich <JBeulich@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Andrey Grodzovsky 2016-06-21 14:26:36 -04:00 committed by David Vrabel
parent 1cf3874130
commit 02ef871eca
1 changed files with 2 additions and 4 deletions
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6
drivers/xen/xen-pciback/conf_space.c
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@ -183,8 +183,7 @@ int xen_pcibk_config_read(struct pci_dev *dev, int offset, int size,
field_start = OFFSET(cfg_entry);
field_end = OFFSET(cfg_entry) + field->size;
if ((req_start >= field_start && req_start < field_end)
|| (req_end > field_start && req_end <= field_end)) {
if (req_end > field_start && field_end > req_start) {
err = conf_space_read(dev, cfg_entry, field_start,
&tmp_val);
if (err)
@ -230,8 +229,7 @@ int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
field_start = OFFSET(cfg_entry);
field_end = OFFSET(cfg_entry) + field->size;
if ((req_start >= field_start && req_start < field_end)
|| (req_end > field_start && req_end <= field_end)) {
if (req_end > field_start && field_end > req_start) {
tmp_val = 0;
err = xen_pcibk_config_read(dev, field_start,