|
 |
a86ca71 |
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
|
|
|
a86ca71 |
Date: Fri, 27 Mar 2015 13:31:11 -0400
|
|
|
a86ca71 |
Subject: [PATCH] xen/pciback: Don't disable PCI_COMMAND on PCI device reset.
|
|
|
a86ca71 |
|
|
|
a86ca71 |
There is no need for this at all. Worst it means that if
|
|
|
a86ca71 |
the guest tries to write to BARs it could lead (on certain
|
|
|
a86ca71 |
platforms) to PCI SERR errors.
|
|
|
a86ca71 |
|
|
|
a86ca71 |
Please note that with af6fc858a35b90e89ea7a7ee58e66628c55c776b
|
|
|
a86ca71 |
"xen-pciback: limit guest control of command register"
|
|
|
a86ca71 |
a guest is still allowed to enable those control bits (safely), but
|
|
|
a86ca71 |
is not allowed to disable them and that therefore a well behaved
|
|
|
a86ca71 |
frontend which enables things before using them will still
|
|
|
a86ca71 |
function correctly.
|
|
|
a86ca71 |
|
|
|
a86ca71 |
This is done via an write to the configuration register 0x4 which
|
|
|
a86ca71 |
triggers on the backend side:
|
|
|
a86ca71 |
command_write
|
|
|
a86ca71 |
\- pci_enable_device
|
|
|
a86ca71 |
\- pci_enable_device_flags
|
|
|
a86ca71 |
\- do_pci_enable_device
|
|
|
a86ca71 |
\- pcibios_enable_device
|
|
|
a86ca71 |
\-pci_enable_resourcess
|
|
|
a86ca71 |
[which enables the PCI_COMMAND_MEMORY|PCI_COMMAND_IO]
|
|
|
a86ca71 |
|
|
|
a86ca71 |
However guests (and drivers) which don't do this could cause
|
|
|
a86ca71 |
problems, including the security issues which XSA-120 sought
|
|
|
a86ca71 |
to address.
|
|
|
a86ca71 |
|
|
|
a86ca71 |
Reported-by: Jan Beulich <jbeulich@suse.com>
|
|
|
a86ca71 |
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
|
|
|
a86ca71 |
---
|
|
|
a86ca71 |
drivers/xen/xen-pciback/pciback_ops.c | 2 --
|
|
|
a86ca71 |
1 file changed, 2 deletions(-)
|
|
|
a86ca71 |
|
|
|
a86ca71 |
diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
|
|
|
a86ca71 |
index c4a0666de6f5..26e651336787 100644
|
|
|
a86ca71 |
--- a/drivers/xen/xen-pciback/pciback_ops.c
|
|
|
a86ca71 |
+++ b/drivers/xen/xen-pciback/pciback_ops.c
|
|
|
a86ca71 |
@@ -119,8 +119,6 @@ void xen_pcibk_reset_device(struct pci_dev *dev)
|
|
|
a86ca71 |
if (pci_is_enabled(dev))
|
|
|
a86ca71 |
pci_disable_device(dev);
|
|
|
a86ca71 |
|
|
|
a86ca71 |
- pci_write_config_word(dev, PCI_COMMAND, 0);
|
|
|
a86ca71 |
-
|
|
|
a86ca71 |
dev->is_busmaster = 0;
|
|
|
a86ca71 |
} else {
|
|
|
a86ca71 |
pci_read_config_word(dev, PCI_COMMAND, &cmd);
|