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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2012-05-23 12:56:59 -0400
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2012-05-24 14:23:01 -0400
commit5842f5768599094758931b74190cdf93641a8e35 (patch)
tree32eb4c87399c9cc60eabace7dd098fd660ca5eaa /drivers/tty/hvc
parenta32c88b9386ce3df87f28dd46bdc3776cd6edf75 (diff)
xen/hvc: Check HVM_PARAM_CONSOLE_[EVTCHN|PFN] for correctness.
We need to make sure that those parameters are setup to be correct. As such the value of 0 is deemed invalid and we find that we bail out. The hypervisor sets by default all of them to be zero and when the hypercall is done does a simple: a.value = d->arch.hvm_domain.params[a.index]; Which means that if the Xen toolstack forgot to setup the proper HVM_PARAM_CONSOLE_EVTCHN (or the PFN one), we would get the default value of 0 and use that. CC: stable@kernel.org Fixes-Oracle-Bug: 14091238 Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/tty/hvc')
-rw-r--r--drivers/tty/hvc/hvc_xen.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 3277f0eec4a7..944eaeb8e0cf 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -214,14 +214,19 @@ static int xen_hvm_console_init(void)
/* already configured */
if (info->intf != NULL)
return 0;
-
+ /*
+ * If the toolstack (or the hypervisor) hasn't set these values, the
+ * default value is 0. Even though mfn = 0 and evtchn = 0 are
+ * theoretically correct values, in practice they never are and they
+ * mean that a legacy toolstack hasn't initialized the pv console correctly.
+ */
r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
- if (r < 0)
+ if (r < 0 || v == 0)
goto err;
info->evtchn = v;
v = 0;
r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
- if (r < 0)
+ if (r < 0 || v == 0)
goto err;
mfn = v;
info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);