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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>
hifive-unleashed-5.1
Konrad Rzeszutek Wilk 2012-05-23 12:56:59 -04:00
parent a32c88b938
commit 5842f57685
1 changed files with 8 additions and 3 deletions
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11
drivers/tty/hvc/hvc_xen.c
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@ -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);