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Commit 5842f576 authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk
Browse files

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: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent a32c88b9

drivers/tty/hvc/hvc_xen.c

+8 −3
Original line number Diff line number Diff line
@@ -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);