From 5842f5768599094758931b74190cdf93641a8e35 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Wed, 23 May 2012 12:56:59 -0400 Subject: [PATCH] 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 --- drivers/tty/hvc/hvc_xen.c | 11 ++++++++--- 1 file 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); -- 2.39.5