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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>
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1 changed files with 8 additions and 3 deletions
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@ -214,14 +214,19 @@ static int xen_hvm_console_init(void)
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/* already configured */
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if (info->intf != NULL)
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return 0;
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/*
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* If the toolstack (or the hypervisor) hasn't set these values, the
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* default value is 0. Even though mfn = 0 and evtchn = 0 are
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* theoretically correct values, in practice they never are and they
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* mean that a legacy toolstack hasn't initialized the pv console correctly.
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*/
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r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
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if (r < 0)
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if (r < 0 || v == 0)
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goto err;
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info->evtchn = v;
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v = 0;
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r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
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if (r < 0)
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if (r < 0 || v == 0)
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goto err;
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mfn = v;
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info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
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