Date: Fri, 18 May 2018 15:21:54 +0200
From: Greg KH <gregkh@linuxfoundation.org>
Subject: [MODERATED] Re: [PATCH v17.1 2/2] [PATCH v17.1 2/2] SSB Fix #2
Message-ID: <20180518132154.GB11225@kroah.com>
References: <20180517031815.016936086@localhost.localdomain>
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To: speck@linutronix.de

On Wed, May 16, 2018 at 11:18:10PM -0400, speck for konrad.wilk_at_oracle.com wrote:
> xen: Don't call non-Xen routines early in the boot
> 
> Commit 2cc42bac1c79 ("x86-64/Xen: eliminate W+X mappings") added a call
> to  get_cpu_cap() to properly set boot_cpu_has(X86_FEATURE_NX) which is
> needed to correctly initialize __supported_pte_mask. Doing this so early
> in the boot can be dangerous --- while this currently works, there is no
> telling what get_cpu_cap() may decide to add in the future. For example,
> if it decides to do a printk (which is not something impossible to
> imagine) a PV guest will not be able to cope with it.

Wait, how does this break?  Does the guest kernel just crash
(hopefully), or does this mess with the host kernel?

confused,

greg k-h