linux-kernel - Re: [RFC 00/10] Process-local memory allocations for hiding KVM secrets

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Message-ID: <63b1b249-6bc7-ffd9-99db-d36dd3f1a962@intel.com>
Date:   Mon, 17 Jun 2019 08:50:35 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Alexander Graf <graf@...zon.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...capital.net>
Cc:     Marius Hillenbrand <mhillenb@...zon.de>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
        linux-mm@...ck.org, Alexander Graf <graf@...zon.de>,
        David Woodhouse <dwmw@...zon.co.uk>,
        the arch/x86 maintainers <x86@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [RFC 00/10] Process-local memory allocations for hiding KVM
 secrets

On 6/17/19 12:38 AM, Alexander Graf wrote:
>> Yes I know, but as a benefit we could get rid of all the GSBASE
>> horrors in
>> the entry code as we could just put the percpu space into the local PGD.
> 
> Would that mean that with Meltdown affected CPUs we open speculation
> attacks against the mmlocal memory from KVM user space?

Not necessarily.  There would likely be a _set_ of local PGDs.  We could
still have pair of PTI PGDs just like we do know, they'd just be a local
PGD pair.