From: Andy Lutomirski <luto@kernel.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Alexander Graf <graf@amazon.com>,
Thomas Gleixner <tglx@linutronix.de>,
Marius Hillenbrand <mhillenb@amazon.de>,
kvm list <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Linux-MM <linux-mm@kvack.org>, Alexander Graf <graf@amazon.de>,
David Woodhouse <dwmw@amazon.co.uk>,
"the arch/x86 maintainers" <x86@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC 00/10] Process-local memory allocations for hiding KVM secrets
Date: Mon, 17 Jun 2019 09:14:50 -0700 [thread overview]
Message-ID: <CALCETrVt=X+FB2cM5hMN9okvbcROFfT4_KMwaKaN2YVvc7UQTw@mail.gmail.com> (raw)
In-Reply-To: <698ca264-123d-46ae-c165-ed62ea149896@intel.com>
On Mon, Jun 17, 2019 at 9:09 AM Dave Hansen <dave.hansen@intel.com> wrote:
>
> On 6/17/19 8:54 AM, Andy Lutomirski wrote:
> >>> 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.
> >>
> > Unfortunately, this would mean that we need to sync twice as many
> > top-level entries when we context switch.
>
> Yeah, PTI sucks. :)
>
> For anyone following along at home, I'm going to go off into crazy
> per-cpu-pgds speculation mode now... Feel free to stop reading now. :)
>
> But, I was thinking we could get away with not doing this on _every_
> context switch at least. For instance, couldn't 'struct tlb_context'
> have PGD pointer (or two with PTI) in addition to the TLB info? That
> way we only do the copying when we change the context. Or does that tie
> the implementation up too much with PCIDs?
Hmm, that seems entirely reasonable. I think the nasty bit would be
figuring out all the interactions with PV TLB flushing. PV TLB
flushes already don't play so well with PCID tracking, and this will
make it worse. We probably need to rewrite all that code regardless.
next prev parent reply other threads:[~2019-06-17 16:15 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-12 17:08 [RFC 00/10] Process-local memory allocations for hiding KVM secrets Marius Hillenbrand
2019-06-12 17:08 ` [RFC 01/10] x86/mm/kaslr: refactor to use enum indices for regions Marius Hillenbrand
2019-06-12 17:08 ` [RFC 02/10] x86/speculation, mm: add process local virtual memory region Marius Hillenbrand
2019-06-12 17:08 ` [RFC 03/10] x86/mm, mm,kernel: add teardown for process-local memory to mm cleanup Marius Hillenbrand
2019-06-12 17:08 ` [RFC 04/10] mm: allocate virtual space for process-local memory Marius Hillenbrand
2019-06-12 17:08 ` [RFC 05/10] mm: allocate/release physical pages " Marius Hillenbrand
2019-06-12 17:08 ` [RFC 06/10] kvm/x86: add support for storing vCPU state in " Marius Hillenbrand
2019-06-12 17:08 ` [RFC 07/10] kvm, vmx: move CR2 context switch out of assembly path Marius Hillenbrand
2019-06-12 17:08 ` [RFC 08/10] kvm, vmx: move register clearing " Marius Hillenbrand
2019-06-12 17:08 ` [RFC 09/10] kvm, vmx: move gprs to process local memory Marius Hillenbrand
2019-06-12 17:08 ` [RFC 10/10] kvm, x86: move guest FPU state into " Marius Hillenbrand
2019-06-12 18:25 ` [RFC 00/10] Process-local memory allocations for hiding KVM secrets Sean Christopherson
2019-06-13 7:20 ` Alexander Graf
2019-06-13 10:54 ` Liran Alon
2019-06-12 19:55 ` Dave Hansen
2019-06-12 20:27 ` Andy Lutomirski
2019-06-12 20:41 ` Dave Hansen
2019-06-12 20:56 ` Andy Lutomirski
2019-06-13 1:30 ` Andy Lutomirski
2019-06-13 1:50 ` Nadav Amit
2019-06-13 16:16 ` Andy Lutomirski
2019-06-13 7:52 ` Alexander Graf
2019-06-13 16:13 ` Andy Lutomirski
2019-06-13 16:20 ` Dave Hansen
2019-06-13 17:29 ` Nadav Amit
2019-06-13 17:49 ` Dave Hansen
2019-06-13 20:05 ` Sean Christopherson
2019-06-14 14:21 ` Thomas Gleixner
2019-06-16 22:18 ` Andy Lutomirski
2019-06-16 22:28 ` Thomas Gleixner
2019-06-17 7:38 ` Alexander Graf
2019-06-17 15:50 ` Dave Hansen
2019-06-17 15:54 ` Andy Lutomirski
2019-06-17 16:03 ` Dave Hansen
2019-06-17 16:14 ` Andy Lutomirski [this message]
2019-06-17 16:53 ` Nadav Amit
2019-06-17 18:07 ` Dave Hansen
2019-06-17 18:45 ` Konrad Rzeszutek Wilk
2019-06-17 18:49 ` Dave Hansen
2019-06-17 18:53 ` Andy Lutomirski
2019-06-17 18:50 ` Nadav Amit
2019-06-17 18:55 ` Dave Hansen
2019-06-13 7:27 ` Alexander Graf
2019-06-13 14:19 ` Dave Hansen
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