From: Ben Hutchings <ben@decadent.org.uk>
To: speck@linutronix.de
Subject: [MODERATED] Re: [PATCH v5 6/8] NX 6
Date: Sun, 13 Oct 2019 23:11:05 +0100 [thread overview]
Message-ID: <e9e61c9219555502b177720af800a67e8fa94020.camel@decadent.org.uk> (raw)
In-Reply-To: <4d3beab5-4021-832d-5c40-a0f657d55631@redhat.com>
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On Thu, 2019-10-10 at 01:08 +0200, speck for Paolo Bonzini wrote:
> On 10/10/19 00:42, speck for Ben Hutchings wrote:
> > I've started trying to backport the NX patches to stable branches, and
> > I think I can take them back as far as 4.9.
> >
> > However, kvm_mmu_zap_all() is a relatively new addition and looks hard
> > to backport. I intend to make the nx_huge_pages parameter read-only
> > (0444 permissions) and delete this "if (new_val != old_val)" block.
> > Does that seem reasonable?
>
> Just replace it with kvm_mmu_invalidate_zap_all_pages (which will be in
> v6, because we have since brought it back from the dead).
>
> You also have to backport commit 833b45de69a6 ("kvm: x86, powerpc: do
> not allow clearing largepages debugfs entry", 2019-09-30) and make the
> new statistic 0444 as well. This is the only other change in v6 for now.
>
> This is the list of prerequisites I had prepared, it should go back to 4.3 or so:
Wow, thanks for this. I still don't think it's worthwile to backport
this mitigation to stable branches older than 4.9 - they never got KVM
mitigations for L1TF so they're already unsuitable for hosting
untrusted guests. After excluding commits older than 4.9, the list is
then:
[...]
> e08d26f0712532c79b5ba6200862eaf2036f8df6 kvm: x86: simplify ept_misconfig
> 9b8ebbdb74b5ad76b9dfd8b101af17839174b126 kvm: x86: extend usage of RET_MMIO_PF_* constants
> 42522d08cdba6d8be4247e4f0770f39f4708b71f KVM: MMU: drop vcpu param in gpte_access
> 0d9ce162cf46c99628cc5da9510b959c7976735b kvm: Convert kvm_lock to a mutex
[...]
> 43fdcda96e2550c6d1c46fb8a78801aa2f7276ed kvm: mmu: Do not release the page inside mmu_set_spte()
> 9de2b2120668d2874570b14105e49235097b70c2 KVM: x86: make FNAME(fetch) and __direct_map more similar
Commit hash should be 3fcf2d1bdeb6a513523cb2c77012a6b047aa859c?
> d679b32611c0102ce33b9e1a4e4b94854ed1812a KVM: x86: remove now unneeded hugepage gfn adjustment
> 1e823556fd3af3635e174f570d0b85b4e72b2b1c KVM: x86: change kvm_mmu_page_get_gfn BUG_ON to WARN_ON
Commit hash should be e9f2a760b158551bfbef6db31d2cae45ab8072e5?
> bf9af89c4146978000eba9b0a1eb43540d893223 KVM: x86: add tracepoints around __direct_map and FNAME(fetch)
Commit hash should be 335e192a3fa415e1202c8b9ecdaaecd643f823cc?
> 833b45de69a6016c4b0cebe6765d526a31a81580 kvm: x86, powerpc: do not allow clearing largepages debugfs entry
>
> None of the backports should be particularly tricky.
In my previous attempt I found it helpful to pick these two that you
didn't mention:
3ff519f29d98 KVM: x86: adjust kvm_mmu_page member to save 8 bytes
00ae831dfe44 x86/cpu: Add Atom Tremont (Jacobsville)
Ben.
--
Ben Hutchings
The obvious mathematical breakthrough [to break modern encryption]
would be development of an easy way to factor large prime numbers.
- Bill Gates
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next prev parent reply other threads:[~2019-10-13 22:11 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1561989149-17323-1-git-send-email-pbonzini@redhat.com>
[not found] ` <1561989149-17323-9-git-send-email-pbonzini@redhat.com>
[not found] ` <8eab605b-df0e-74d0-e448-986149edf33e@redhat.com>
2019-10-02 20:38 ` [MODERATED] Re: [PATCH v5 8/8] NX 8 Pawan Gupta
2019-10-02 20:59 ` Paolo Bonzini
2019-10-07 19:45 ` Pawan Gupta
2019-10-09 6:13 ` Paolo Bonzini
2019-10-09 14:41 ` Pawan Gupta
2019-10-09 15:10 ` Paolo Bonzini
2019-10-10 5:53 ` Pawan Gupta
2019-10-10 16:14 ` Paolo Bonzini
2019-10-10 16:50 ` Paolo Bonzini
2019-10-10 17:37 ` Paolo Bonzini
[not found] ` <1561989149-17323-7-git-send-email-pbonzini@redhat.com>
[not found] ` <alpine.DEB.2.21.1907022244530.1802@nanos.tec.linutronix.de>
[not found] ` <4c4447ba-838d-cd85-f35b-468508437b61@intel.com>
[not found] ` <alpine.DEB.2.21.1907022303250.1802@nanos.tec.linutronix.de>
2019-10-09 0:14 ` [MODERATED] Re: [PATCH v5 6/8] NX 6 Pawan Gupta
2019-10-09 22:42 ` Ben Hutchings
2019-10-09 22:52 ` Junaid Shahid
2019-10-09 23:05 ` Ben Hutchings
2019-10-09 23:03 ` Kanth Ghatraju
2019-10-09 23:08 ` Paolo Bonzini
2019-10-09 23:20 ` Kanth Ghatraju
2019-10-31 22:54 ` [MODERATED] NX backports (was Re: [PATCH v5 6/8] NX 6) Paolo Bonzini
2019-10-13 22:11 ` Ben Hutchings [this message]
2019-10-14 6:57 ` [MODERATED] Re: [PATCH v5 6/8] NX 6 Paolo Bonzini
2019-11-04 19:43 ` mark gross
2019-11-05 12:28 ` [MODERATED] Re: ***UNCHECKED*** " Michal Hocko
2019-11-05 14:53 ` mark gross
2019-11-05 17:03 ` mark gross
2019-10-14 20:46 ` [MODERATED] " Pawan Gupta
2019-10-15 6:24 ` Greg KH
2019-10-15 10:46 ` Jiri Kosina
2019-10-15 21:19 ` Pawan Gupta
2019-10-17 23:50 ` Ben Hutchings
[not found] ` <1561989149-17323-2-git-send-email-pbonzini@redhat.com>
2019-10-09 23:01 ` [MODERATED] Re: [PATCH v5 1/8] NX 1 Ben Hutchings
2019-10-10 1:33 ` Pawan Gupta
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