Intel Core processors since at least Nehalem speculate past #NM, which is the
mechanism by which lazy FPU context switching is implemented.
On affected processors, Xen must use fully eager FPU context switching to
prevent guests from being able to read FPU state (SSE/AVX/etc) from previously
scheduled vcpus.
This is part of XSA-267 / CVE-2018-3665
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
The 4.10 release preparation was significantly more hairy than ideal.
(We seem to have a good overall outcome despite, rather than because
of, our approach.)
This is the second time (at least) that we have come close to failure
by committing to a release date before the exact code to be released
is known and has been made and tested.
Evidently our docs makes it insufficiently clear not to do that.
CC: Julien Grall <julien.grall@arm.com>
Acked-by: Juergen Gross <jgross@suse.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Lars Kurth <lars.kurth@citrix.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
To combat GPZ SP4 "Speculative Store Bypass", Intel have extended their
speculative sidechannel mitigations specification as follows:
* A feature bit to indicate that Speculative Store Bypass Disable is
supported.
* A new bit in MSR_SPEC_CTRL which, when set, disables memory disambiguation
in the pipeline.
* A new bit in MSR_ARCH_CAPABILITIES, which will be set in future hardware,
indicating that the hardware is not susceptible to Speculative Store Bypass
sidechannels.
For contemporary processors, this interface will be implemented via a
microcode update.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
AMD processors will execute loads and stores with the same base register in
program order, which is typically how a compiler emits code.
Therefore, by default no mitigating actions are taken, despite there being
corner cases which are vulnerable to the issue.
For performance testing, or for users with particularly sensitive workloads,
the `spec-ctrl=ssbd` command line option is available to force Xen to disable
Memory Disambiguation on applicable hardware.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
"make -C docs all" fails due to incorrect markdown syntax in
livepatch.markdown. Correct it.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Misc fixes:
* Insert real URLs
* Drop trailing whitespace
* Consistent alignment and indentation for code blocks and lists
* Consistent capitalisation
* Consistent use of `` blocks for command line arguments and function names
* Rearrange things not to leave < and > in the text
No change in content. The document now reads rather more consistently in HTML
and PDF form.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
In hindsight, the options for `bti=` aren't as flexible or useful as expected
(including several options which don't appear to behave as intended).
Changing the behaviour of an existing option is problematic for compatibility,
so introduce a new `spec-ctrl=` in the hopes that we can do better.
One common way of deploying Xen is with a single PV dom0 and all domUs being
HVM domains. In such a setup, an administrator who has weighed up the risks
may wish to forgo protection against malicious PV domains, to reduce the
overall performance hit. To cater for this usecase, `spec-ctrl=no-pv` will
disable all speculative protection for PV domains, while leaving all
speculative protection for HVM domains intact.
For coding clarity as much as anything else, the suboptions are grouped by
logical area; those which affect the alternatives blocks, and those which
affect Xen's in-hypervisor settings. See the xen-command-line.markdown for
full details of the new options.
While changing the command line options, take the time to change how the data
is reported to the user. The three DEBUG printks are upgraded to unilateral,
as they are all relevant pieces of information, and the old "mitigations:"
line is split in the two logical areas described above.
Sample output from booting with `spec-ctrl=no-pv` looks like:
(XEN) Speculative mitigation facilities:
(XEN) Hardware features: IBRS/IBPB STIBP IBPB
(XEN) Compiled-in support: INDIRECT_THUNK
(XEN) Xen settings: BTI-Thunk RETPOLINE, SPEC_CTRL: IBRS-, Other: IBPB
(XEN) Support for VMs: PV: None, HVM: MSR_SPEC_CTRL RSB
(XEN) XPTI (64-bit PV only): Dom0 enabled, DomU enabled
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
When SUPPORT.md uses the syntax
Status, <some thing>: <support status>
the caveats were lost (not footnoted) because they were attached
only to <some thing>.
Caveats occur in running text, so they are necessarily part of a real
section, not an individual status line like that. So attach them to
the RealSectNode, and look there for them.
Reported-by: Lars Kurth <lars.kurth@citrix.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Lars Kurth <Lars.kurth@citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
credit2_cap_period_ms isn't mentioned in xen-command-line.markdown.
Add a description.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Many of the architecture specific boot parameters are not qualified
as such. Correct that. Reorder PKU to be alphabetical.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Avoid flushing the complete TLB when switching %cr3 for mitigation of
Meltdown by using the PCID feature if available.
We are using 4 PCID values for a 64 bit pv domain subject to XPTI and
2 values for the non-XPTI case:
- guest active and in kernel mode
- guest active and in user mode
- hypervisor active and guest in user mode (XPTI only)
- hypervisor active and guest in kernel mode (XPTI only)
We use PCID only if PCID _and_ INVPCID are supported. With PCID in use
we disable global pages in cr4. A command line parameter controls in
which cases PCID is being used.
As the non-XPTI case has shown not to perform better with PCID at least
on some machines the default is to use PCID only for domains subject to
XPTI.
With PCID enabled we always disable global pages. This avoids having to
either flush the complete TLB or do a cycle through all PCID values
when invalidating a single global page.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
If possible use the INVPCID instruction for flushing the TLB instead of
toggling cr4.pge for that purpose.
While at it remove the dependency on cr4.pge being required for mtrr
loading, as this will be required later anyway.
Add a command line option "invpcid" for controlling the use of
INVPCID (default to true).
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Instead of switching XPTI globally on or off add a per-domain flag for
that purpose. This allows to modify the xpti boot parameter to support
running dom0 without Meltdown mitigations. Using "xpti=no-dom0" as boot
parameter will achieve that.
Move the xpti boot parameter handling to xen/arch/x86/pv/domain.c as
it is pv-domain specific.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Preparing a real release, not just an RC, involves making commits.
Typically, those will be on staging-$x. The tag will refer to them,
and the checklist already says to push them to xenbits.
But if the *branch* is not pushed, then people who just "git fetch"
won't get the tag because it refers to commits they don't have.
(Because of the strange rules git has about tag fetching.)
Worse, the same may be true of people who "git clone".
And anyway, those commits *should* be fed to staging-$x.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
The old instructions were obsolete. Here are the details I used when
branching for 4.10.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Some underscores are not escaped in xen-command-line.markdown.
Correct that.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Some of the boot parameters in docs/misc/xen-command-line.markdown are
not in the correct alphabetically order. Correct that.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Clarify what is expected of the release technician for SUPPORT.md: fix
the version number field. The support dates will be set by the
release manageer.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
This contains instructions and shell runes for the Release Technician,
who is the person doing the technical admin to construct the release,
fork branches, make tags and tarballs, etc.
Rename it to make this clearer.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Each document has its own objects in @insections. Only the first
RealSect encountered ends up in the main $toplevel_sectlist tree.
This means that trying to unify the Caveats information for all
version in the RealSect (the $insection) does not work. The caveats
for all versions that aren't the first one where this section was seen
end up in the @insections array during parsing of that version, but
not recorded in the main tree.
The result was that footnotes would only appear in the output for
versions which were the most recent version where that feature row or
category appeared. The other footnotes would be lost.
Instead, store HasCaveat in the sectnode. That means ri_Para needs to
find the sectnode.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
We are going to want to add a call site for this.
No functional change.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Non-leaf sections with footnotes must have a row of their own, for
just that section, because footnotes only appear if there is status
information.
In that case, the footnote applies to only the rows for that section
in the markdown document, ie that RealSect.
And of course for a leaf section that is true too.
So for footnoes we always want to use a rowspan of the number of
Status elements in the section. So (i) calculate this in
count_rows_sectlist and (ii) use it, instead of the total number of
rows including all the subsections', when writing out the footnote
ref.
This bug has been present in this script since the beginning.
Also, while we're here, suppress the rowspan if it would be 1.
Reported-by: Lars Kurth <lars.kurth@citrix.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Running text in feature sections in the markdown document currently
might be (i) a caveat, qualifying or clarifying the support statement
(ii) a plain description of the feature.
Caveats can be version-specific and deserve the [*] annotation in the
relevant feature matrix cell. They must link to SUPPORT.html for the
specific version.
Descriptions are not version specific. In that case the [*]
annotation is visusal noise. Rather, it is better to make a hyperlink
out of the text which is being expanded on. The hyperlink can point
to any appropriate version.
There is a question about how to notate this distinction in
SUPPORT.md. After IRL discussion with George and Lars I propose that
we should put text which helps describe a feature (ie, which expands
on a section heading) after the heading but before the Status
indications; whereas, caveats and supplementary information about
the actual status, should follow the Status block.
This patch implements this distinction in the support matrix
generator. Only paragraphs containing _only_ italic content count as
descriptive; anything else is treated as a caveat.
In the code:
* Add a new entry to RealSect, HasDescription
* When parsing, track whether we are before or after the first Status
block in a new variable $has_feature.
* In ri_Para, set HasDescription set to the input document index
when we encounter text before the first feature.
* When writing a `heading' (ie, the table cell for a feature name)
look for HasDescription and make an appropriate hyperlink.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
7782db9260 "docs/gen-html-index: Extract titles from HTML documents"
requires HTML::TreeBuilder::XPath.
This is sadly not as widely available as I had hoped. Work around
this problem by making the use of this module optional: instead of
`use'ing at the toplevel, we `require' it in the eval. If it's not
present, then the title is simply not extracted and the filename is
used as before, which is tolerable.
Also add some debugging.
Reported-by: Doug Goldstein <cardoe@cardoe.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Reviewed-by: Doug Goldstein <cardoe@cardoe.com>
Tested-by: Doug Goldstein <cardoe@cardoe.com>
A section in the SUPPORT.md may mention multiple
Status, something: Supported
and then have some text. The text is linked to from [*] footnotes
in the table. But, this means that each bit of text needs to
apply to multiple rows.
Before this commit this was a separate [*] after each applicable item.
But multiple apparently-different links to the same thing are annoying
for the reader.
So, in this commit we combine them. Formatting the result is not
entirely trivial.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
---
v3: New patch
v3.1: Drop `}' in multi-row [*] notes. I put this in to help work
around firefox bugs eg
https://bugzilla.mozilla.org/show_bug.cgi?id=244135
but I have been convinced it is not generally wanted.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
This archaeology script:
- figures out what the current and previous Xen versions were
- looks for appropriate git branches for them
- finds SUPPORT.md for each one
- feeds its findings to parse-support-md
We do not intend to integrate this into docs/Makefile, because it
relies on the git history. Instead, we will take the rune provided in
the head comment and paste a variant of it into an appropriate cronjob
on xenbits.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Acked-by: Lars Kurth <lars.kurth@citrix.com>
---
v3: Provide -D option.
This utility reads json format pandoc output, from parsing one or more
SUPPORT.md files, and generates an HTML table element containing the
principal version and feature information.
This is rather hairier than I anticipated when I started out; hence
the 400-odd-line Perl script.
Machinery to assemble the appropriate inputs for parse-support-md
will be in the next commit.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Acked-by: Lars Kurth <lars.kurth@citrix.com>
---
v2: New in this version of the series.
v3: Refactor to introduce RealSect
v3: Add [*] footnote to all applicable entries, not just the last
We are going to want to format SUPPORT.md which does not match the
filename patterns in docs/. So provide a way to make an ad-hoc rule
using pandoc with the standard options.
No functional change in this patch.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Acked-by: Lars Kurth <lars.kurth@citrix.com>
Allow the path to be set from a configure command line option.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
[ wei: run autogen.sh ]
Add a short entry to the xl.cfg man page about pvcalls.
Also add LIBXL_HAVE_PVCALLS to mark the presence of pvcalls support in
libxl.
Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Add pvcalls support to libxl and xl. Create the appropriate pvcalls
entries in xenstore.
Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Make it possible to get and set a (Credit1) scheduler's
vCPU migration delay via the SCHEDOP sysctl, from both
libxl and xl (no change needed in libxc).
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
The man for xl.cfg have the "devtype=hostdev" option, but xl only
understand "type=hostdev", fix the manual to reflect actual
implementation.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
XSA-256 forces the local APIC to always be enabled for PVH guests, so
ignore any apic option for PVH guests. Update the documentation
accordingly.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
All this information is now covered in SUPPORT.md.
Most of the emulated hardware is obvious a couple of the items are
worth pointing out specifically.
"xen_disk" is listed under "Blkback"
"...the PCI host bridge and the PIIX3 chipset...": This statement is
redundant -- the PCI host bridge is a part of the piix3 chipset, which
is listed as supported.
xenfb: The "graphics" side of "xenfb" is listed under "PV Framebuffer
(backend)", and the "input" side of "xenfb" (including both keyboard
and mouse) is listed under "PV Keyboard (backend)".
Backing storage image format is listed in the "Blkback" section.
Fix 'stdvga' spelling while we're here.
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Xen does not properly support big.LITTLE platform. All vCPUs of a guest
will always have the MIDR of the boot CPU (see arch_domain_create).
At best the guest may see unreliable performance (vCPU switching between
big and LITTLE), at worst the guest will become unreliable or insecure.
This is becoming more apparent with branch predictor hardening in Linux
because they target a specific kind of CPUs and may not work on other
CPUs.
For the time being, park any CPUs with a MDIR different from the boot
CPU. This will be revisited in the future once Xen gains understanding
of big.LITTLE.
[1] https://lists.xenproject.org/archives/html/xen-devel/2016-12/msg00826.html
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Oleksandr Tyshchenkko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Ian Jackson