Commit Graph
12720 Commits
Author SHA1 Message Date
Wei Liu 9b8375a272 xl.conf: Add global affinity masks
XSA-273 involves one hyperthread being able to use Spectre-like
techniques to "spy" on another thread.  The details are somewhat
complicated, but the upshot is that after all Xen-based mitigations
have been applied:

* PV guests cannot spy on sibling threads
* HVM guests can spy on sibling threads

(NB that for purposes of this vulnerability, PVH and HVM guests are
identical.  Whenever this comment refers to 'HVM', this includes PVH.)

There are many possible mitigations to this, including disabling
hyperthreading entirely.  But another solution would be:

* Specify some cores as PV-only, others as PV or HVM
* Allow HVM guests to only run on thread 0 of the "HVM-or-PV" cores
* Allow PV guests to run on the above cores, as well as any thread of the PV-only cores.

For example, suppose you had 16 threads across 8 cores (0-7).  You
could specify 0-3 as PV-only, and 4-7 as HVM-or-PV.  Then you'd set
the affinity of the HVM guests as follows (binary representation):

0000000010101010

And the affinity of the PV guests as follows:

1111111110101010

In order to make this easy, this patches introduces three "global affinity
masks", placed in xl.conf:

    vm.cpumask
    vm.hvm.cpumask
    vm.pv.cpumask

These are parsed just like the 'cpus' and 'cpus_soft' options in the
per-domain xl configuration files.  The resulting mask is AND-ed with
whatever mask results at the end of the xl configuration file.
`vm.cpumask` would be applied to all guest types, `vm.hvm.cpumask`
would be applied to HVM and PVH guest types, and `vm.pv.cpumask`
would be applied to PV guest types.

The idea would be that to implement the above mask across all your
VMs, you'd simply add the following two lines to the configuration
file:

    vm.hvm.cpumask=8,10,12,14
    vm.pv.cpumask=0-8,10,12,14

See xl.conf manpage for details.

This is part of XSA-273 / CVE-2018-3646.

Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
(cherry picked from commit aa67b97ed3)

PVH guest type in toolstack is not available in this version of Xen.
Change code and manpage to cope. Also xl is still part of libxl in
thsi version, manually backport code to relevant places.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
2018-08-14 17:33:43 +01:00
Andrew Cooper f440b31efe x86/spec-ctrl: CPUID/MSR definitions for L1D_FLUSH
This is part of XSA-273 / CVE-2018-3646.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 3563fc2b27)
2018-08-14 17:29:09 +01:00
Christian Lindig df66c1cb19 tools/oxenstored: Make evaluation order explicit
In Store.path_write(), Path.apply_modify() updates the node_created
reference and both the value of apply_modify() and node_created are
returned by path_write().

At least with OCaml 4.06.1 this leads to the value of node_created being
returned *before* it is updated by apply_modify().  This in turn leads
to the quota for a domain not being updated in Store.write().  Hence, a
guest can create an unlimited number of entries in xenstore.

The fix is to make evaluation order explicit.

This is XSA-272.

Signed-off-by: Christian Lindig <christian.lindig@citrix.com>
Reviewed-by: Rob Hoes <rob.hoes@citrix.com>
(cherry picked from commit 73392c7fd1)
2018-08-14 17:27:59 +01:00
Ian Jackson b292518812 libxl: restore passing "readonly=" to qemu for SCSI disks
A read-only check was introduced for XSA-142, commit ef6cb76026 ("libxl:
relax readonly check introduced by XSA-142 fix") added the passing of
the extra setting, but commit dab0539568 ("Introduce COLO mode and
refactor relevant function") dropped the passing of the setting again,
quite likely due to improper re-basing.

Restore the readonly= parameter to SCSI disks.  For IDE disks this is
supposed to be rejected; add an assert.  And there is a bare ad-hoc
disk drive string in libxl__build_device_model_args_new, which we also
update.

This is XSA-266.

Reported-by: Andrew Reimers <andrew.reimers@orionvm.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
master commit: dd64d3c41a
master date: 2018-06-28 09:05:06 +0200
2018-06-28 11:31:34 +02:00
Ian Jackson 790847d237 libxl: qemu_disk_scsi_drive_string: Break out common parts of disk config
The generated configurations are identical apart from, in some cases,
reordering of the id=%s element.  So, overall, no functional change.

This is part of XSA-266.

Reported-by: Andrew Reimers <andrew.reimers@orionvm.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
master commit: 724e5aa31b
master date: 2018-06-28 09:04:55 +0200
2018-06-28 11:31:21 +02:00
Jan Beulich a8d37eef31 libxc/x86/PV: don't hand through CPUID leaf 0x80000008 as is
Just like for HVM the feature set should be used for EBX output, while
EAX should be restricted to the low 16 bits and ECX/EDX should be zero.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 849cc9ac56
master date: 2018-05-29 10:51:02 +0100
2018-06-28 11:28:12 +02:00
Andrew Cooper 55c1e8486b x86/Intel: Mitigations for GPZ SP4 - Speculative Store Bypass
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>
master commit: 9df52a25e0
master date: 2018-05-21 14:20:06 +0100
2018-05-29 10:39:07 +02:00
Jan Beulich 3478fb798b x86: disable XPTI when RDCL_NO
Use the respective ARCH_CAPABILITIES MSR bit, but don't expose the MSR
to guests yet.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
master commit: bee0732d20
master date: 2018-04-05 15:48:23 +0100
2018-05-18 13:18:51 +02:00
Andrew Cooper d355f02335 x86/emul: Fix emulator test harness build following a backport of 7c508612
The x86 emulator doesn't need to employ any Spectre v2 mitigations.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
2018-05-09 18:08:15 +01:00
Andrew Cooper 236b8be22d x86/emul: Fix emulator test harness build following the backport of ff555d59e8
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
2018-05-09 16:54:32 +01:00
Anthony PERARD e61305042e libxl: Specify format of inserted cdrom
Without this extra parameter on the QMP command, QEMU will guess the
format of the new file.

This is XSA-258.

Reported-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
master commit: d8f65e68a7
master date: 2018-04-25 14:38:47 +0200
2018-04-25 14:50:19 +02:00
Andrew Cooper bbd12188fa tools/libxc: Fix restoration of PV MSRs after migrate
There are two bugs in process_vcpu_msrs() which clearly demonstrate that I
didn't test this bit of Migration v2 very well when writing it...

vcpu->msrsz is always expected to be a multiple of xen_domctl_vcpu_msr_t
records in a spec-compliant stream, so the modulo yields 0 for the msr_count,
rather than the actual number sent in the stream.

Passing 0 for the msr_count causes the hypercall to exit early, and hides the
fact that the guest handle is inserted into the wrong field in the domctl
union.

The reason that these bugs have gone unnoticed for so long is that the only
MSRs passed like this for PV guests are the AMD DBGEXT MSRs, which only exist
in fairly modern hardware, and whose use doesn't appear to be implemented in
any contemporary PV guests.

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: Julien Grall <julien.grall@linaro.org>
(cherry picked from commit f1a0a8c3fe)
(cherry picked from commit 56d203b0f0e28a5d5935889587ca47a34606c556)
(cherry picked from commit 03f947472f)
2018-02-27 16:00:07 +00:00
Andrew Cooper 60e129725a tools/libxc: Avoid generating inappropriate zero-content records
The code as written attempted to elide zero-content records, as such records
serve no purpose but come with a performance hit.  Unfortunately, in the case
where the hypervisor reported max size is non-zero, but the actual size is
zero, the record is not elided.

This previously tripped up the sanity checks in the restore side of migration,
but as the underlying reasons for eliding the records in the first place are
still valid, fix the elision logic.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
(cherry picked from commit 72efb1df62)
(cherry picked from commit c31070f350)
2018-02-27 16:00:02 +00:00
Tim Deegan e54670ff26 tools/kdd: don't use a pointer to an unaligned field.
The 'val' field in the packet is byte-aligned (because it is part of a
packed struct), but the pointer argument to kdd_rdmsr() has the normal
alignment constraints for a uint64_t *.  Use a local variable to make sure
the passed pointer has the correct alignment.

Reported-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Tim Deegan <tim@xen.org>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: bfd9a2095f
master date: 2017-03-15 10:57:00 +0000
2018-02-15 13:10:54 +01:00
Jan Beulich 7d56ef3015 libxc: fix build (introduce _AC())
Signed-off-by: Jan Beulich <jbeulich@suse.com>
2018-02-15 10:15:45 +01:00
Andrew Cooper c947e1e23d x86/cpuid: Handling of IBRS/IBPB, STIBP and IBRS for guests
Intel specifies IBRS/IBPB (combined, in a single bit) and STIBP as a separate
bit.  AMD specifies IBPB alone in a 3rd bit.

AMD's IBPB is a subset of Intel's combined IBRS/IBPB.  For performance
reasons, administrators might wish to express "IBPB only" even on Intel
hardware, so we allow the AMD bit to be used for this purpose.

The behaviour of STIBP is more complicated.

It is our current understanding that STIBP will be advertised on HT-capable
hardware irrespective of whether HT is enabled, but not advertised on
HT-incapable hardware.  However, for ease of virtualisation, STIBP's
functionality is ignored rather than reserved by microcode/hardware on
HT-incapable hardware.

For guest safety, we treat STIBP as special, always override the toolstack
choice, and always advertise STIBP if IBRS is available.  This removes the
corner case where STIBP is not advertised, but the guest is running on
HT-capable hardware where it does matter.

Finally as a bugfix, update the libxc CPUID logic to understand the e8b
feature leaf, which has the side effect of also offering CLZERO to guests on
applicable hardware.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: d297b56682
master date: 2018-01-26 14:10:21 +0000
2018-02-14 11:36:48 +01:00
Andrew Cooper f9616884e1 x86/feature: Definitions for Indirect Branch Controls
Contemporary processors are gaining Indirect Branch Controls via microcode
updates.  Intel are introducing one bit to indicate IBRS and IBPB support, and
a second bit for STIBP.  AMD are introducing IBPB only, so enumerate it with a
separate bit.

Furthermore, depending on compiler and microcode availability, we may want to
run Xen with IBRS set, or clear.

To use these facilities, we synthesise separate IBRS and IBPB bits for
internal use.  A lot of infrastructure is required before these features are
safe to offer to guests.

This is part of XSA-254.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
master commit: 0d703a701c
master date: 2018-01-16 17:45:50 +0000
2018-02-14 11:34:14 +01:00
Andrew Cooper 0e6c6fc449 x86/entry: Remove support for partial cpu_user_regs frames
Save all GPRs on entry to Xen.

The entry_int82() path is via a DPL1 gate, only usable by 32bit PV guests, so
can get away with only saving the 32bit registers.  All other entrypoints can
be reached from 32 or 64bit contexts.

This is part of XSA-254.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: f9eb74789a
master date: 2018-01-05 19:57:07 +0000
2018-01-17 17:22:34 +01:00
Bernd Kuhls df0949d197 tools/libxc/xc_dom_arm: add missing variable initialization
The variable domctl.u.address_size.size may remain uninitialized if
guest_type is not one of xen-3.0-aarch64 or xen-3.0-armv7l. And the
code precisely checks if this variable is still 0 to decide if the
guest type is supported or not.

This fixes the following build failure with gcc 7.x:

xc_dom_arm.c:229:31: error: 'domctl.u.address_size.size' may be used uninitialized in this function [-Werror=maybe-uninitialized]
     if ( domctl.u.address_size.size == 0 )

Patch originally taken from
https://www.mail-archive.com/xen-devel@lists.xen.org/msg109313.html.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
(cherry picked from commit 88bfbf90e3)
2017-10-17 13:09:51 -07:00
Xiong Zhang c3fa5cdf3f hvmloader: use base instead of pci_mem_start for find_next_rmrr()
find_next_rmrr(base) is used to find the lowest RMRR ending above base
but below 4G. Current method couldn't cover the following situation:
a. two rmrr exist, small gap between them
b. pci_mem_start and mem_resource.base is below the first rmrr.base
c. find_next_rmrr(pci_mem_start) will find the first rmrr
d. After aligning mem_resource.base to bar size,
   first_rmrr.end < new_base < second_rmrr.base and
   new_base + bar_sz > second_rmrr.base.
   So the new bar will overlap with the second rmrr and doesn't overlap
with the first rmrr.
But the next_rmrr point to the first rmrr, then check_overlap() couldn't
find the overlap. Finally assign a wrong address to bar.

This patch using aligned new base to find the next rmrr, could fix the
above case and find all the overlapped rmrr with new base.

Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: ecc607b185
master date: 2017-08-28 10:51:24 +0200
2017-10-06 15:14:20 +02:00
Juergen Gross 3331050a1a tools/xenstore: dont unlink connection object twice
A connection object of a domain with associated stubdom has two
parents: the domain and the stubdom. When cleaning up the list of
active domains in domain_cleanup() make sure not to unlink the
connection twice from the same domain. This could happen when the
domain and its stubdom are being destroyed at the same time leading
to the domain loop being entered twice.

Additionally don't use talloc_free() in this case as it will remove
a random parent link, leading eventually to a memory leak. Use
talloc_unlink() instead specifying the context from which the
connection object should be removed.

This is CVE-2017-14317 / XSA-233.

Reported-by: Eric Chanudet <chanudete@ainfosec.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Ian Jackson <ian.jackson@eu.citrix.com>
master commit: 562a1c0f7e
master date: 2017-09-12 14:44:56 +0200
2017-09-12 15:10:44 +02:00
Olaf Hering b704b1a09b rombios: prevent building with PIC/PIE
If the default compiler silently defaults to to -fPIC/-fPIE building
rombios fails:

 ld -melf_i386 -s -r 32bitbios.o tcgbios/tcgbiosext.o util.o pmm.o -o 32bitbios_all.o
 There are undefined symbols in the BIOS:
          U _GLOBAL_OFFSET_TABLE_
 make[10]: *** [Makefile:26: 32bitbios_all.o] Error 11

Prevent the failure by enforcing non-PIC/PIE mode.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 672949d6c6
master date: 2017-06-26 14:32:46 +0100
2017-08-28 13:01:50 +02:00
Jan Beulich 84cd8d3fbd Revert "hvmloader: avoid tests when they would clobber used memory"
This reverts commit 164c34dd23
as not applicable to upstream 4.7 (I was misguided by local
backports).
2017-06-13 15:22:22 +02:00
Jan Beulich aadb70a471 Revert "hvmloader: don't include non-existing header"
This reverts commit 0aa86168ee.
2017-06-13 15:21:51 +02:00
Tamas K Lengyel cb799f1947 xen/arm: flush icache as well when XEN_DOMCTL_cacheflush is issued
When the toolstack modifies memory of a running ARM VM it may happen
that the underlying memory of a current vCPU PC is changed. Without
flushing the icache the vCPU may continue executing stale instructions.

Also expose the xc_domain_cacheflush through xenctrl.h.

Signed-off-by: Tamas K Lengyel <tamas.lengyel@zentific.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
master-commit-id: fe6e8188f3
2017-06-12 13:52:47 -07:00
Jan Beulich 0aa86168ee hvmloader: don't include non-existing header
On this branch the needed definitions still live in xen/xen.h.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
2017-06-12 09:21:04 +02:00
Jan Beulich 164c34dd23 hvmloader: avoid tests when they would clobber used memory
First of all limit the memory range used for testing to 4Mb: There's no
point placing page tables right above 8Mb when they can equally well
live at the bottom of the chunk at 4Mb - rep_io_test() cares about the
5Mb...7Mb range only anyway. In a subsequent patch this will then also
allow simply looking for an unused 4Mb range (instead of using a build
time determined one).

Extend the "skip tests" condition beyond the "is there enough memory"
question.

Reported-by: Charles Arnold <carnold@suse.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Gary Lin <glin@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 0d6968635c
master date: 2017-05-19 16:04:38 +0200
2017-06-09 13:51:34 +02:00
Ian Jackson 7a0bf3eef7 tools: ocaml: In configure, check for ocamlopt
If ocaml.m4 didn't find ocamlopt, disable all the ocaml builds.

Currently our Makefiles do not work properly when the native code
compiler (`ocamlopt') is not available.  In principle this should be
fixed to fall back to bytecode, but this is not a task for this stage
of the Xen 4.9 release.

Without this change, we cannot build on systems with only ocamlc.
That includes Debian jessie ARM64, as used on the new ARM64 hardware
in the Xen Project CI test lab.

When the Makefiles are fixed, this commit should be reverted.

Committers: Please rerun autogen.sh.

CC: Julien Grall <julien.grall@arm.com>
CC: Christian Lindig <christian.lindig@citrix.com>
CC: Jonathan Ludlam <Jonathan.Ludlam@citrix.com>
CC: David Scott <dave@recoil.org>
CC: Wei Liu <wei.liu2@citrix.com>
Tested-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
(cherry picked from commit 4d0240e033)
(cherry picked from commit 4057c6ea80)
2017-05-18 15:48:26 +01:00
Andrew Cooper 1956c9e91d tools/libxc: Tolerate specific zero-content records in migration v2 streams
The migration v2 save code was written to avoid sending data records with no
content, as such records serve no purpose but come with a performance hit.
The restore code sanity checks this expectation.

Under some circumstances (most notably, on AMD hardware with Debug Extensions,
and a PV guest kernel which is not using the feature), the save code would
generate a record with no content, which trips the sanity check in the restore
code.

As the stream is otherwise fine, tolerate these records and avoid failing the
migration.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
(cherry picked from commit 119ee4d773)
(cherry picked from commit 834ea870c5)
2017-05-16 15:42:23 +01:00
Seraphime Kirkovski 6a689975c6 libxc: fix segfault on uninitialized xch->fmem
Currently in xc_interface_open, xch->fmem is not initialized
and in some rare case the code fails before ever assigning a value
to it.

I got this in master:

   $ sudo ./xl/xl run
   xencall: error: Could not obtain handle on privileged command interface: No such file or directory
   Segmentation fault

This initializes the whole xch_buff to 0.

Signed-off-by: Seraphime Kirkovski <kirkseraph@gmail.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
(cherry picked from commit c4bdbec00c)
(cherry picked from commit efd2ff999d)
2017-05-16 15:42:21 +01:00
Thomas Sanders 6cf0da5951 oxenstored: trim history in the frequent_ops function
We were trimming the history of commits only at the end of each
transaction (regardless of how it ended).

Therefore if non-transactional writes were being made but no
transactions were being ended, the history would grow
indefinitely. Now we trim the history at regular intervals.

Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
2017-04-05 15:14:43 +01:00
Thomas Sanders c93ec9a485 oxenstored transaction conflicts: improve logging
For information related to transaction conflicts, potentially frequent
logging at "info" priority has been changed to "debug" priority, and
once per two minutes there is an "info" priority summary.

Additional detailed logging has been added at "debug" priority.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
2017-04-05 15:14:43 +01:00
Thomas Sanders e2141f1a57 oxenstored: don't wake to issue no conflict-credit
In the main loop, when choosing the timeout for the select function
call, we were setting it so as to wake up to issue conflict-credit to
any domains that could accept it. When xenstore is idle, this would
mean waking up every 50ms (by default) to do no work. With this
commit, we check whether any domain is below its cap, and if not then
we set the timeout for longer (the same timeout as before the
conflict-protection feature was added).

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
2017-04-05 15:14:43 +01:00
Thomas Sanders 75ce43b86e oxenstored: do not commit read-only transactions
The packet telling us to end the transaction has always carried an
argument telling us whether to commit.

If the transaction made no modifications to the tree, now we ignore
that argument and do not commit: it is just a waste of effort.

This makes read-only transactions immune to conflicts, and means that
we do not need to store any of their details in the history that is
used for assigning blame for conflicts.

We count a transaction as a read-only transaction only if it contains
no operations that modified the tree.

This means that (for example) a transaction that creates a new node
then deletes it would NOT count as read-only, even though it makes no
change overall. A more sophisticated algorithm could judge the
transaction based on comparison of its initial and final states, but
this would add complexity and computational cost.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
2017-04-05 15:14:43 +01:00
Thomas Sanders a7f74db8dc oxenstored: allow self-conflicts
We already avoid inter-domain conflicts but now allow intra-domain
conflicts.  Although there are no known practical examples of a domain
that might perform operations that conflict with its own transactions,
this is conceivable, so here we avoid changing those semantics
unnecessarily.

When a transaction commit fails with a conflict and we look through
the history of commits to see which connection(s) to blame, ignore
historical commits that were made by the same connection as the
failing commit.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
2017-04-05 15:14:43 +01:00
Jonathan Davies 8106372fdf oxenstored: blame the connection that caused a transaction conflict
Blame each connection found to have made a commit that would cause this
transaction to fail. Each blamed connection is penalised by having its
conflict-credit decremented.

Note the change in semantics for the replay function: we no longer stop after
finding the first operation that can't be replayed. This allows us to identify
all operations that conflicted with this transaction, not just the one that
conflicted first.

Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
v1 Reviewed-by: Christian Lindig <christian.lindig@citrix.com>

Changes since v1:
 * use correct log levels for informational messages
Changes since v2:
 * fix the blame algorithm and improve logging
   (fix was reviewed by Jonathan Davies)

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
2017-04-05 15:14:43 +01:00
Jonathan Davies 5029638296 oxenstored: track commit history
Since the list of historic activity cannot grow without bound, it is safe to use
this to track commits.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Thomas Sanders <thomas.sanders@citrix.com>
2017-04-05 15:14:43 +01:00
Thomas Sanders 4a48e47405 oxenstored: discard old commit-history on txn end
The history of commits is to be used for working out which historical
commit(s) (including atomic writes) caused conflicts with a
currently-failing commit of a transaction. Any commit that was made
before the current transaction started cannot be relevant. Therefore
we never need to keep history from before the start of the
longest-running transaction that is open at any given time: whenever a
transaction ends (with or without a commit) then if it was the
longest-running open transaction we can delete history up until start
of the the next-longest-running open transaction.

Some transactions might stay open for a very long time, so if any
transaction exceeds conflict_max_history_seconds then we remove it
from consideration in this context, and will not guarantee to keep
remembering about historical commits made during such a transaction.

We implement this by keeping a list of all open transactions that have
not been open too long. When a transaction ends, we remove it from the
list, along with any that have been open longer than the maximum; then
we delete any history from before the start of the longest-running
transaction remaining in the list.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
2017-04-05 15:14:43 +01:00
Jonathan Davies 167d9890c1 oxenstored: only record operations with side-effects in history
There is no need to record "read" operations as they will never cause another
transaction to fail.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Thomas Sanders <thomas.sanders@citrix.com>
2017-04-05 15:14:43 +01:00
Jonathan Davies 42ca46bcdc oxenstored: support commit history tracking
Add ability to track xenstore tree operations -- either non-transactional
operations or committed transactions.

For now, the call to actually retain commits is commented out because history
can grow without bound.

For now, we call record_commit for all non-transactional operations. A
subsequent patch will make it retain only the ones with side-effects.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
2017-04-05 15:14:43 +01:00
Jonathan Davies d431ba30ba oxenstored: add transaction info relevant to history-tracking
Specifically:
 * retain the original store (not just the root) in full transactions
 * store commit count at the time of the start of the transaction

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
2017-04-05 15:14:43 +01:00
Thomas Sanders 51833a2428 oxenstored: ignore domains with no conflict-credit
When processing connections, skip those from domains with no remaining
conflict-credit.

Also, issue a point of conflict-credit at regular intervals, the
period being set by the configuration option "conflict-max-history-
seconds".  When issuing conflict-credit, we give a point either to
every domain at once (one each) or only to the single domain at the
front of the queue, depending on the configuration option
"conflict-rate-limit-is-aggregate".

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
2017-04-05 15:14:43 +01:00
Thomas Sanders 9e82ebf1ed oxenstored: handling of domain conflict-credit
This commit gives each domain a conflict-credit variable, which will
later be used for limiting how often a domain can cause other domain's
transaction-commits to fail.

This commit also provides functions and data for manipulating domains
and their conflict-credit, and checking whether they have credit.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
2017-04-05 15:14:43 +01:00
Thomas Sanders fb79c3a3e8 oxenstored: comments explaining some variables
It took a while of reading and reasoning to work out what these are
for, so here are comments to make life easier for everyone reading
this code in future.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
2017-04-05 15:14:43 +01:00
Ian Jackson 1df3d6c34b xenstored: Log when the write transaction rate limit bites
Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>

plus:

xenstore: dont increment bool variable
Instead of incrementing a bool variable just set it to true.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
2017-04-05 15:13:17 +01:00
Ian Jackson 8b77a2c05e xenstored: apply a write transaction rate limit
This avoids a rogue client being about to stall another client (eg the
toolstack) indefinitely.

This is XSA-206.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>

Backported to 4.8 (not entirely trivial).

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
2017-04-05 15:13:08 +01:00
Paul Durrant b5c7deaaf2 tools/libxenctrl: fix error check after opening libxenforeignmemory
Checking the value of xch->xcall is clearly incorrect. The code should be
checking xch->fmem (i.e. the return of the previously called function).

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
(cherry picked from commit 80a7d04f53)
(cherry picked from commit e0354e65fe)
2017-04-05 14:24:49 +01:00
Juergen Gross e0b9499697 libxl: correct xenstore entry for empty cdrom
Specifying an empty cdrom device will result in a Xenstore entry

params = aio:(null)

as the physical device path isn't existing. This lets a domain booted
via OVMF hang as OVMF is checking for "aio:" only in order to detect
the empty cdrom case.

Use an empty string for the physical device path in this case. As a
cdrom device for HVM is always backed by qdisk we only need to cover this
backend.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
(cherry picked from commit a085f0ca12)
2017-04-05 14:23:19 +01:00
Andrew Cooper 099f67b7a1 x86/emul: Correct the decoding of mov to/from cr/dr
The mov to/from cr/dr behave as if they were encoded with Mod = 3.  When
encoded with Mod != 3, no displacement or SIB bytes are fetched.

Add a test with a deliberately malformed ModRM byte.  (Also add the
automatically-generated simd.h to .gitignore.)

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: c2e316b2f2
master date: 2017-03-07 17:29:16 +0000
2017-03-14 14:01:40 +01:00
Ian Jackson dc309dd5d9 tools/libxl: libxl_set_memory_target: Fix compile error in backport
013ee593ca the backport of "libxl: fix libxl_set_memory_target"
was broken:

  libxl.c:5034:5: error: 'r' undeclared (first use in this function)

This is because this old version of the function uses
(inappropriately) rc for libxc error returns.

Fix this by introducing `int r'.  We now use this in our backport,
even though the rest of the function is incoherent about the use of
rc.

Reported-by: Doug Goldstein <cardoe@cardoe.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
2017-01-21 18:52:28 +00:00