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>
master commit: 3352afc26c
master date: 2018-05-16 12:19:10 +0100
The current XPTI implementation isolates the directmap (and therefore a lot of
guest data), but a large quantity of CPU0's state (including its stack)
remains visible.
Furthermore, an attacker able to read .text is in a vastly superior position
to normal when it comes to fingerprinting Xen for known vulnerabilities, or
scanning for ROP/Spectre gadgets.
Collect together the entrypoints in .text.entry (currently 3x4k frames, but
can almost certainly be slimmed down), and create a common mapping which is
inserted into each per-cpu shadow. The stubs are also inserted into this
mapping by pointing at the in-use L2. This allows stubs allocated later (SMP
boot, or CPU hotplug) to work without further changes to the common mappings.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
x86/xpti: really hide almost all of Xen image
Commit 422588e885 ("x86/xpti: Hide almost all of .text and all
.data/.rodata/.bss mappings") carefully limited the Xen image cloning to
just entry code, but then overwrote the just allocated and populated L3
entry with the normal one again covering both Xen image and stubs.
Drop the respective code in favor of an explicit clone_mapping()
invocation. This in turn now requires setup_cpu_root_pgt() to run after
stub setup in all cases. Additionally, with (almost) no unintended
mappings left, the BSP's IDT now also needs to be page aligned.
The moving ahead of cleanup_cpu_root_pgt() is not strictly necessary
for functionality, but things are more logical this way, and we retain
cleanup being done in the inverse order of setup.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
x86/traps: Put idt_table[] back into .bss
c/s d1d6fc97d "x86/xpti: really hide almost all of Xen image" accidentially
moved idt_table[] from .bss to .data by virtue of using the page_aligned
section. We also have .bss.page_aligned, so use that.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
master commit: 422588e885
master date: 2018-02-15 11:08:27 +0000
master commit: d1d6fc97d6
master date: 2018-03-06 16:46:27 +0100
master commit: 044fedfaa2
master date: 2018-03-09 15:42:24 +0000
Issuing an IBPB command flushes the Branch Target Buffer, so that any poison
left by one vcpu won't remain when beginning to execute the next.
The cost of IBPB is substantial, and skipped on transition to idle, as Xen's
idle code is robust already. All transitions into vcpu context are fully
serialising in practice (and under consideration for being retroactively
declared architecturally serialising), so a cunning attacker cannot use SP1 to
try and skip the flush.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: a2ed643ed7
master date: 2018-01-26 14:10:21 +0000
See the logic and comments in init_speculation_mitigations() for further
details.
There are two controls for RSB overwriting, because in principle there are
cases where it might be safe to forego rsb_native (Off the top of my head,
SMEP active, no 32bit PV guests at all, no use of vmevent/paging subsystems
for HVM guests, but I make no guarantees that this list of restrictions is
exhaustive).
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
x86/spec_ctrl: Fix determination of when to use IBRS
The original version of this logic was:
/*
* On Intel hardware, we'd like to use retpoline in preference to
* IBRS, but only if it is safe on this hardware.
*/
else if ( boot_cpu_has(X86_FEATURE_IBRSB) )
{
if ( retpoline_safe() )
thunk = THUNK_RETPOLINE;
else
ibrs = true;
}
but it was changed by a request during review. Sadly, the result is buggy as
it breaks the later fallback logic by allowing IBRS to appear as available
when in fact it isn't.
This in practice means that on repoline-unsafe hardware without IBRS, we
select THUNK_JUMP despite intending to select THUNK_RETPOLINE.
Reported-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 2713715305
master date: 2018-01-26 14:10:21 +0000
master commit: 30cbd0c83e
master date: 2018-02-06 18:32:58 +0000
Instead of gaining yet another top level boolean, introduce a more generic
cpuid= option. Also introduce a helper function to parse a generic boolean
value.
This is part of XSA-254.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
xen/cmdline: Fix parse_boolean() for unadorned values
A command line such as "cpuid=no-ibrsb,no-stibp" tickles a bug in
parse_boolean() because the separating comma fails the NUL case.
Instead, check for slen == nlen which accounts for the boundary (if any)
passed via the 'e' parameter.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 7850b1c007
master date: 2018-01-16 17:45:50 +0000
master commit: ac37ec1dde
master date: 2018-01-31 10:47:12 +0000
Depending on hardware and microcode availability, we will want to replace
IND_THUNK_REPOLINE with other implementations.
For AMD hardware, choose IND_THUNK_LFENCE in preference to retpoline if lfence
is known to be (or was successfully made) dispatch serialising.
This is part of XSA-254.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 858cba0d4c
master date: 2018-01-16 17:45:50 +0000
First of all we don't need it on AMD systems. Additionally allow its use
to be controlled by command line option. For best backportability, this
intentionally doesn't use alternative instruction patching to achieve
the intended effect - while we likely want it, this will be later
follow-up.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: e871e80c38
master date: 2018-01-16 17:50:59 +0100
Allowing pagetables to point to other pagetables of the same level
(often called 'linear pagetables') has been included in Xen since its
inception; but recently it has been the source of a number of subtle
reference-counting bugs.
It is not used by Linux or MiniOS; but it is used by NetBSD and Novell
Netware. There are significant numbers of people who are never going
to use the feature, along with significant numbers who need the
feature.
Add a Kconfig option for the feature (default to 'y'). Also add a
command-line option to control whether PV linear pagetables are
allowed (default to 'true').
NB that we leave linear_pt_count in the page struct. It's in a union,
so its presence doesn't increase the size of the data struct.
Changing the layout of the other elements based on configuration
options is asking for trouble however; so we'll just leave it there
and ASSERT that it's zero.
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 3285e75dea
master date: 2017-10-27 14:36:45 +0100
The way the lock is currently being used in get_maptrack_handle(), it
protects only the maptrack limit: The function acts on current's list
only, so races on list accesses are impossible even without the lock.
Otoh list access races are possible between __get_maptrack_handle() and
put_maptrack_handle(), due to the invocation of the former for other
than current from steal_maptrack_handle(). Introduce a per-vCPU lock
for list accesses to become race free again. This lock will be
uncontended except when it becomes necessary to take the steal path,
i.e. in the common case there should be no meaningful performance
impact.
When in get_maptrack_handle adds a stolen entry to a fresh, empty,
freelist, we think that there is probably no concurrency. However,
this is not a fast path and adding the locking there makes the code
clearly correct.
Also, while we are here: the stolen maptrack_entry's tail pointer was
not properly set. Set it.
This is CVE-2017-12136 / XSA-228.
Reported-by: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
master commit: 02cbeeb620
master date: 2017-08-15 15:07:25 +0200
Introduce new Xen command line parameter called "vwfi", which stands for
virtual wfi. The default is "trap": Xen traps guest wfi and wfe
instructions. In the case of wfi, Xen calls vcpu_block on the guest
vcpu; in the case of guest wfe, Xen calls vcpu_yield on the guest vcpu.
The behavior can be changed by setting vwfi to "native", in that case
Xen doesn't trap neither wfi nor wfe, running them in guest context.
The result is strong reduction in irq latency (from 5000ns to 2000ns,
measured using https://github.com/edgarigl/tbm, the physical timer, and
1 pcpu dedicated to 1 vcpu). The downside is that the scheduler thinks
that the guest is busy when actually is sleeping, leading to suboptimal
scheduling decisions.
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Benchmarks have shown that per-socket runqueues arrangement
behaves better (e.g., we achieve better load balancing)
than the current per-core default.
Here's an example (coming from
https://lists.xen.org/archives/html/xen-devel/2016-06/msg02287.html ):
|=======================================|
| XEN BUILD TIME, LOW LOAD, NO NOISE |
|---------------------------------------|
| runq=core runq=socket |
| 35.200 33.433 |
|---------------------------------------|------------------------------|
| XEN BUILD TIME, HIGH LOAD, NO NOISE | IPERF, HIGH LOAD, NO NOISE |
|---------------------------------------|------------------------------|
| runq=core runq=socket | runq=core runq=socket |
| 18.013 18.530 | 23.200 23.466 |
|---------------------------------------|------------------------------|
| XEN BUILD TIME, LOW LOAD, WITH NOISE |
|------------------------------------- |
| runq=core runq=socket |
| 45.866 39.493 |
|---------------------------------------|------------------------------|
| XEN BUILD TIME, HIGH LOAD, WITH NOISE | IPERF, HIGH LOAD, WITH NOISE |
|---------------------------------------|------------------------------|
| runq=core runq=socket | runq=core runq=socket |
| 36.840 29.080 | 19.967 21.000 |
|=======================================|==============================|
The only reason why we went for per-core, initially, was to
introduce some form of hyperthreading support. Now we have
hyperthreading support, independently from how runqueues
are organized (9bb9c7388 "xen: credit2: implement true SMT
support"), and thus we can switch to per-socket.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
It is possible for PVHv2 guests to get the hardware description from ACPI
tables, add this to the documentation also.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
On PVHv2 guests the local APIC can also be used to start APs if present.
Amend the documentation in order to reflect this.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
docs/misc/xenstore.txt states that xenstored will use "0" as a valid
transaction id after 2^32 transactions. This is not true. Remove that
statement.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
SMEP/SMAP is a security feature to prevent kernel executing/accessing
user address involuntarily, any such behavior will lead to a page fault.
SMEP/SMAP is open (in CR4) for both Xen and HVM guest in earlier code.
SMEP/SMAP bit set in Xen CR4 would enforce security checking for 32-bit
PV guest which will suffer unknown SMEP/SMAP page fault when guest
kernel attempt to access user address although SMEP/SMAP is close for
PV guests.
This patch introduces a new boot option value "hvm" for "sm{e,a}p", it
is going to diable SMEP/SMAP for Xen hypervisor while enable them for
HVM. In this way, 32-bit PV guest will not suffer SMEP/SMAP security
issue. Users can choose whether open SMEP/SMAP for Xen itself,
especially when they are going to run 32-bit PV guests.
Signed-off-by: He Chen <he.chen@linux.intel.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
[Fixed up command line docs]
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Couple of reasons:
- It can lead to security issues (see row-hammer, KSM and such
attacks).
- Code is quite complex.
- Deduplication is good if the pages themselves are the same
but that is hardly guaranteed.
- We got some gains (if pages are deduped) but at the cost of
making code less maintainable.
- tze depends on deduplication code.
As such, deleting it.
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
If the distance is too big we are in trouble - as our relocation
distance can surely be clipped, or still have a valid width - but
cause an overflow of distance.
On various architectures the maximum displacement for a unconditional
branch/jump varies. ARM32 is +/- 32MB, ARM64 is +/- 128MB while x86
for 32-bit relocations is +/- 2G.
Note: On x86 we could use the 64-bit jmpq instruction which
would provide much bigger displacement to do a jump, but we would
still have issues with the new function not being able to reach
any of the old functions (as all the relocations would assume 32-bit
displacement). And "furthermore would require an register or
memory location to load/store the address to." (From Jan).
On ARM the conditional branch supports even a smaller displacement
but fortunately we are not using that.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
As compared to x86 the va of the hypervisor .text
is locked down - we cannot modify the running pagetables
to have the .ro flag unset. We borrow the same idea that
alternative patching has - which is to vmap the entire
.text region and use the alternative virtual address
for patching.
Since we are doing vmap we may fail, hence the
arch_livepatch_quiesce was changed (see "x86,arm:
Change arch_livepatch_quiesce() declaration") to return
an error value which will be bubbled in payload->rc and
provided to the user (along with messages in the ring buffer).
The livepatch virtual address space (where the new functions
are) needs to be close to the hypervisor virtual address
so that the trampoline can reach it. As such we re-use
the BOOT_RELOC_VIRT_START which is not used after bootup
(alternatively we can also use the space after the _end to
FIXMAP_ADDR(0), but that may be too small).
The ELF relocation engine at the start was coded from
the "ELF for the ARM 64-bit Architecture (AArch64)"
(http://infocenter.arm.com/help/topic/com.arm.doc.ihi0056b/IHI0056B_aaelf64.pdf)
but after a while of trying to write the correct bit shifting
and masking from scratch I ended up borrowing from Linux, the
'reloc_insn_imm' (Linux v4.7 arch/arm64/kernel/module.c function.
See 257cb251925f854da435cbf79b140984413871ac "arm64: Loadable modules")
And while at it - we also utilize code from Linux to construct
the right branch instruction (see "arm64/insn: introduce
aarch64_insn_gen_{nop|branch_imm}() helper functions").
In the livepatch payload loading code we tweak the #ifdef to
only exclude ARM_32. The exceptions are not part of ARM 32/64 hence
they are still behind the #ifdef.
We also expand the MAINTAINERS file to include the arm64 and arm32
platform specific livepatch file.
Acked-by: Julien Grall <julien.grall@arm.com>
Acked-by: Jan Beulich <jbeulich@suse.com> [non-arm parts]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Add hook functions which run during patch apply and patch revert.
Hook functions are used by livepatch payloads to manipulate data
structures during patching, etc.
One use case is the XSA91. As Martin mentions it:
"If we have shadow variables, we also need an unload hook to garbage
collect all the variables introduced by a hotpatch to prevent memory
leaks. Potentially, we also want to pre-reserve memory for static or
existing dynamic objects in the load-hook instead of on the fly.
For testing and debugging, various applications are possible.
In general, the hooks provide flexibility when having to deal with
unforeseen cases, but their application should be rarely required (<
10%)."
Furthermore include a test-case for it.
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The NOP functionality will NOP any of the code at
the 'old_addr' or at 'name' if the 'new_addr' is zero.
The purpose of this is to NOP out calls, such as:
e8 <4-bytes-offset>
(5 byte insn), or on ARM a 4 byte insn for branching.
We need the EIP of where we need to the NOP, and that can
be provided via the `old_addr` or `name`.
If the `old_addr` is provided we will NOP 'new_size'
amount of bytes at that location.
The amount is up to 31 instructions if desired (which is
the size of the opaque member). If there is a need to NOP
more then: a) more 'struct livepatch_func' structures need
to be present, b) we have to implement a variable size
buffer (in the future), or c) first byte an unconditional
branch skipping the to be disabled code (of course provided
there are no branch targets in the middle).
While at it, also unify the code on x86 patching so
it is a bit simpler (instead of two seperate writes
just make it one memcpy).
And introduce a general livepatch_insn_len inline function
that would depend on platform specific instruction size
(for a unconditional branch). As such we also rename the
PATCH_INSN_SIZE to ARCH_PATCH_INSN_SIZE.
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
On general this is unhealthy - as the payload's .bss (definitly)
or .data (maybe) will be modified once the payload is running.
Doing an revert and then re-applying the payload with a non-pristine
.bss or .data can lead to unforseen consequences (.bss are assumed
to always contain zero value but now they may have a different value).
There is one exception - if the payload contains only one .data section
- the .livepatch.funcs, then it is OK to re-apply an revert.
We detect this rather simply (if there is one RW section and its name
is .livepatch.funcs) - but the payload may have many other RW sections
that are not used at all (such as .bss or .data sections with zero
length). To not account those we also ignore sections with sh_size
being zero.
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Extend the "tsc" boot parameter is to further relax TSC restrictions and
allow it to be used on machines that guarantee reliable TSC across
sockets. This is up to board manufacturers and there's no way for the OS
to probe this property, therefore user needs to explicitly set this option.
Also make one style adjustment that is to remove the unnecessary
parenthesis around clearing TSC_RELIABLE.
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Recent x86/time changes improved a lot of the monotonicity in xen
timekeeping, making it much harder to observe time going backwards.
Although platform timer can't be expected to be perfectly in sync with
TSC and so get_s_time won't be guaranteed to always return
monotonically increasing values across cpus. This is the case in some
of the boxes I am testing with, observing sometimes ~100 warps (of
very few nanoseconds each) after a few hours.
This patch introduces support for using TSC as platform time source
which is the highest resolution time and most performant to get.
Though there are also several problems associated with its usage, and
there isn't a complete (and architecturally defined) guarantee that
all machines will provide reliable and monotonic TSC in all cases (I
believe Intel to be the only that can guarantee that?). For this reason
it's not used unless administrator changes "clocksource" boot option
to "tsc". Initializing TSC clocksource requires all CPUs up to have
the tsc reliability checks performed. init_xen_time is called before
all CPUs are up, so for example we would start with HPET (or ACPI,
PIT) at boot time, and switch later to TSC. The switch then happens on
verify_tsc_reliability initcall that is invoked when all CPUs are up.
When attempting to initialize TSC we also check for time warps and if
it has invariant TSC. Note that while we deem reliable a CONSTANT_TSC
with no deep C-states, it might not always be the case, so we're
conservative and allow TSC to be used as platform timer only with
invariant TSC. Additionally we check if CPU Hotplug isn't meant to be
performed on the host which will either be when max vcpus and
num_present_cpu are the same. This is because a newly hotplugged CPU
may not satisfy the condition of having all TSCs synchronized - so
when having tsc clocksource being used we allow offlining CPUs but not
onlining any ones back. Finally we prevent TSC from being used as
clocksource on multiple sockets because it isn't guaranteed to be
invariant. Further relaxing of this last requirement is added in a
separate patch, such that we allow vendors with such guarantee to use
TSC as clocksource. In case any of these conditions is not met, we
keep the clocksource that was previously initialized on init_xen_time.
Since b64438c7c ("x86/time: use correct (local) time stamp in
constant-TSC calibration fast path") updates to cpu time use local
stamps, which means platform timer is only used to seed the initial
cpu time. We further introduce a new rendezvous function
(nop_rendezvous) which doesn't require synchronization between master
and slave CPUS and just reads calibration_rendezvous struct and writes
it down the stime and stamp to the cpu_calibration struct to be used
later on. With clocksource=tsc there is no need to be in sync with
another clocksource, so we reseed the local/master stamps to be values
of TSC and update the platform time stamps accordingly. Time
calibration is set to 1sec after we switch to TSC, thus these stamps
are reseeded to also ensure monotonic returning values right after the
point we switch to TSC. This is to remove the possibility of having
inconsistent readings in this short period (i.e. until calibration
fires).
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
SCTLR_EL3.HCR does not exists in the documentation (see D7.2.80 in ARM
DDI 0487A.j). It was meant to be SCTRL_EL3.HCE.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Fix commit f6d4cf5 ("docs: document old SUSE/Novell unplug for HVM").
The values which VMDP used to control either NIC or disk are flipped.
What the code does is:
case 8:
if (val == 1 ) {
ide_unplug_harddisks();
} else if (val == 2) {
pci_unplug_netifs();
net_tap_shutdown_all();
}
break;
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Blktap2 is effectively dead code for a few years.
Notable changes in this patch:
0. Unhook blktap2 from build system
1. Now libxl no longer supports TAP disk backend, appropriate assertions
are added and some code paths now return ERROR_FAIL
2. Tap is no longer a supported backend in doc
3. Remove relevant entries in MAINTAINERS
A patch to actually remove blktap2 directory will come later.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: George Dunlap <George.Dunlap@eu.citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
SMEP/SMAP is a security feature to prevent kernel executing/accessing
user address involuntarily, any such behavior will lead to a page fault.
SMEP/SMAP is open (in CR4) for both Xen and HVM guest in earlier code.
SMEP/SMAP bit set in Xen CR4 would enforce security checking for 32-bit
PV guest which will suffer unknown SMEP/SMAP page fault when guest
kernel attempt to access user address although SMEP/SMAP is close for
PV guests.
This patch introduces a new boot option value "hvm" for "sm{e,a}p", it
is going to diable SMEP/SMAP for Xen hypervisor while enable them for
HVM. In this way, 32-bit PV guest will not suffer SMEP/SMAP security
issue. Users can choose whether open SMEP/SMAP for Xen itself,
especially when they are going to run 32-bit PV guests.
Signed-off-by: He Chen <he.chen@linux.intel.com>
[jbeulich: doc and style adjustments]
Reviewed-by: Jan Beulich <jbeulich@suse.com>
The C struct in the document is no more in sync with the actual
definition of the PVHv2 boot start info.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
The ARM erratum applies to certain revisions of Cortex-A57. The
processor may report a Stage 2 translation fault as the result of
Stage 1 fault for load crossing a page boundary when there is a
permission fault or device memory fault at stage 1 and a translation
fault at Stage 2.
So Xen needs to check that Stage 1 translation does not generate a fault
before handling the Stage 2 fault. If it is a Stage 1 translation fault,
return to the guest to let the processor injecting the correct fault.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
The ARM erratum 832075 applies to certain revisions of Cortex-A57, one
of the workarounds is to change device loads into using load-acquire
semantics.
Use the alternative framework to enable the workaround only on affected
cores.
Whilst a guest could trigger the deadlock, it can be broken when the
processor is receiving an interrupt. As the Xen scheduler will always setup
a timer (firing to every 1ms to 300ms depending on the running time
slice) on each processor, the deadlock would last only few milliseconds
and only affects the guest time slice.
Therefore a malicious guest could only hurt itself. Note that all the
guests should implement/enable the workaround for the affected cores.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
The ARM errata 819472, 827319 and 824069 define the same workaround for
these hardware issues in certain Cortex-A53 parts.
The cache instructions "dc cvac" and "dc cvau" need to be upgraded to
"dc civac".
Use the alternative framework to replace those instructions only on
affected cores.
Whilst the errata affect cache instructions issued at any exception
level, it is not necessary to trap EL1/EL0 data cache instructions
access in order to upgrade them. Indeed the data cache corruption would
always be at the address used by the data cache instructions. Note that
this address could point to a shared memory between guests and the
hypervisors, however all the information present in it are be validated
before any use.
Therefore a malicious guest could only hurt itself. Note that all the
guests should implement/enable the workaround for the affected cores.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
The new document will help to keep track of each erratum Xen is able to
handle.
The text is based on the Linux doc in Documents/arm64/silicon-errata.txt.
Also list the current errata that Xen is aware of.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The existing load tracking code was hard to understad and
maintain, and not entirely consistent. This is due to a
number of reasons:
- code and comments were not in perfect sync, making it
difficult to figure out what the intent of a particular
choice was (e.g., the choice of 18 for load_window_shift);
- the math, although effective, was not entirely consistent.
In fact, we were doing (if W is the lenght of the window):
avgload = (delta*load*W + (W - delta)*avgload)/W
avgload = avgload + delta*load - delta*avgload/W
which does not match any known variant of 'smoothing
moving average'. In fact, it should have been:
avgload = avgload + delta*load/W - delta*avgload/W
(for details on why, see the doc comments inside this
patch.). Furthermore, with
avgload ~= avgload + W*load - avgload
avgload ~= W*load
The reason why the formula above sort of worked was because
the number of bits used for the fractional parts of the
values used in fixed point math and the number of bits used
for the lenght of the window were the same (load_window_shift
was being used for both).
This may look handy, but it introduced a (not especially well
documented) dependency between the lenght of the window and
the precision of the calculations, which really should be
two independent things. Especially if treating them as such
(like it is done in this patch) does not lead to more
complex maths (same number of multiplications and shifts, and
there is still room for some optimization).
Therefore, in this patch, we:
- split length of the window and precision (and, since there
is already a command line parameter for length of window,
introduce one for precision too),
- align the math with one proper incarnation of exponential
smoothing (at no added cost),
- add comments, about the details of the algorithm and the
math used.
While there fix a couple of style issues as well (pointless
initialization, long lines, comments).
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
This adds a Kconfig option and support for including the XSM policy from
tools/flask/policy in the hypervisor so that the bootloader does not
need to provide a policy to get sane behavior from an XSM-enabled
hypervisor. The policy provided by the bootloader, if present, will
override the built-in policy.
The XSM policy is not moved out of tools because that remains the
primary location for installing and configuring the policy.
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
The parameter 'iommu_dev_iotlb_timeout' specifies the timeout
of device IOTLB invalidation in milliseconds. By default, the
timeout is 1000 milliseconds, which can be boot-time changed.
We also confirmed with VT-d hardware team that 1 milliseconds
is large enough for VT-d IOMMU internal invalidation.
the existing panic() is eliminated and we bubble up the timeout
of device IOTLB invalidation for further processing, as the
PCI-e Address Translation Services (ATS) mandates a timeout of
60 seconds for device IOTLB invalidation. Obviously we can't
spin for 60 seconds or otherwise Xen hypervisor hangs.
Signed-off-by: Quan Xu <quan.xu@intel.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
This adds a Kconfig option and support for including the XSM policy from
tools/flask/policy in the hypervisor so that the bootloader does not
need to provide a policy to get sane behavior from an XSM-enabled
hypervisor. The policy provided by the bootloader, if present, will
override the built-in policy.
Enabling this option only builds the policy if checkpolicy is available
during compilation of the hypervisor; otherwise, it does nothing. The
XSM policy is not moved out of tools because that remains the primary
location for installing and configuring the policy.
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Doug Goldstein <cardoe@cardoe.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>
Originally hvm_fep was guarded by NDEBUG, which means it was only
available to debug builds.
However there is value in having it in non-debug builds as well. Users
can use it to run tests in a setup that replicates a production
environment.
Make it clear with a sync_console style warning that this option can't
be used in production setup. Update command line documentation
accordingly. Finally mark Xen as tainted when this feature is used.
Add a kconfig option under x86 to configure hvm_fep.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Doug Goldstein <cardoe@cardoe.com>
This also renames the example users created by vm_role.
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Reviewed-by: Doug Goldstein <cardoe@cardoe.com>
Quite frequently the watchdog would hit an innocent CPU, e.g. one
trying to acquire a spin lock a remote CPU holds for extended periods
of time, or a random CPU in TSC calbration rendezvous. In such cases
the register and stack dump for that CPU doesn't really help in the
analysis of the problem.
To keep things reasonable on large systems, only log CS:RIP by default.
This can be overridden via a new command line option such that full
register/stack state would get logged.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
.. in the design document. The official location is:
git://xenbits.xen.org/livepatch-build-tools.git
Wiki is also updated with this URL.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Rather than just allowing a fixed address or fully automatic placement,
also allow for specifying an upper bound. Especially on EFI systems,
where firmware memory use is commonly less predictable than on legacy
BIOS ones, this makes success of the reservation more likely when
automatic placement is not an option (e.g. because of special DMA
restrictions of devices involved in actually carrying out the dump).
Also take the opportunity to actually add text to the "crashkernel"
entry in the command line option doc.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Convert the crash_debug option to Kconfig as CONFIG_CRASH_DEBUG. This
was previously togglable on the command line so this adds a message for
users enabling it from the command line to tell them to enable it from
make menuconfig.
Signed-off-by: Doug Goldstein <cardoe@cardoe.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Andrew Cooper
Jan Beulich
George Dunlap
Olaf Hering
Stefano Stabellini
Dario Faggioli
Roger Pau Monne
Juergen Gross
He Chen
Konrad Rzeszutek Wilk
Shannon Zhao
Ross Lagerwall
Joao Martins
Julien Grall
Wei Liu
Anthony PERARD
Daniel De Graaf
Quan Xu
Konrad Rzeszutek Wilk
Doug Goldstein