If the payload had the sections mentioned but the hypervisor
did not support some of them (say on ARM the .ex_table) - instead
of ignoring them - it should forbid loading of such payload.
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
x86 implements all of them by default - and we just
add two extra HAS_ variables to be declared in autoconf.h.
ARM 64 only has alternative while ARM 32 has none of them.
And while at it change the livepatch common code that
would benefit from this.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com> [relevant parts]
Suggested-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
No functional change. We resist the temptation to move
the entries in the Kconfig file to be more in alphabetical
order as the "arm/x86/common: Add HAS_[ALTERNATIVE|EX_TABLE]"
will move one of the entries to common file.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Suggested-by: Jan Beulich <JBeulich@suse.com>
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>
With "livepatch: NOP if func->new_addr is zero." that name
makes no more sense as we also NOP now.
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Suggested-by: Jan Beulich <jbeulich@suse.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>
The initial patch: 11ff40fa7b
"xen/xsplice: Hypervisor implementation of XEN_XSPLICE_op" caps the
size of the binary at 2MB. We follow that in capping the size
of the .BSSes to be at maximum 2MB.
We also bubble up the payload limit and this one in one #define
called LIVEPATCH_MAX_SIZE to make it easier to find these
arbitrary limits.
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.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>
This patch proposes relying on host TSC synchronization and
passthrough to the guest, when running on a TSC-safe platform. On
time_calibration we retrieve the platform time in ns and the counter
read by the clocksource that was used to compute system time. We can
guarantee that on a platform with a constant and reliable TSC, that the
time read on vcpu B right after A is bigger independently of the VCPU
calibration error. Since pvclock time infos are monotonic as seen by any
vCPU set PVCLOCK_TSC_STABLE_BIT, which then enables usage of VDSO on
Linux. IIUC, this is similar to how it's implemented on KVM. Add also a
comment regarding this bit changing and that guests are expected to
check this bit on every read.
Should note that I've yet to see time going backwards in a long running
test I ran for 2 weeks (in a dual socket machine), plus few other
tests I did on older platforms.
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>
To allow the caller to fetch the last read from the clocksource which
was used to calculate system_time. This is a prerequisite for a
subsequent patch that will use this last read.
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
And accomodate platform time source initialization in
try_platform_time(). This is a preparatory patch for deferring
TSC clocksource initialization to the stage where all CPUS are
up (verify_tsc_reliability init call).
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Intermediate stages of building a target should be made with
temporary files that are copied to final target in the end.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-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>
The invalidation of the instructions cache requires barriers to ensure
the completion of the invalidation before continuing (see B2.3.4 in ARM
DDI 0487A.j).
This was overlooked in commit fb9d877 "xen/arm64: Add an helper to
invalidate all instruction caches".
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Right now the contents of 'name' are all located in
the .data section. We want them in the .rodata section
so change the type to have const on them.
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
As currently during the injection of the build-id it ends up
being marked as AW. We want it to be read-only.
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Right now, two out of the three events related to
context switch (that is TRC_SCHED_SWITCH_INFPREV and
TRC_SCHED_SWITCH_INFNEXT) only report the domain id,
and not the vcpu id.
That's omitting a useful piece of information, and
even if we be figured that out by looking at other
records, that's unnecessarily complicated (especially
if working on a trace from a sctipt).
This changes both the tracing code in Xen and the parsing
code in tools at once, to avoid introducing transitional
regressions.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
Add HVM usb passthrough support to libxl by using qemu's capability
to emulate standard USB controllers.
A USB controller is added via qmp command to the emulated hardware
when a usbctrl device of type DEVICEMODEL is requested. Depending on
the requested speed the appropriate hardware type is selected. A host
USB device can then be added to the emulated USB controller via qmp
command.
Removing of the devices is done via qmp commands, too.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
With the planned support of HVM USB passthrough via the USB emulation
capabilities of qemu libxl has to support guest devices which have no
back- and frontend. Information about those devices will live in the
libxl part of Xenstore only.
Add some basic support to libxl to be able to cope with this scenario.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
In case of failure when trying to add a new USB controller to a domain
libxl might leak xenstore entries. Add a function to remove them and
call this function in case of failure.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
This patch implemented parts of TODO left in commit id
a902c12ee4 (More efficient TLB-flush
filtering in alloc_heap_pages()). It moved TLB-flush filtering out into
populate_physmap. Because of TLB-flush in alloc_heap_pages, it's very slow
to create a guest with memory size of more than 100GB on host with 100+
cpus.
This patch introduced a "MEMF_no_tlbflush" bit to memflags to indicate
whether TLB-flush should be done in alloc_heap_pages or its caller
populate_physmap. Once this bit is set in memflags, alloc_heap_pages will
ignore TLB-flush. To use this bit after vm is created might lead to
security issue, that is, this would make pages accessible to the guest B,
when guest A may still have a cached mapping to them.
Therefore, this patch also introduced a "creation_finished" field to struct
domain to indicate whether this domain has ever got unpaused by hypervisor.
MEMF_no_tlbflush can be set only during vm creation phase when
creation_finished is still false before this domain gets unpaused for the
first time.
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
This patch cleaned up the code by replacing complicated tlbflush check and
operation with inline functions. We should use those inline functions to
avoid the complicated tlbflush check and tlbflush operations when
implementing TODOs left in commit a902c12ee4
(More efficient TLB-flush filtering in alloc_heap_pages()).
"#include <asm/flushtlb.h>" is removed from xen/arch/x86/acpi/suspend.c to
avoid the compiling error after we include "<asm/flushtlb.h>" to
xen/include/xen/mm.h.
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
3a7f872a ("tools: lift BUILD_BUG_ON to a tools header file") was taken
out from an rather old half finished branch by dropping unrelated
changes. Unfortunately two issues sneaked in.
1. Hvmloader should be standalone. Revert the changes to hvmloader.
2. The define guard in libs.h was erroneously deleted. Add that back.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
In a linux part an ioctl(gntdev, IOCTL_GNTDEV_GRANT_COPY, ..)
system call is invoked. In mini-os the operation is yet not
implemented. For the OSs that does not implement gnttab the
call of the grant copy operation causes abort.
Signed-off-by: Paulina Szubarczyk <paulinaszubarczyk@gmail.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
[ wei: modify this patch to use BUILD_BUG_ON in xen-tools/libs.h ]
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Only define BUILD_BUG_ON when there isn't one already, because mini-os
currently leaks that.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Currently it is only possible to set mem_access restrictions only for
a contiguous range of GFNs (or, as a particular case, for a single GFN).
This patch introduces a new libxc function taking an array of GFNs.
The alternative would be to set each page in turn, using a userspace-HV
roundtrip for each call, and triggering a TLB flush per page set.
Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Tamas K Lengyel <tamas@tklengyel.com>
Acked-by: Julien Grall <julien.grall@arm.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
Replace mbi with mbi_out and mbi_old with mbi_in and rearrange code
a bit to make it more readable. Additionally, this way multiboot (v1)
protocol implementation and future multiboot2 protocol implementation
will use the same variable naming convention.
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Create generic alloc and copy functions. We need
separate tools for memory allocation and copy to
provide multiboot2 protocol support.
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
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>
Setting response flags in vm_event are only ever safe if the vCPUs are paused.
To reflect this we move all checks within the if block that already checks
whether this is the case. Checks that are only supported on one architecture
we relocate the bitmask operations to the arch-specific handlers to avoid
the overhead on architectures that don't support it.
Furthermore, we clean-up the emulation checks so it more clearly represents the
decision-logic when emulation should take place. As part of this we also
set the stage to allow emulation in response to other types of events, not just
mem_access violations.
Signed-off-by: Tamas K Lengyel <tamas.lengyel@zentific.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
We don't currently emulate it, so guests should not be misguided to
believe they can (try to) use it.
For now, simply return zero to guests for platform MSR reads, and only
accept (by discarding) writes of zero. If ever there will be bits we
can safely expose to guests, let's handle them by white listing.
(As a side note - according to SDM version 059 bit 31 is reserved on
all known families.)
Reported-by: Kyle Huey <me@kylehuey.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citix.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Which is only used by Livepatch code. The purpose behind
this call is to modify the page table entries flags.
Specifically the .ro and .nx flags. The current mechanism
puts cache attributes in the flags and the .ro and .nx are
locked down and assumed to be .ro=0, nx=1.
Livepatch needs .nx=0 and also .ro to be set to 1.
We introduce a new 'flags' where various bits determine
whether .ro and .nx bits are set or cleared. We can't use
an enum as the function prototype would diverge from x86.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
If wanting to migrate a vcpu that is actually running,
we need to ask the scheduler to chime in as soon as
possible, to have the vcpu itself stopped and actually
moved.
Make sure this happens by, after setting all the relevant
flags, raising the scheduler softirq.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
If there are idle pcpus inside the waking vcpu's
soft-affinity mask, we should really tickle one
of them (this is one of the purposes of the
__runq_tickle() function itself!), not just
any idle pcpu.
The issue has been introduced in 02ea503182
("credit1: properly deal with pCPUs not in any cpupool"),
where the usage of idle_mask is changed, without
updating the bottom of the function, where it
is also referenced.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
If, when vcpu x wakes up, there are no idle pcpus in x's
soft-affinity, we just go ahead and look at its hard
affinity. This basically means that, if, in __runq_tickle(),
new_idlers_empty is true, balance_step is equal to
CSCHED_BALANCE_HARD_AFFINITY, and that calling
csched_balance_cpumask() for whatever vcpu, would just
return the vcpu's cpu_hard_affinity.
Therefore, don't bother calling it (it's just pure
overhead) and use cpu_hard_affinity directly.
For this very reason, this patch should only be
a (slight) optimization, and entail no functional
change.
As a side note, it would make sense to do what the
patch does, even if we could be inside the
[[ new_idlers_empty && new->pri > cur->pri ]] if
with balance_step equal to CSCHED_BALANCE_SOFT_AFFINITY.
In fact, what is actually happening is:
- vcpu x is waking up, and (since there aren't suitable
idlers, and it's entitled for it) it is preempting
vcpu y;
- vcpu y's hard-affinity is a superset of its
soft-affinity mask.
Therefore, it makes sense to use wider possible mask,
as by doing that, we maximize the probability of
finding an idle pcpu in there, to which we can send
vcpu y, which then will be able to run.
While there, also fix the comment, which included
an awkward parenthesis nesting.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
Add a new xl command "qemu-monitor-command" to issue arbitrary commands
to a domain's device model. Syntax is:
xl qemu-monitor-command <domain> <command>
The command is issued via qmp human-monitor-command command. Any
information returned by the command is printed to stdout.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
No need to have the same logic twice. (Note that the type change does
not affect the put_user() instances, as they derive their access size
from the second [pointer] argument.)
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Page tables get pre-populated with physical addresses which, due to
living inside the Xen image, will never exceed 32 bits in width. That
in turn results in the tool generating the relocations to produce
32-bit relocations for them instead of the 64-bit ones needed for
relocating virtual addresses. Hence instead of special casing page
tables in the processing of 64-bit relocations, let's be more rigid
and refuse them (as being indicative of something else having gone
wrong in the build process).
Signed-off-by: Jan Beulich <jbeulich@suse.com>
The current_cpu_data indicates the cpuinfo for the current cpu.
There is no need to fill the current_cpu_data from boot_cpu_data,
because the following call to identify_cpu will override it.
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
compress_xsave_states() mustn't read xstate_bv or xcomp_bv before first
confirming that the input buffer is large enough. It also doesn't cope with
compressed input. Make all of these problems the callers responsbility to
ensure.
Simplify the decompression logic by inlining get_xsave_addr(). As xstate_bv
is previously validated, dest won't ever been NULL.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
c/s da62246e "x86/xsaves: enable xsaves/xrstors/xsavec in xen" broke migration
of PV guests which were not using xsave.
In such a case, compress_xsave_states() gets passed a zero length buffer. The
first thing it tries to do is ASSERT() on user-provided data, if it hadn't
already wandered off the end of the buffer to do so.
Perform more verification of the input buffer before passing it to
compress_xsave_states(). This involves making xsave_area_compressed() public.
Similar problems exist on the HVM side, so make equivalent adjustments there.
This doesn't manifest in general, as hvm_save_cpu_xsave_states() elides the
entire record if xsave isn't used, but is a problem if a caller were to
construct an xsave record manually.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <JBeulich@suse.com>
Without checking the size input, the memcpy() for the uncompressed path might
read off the end of the vcpu's xsave_area. Both callers pass the approprite
size, so hold them to it with a BUG_ON().
The compressed path is currently dead code, but its attempt to avoid leaking
uninitalised data was incomplete. Work around this by zeroing the whole rest
of the buffer before decompression.
The loop skips all bits which aren't set in xstate_bv, meaning that the
memset() was dead code. The logic is more obvious with get_xsave_addr()
expanded inline, allowing for quite a lot of simplification, including all the
NULL pointer logic.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <JBeulich@suse.com>
Konrad Rzeszutek Wilk