With all other plumbing in place, activate shadow stacks when possible.
Note that CET shares the similar problems to SMEP/SMAP with Ring1 being
supervisor to the processor, and that the layout of the shadow stack differs
between an IRET to Ring 1 and Ring 3. Therefore, we disable PV32 when CET is
enabled. Compatibility can be maintained if necessary via PV-Shim.
The BSP needs to wait until alternatives have run (to avoid interaction with
CR0.WP), and after the first reset_stack_and_jump() to avoid having a pristine
shadow stack interact in problematic ways with an in-use regular stack.
Activate shadow stack in reinit_bsp_stack().
APs have all infrastructure set up by the booting CPU, so enable shadow stacks
before entering C. Adjust the logic to call start_secondary rather than jump
to it, so stack traces make more sense.
The crash path needs to turn CET off to avoid interfering with the crash
kernel's environment.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
The SYSCALL/SYSENTER/SYSRET paths need to use {SET,CLR}SSBSY. The IRET to
guest paths must not. In the SYSRET path, re-position the mov which loads rip
into %rcx so we can use %rcx for CLRSSBSY, rather than spilling another
register to the stack.
While we can in principle detect shadow stack corruption and a failure to
clear the supervisor token busy bit in the SYSRET path (by inspecting the
carry flag following CLRSSBSY), we cannot detect similar problems for the IRET
path (IRET is specified not to fault in this case).
We will double fault at some point later, when next trying to enter Xen, due
to an already-set supervisor shadow stack busy bit. As SYSRET is a uncommon
path anyway, avoid the added complexity for no appreciable gain.
The IST switch onto the primary stack is not great as we have an instruction
boundary with no shadow stack. This is the least bad option available.
These paths are not used before shadow stacks are properly established, so can
use alternatives to avoid extra runtime CET detection logic.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Ensure the dirty bit is clear when creating read-only EFI mappings.
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
The current alternatives algorithm clears CR0.WP and writes into .text. This
has a side effect of the mappings becoming shadow stacks once CET is active.
Adjust _alternative_instructions() to clean up after itself. This involves
extending the set of bits modify_xen_mappings() to include Dirty (and Accessed
for good measure).
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
When adjusting an IRET frame to recover from a fault, and equivalent
adjustment needs making in the shadow IRET frame.
The adjustment in exception_with_ints_disabled() could in principle be an
alternative block rather than an ifdef, as the only two current users of
_PRE_EXTABLE() are IRET-to-guest instructions. However, this is not a
fastpath, and this form is more robust to future changes.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
The 32 calls need dropping from the shadow stack as well as the regular stack.
To shorten the code, we can use the 32bit forms of RDSSP/INCSSP, but need to
double up the input to INCSSP to counter the operand size based multiplier.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
We need to unwind up to the supervisor token. See the comment for details.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
When executing an IRET-to-self, the shadow stack must agree with the regular
stack. We can't manipulate SSP directly, so have to fake a shadow IRET frame
by executing 3 CALLs, then editing the result to look correct.
This is not a fastpath, is called on the BSP long before CET can be set up,
and may be called on the crash path after CET is disabled. Use the fact that
INCSSP is allocated from the hint nop space to construct a test for CET being
active which is safe on all processors.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Introduce HYPERVISOR_SHSTK pagetable constants, which are Read-Only + Dirty.
Use these in place of _PAGE_RW for memguard_guard_stack(), to create real
shadow stacks on capable hardware.
Supervisor shadow stacks need a token written at the top, which is most easily
done before making the frame read only.
Allocate the shadow IST stack block in struct tss_page. It doesn't strictly
need to live here, but it is a convenient location (and XPTI-safe, for testing
purposes), and placing it ahead of the TSS doesn't risk colliding with a bad
IO Bitmap offset and turning into some IO port permissions.
Have load_system_tables() set up the shadow IST stack table when setting up
the regular IST in the TSS.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
We have two free pages in the current stack. A useful property of shadow
stacks and regular stacks is that they act as each others guard pages as far
as OoB writes go. As wild OoB stack reads aren't likely, we don't lose any
meaningful protection from using read-only guard pages in general (rather than
non-present guard pages), but result is far simpler for Xen as a whole by not
having a feature/mode dependent stack configuration.
Move the regular IST stacks up by one page, to allow their shadow stack page
to be in slot 0. The primary shadow stack uses slot 5.
As the shadow IST stacks are only 1k large, shuffle the order of IST vectors
to have #DF numerically highest, so there is no chance of a shadow stack
overflow clobbering the supervisor token.
The XPTI code already breaks the MEMORY_GUARD abstraction for stacks by
forcing it to be in effect (i.e. guard page not present). To avoid having too
many configurations, do away with the concept entirely, and unconditionally
map the pages in their read-only form.
A later change will turn these properly into shadow stacks. Some of the
comments written here are the intended result, and will become true in the
subsequent change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
For now, any #CP exception or shadow stack #PF indicate a bug in Xen, but
attempt to recover from #CP if taken in guest context.
This will of course have to change as part of introducing CET-SS support for
PV guests.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Introduce CONFIG_HAS_AS_CET_SS to determine whether CET Shadow Stack
instructions are supported in the assembler, and CONFIG_XEN_SHSTK as the main
build option.
Introduce cet={no-,}shstk to for a user to select whether or not to use shadow
stacks at runtime, and X86_FEATURE_XEN_SHSTK to determine Xen's overall
enablement of shadow stacks.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
UD faults never had any diagnostics printed, and the others were inconsistent.
Don't use dprintk() because identifying traps.c is actively unhelpful in the
message, as it is the location of the fixup, not the fault. Use the new
vec_name() infrastructure, rather than leaving raw numbers for the log.
(XEN) Running stub recovery selftests...
(XEN) Fixup #UD[0000]: ffff82d07fffd040 [ffff82d07fffd040] -> ffff82d0403ac9d6
(XEN) Fixup #GP[0000]: ffff82d07fffd041 [ffff82d07fffd041] -> ffff82d0403ac9d6
(XEN) Fixup #SS[0000]: ffff82d07fffd040 [ffff82d07fffd040] -> ffff82d0403ac9d6
(XEN) Fixup #BP[0000]: ffff82d07fffd041 [ffff82d07fffd041] -> ffff82d0403ac9d6
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
For one, they render the vector in a different base.
Introduce X86_EXC_* constants and vec_name() to refer to exceptions by their
mnemonic, which starts bringing the code/diagnostics in line with the Intel
and AMD manuals.
Provide constants for every archtiecturally defined exception, even those not
implemented by Xen yet, as do_reserved_trap() is a catch-all handler.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
xen/tools/binfile contains a bash specific command (let). This leads
to build failures on systems not using bash as /bin/sh.
Replace "let SHIFT=$OPTIND-1" by "SHIFT=$((OPTIND-1))".
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Andrew Cooper <andrew.cooper3@citrix.com>
The ARM side of the cpu_nr_siblings() was missing a return type. OSSTest
reports:
/home/osstest/build.150502.build-arm64-xsm/xen/xen/include/asm/cpufeature.h:67:15:
error: return type defaults to 'int' [-Werror=implicit-int]
static inline cpu_nr_siblings(unsigned int)
^~~~~~~~~~~~~~~
My local build test then reported:
/local/xen.git/xen/include/asm/cpufeature.h: In function ‘cpu_nr_siblings’:
/local/xen.git/xen/include/asm/cpufeature.h:67:1: error: parameter name omitted
static inline int cpu_nr_siblings(unsigned int)
^
Fix it up to match its x86 counterpart.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
toggle_guest_pt() is called in pairs, to read guest kernel data
structures when emulating a guest userspace action. Hence this doesn't
modify cr3 from the guest's point of view, and therefore doesn't need
any resync on the exit-to-guest path. Therefore move the updating of
->pv_cr3 and ->root_pgt_changed into toggle_guest_mode(), since undoing
the changes during the second of these invocations wouldn't be a safe
thing to do.
While at it, add a comment ahead of toggle_guest_pt() to clarify its
intended usage.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Commit 534519f051 ("xen: Have Kconfig check $(CC)'s version")
introduced the use of CLANG_FLAGS in Kconfig which is used when
testing for other CFLAGS via $(cc-option ...) but CLANG_FLAGS doesn't
exist in the Xen build system. (It's a Linux/Kbuild variable that
haven't been added yet.)
The missing CLANG_FLAGS isn't an issue for $(cc-option ..) but it
would be when $(as-instr ..) gets imported from Kbuild to tests
assembly instruction. We need to know if we are going to use clang's
assembler or not.
CLANG_FLAGS needs to be calculated before we call Kconfig.
So, this patch adds CLANG_FLAGS which may contain two flags which are
needed for further testing of $(CC)'s capabilities:
-no-integrated-as
This flags isn't new, but simply tested earlier so that it can be
used in Kconfig. The flags is only added for x86 builds like
before.
-Werror=unknown-warning-option
The one is new and is to make sure that the warning is enabled,
even though it is by default but could be disabled in a particular
build of clang, see Linux's commit e8de12fb7cde ("kbuild: Check
for unknown options with cc-option usage in Kconfig and clang")
It is present in clang 3.0.0, according Linux's commit
589834b3a009 ("kbuild: Add -Werror=unknown-warning-option to
CLANG_FLAGS").
(The "note" that say that the flags was only added once wasn't true
when tested on CentOS 6, so the patch uses $(or) and the flag will only
be added once.)
Fixes: 534519f051 ("xen: Have Kconfig check $(CC)'s version")
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
In Credit2 CPUs (can) share runqueues, depending on the topology. For
instance, with per-socket runqueues (the default) all the CPUs that are
part of the same socket share a runqueue.
On platform with a huge number of CPUs per socket, that could be a
problem. An example is AMD EPYC2 servers, where we can have up to 128
CPUs in a socket.
It is of course possible to define other, still topology-based, runqueue
arrangements (e.g., per-LLC, per-DIE, etc). But that may still result in
runqueues with too many CPUs on other/future platforms. For instance, a
system with 96 CPUs and 2 NUMA nodes will end up having 48 CPUs per
runqueue. Not as bad, but still a lot!
Therefore, let's set a limit to the max number of CPUs that can share a
Credit2 runqueue. The actual value is configurable (at boot time), the
default being 16. If, for instance, there are more than 16 CPUs in a
socket, they'll be split among two (or more) runqueues.
Note: with core scheduling enabled, this parameter sets the max number
of *scheduling resources* that can share a runqueue. Therefore, with
granularity set to core (and assumint 2 threads per core), we will have
at most 16 cores per runqueue, which corresponds to 32 threads. But that
is fine, considering how core scheduling works.
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
If we need to know within which pool a particular scheduler
is working, we can do that by querying the cpupool pointer
of any of the sched_resource-s (i.e., ~ any of the CPUs)
assigned to the scheduler itself.
Basically, we pick any sched_resource that we know uses that
scheduler, and we check its *cpupool pointer. If we really
know that the resource uses the scheduler, this is fine, as
it also means the resource is inside the pool we are
looking for.
But, of course, we can't do that for a pool/scheduler that has
not any been given any sched_resource yet (or if we do not
know whether or not it has any sched_resource).
To overcome such limitation, add a back pointer from the
scheduler, to its own pool.
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
As it will be useful in later changes. While there, fix
the doc-comment.
No functional change intended.
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Just move the big if() condition in an inline function.
No functional change intended.
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
This is partly to adjust the description of 'k' and 's' seeing as they have
changed, but mostly restructuring the information for clarity.
In particular, use indentation to clearly separate the areas discussing libxl
format from xend format. In addition, extend the xend format section to
discuss subleaf notation.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
With all other pieces in place, it is now safe to restore the CPUID and MSR
data in the migration stream, rather than discarding them and using the higher
level toolstacks compatibility logic.
While this is a small patch, it has large implications for migrated/resumed
domains. Most obviously, the CPU family/model/stepping data,
cache/tlb/etc. will no longer change behind the guests back.
Another change is the interpretation of the Xend cpuid strings. The 'k'
option is not a sensible thing to have ever supported, and 's' is how how the
stream will end up behaving.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Pre Xen-4.14 streams will not contain any CPUID/MSR information. There is
nothing libxc can do about this, and will have to rely on the higher level
toolstack to provide backwards compatibility.
To facilitate this, extend the static_data_done() callback, highlighting the
missing information, and modify libxl to use it. At the libxc level, this
requires an arch-specific hook which, for now, always reports CPUID and MSR as
missing. This will be adjusted in a later change.
No overall functional change - this is just plumbing.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
With the destination side now able to understand X86_{CPUID,MSR}_DATA
records (and compatibly handle their absense), update the sending logic to
obtain and forward this data from Xen.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
For now, the data are just stashed, and discarded at the end.
A future change will restore the data, once libxl has been adjusted to avoid
clobbering the data.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
CPUID handling needs to be earlier in construction. Move it from its current
position in libxl__build_post() to libxl__build_pre() for fresh builds, and
libxl__srm_callout_callback_static_data_done() for the migration/resume case.
Later changes will make the migration/resume case conditional on whether CPUID
data was present in the migration stream, and the libxc layer took care of
restoring it.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
This will be needed shortly to provide backwards compatiblity for migration
streams which do not have CPUID information contained within them.
No functional change yet.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Introduce a new static_data() hook which is responsible for writing out
any static data records. The HVM side continues to be a no-op, while
the PV side moves write_x86_pv_info() into this earlier hook. The the
common code writes out a STATIC_DATA_END record, and the stream version
is bumped to 3.
Update convert-legacy-stream to write a v3 stream, because this will
bypass the compatibly logic in libxc.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
A v3 stream can compatibly read a v2 stream by inferring the position of the
STATIC_DATA_END record.
v2 compatibility is only needed for x86. No other architectures exist yet,
but they will have a minimum of v3 when introduced.
The x86 HVM compatibility point being in handle_page_data() (which is common
code) is a bit awkward. However, as the two compatibility points are subtly
different, and it is (intentionally) not possible to call into arch specific
code from common code (except via the ops hooks), use some #ifdef-ary and
opencode the check, rather than make handle_page_data() a per-arch helper.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Higher level toolstacks may wish to know when the static data is complete, so
introduce a restore_callback for the purpose.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Migration data can be split into two parts - that which is invariant of
guest execution, and that which is not. Separate these two with the
STATIC_DATA_END record.
The short term, we want to move the x86 CPU Policy data into the stream.
In the longer term, we want to provisionally send the static data only
to the destination as a more robust compatibility check. In both cases,
we will want a callback into the higher level toolstack.
Mandate the presence of the STATIC_DATA_END record, and declare this v3,
along with instructions for how to compatibly interpret a v2 stream.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Migration v3 is in the process of being introduced, meaning that the code has
to cope with both versions. Use an explicit 2 for now.
For the verify-stream-v2 and convert-legacy-stream scripts, update text to say
"v2 (or later)". What matters is the distinction vs legacy streams.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
The patch 1e9bc407cf mistakenly converted the altp2m config option to a
boolean. This is incorrect and breaks external-only usecases of altp2m that
is set with a value of 2.
Signed-off-by: Tamas K Lengyel <tamas@tklengyel.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Update connection record details:
- make flags common for sockets and domains (makes it easier to have a
C union for conn-spec)
- add pending incoming data (needed for handling partially read
requests when doing live update)
- add partial response length (needed for proper split to individual
responses after live update)
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Clang doesn't support attribute error, and the possible equivalents
like diagnose_if don't seem to work well in this case as they trigger
when when the function is not called (just by being used by the
APPEND_CALL macro).
Define nocall to a noop on clang until a proper solution can be found.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Julien Grall <jgrall@amazon.com>
[jb: error -> __error__]
Acked-by: Jan Beulich <jbeulich@suse.com>
Both SHDEPS_libxendevicemodel and SHDEPS_libxenhypfs have a bug by
adding $(SHLIB_xencall) instead of $(SHLIB_libxencall).
The former seems not to have any negative impact, probably because
it is not used anywhere in Xen without the correct $(SHLIB_libxencall)
being used, too.
Fixes: 86234eafb9 ("libs: add libxenhypfs")
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Juergen Gross <jgross@suse.com>
Note that FPU selector handling as well as MXCSR mask saving for now
does not honor differences between host and guest visible featuresets.
While for Intel operation of the insns with CR4.OSFXSR=0 is
implementation dependent, use the easiest solution there: Simply don't
look at the bit in the first place. For AMD and alike the behavior is
well defined, so it gets handled together with FFXSR.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
While the Intel SDM claims that FRSTOR itself may raise #MF upon
completion, this was confirmed by Intel to be a doc error which will be
corrected in due course; behavior is like FLDENV, and like old hard copy
manuals describe it.
Re-arrange a switch() statement's case label order to allow for
fall-through from FLDENV handling to FNSTENV's.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
To avoid introducing another boolean into emulator state, the
rex_prefix field gets (ab)used to convey the real/VM86 vs protected mode
info (affecting structure layout, albeit not size) to x86_emul_blk().
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Note that the ISA extensions document revision 038 doesn't specify
exception behavior for ModRM.mod == 0b11; assuming #UD here.
No tests are being added to the harness - this would be quite hard,
we can't just issue the insns against RAM. Their similarity with
MOVDIR64B should have the test case there be god enough to cover any
fundamental flaws.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Introduce a new blk() hook, paralleling the rmw() one in a certain way,
but being intended for larger data sizes, and hence its HVM intermediate
handling function doesn't fall back to splitting the operation if the
requested virtual address can't be mapped.
Note that SDM revision 071 doesn't specify exception behavior for
ModRM.mod == 0b11; assuming #UD here.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Andrew Cooper <andrew.cooper@citrix.com>
In a pure PV environment (the PV shim in particular) we don't really
need emulation of all these. To limit #ifdef-ary utilize some of the
CASE_*() macros we have, by providing variants expanding to
(effectively) nothing (really a label, which in turn requires passing
-Wno-unused-label to the compiler when build such configurations).
Due to the mixture of macro and #ifdef use, the placement of some of
the #ifdef-s is a little arbitrary.
The resulting object file's .text is less than half the size of the
original, and looks to also be compiling a little more quickly.
This is meant as a first step; more parts can likely be disabled down
the road.
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Bregrudingly-acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
x86emul_is_mem_{access,write}() (and their interaction with
x86_decode()) have become sufficiently complex that we should have a way
to test this logic. Start by covering legacy encoded GPR insns, with the
exception of a few the main emulator doesn't support yet (left as
comments in the respective tables, or about to be added by subsequent
patches). This has already helped spot a few flaws in said logic,
addressed by (revised) earlier patches.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Unlike similarly encoded insns these don't write their memory operands,
and hence x86_is_mem_write() should return false for them. However,
rather than adding special logic there, rework how their emulation gets
done, by making decoding attributes properly describe the r/o nature of
their memory operands:
- change the table entries for opcodes 0x38 and 0x39, with no other
adjustments to the attributes later on,
- for the other opcodes, leave the table entries as they are, and
override the attributes for the specific sub-cases (identified by
ModRM.reg).
For opcodes 0x38 and 0x39 the change of the table entries implies
changing the order of operands as passed to emulate_2op_SrcV(), hence
the splitting of the cases in the main switch().
Note how this also allows dropping custom LOCK prefix checks.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Andrew Cooper