The field is not used anymore, we can remove it.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190422210448.2488-4-ehabkost@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> [on mingw64]
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
qtest_available() will always return 0 on non-POSIX systems.
It's simpler to just not compile the accelerator code on those
systems instead of relying on the AccelClass::available function.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190422210448.2488-3-ehabkost@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> [on mingw64]
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
QTest has two parts: the server (-qtest) and the accelerator
(-machine accel=qtest). The accelerator depends on CONFIG_POSIX
due to its usage of sigwait(), but the server doesn't.
Move the accel code to accel/qtest.c. Later we will disable
compilation of accel/qtest.c on non-POSIX systems.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190422210448.2488-2-ehabkost@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[thuth: added fixup for MAINTAINERS file]
Signed-off-by: Thomas Huth <thuth@redhat.com>
This change adapts io_readx() to its input access_type. Currently
io_readx() treats any memory access as a read, although it has an
input argument "MMUAccessType access_type". This results in:
1) Calling the tlb_fill() only with MMU_DATA_LOAD
2) Considering only entry->addr_read as the tlb_addr
Buglink: https://bugs.launchpad.net/qemu/+bug/1825359
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Shahab Vahedi <shahab.vahedi@gmail.com>
Message-Id: <20190420072236.12347-1-shahab.vahedi@gmail.com>
[rth: Remove assert; fix expression formatting.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
If a TB generates too much code, try again with fewer insns.
Fixes: https://bugs.launchpad.net/bugs/1824853
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
In order to handle TB's that translate to too much code, we
need to place the control of the length of the translation
in the hands of the code gen master loop.
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
CPUClass method dump_statistics() takes an fprintf()-like callback and
a FILE * to pass to it. Most callers pass fprintf() and stderr.
log_cpu_state() passes fprintf() and qemu_log_file.
hmp_info_registers() passes monitor_fprintf() and the current monitor
cast to FILE *. monitor_fprintf() casts it right back, and is
otherwise identical to monitor_printf().
The callback gets passed around a lot, which is tiresome. The
type-punning around monitor_fprintf() is ugly.
Drop the callback, and call qemu_fprintf() instead. Also gets rid of
the type-punning, since qemu_fprintf() takes NULL instead of the
current monitor cast to FILE *.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190417191805.28198-15-armbru@redhat.com>
dump_exec_info() takes an fprintf()-like callback and a FILE * to pass
to it.
Its only caller hmp_info_jit() passes monitor_fprintf() and the
current monitor cast to FILE *. monitor_fprintf() casts it right
back, and is otherwise identical to monitor_printf(). The
type-punning is ugly.
Drop the callback, and call qemu_printf() instead.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190417191805.28198-5-armbru@redhat.com>
dump_opcount_info() takes an fprintf()-like callback and a FILE * to
pass to it.
Its only caller hmp_info_opcount() passes monitor_fprintf() and the
current monitor cast to FILE *. monitor_fprintf() casts it right
back, and is otherwise identical to monitor_printf(). The
type-punning is ugly.
Drop the callback, and call qemu_printf() instead.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190417191805.28198-4-armbru@redhat.com>
When the user specifies a list of accelerators, we pick the first one
that initializes successfully. Recent commit 1a3ec8c156 broke that.
Reproducer:
$ qemu-system-x86_64 --machine accel=xen:tcg
xencall: error: Could not obtain handle on privileged command interface: No such file or directory
xen be core: xen be core: can't open xen interface
can't open xen interface
qemu-system-x86_64: failed to initialize Xen: Operation not permitted
qemu-system-x86_64: /home/armbru/work/qemu/qom/object.c:436: object_set_accelerator_compat_props: Assertion `!object_compat_props[0]' failed.
Root cause: we register accelerator compat properties even when the
accelerator fails. The failed assertion is
object_set_accelerator_compat_props() telling us off. Fix by calling
it only for the accelerator that succeeded.
Fixes: 1a3ec8c156
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20190401090827.20793-6-armbru@redhat.com>
Almost all trace-events point to docs/devel/tracing.txt in a comment
right at the beginning. Touch up the ones that don't.
[Updated with Markus' new commit description wording.
--Stefan]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190314180929.27722-2-armbru@redhat.com
Message-Id: <20190314180929.27722-2-armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Compatibility properties started life as a qdev property thing: we
supported them only for qdev properties, and implemented them with the
machinery backing command line option -global.
Recent commit fa0cb34d22 put them to use (tacitly) with memory
backend objects (subtypes of TYPE_MEMORY_BACKEND). To make that
possible, we first moved the work of applying them from the -global
machinery into TYPE_DEVICE's .instance_post_init() method
device_post_init(), in commits ea9ce8934c and b66bbee39f, then made
it available to TYPE_MEMORY_BACKEND's .instance_post_init() method
host_memory_backend_post_init() as object_apply_compat_props(), in
commit 1c3994f6d2.
Note the code smell: we now have function name starting with object_
in hw/core/qdev.c. It has to be there rather than in qom/, because it
calls qdev_get_machine() to find the current accelerator's and
machine's compat_props.
Turns out calling qdev_get_machine() there is problematic. If we
qdev_create() from a machine's .instance_init() method, we call
device_post_init() and thus qdev_get_machine() before main() can
create "/machine" in QOM. qdev_get_machine() tries to get it with
container_get(), which "helpfully" creates it as "container" object,
and returns that. object_apply_compat_props() tries to paper over the
problem by doing nothing when the value of qdev_get_machine() isn't a
TYPE_MACHINE. But the damage is done already: when main() later
attempts to create the real "/machine", it fails with "attempt to add
duplicate property 'machine' to object (type 'container')", and
aborts.
Since no machine .instance_init() calls qdev_create() so far, the bug
is latent. But since I want to do that, I get to fix the bug first.
Observe that object_apply_compat_props() doesn't actually need the
MachineState, only its the compat_props member of its MachineClass and
AccelClass. This permits a simple fix: register MachineClass and
AccelClass compat_props with the object_apply_compat_props() machinery
right after these classes get selected.
This is actually similar to how things worked before commits
ea9ce8934c and b66bbee39f, except we now register much earlier. The
old code registered them only after the machine's .instance_init()
ran, which would've broken compatibility properties for any devices
created there.
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190308131445.17502-2-armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Instead of deny build of QEMU without a default accelerator, simply
report an error when the user haven't passed -accel or -machine accel=
and TCG and KVM isn't builtin.
./configure already check that at least one accelerator is available.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
On ARM, the kvm_type will be resolved by querying the KVMState.
Let's add the MachineState handle to the callback so that we
can retrieve the KVMState handle. in kvm_init, when the callback
is called, the kvm_state variable is not yet set.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-id: 20190304101339.25970-5-eric.auger@redhat.com
[ppc parts]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Add a couple of traces around the kvm_set_ioeventfd* calls.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20190212134758.10514-4-dgilbert@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
We are failing to take into account that tlb_fill() can cause a
TLB resize, which renders prior TLB entry pointers/indices stale.
Fix it by re-doing the TLB entry lookups immediately after tlb_fill.
Fixes: 86e1eff8bc ("tcg: introduce dynamic TLB sizing", 2019-01-28)
Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20190209162745.12668-3-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
In commit f7b78602fd we added the CPU cluster number to the
cflags field of the TB hash; this included adding it to the value
kept in tb->cflags, since we pass that field directly into the hash
calculation in some places. Unfortunately we forgot to check whether
other parts of the code were doing comparisons against tb->cflags
that would need to be updated.
It turns out that there is exactly one such place: the
tb_lookup__cpu_state() function checks whether the TB it has
found in the tb_jmp_cache has a tb->cflags matching the cf_mask
that is passed in. The tb->cflags has the cluster_index in it
but the cf_mask does not.
Hoist the "add cluster index to the cf_mask" code up from
tb_htable_lookup() to tb_lookup__cpu_state() so it can be considered
in the "did this TB match in the jmp cache" condition, as well as
when we do the full hash lookup by physical PC, flags, etc.
(tb_htable_lookup() is only called from tb_lookup__cpu_state(),
so this change doesn't require any further knock-on changes.)
Fixes: f7b78602fd ("accel/tcg: Add cluster number to TCG TB hash")
Tested-by: Cleber Rosa <crosa@redhat.com>
Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reported-by: Howard Spoelstra <hsp.cat7@gmail.com>
Reported-by: Cleber Rosa <crosa@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20190205151810.571-1-peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Just like we do in cpu_exec().
Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We forgot to add this check in faa9372c07 ("translate-all:
introduce assert_no_pages_locked", 2018-06-15); we only added
it after returning from a longjmp in cpu_exec_step_atomic. Fix it.
Signed-off-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It's either "GNU *Library* General Public version 2" or "GNU Lesser
General Public version *2.1*", but there was no "version 2.0" of the
"Lesser" library. So assume that version 2.1 is meant here.
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1548252536-6242-5-git-send-email-thuth@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Include the cluster number in the hash we use to look
up TBs. This is important because a TB that is valid
for one cluster at a given physical address and set
of CPU flags is not necessarily valid for another:
the two clusters may have different views of physical
memory, or may have different CPU features (eg FPU
present or absent).
We put the cluster number in the high 8 bits of the
TB cflags. This gives us up to 256 clusters, which should
be enough for anybody. If we ever need more, or need
more bits in cflags for other purposes, we could make
tb_hash_func() take more data (and expand qemu_xxhash7()
to qemu_xxhash8()).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20190121152218.9592-4-peter.maydell@linaro.org
In cpu_signal_handler() for aarch64 hosts, currently we parse
the faulting instruction to see if it is a load or a store.
Since the 3.16 kernel (~2014), the kernel has provided us with
the syndrome register for a fault, which includes the WnR bit.
Use this instead if it is present, only falling back to
instruction parsing if not.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190108180014.32386-1-peter.maydell@linaro.org
Now that all tcg backends support TCG_TARGET_IMPLEMENTS_DYN_TLB,
remove the define and the old code.
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Disabled in all TCG backends for now.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20190116170114.26802-3-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Currently we evict an entry to the victim TLB when it doesn't match
the current address. But it could be that there's no match because
the current entry is empty (i.e. all -1's, for instance via tlb_flush).
Do not evict the entry to the vtlb in that case.
This change will help us keep track of the TLB's use rate, which
we'll use to implement a policy for dynamic TLB sizing.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20190116170114.26802-2-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Most list head structs need not be given a name. In most cases the
name is given just in case one is going to use QTAILQ_LAST, QTAILQ_PREV
or reverse iteration, but this does not apply to lists of other kinds,
and even for QTAILQ in practice this is only rarely needed. In addition,
we will soon reimplement those macros completely so that they do not
need a name for the head struct. So clean up everything, not giving a
name except in the rare case where it is necessary.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
osdep.h will also define the available Windows API version for QEMU.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20181122110039.15972-2-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When compiling with "--disable-tcg", we currently still use "tcg"
as default accelerator. "kvm" should be used in this case instead.
Also, some downstream distros provide QEMU binaries which have "kvm"
in their names (e.g. "qemu-kvm" on RHEL or "kvm" on Ubuntu) that use
KVM by default - and some users might want to do something similar
with upstream binaries, too. Accomodate them by using "kvm:tcg" as
default when we detect such a binary name.
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1538748792-19444-1-git-send-email-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Instead of registering compat properties as globals, let's keep them
in their own array, to avoid mixing with user globals.
Introduce object_apply_global_props() function, to apply compatibility
properties from a GPtrArray.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <c445175310fa836b61fd862a55628907f0093194.1545246859.git.alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
global_props is only used for Xen xen_compat_props. It's a static
array of GlobalProperty, like machine globals in SET_MACHINE_COMPAT().
Let's register the globals the same way, without extra copy allocation.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20181204142023.15982-5-marcandre.lureau@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This is essentially redundant with tlb_c.dirty.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Especially for guests with large numbers of tlbs, like ARM or PPC,
we may well not use all of them in between flush operations.
Remember which tlbs have been used since the last flush, and
avoid any useless flushing.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Our only statistic so far was "full" tlb flushes, where all mmu_idx
are flushed at the same time.
Now count "partial" tlb flushes where sets of mmu_idx are flushed,
but the set is not maximal. Account one per mmu_idx flushed, as
that is the unit of work performed.
We don't actually count elided flushes yet, but go ahead and change
the interface presented to the monitor all at once.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The difference between the two sets of APIs is now miniscule.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The difference between the two sets of APIs is now miniscule.
This allows tlb_flush, tlb_flush_all_cpus, and tlb_flush_all_cpus_synced
to be merged with their corresponding by_mmuidx functions as well. For
accounting, consider mmu_idx_bitmask = ALL_MMUIDX_BITS to be a full flush.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The rest of the tlb victim cache is per-tlb,
the next use index should be as well.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The set of large pages in the kernel is probably not the same
as the set of large pages in the application. Forcing one
range to cover both will flush more often than necessary.
This allows tlb_flush_page_async_work to flush just the one
mmu_idx implicated, which in turn allows us to remove
tlb_check_page_and_flush_by_mmuidx_async_work.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Protect it with the tlb_lock instead of using atomics.
The move puts it in or near the same cacheline as the lock;
using the lock means we don't need a second atomic operation
in order to perform the update. Which makes it cheap to also
update pending_flush in tlb_flush_by_mmuidx_async_work.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The bugs this was working around were fixed with commits
022d6378c7 target/unicore32: remove tlb_flush from uc32_init_fn
6e11beecfd target/alpha: remove tlb_flush from alpha_cpu_initfn
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This is the first of several moves to reduce the size of the
CPU_COMMON_TLB macro and improve some locality of refernce.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
GCC7+ will no longer advertise support for 16-byte __atomic operations
if only cmpxchg is supported, as for x86_64. Fortunately, x86_64 still
has support for __sync_compare_and_swap_16 and we can make use of that.
AArch64 does not have, nor ever has had such support, so open-code it.
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Isolate the computation of an index from an address into a
helper before we change that function.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
[ cota: convert tlb_vaddr_to_host; use atomic_read on addr_write ]
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181009175129.17888-2-cota@braap.org>
Currently we rely on atomic operations for cross-CPU invalidations.
There are two cases that these atomics miss: cross-CPU invalidations
can race with either (1) vCPU threads flushing their TLB, which
happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB,
which updates .addr_write with a regular store. This results in
undefined behaviour, since we're mixing regular and atomic ops
on concurrent accesses.
Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table
and the corresponding victim cache now hold the lock.
The readers that do not hold tlb_lock must use atomic reads when
reading .addr_write, since this field can be updated by other threads;
the conversion to atomic reads is done in the next patch.
Note that an alternative fix would be to expand the use of atomic ops.
However, in the case of TLB flushes this would have a huge performance
impact, since (1) TLB flushes can happen very frequently and (2) we
currently use a full memory barrier to flush each TLB entry, and a TLB
has many entries. Instead, acquiring the lock is barely slower than a
full memory barrier since it is uncontended, and with a single lock
acquisition we can flush the entire TLB.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181009174557.16125-6-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
