Move declarations out of qemu-common.h for functions declared in
utils/ files: e.g. include/qemu/path.h for utils/path.c.
Move inline functions out of qemu-common.h and into new files (e.g.
include/qemu/bcd.h)
Backports commit f348b6d1a53e5271cf1c9f9acc4646b4b98c1771 from qemu
Commit 57cb38b included qapi/error.h into qemu/osdep.h to get the
Error typedef. Since then, we've moved to include qemu/osdep.h
everywhere. Its file comment explains: "To avoid getting into
possible circular include dependencies, this file should not include
any other QEMU headers, with the exceptions of config-host.h,
compiler.h, os-posix.h and os-win32.h, all of which are doing a
similar job to this file and are under similar constraints."
qapi/error.h doesn't do a similar job, and it doesn't adhere to
similar constraints: it includes qapi-types.h. That's in excess of
100KiB of crap most .c files don't actually need.
Add the typedef to qemu/typedefs.h, and include that instead of
qapi/error.h. Include qapi/error.h in .c files that need it and don't
get it now. Include qapi-types.h in qom/object.h for uint16List.
Update scripts/clean-includes accordingly. Update it further to match
reality: replace config.h by config-target.h, add sysemu/os-posix.h,
sysemu/os-win32.h. Update the list of includes in the qemu/osdep.h
comment quoted above similarly.
This reduces the number of objects depending on qapi/error.h from "all
of them" to less than a third. Unfortunately, the number depending on
qapi-types.h shrinks only a little. More work is needed for that one.
Backports commit da34e65cb4025728566d6504a99916f6e7e1dd6a from qemu
After reporting an error, ram_block_add was going on with the registration
of the RAMBlock. The visible effect is that it unlocked the ramlist
mutex twice.
Backports commit 39c350ee12e733070e63d64a21bd42607366ea99 from qemu
Under heavy workloads the lookup will likely end up with the same
MemoryRegionSection from last time. Using a pointer to cache the result,
like ram_list.mru_block, significantly reduces cost of
address_space_translate.
During address space topology update, as->dispatch will be reallocated
so the pointer is invalidated automatically.
Perf reports a visible drop on the cpu usage, because phys_page_find is
not called. Before:
2.35% qemu-system-x86_64 [.] phys_page_find
0.97% qemu-system-x86_64 [.] address_space_translate_internal
0.95% qemu-system-x86_64 [.] address_space_translate
0.55% qemu-system-x86_64 [.] address_space_lookup_region
After:
0.97% qemu-system-x86_64 [.] address_space_translate_internal
0.97% qemu-system-x86_64 [.] address_space_lookup_region
0.84% qemu-system-x86_64 [.] address_space_translate
Backports commit 729633c2bc30496073431584eb6e304776b4ebd4 from qemu
This will be shared by the next patch.
Also add a comment explaining the unobvious condition on "size.hi".
Backports commit 29cb533d8cbff1330717619780c2f1dfe764e003 from qemu
All references to mr->ram_addr are replaced by
memory_region_get_ram_addr(mr) (except for a few assertions that are
replaced with mr->ram_block).
Backports commit 8e41fb63c5bf29ecabe0cee1239bf6230f19978a from qemu
We don't force "const" qualifiers with pointers in QEMU, but it's still
good to keep a clean function interface. Assigning to mr->ram_block is
in this sense ugly - one initializer mutating its owning object's state.
Move it to memory_region_init_*, where mr->ram_addr is assigned.
Backports commit 0a75601853c00f3729fa62c49ec0d4bb1e3d9bc1 from qemu
Previously we return RAMBlock.offset; now return the pointer to the
whole structure.
ram_block_add returns void now, error is completely passed with errp.
Backports commit 528f46af6ecd1e300db18684969104d4067b867b from qemu
these two functions consume too much cpu overhead to
find the RAMBlock by ram address.
After this patch, we can pass the RAMBlock pointer
to them so that they don't need to find the RAMBlock
anymore most of the time. We can get better performance
in address translation processing.
Backports commit 3655cb9c7375a595a8051ec677c515b24d5c1fe6 from qemu
Each RAM memory region has a unique corresponding RAMBlock.
In the current realization, the memory region only stored
the ram_addr which means the offset of RAM address space,
We need to qurey the global ram.list to find the ram block
by ram_addr if we want to get the ram block, which is very
expensive.
Now, we store the RAMBlock pointer into memory region
structure. So, if we know the mr, we can easily get the
RAMBlock.
Backports commit 58eaa2174e99d9a05172d03fd2799ab8fd9e6f60 from qemu
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.
This commit was created with scripts/clean-includes.
Backports commit 7b31bbc2e68605ab2f10dc609dd54cf4c7b5f49a from qemu
address_space_translate_internal will clamp the *plen length argument
based on the size of the memory region being queried. The iommu walker
logic in addresss_space_translate was ignoring this by discarding the
post fn call value of *plen. Fix by just always using *plen as the
length argument throughout the fn, removing the len local variable.
This fixes a bootloader bug when a single elf section spans multiple
QEMU memory regions.
Backports commit 23820dbfc79d1c9dce090b4c555994f2bb6a69b3 from qemu
Add a MemoryRegion property, which if set is used to construct
the CPU's initial (default) AddressSpace.
Backports commit 6731d864f80938e404dc3e5eb7f6b76b891e3e43 from qemu
When accessing the dispatch pointer in an AddressSpace within an RCU
critical section we should always use atomic_rcu_read(). Fix an
access within memory_region_section_get_iotlb() which was incorrectly
doing a direct pointer access.
Backports commit 0b8e2c1002afddc8ef3d52fa6fc29e4768429f98 from qemu
check the return value of the function it calls and error if it's non-0
Fixup qemu_rdma_init_one_block that is the only current caller,
and rdma_add_block the only function it calls using it.
Pass the name of the ramblock to the function; helps in debugging.
Backports commit e3807054e20fb3b94d18cb751c437ee2f43b6fac from qemu
It is not necessary to munmap an area before remapping it with MAP_FIXED;
if the memory region specified by addr and len overlaps pages of any
existing mapping, then the overlapped part of the existing mapping will
be discarded.
On the other hand, if QEMU does munmap the pages, there is a small
probability that another mmap sneaks in and catches the just-freed
portion of the address space. In effect, munmap followed by
mmap(MAP_FIXED) is a use-after-free error, and Coverity flags it
as such. Fix it.
Backports commit f18c69cfc554cf9776eb3c35b7510e17541afacb from qemu
This reverts commit c3c1bb9.
It causes problems with boards that declare memory regions shorter
than the registers they contain.
Backports commit 4025446f0ac6213335c22ec43f3c3d8362ce7286 from qemu
Block size must fundamentally be a multiple of target page size.
Aligning automatically removes need to worry about the alignment
from callers.
Note: the only caller of qemu_ram_resize (acpi) already happens to have
size padded to a power of 2, but we would like to drop the padding in
ACPI core, and don't want to expose target page size knowledge to ACPI
Backports commit 129ddaf31be583fb7c97812e07e028661005ce42 from qemu
Allow "unlocked" reads of the ram_list by using an RCU-enabled QLIST.
The ramlist mutex is kept. call_rcu callbacks are run with the iothread
lock taken, but that may change in the future. Writers still take the
ramlist mutex, but they no longer need to assume that the iothread lock
is taken.
Readers of the list, instead, no longer require either the iothread
or ramlist mutex, but they need to use rcu_read_lock() and
rcu_read_unlock().
One place in arch_init.c was downgrading from write side to read side
like this:
qemu_mutex_lock_iothread()
qemu_mutex_lock_ramlist()
...
qemu_mutex_unlock_iothread()
...
qemu_mutex_unlock_ramlist()
and the equivalent idiom is:
qemu_mutex_lock_ramlist()
rcu_read_lock()
...
qemu_mutex_unlock_ramlist()
...
rcu_read_unlock()
Backports the write barriers from commit 0dc3f44aca18b1be8b425f3f4feb4b3e8d68de2e in qemu
Coverity flags this as "dereference after null check". Not quite a
dereference, since it will just EFAULT, but still nice to fix.
Backports commit a904c91196a9c5dbd7b9abcd3d40b0824286fb1c from qemu
The TARGET_HAS_ICE #define is intended to indicate whether a target-*
guest CPU implementation supports the breakpoint handling. However,
all our guest CPUs have that support (the only two which do not
define TARGET_HAS_ICE are unicore32 and openrisc, and in both those
cases the bp support is present and the lack of the #define is just
a bug). So remove the #define entirely: all new guest CPU support
should include breakpoint handling as part of the basic implementation.
Backports commit ec53b45bcd1f74f7a4c31331fa6d50b402cd6d26 from qemu
host pointer accesses force pointer math, let's
add a wrapper to make them safer.
Backports relevant parts of commit 1240be24357ee292f8d05aa2abfdba75dd0ca25d from qemu
Otherwise fw_cfg accesses are split into 4-byte ones before they reach the
fw_cfg ops / handlers.
Backports commit ff6cff7554be06e95f8d712f66cd16bd6681c746 from qemu
Loading the BIOS in the mac99 machine is interesting, because there is a
PROM in the middle of the BIOS region (from 16K to 32K). Before memory
region accesses were clamped, when QEMU was asked to load a BIOS from
0xfff00000 to 0xffffffff it would put even those 16K from the BIOS file
into the region. This is weird because those 16K were not actually
visible between 0xfff04000 and 0xfff07fff. However, it worked.
After clamping was added, this also worked. In this case, the
cpu_physical_memory_write_rom_internal function split the write in
three parts: the first 16K were copied, the PROM area (second 16K) were
ignored, then the rest was copied.
Problems then started with commit 965eb2f (exec: do not clamp accesses
to MMIO regions, 2015-06-17). Clamping accesses is not done for MMIO
regions because they can overlap wildly, and MMIO registers can be
expected to perform full-width accesses based only on their address
(with no respect for adjacent registers that could decode to completely
different MemoryRegions). However, this lack of clamping also applied
to the PROM area! cpu_physical_memory_write_rom_internal thus failed
to copy the third range above, i.e. only copied the first 16K of the BIOS.
In effect, address_space_translate is expecting _something else_ to do
the clamping for MMIO regions if the incoming length is large. This
"something else" is memory_access_size in the case of address_space_rw,
so use the same logic in cpu_physical_memory_write_rom_internal.
Backports commit b242e0e0e2969c044a318e56f7988bbd84de1f63 from qemu
Because the clamping was done against the MemoryRegion,
address_space_rw was effectively broken if a write spanned
multiple sections that are not linear in underlying memory
(with the memory not being under an IOMMU).
This is visible with the MIPS rc4030 IOMMU, which is implemented
as a series of alias memory regions that point to the actual RAM.
Backports commit e4a511f8cc6f4a46d409fb5c9f72c38ba45f8d83 from qemu
It is common for MMIO registers to overlap, for example a 4 byte register
at 0xcf8 (totally random choice... :)) and a 1 byte register at 0xcf9.
If these registers are implemented via separate MemoryRegions, it is
wrong to clamp the accesses as the value written would be truncated.
Hence for these regions the effects of commit 23820db (exec: Respect
as_translate_internal length clamp, 2015-03-16, previously applied as
commit c3c1bb9) must be skipped.
Backports commit 965eb2fcdfe919ecced6c34803535ad32dc1249c from qemu
Use cpu_get_phys_page_attrs_debug() when doing virtual-to-physical
conversions in debug related code, so that we can obtain the right
address space index and thus select the correct AddressSpace,
rather than always using cpu->as.
Backports commit 5232e4c798ba7a46261d3157b73d08fc598e7dcb from qemu
Add a function to return the AddressSpace for a CPU based on
its numerical index. (Callers outside exec.c don't have access
to the CPUAddressSpace struct so can't just fish it out of the
CPUState struct directly.)
Backports commit 651a5bc03705102de519ebf079a40ecc1da991db from qemu
Pass the MemTxAttrs for the memory access to iotlb_to_region(); this
allows it to determine the correct AddressSpace to use for the lookup.
Backports commit a54c87b68a0410d0cf6f8b84e42074a5cf463732 from qemu
When looking up the MemoryRegionSection for the new TLB entry in
tlb_set_page_with_attrs(), use cpu_asidx_from_attrs() to determine
the correct address space index for the lookup, and pass it into
address_space_translate_for_iotlb().
Backports commit d7898cda81b6efa6b2d7a749882695cdcf280eaa from qemu
Allow multiple calls to cpu_address_space_init(); each
call adds an entry to the cpu->ases array at the specified
index. It is up to the target-specific CPU code to actually use
these extra address spaces.
Since this multiple AddressSpace support won't work with
KVM, add an assertion to avoid confusing failures.
Backports commit 12ebc9a76dd7702aef0a3618717a826c19c34ef4 from qemu
Rather than setting cpu->as unconditionally in cpu_exec_init
(and then having target-i386 override this later), don't set
it until the first call to cpu_address_space_init.
This requires us to initialise the address space for
both TCG and KVM (KVM doesn't need the AS listener but
it does require cpu->as to be set).
For target CPUs which don't set up any address spaces (currently
everything except i386), add the default address_space_memory
in qemu_init_vcpu().
Backports commit 56943e8cc14b7eeeab67d1942fa5d8bcafe3e53f from qemu
memcpy can take a large amount of time for small reads and writes.
Handle the common case of reading s/g descriptors from memory (there
is no corresponding "write" case that is as common, because writes
often use address_space_st* functions) by inlining the relevant
parts of address_space_read into the caller.
Backports commit 3cc8f884996584630734a90c9b3c535af81e3c92 from qemu
We want to inline the case where there is only one iteration, because
then the compiler can also inline the memcpy. As a start, extract
everything after the first address_space_translate call.
Backports commit a203ac702e0720135fac8b1f2061d119814c1798 from qemu
Rather than dispatching on is_write for every iteration, make
address_space_rw call one of the two functions. The amount of
duplicate logic is pretty small, and memory_access_is_direct can
be tweaked so that it inlines better in the callers.
Backports commit eb7eeb88628074207dd611472e712af775985e73 from qemu
Replace qemu_ram_free_from_ptr() with qemu_ram_free().
The only difference between qemu_ram_free_from_ptr() and
qemu_ram_free() is that g_free_rcu() is used instead of
call_rcu(reclaim_ramblock). We can safely replace it because:
* RAM blocks allocated by qemu_ram_alloc_from_ptr() always have
RAM_PREALLOC set;
* reclaim_ramblock(block) will do nothing except g_free(block)
if RAM_PREALLOC is set at block->flags.
Backports commit a29ac16632aec6065c72985b9f7eeb1ca6fbef4a from qemu
memory_region_unref(mr) can free memory.
For example I got:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f43280d4700 (LWP 4462)]
0x00007f43323283c0 in phys_section_destroy (mr=0x7f43259468b0)
at /home/don/xen/tools/qemu-xen-dir/exec.c:1023
1023 if (mr->subpage) {
(gdb) bt
at /home/don/xen/tools/qemu-xen-dir/exec.c:1023
at /home/don/xen/tools/qemu-xen-dir/exec.c:1034
at /home/don/xen/tools/qemu-xen-dir/exec.c:2205
(gdb) p mr
$1 = (MemoryRegion *) 0x7f43259468b0
And this change prevents this.
Backports commit 55b4e80b047300e1512df02887b7448ba3786b62 from qemu
Add a function to find a RAMBlock by name; use it in two
of the places that already open code that loop; we've
got another use later in postcopy.
Backports commit e3dd74934f2d2c8c67083995928ff68e8c1d0030 from qemu
Postcopy sends RAMBlock names and offsets over the wire (since it can't
rely on the order of ramaddr being the same), and it starts out with
HVA fault addresses from the kernel.
qemu_ram_block_from_host translates a HVA into a RAMBlock, an offset
in the RAMBlock and the global ram_addr_t value.
Rewrite qemu_ram_addr_from_host to use qemu_ram_block_from_host.
Provide qemu_ram_get_idstr since its the actual name text sent on the
wire.
Backports commit 422148d3e56c3c9a07c0cf36c1e0a0b76f09c357 from qemu
Whenever the MRU cache hits for the list of RAM blocks, qemu_get_ram_block
does an unnecessary write that causes a processor cache line to bounce
from one core to another. This causes a performance hit.
Backports commit 68851b98e5bf6d397498b74f1776801274ab8d48 from qemu
This makes ROM blocks resizeable. This infrastructure is required for other
functionality we have queued.
Backports commit aaf03019175949eda5087329448b8a0033b89479 from qemu
This ensures that cpu_reload_memory_map() is called as soon as
tcg_cpu_address_space_init() is called, and before cpu->memory_dispatch
is used. qemu-system-s390x never changes the address spaces after
tcg_cpu_address_space_init() is called, and thus tcg_commit() is never
called. This causes a SIGSEGV.
Because memory_map_init() will now call mem_commit(), we have to
initialize io_mem_* before address_space_memory and friends.
Backports commit 680a4783dc13f1059c03d11da58193d76c19ead6 from qemu
Anonymous and file-backed RAM allocation are now almost exactly the same.
Reduce code duplication by moving RAM mmap code out of oslib-posix.c and
exec.c.
Backports commit 794e8f301a17953efa78ab7538019ec43c59e82a from qemu
Change tlb_set_dirty() to accept a CPU instead of an env pointer. This
allows for removal of another CPUArchState usage from prototypes that
need to be QOMified.
Backports commit bcae01e468d961ad9afaf4148329147e4be209ab from qemu
Use pow2floor() to round down to the nearest power of 2,
rather than an inline calculation.
Backports commit 6554f5c03793bb8a3d5dedcebf758a1694fa186c from qemu
The callers (most of them in target-foo/cpu.c) to this function all
have the cpu pointer handy. Just pass it to avoid an ENV_GET_CPU() from
core code (in exec.c).
Backports commit 4bad9e392e788a218967167a38ce2ae7a32a6231 from qemu
All of the core-code usages of this API have the cpu pointer handy so
pass it in. There are only 3 architecture specific usages (2 of which
are commented out) which can just use ENV_GET_CPU() locally to get the
cpu pointer. The reduces core code usage of the CPU env, which brings
us closer to common-obj'ing these core files.
Backports commit bbd77c180d7ff1b04a7661bb878939b2e1d23798 from qemu
QOM objects are already zero-filled when instantiated, there's no need
to explicitly set numa_node to 0.
Backports commit 199fc85acd0571902eeefef6ea861b8ba4c8201f from qemu
Loading the BIOS in the mac99 machine is interesting, because there is a
PROM in the middle of the BIOS region (from 16K to 32K). Before memory
region accesses were clamped, when QEMU was asked to load a BIOS from
0xfff00000 to 0xffffffff it would put even those 16K from the BIOS file
into the region. This is weird because those 16K were not actually
visible between 0xfff04000 and 0xfff07fff. However, it worked.
After clamping was added, this also worked. In this case, the
cpu_physical_memory_write_rom_internal function split the write in
three parts: the first 16K were copied, the PROM area (second 16K) were
ignored, then the rest was copied.
Problems then started with commit 965eb2f (exec: do not clamp accesses
to MMIO regions, 2015-06-17). Clamping accesses is not done for MMIO
regions because they can overlap wildly, and MMIO registers can be
expected to perform full-width accesses based only on their address
(with no respect for adjacent registers that could decode to completely
different MemoryRegions). However, this lack of clamping also applied
to the PROM area! cpu_physical_memory_write_rom_internal thus failed
to copy the third range above, i.e. only copied the first 16K of the BIOS.
In effect, address_space_translate is expecting _something else_ to do
the clamping for MMIO regions if the incoming length is large. This
"something else" is memory_access_size in the case of address_space_rw,
so use the same logic in cpu_physical_memory_write_rom_internal.
Backports commit b242e0e0e2969c044a318e56f7988bbd84de1f63 from qemu
The cpu_physical_memory_reset_dirty() function is sometimes used
together with cpu_physical_memory_get_dirty(). This is not atomic since
two separate accesses to the dirty memory bitmap are made.
Turn cpu_physical_memory_reset_dirty() and
cpu_physical_memory_clear_dirty_range_type() into the atomic
cpu_physical_memory_test_and_clear_dirty().
Backports commit 03eebc9e3246b9b3f5925aa41f7dfd7c1e467875 from qemu
Most of the time, not all bitmaps have to be marked as dirty;
do not do anything if the interesting ones are already dirty.
Previously, any clean bitmap would have cause all the bitmaps to be
marked dirty.
In fact, unless running TCG most of the time bitmap operations need
not be done at all, because memory_region_is_logging returns zero.
In this case, skip the call to cpu_physical_memory_range_includes_clean
altogether as well.
With this patch, cpu_physical_memory_set_dirty_range is called
unconditionally, so there need not be anymore a separate call to
xen_modified_memory.
Backports commit e87f7778b64d4a6a78e16c288c7fdc6c15317d5f from qemu
While it is obvious that cpu_physical_memory_get_dirty returns true even if
a single page is dirty, the same is not true for cpu_physical_memory_get_clean;
one would expect that it returns true only if all the pages are clean, but
it actually looks for even one clean page. (By contrast, the caller of that
function, cpu_physical_memory_range_includes_clean, has a good name).
To clarify, rename the function to cpu_physical_memory_all_dirty and return
true if _all_ the pages are dirty. This is the opposite of the previous
meaning, because "all are 1" is the same as "not (any is 0)", so we have to
modify cpu_physical_memory_range_includes_clean as well
Backports commit 72b47e79cef36ed6ffc718f10e21001d7ec2a66f from qemu
phys_page_set_level is writing zeroes to a struct that has just been
filled in by phys_map_node_alloc. Instead, tell phys_map_node_alloc
whether to fill in the page "as a leaf" or "as a non-leaf".
memcpy is faster than struct assignment, which copies each bitfield
individually. A compiler bug (https://gcc.gnu.org/PR66391), and
small memcpys like this one are special-cased anyway, and optimized
to a register move, so just use the memcpy.
This cuts the cost of phys_page_set_level from 25% to 5% when
booting qboot.
Backports commit db94604b20278c1dc227a04e4c564d80230e6c3f from qemu
address_space_translate_internal will clamp the *plen length argument
based on the size of the memory region being queried. The iommu walker
logic in addresss_space_translate was ignoring this by discarding the
post fn call value of *plen. Fix by just always using *plen as the
length argument throughout the fn, removing the len local variable.
This fixes a bootloader bug when a single elf section spans multiple
QEMU memory regions.
Backports commit 23820dbfc79d1c9dce090b4c555994f2bb6a69b3 from qemu
There could be a race condition when two processes call
address_space_map concurrently and both want to use the bounce buffer.
Add an in_use flag in BounceBuffer to sync it.
Backports commit c2cba0ffe495b60c4cc58080281e99c7a6580d4b from qemu
Add new address_space_ld*/st* functions which allow transaction
attributes and error reporting for basic load and stores. These
are named to be in line with the address_space_read/write/rw
buffer operations.
The existing ld/st*_phys functions are now wrappers around
the new functions.
Backports commit 500131154d677930fce35ec3a6f0b5a26bcd2973 from qemu
Make address_space_rw take transaction attributes, rather
than always using the 'unspecified' attributes.
Backports commit 5c9eb0286c819c1836220a32f2e1a7b5004ac79a from qemu
Convert the subpage memory ops to _with_attrs; this will allow
us to pass the attributes through to the underlying access
functions. (Nothing uses the attributes yet.)
Backports commit f25a49e0057bbfcc2b1111f60785d919b6ddaeea from qemu
Rather than retaining io_mem_read/write as simple wrappers around
the memory_region_dispatch_read/write functions, make the latter
public and change all the callers to use them, since we need to
touch all the callsites anyway to add MemTxAttrs and MemTxResult
support. Delete io_mem_read and io_mem_write entirely.
(All the callers currently pass MEMTXATTRS_UNSPECIFIED
and convert the return value back to bool or ignore it.)
Backports commit 3b6434953934e6d4a776ed426d8c6d6badee176f from qemu
Define an API so that devices can register MemoryRegionOps whose read
and write callback functions are passed an arbitrary pointer to some
transaction attributes and can return a success-or-failure status code.
This will allow us to model devices which:
* behave differently for ARM Secure/NonSecure memory accesses
* behave differently for privileged/unprivileged accesses
* may return a transaction failure (causing a guest exception)
for erroneous accesses
This patch defines the new API and plumbs the attributes parameter through
to the memory.c public level functions io_mem_read() and io_mem_write(),
where it is currently dummied out.
The success/failure response indication is also propagated out to
io_mem_read() and io_mem_write(), which retain the old-style
boolean true-for-error return.
Backports commit cc05c43ad942165ecc6ffd39e41991bee43af044 from qemu
After the previous patch, TLBs will be flushed on every change to
the memory mapping. This patch augments that with synchronization
of the MemoryRegionSections referred to in the iotlb array.
With this change, it is guaranteed that iotlb_to_region will access
the correct memory map, even once the TLB will be accessed outside
the BQL.
Backports commit 9d82b5a792236db31a75b9db5c93af69ac07c7c5 from qemu
This for now is a simple TLB flush. This can change later for two
reasons:
1) an AddressSpaceDispatch will be cached in the CPUState object
2) it will not be possible to do tlb_flush once the TCG-generated code
runs outside the BQL.
Backports commit 76e5c76f2e2e0d20bab2cd5c7a87452f711654fb from qemu
