Currently, phys_node_map and phys_sections are shared by all
of the AddressSpaceDispatch.  When updating mem topology, all
AddressSpaceDispatch will rebuild dispatch tables sequentially
on them.  In order to prepare for RCU access, leave the old
memory map alive while the next one is being accessed.

When rebuilding, the new dispatch tables will build and lookup
next_map; after all dispatch tables are rebuilt, we can switch
to next_* and free the previous table.

Based on a patch from Liu Ping Fan.
Signed-off-by: NLiu Ping Fan <qemulist@gmail.com>
Reviewed-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Sections like phys_section_unassigned always have fixed address
in phys_sections.  Declared as macro, so we can use them
when having more than one phys_sections array.
Signed-off-by: NLiu Ping Fan <pingfank@linux.vnet.ibm.com>
Signed-off-by: NLiu Ping Fan <qemulist@gmail.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Object reference counts will soon be changed outside the BQL. So we need
to use atomics in object_ref/unref.

Based on a patch by Liu Ping Fan.
Signed-off-by: NLiu Ping Fan <qemulist@gmail.com>
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

With this change, a FlatView can be used even after a concurrent
update has replaced it.  Because we do not yet have RCU, we use a
mutex to protect the small critical sections that read/write the
as->current_map pointer.  Accesses to the FlatView can be done
outside the mutex.

If a MemoryRegion will be used after the FlatView is unref-ed (or after
a MemoryListener callback is returned), a reference has to be added to
that MemoryRegion. memory_region_find already does it for the region
that it returns.  The same will be done for address_space_translate
as soon as the dispatch tree is also converted to RCU-style.
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This is the first step towards converting as->current_map to
RCU-style updates, where the FlatView updates run concurrently
with uses of an old FlatView.
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We will soon require accesses to as->current_map to be placed under
a lock (with reference counting so as to keep the critical section
small).  To simplify this change, always fetch as->current_map into
a local variable and access it through that variable.
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We're already using them in several places, but __sync builtins are just
too ugly to type, and do not provide seqcst load/store operations.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We are using the same struct name for two devices.  8250 is widespread
enough that this causes some confusion, rename the other instance.
Reviewed-by: NAndreas Faerber <afaerber@suse.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The iothread mutex might be released between map and unmap, so the
mapped region might disappear.
Reviewed-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

First of all, rename "todo" to "done".

Second, clearly separate the case of done == 0 with the case of done != 0.
This will help handling reference counting in the next patch.

Third, this test:

             if (memory_region_get_ram_addr(mr) + xlat != raddr + todo) {

does not guarantee that the memory region is the same across two iterations
of the while loop.  For example, you could have two blocks:

A) size 640 K, mapped at physical address 0, ram_addr_t 0
B) size 64 K, mapped at physical address 0xa0000, ram_addr_t 0xa0000

then mapping 1 M starting at physical address zero will erroneously treat
B as the continuation of block A.  qemu_ram_ptr_length ensures that no
invalid memory is accessed, but it is still a pointless complication of
the algorithm.  The patch makes the logic clearer with an explicit test
that the memory region is the same.
Reviewed-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

It will be needed in the next patch.
Reviewed-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

After the next patch it would not be used elsewhere anyway.  Also,
the _nofail and the standard versions of this function return different
things, which is confusing.  Removing the function from the public headers
limits the confusion.
Reviewed-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This function is not used outside the iothread mutex, so it
can use ram_list.mru_block.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Add ref/unref calls at the following places:

- places where memory regions are stashed by a listener and
  used outside the BQL (including in Xen or KVM).

- memory_region_find callsites

- creation of aliases and containers (only the aliased/contained
  region gets a reference to avoid loops)

- around calls to del_subregion/add_subregion, where the region
  could disappear after the first call
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This new API will avoid having too many memory_region_ref/unref
in paths that currently use memory_region_find.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Reviewed-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Whenever memory regions are accessed outside the BQL, they need to be
preserved against hot-unplug.  MemoryRegions actually do not have their
own reference count; they piggyback on a QOM object, their "owner".
The owner is set at creation time, and there is a function to retrieve
the owner.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>