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exec: fix migration with devices that use address_space_rw

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Devices that use address_space_rw to write large areas to memory
(as opposed to address_space_map/unmap) were broken with respect
to migration since fe680d0 (exec: Limit translation limiting in
address_space_translate to xen, 2014-05-07).  Such devices include
IDE CD-ROMs.

The reason is that invalidate_and_set_dirty (called by address_space_rw
but not address_space_map/unmap) was only setting the dirty bit for
the first page in the translation.

To fix this, introduce cpu_physical_memory_set_dirty_range_nocode that
is the same as cpu_physical_memory_set_dirty_range except it does not
muck with the DIRTY_MEMORY_CODE bitmap.  This function can be used if
the caller invalidates translations with tb_invalidate_phys_page_range.

There is another difference between cpu_physical_memory_set_dirty_range
and cpu_physical_memory_set_dirty_flag; the former includes a call
to xen_modified_memory.  This is handled separately in
invalidate_and_set_dirty, and is not needed in other callers of
cpu_physical_memory_set_dirty_range_nocode, so leave it alone.

Just one nit: now that invalidate_and_set_dirty takes care of handling
multiple pages, there is no need for address_space_unmap to wrap it
in a loop.  In fact that loop would now be O(n^2).

Reported-by: Dave Gilbert <dgilbert@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-07-21 16:45:18 +02:00
parent fa666c10f2
commit 6886867e98
2 changed files with 15 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

11
include/exec/ram_addr.h
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@ -71,6 +71,17 @@ static inline void cpu_physical_memory_set_dirty_flag(ram_addr_t addr,
set_bit(addr >> TARGET_PAGE_BITS, ram_list.dirty_memory[client]);
}
static inline void cpu_physical_memory_set_dirty_range_nocode(ram_addr_t start,
ram_addr_t length)
{
unsigned long end, page;
end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS;
page = start >> TARGET_PAGE_BITS;
bitmap_set(ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION], page, end - page);
bitmap_set(ram_list.dirty_memory[DIRTY_MEMORY_VGA], page, end - page);
}
static inline void cpu_physical_memory_set_dirty_range(ram_addr_t start,
ram_addr_t length)
{