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memory: replace cpu_physical_memory_reset_dirty() with test-and-clear

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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().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <1417519399-3166-6-git-send-email-stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2014-12-02 11:23:18 +00:00 • committed by Paolo Bonzini
parent 20015f72bd
commit 03eebc9e32
4 changed files with 33 additions and 38 deletions
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23
exec.c
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@ -852,16 +852,27 @@ static void tlb_reset_dirty_range_all(ram_addr_t start, ram_addr_t length)
}
/* Note: start and end must be within the same ram block. */
void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t length,
unsigned client)
bool cpu_physical_memory_test_and_clear_dirty(ram_addr_t start,
ram_addr_t length,
unsigned client)
{
if (length == 0)
return;
cpu_physical_memory_clear_dirty_range_type(start, length, client);
unsigned long end, page;
bool dirty;
if (tcg_enabled()) {
if (length == 0) {
return false;
}
end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS;
page = start >> TARGET_PAGE_BITS;
dirty = bitmap_test_and_clear_atomic(ram_list.dirty_memory[client],
page, end - page);
if (dirty && tcg_enabled()) {
tlb_reset_dirty_range_all(start, length);
}
return dirty;
}
/* Called from RCU critical section */