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physmem: factor out memory_region_is_ram_device() check in memory_access_is_direct()

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As documented in commit 4a2e242bbb306 ("memory: Don't use memcpy for
ram_device regions"), we disallow direct access to RAM DEVICE regions.

Let's make this clearer to prepare for further changes. Note that romd
regions will never be RAM DEVICE at the same time.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20250210084648.33798-2-david@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
This commit is contained in:
David Hildenbrand 2025-02-10 09:46:42 +01:00 committed by Peter Xu
parent f051a9c4dc
commit 52012209e1
1 changed files with 10 additions and 3 deletions
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13
include/exec/memory.h
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@ -2997,12 +2997,19 @@ bool prepare_mmio_access(MemoryRegion *mr);
static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
{
/*
* RAM DEVICE regions can be accessed directly using memcpy, but it might
* be MMIO and access using mempy can be wrong (e.g., using instructions not
* intended for MMIO access). So we treat this as IO.
*/
if (memory_region_is_ram_device(mr)) {
return false;
}
if (is_write) {
return memory_region_is_ram(mr) && !mr->readonly &&
!mr->rom_device && !memory_region_is_ram_device(mr);
!mr->rom_device;
} else {
return (memory_region_is_ram(mr) && !memory_region_is_ram_device(mr)) ||
memory_region_is_romd(mr);
return memory_region_is_ram(mr) || memory_region_is_romd(mr);
}
}