Il 17/07/2013 11:50, Markus Armbruster ha scritto: > Richard Henderson <r...@twiddle.net> writes: > >> Honor the implementation maximum access size, and at least check >> the minimum access size. >> >> Reviewed-by: Paolo Bonzini <pbonz...@redhat.com> >> Signed-off-by: Richard Henderson <r...@twiddle.net> > > Fails for me: > > qemu-system-x86_64: /work/armbru/qemu/exec.c:1927: memory_access_size: > Assertion `l >= access_size_min' failed.
This: unsigned access_size_min = mr->ops->impl.min_access_size; unsigned access_size_max = mr->ops->impl.max_access_size; must be respectively: unsigned access_size_min = 1; unsigned access_size_max = mr->ops->valid.max_access_size; access_size_min can be 1 because erroneous accesses must not crash QEMU, they should trigger exceptions in the guest or just return garbage (depending on the CPU). I'm not sure I understand the comment, placing a 4-byte field at the last byte of a region makes no sense (unless impl.unaligned is true). access_size_max can be mr->ops->valid.max_access_size because memory.c can and will still break accesses bigger than mr->ops->impl.max_access_size. Markus, can you try the minimal patch above? Or this one that also does the consequent simplifications. diff --git a/exec.c b/exec.c index c99a883..0904283 100644 --- a/exec.c +++ b/exec.c @@ -1898,14 +1898,8 @@ static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write) static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr) { - unsigned access_size_min = mr->ops->impl.min_access_size; - unsigned access_size_max = mr->ops->impl.max_access_size; + unsigned access_size_max = mr->ops->valid.max_access_size; - /* Regions are assumed to support 1-4 byte accesses unless - otherwise specified. */ - if (access_size_min == 0) { - access_size_min = 1; - } if (access_size_max == 0) { access_size_max = 4; } @@ -1922,9 +1916,6 @@ static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr) if (l > access_size_max) { l = access_size_max; } - /* ??? The users of this function are wrong, not supporting minimums larger - than the remaining length. C.f. memory.c:access_with_adjusted_size. */ - assert(l >= access_size_min); return l; } Paolo