Paolo Bonzini <pbonz...@redhat.com> writes: > Il 17/07/2013 17:50, Anthony Liguori ha scritto: >> Paolo Bonzini <pbonz...@redhat.com> writes: >> >>> 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. >> >> FYI, the reproducer is very simple: >> >> qemu-system-x86_64 -usb > > My patch works.
Yes, can you send a SoB and submit as a top level? Right now uhci is completely broken. Regards, Anthony Liguori > > Paolo > >> Regards, >> >> Anthony Liguori >> >>> >>> 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 >>