Il 19/06/2013 13:44, Markus Armbruster ha scritto:
> Old S390 KVM wants guest RAM mapped in a peculiar way. Commit 6b02494
> implemented that.
>
> When qemu_ram_remap() got added in commit cd19cfa, its code carefully
> mimicked the allocation code: peculiar way if defined(TARGET_S390X) &&
> defined(CONFIG_KVM), else normal way.
>
> For new S390 KVM, we actually want the normal way. Commit fdec991
> changed qemu_ram_alloc_from_ptr() accordingly, but forgot to update
> qemu_ram_remap(). If qemu_ram_alloc_from_ptr() maps RAM the normal
> way, but qemu_ram_remap() remaps it the peculiar way, remapping
> changes protection and flags, which it shouldn't.
>
> Fortunately, this can't happen, as we never remap on S390.
>
> Replace the incorrect code with an assertion.
>
> Thanks to Christian Borntraeger for help with assessing the bug's
> (non-)impact.
>
> Signed-off-by: Markus Armbruster <arm...@redhat.com>
> ---
> exec.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index c45eb33..a0f18fe 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1229,15 +1229,16 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t
> length)
> area = mmap(vaddr, length, PROT_READ | PROT_WRITE,
> flags, block->fd, offset);
> } else {
> -#if defined(TARGET_S390X) && defined(CONFIG_KVM)
> - flags |= MAP_SHARED | MAP_ANONYMOUS;
> - area = mmap(vaddr, length,
> PROT_EXEC|PROT_READ|PROT_WRITE,
> - flags, -1, 0);
> -#else
> + /*
> + * Remap needs to match alloc. Accelerators that
> + * set phys_mem_alloc never remap. If they did,
> + * we'd need a remap hook here.
> + */
> + assert(!phys_mem_alloc);
Probably "assert(phys_mem_alloc == qemu_anon_ram_alloc)"?
Otherwise all looks fine.
Paolo
> flags |= MAP_PRIVATE | MAP_ANONYMOUS;
> area = mmap(vaddr, length, PROT_READ | PROT_WRITE,
> flags, -1, 0);
> -#endif
> }
> if (area != vaddr) {
> fprintf(stderr, "Could not remap addr: "
>
