On Thu, 13 Dec 2018 15:54:47 +0100
David Hildenbrand <da...@redhat.com> wrote:
> On 13.12.18 15:48, Igor Mammedov wrote:
> > On Thu, 13 Dec 2018 13:35:28 +0100
> > David Hildenbrand <da...@redhat.com> wrote:
> >
> >> On 13.12.18 13:28, Igor Mammedov wrote:
> >>> On Wed, 12 Dec 2018 10:28:21 +0100
> >>> David Hildenbrand <da...@redhat.com> wrote:
> >>>
> >>>> Let's rewrite it properly using ranges. This fixes certain overflows that
> >>>> are right now possible. E.g.
> >>>>
> >>>> qemu-system-x86_64 -m 4G,slots=20,maxmem=40G -M pc \
> >>>> -object memory-backend-file,id=mem1,share,mem-path=/dev/zero,size=2G
> >>>> -device pc-dimm,memdev=mem1,id=dimm1,addr=-0x40000000
> >>>>
> >>>> Now properly errors out instead of succeeding. (Note that qapi
> >>>> parsing of huge uint64_t values is broken and fixes are on the way)
> >>>>
> >>>> "can't add memory device [0xffffffffa0000000:0x80000000], usable range
> >>>> for
> >>>> memory devices [0x140000000:0xe00000000]"
> >>>>
> >>>> Signed-off-by: David Hildenbrand <da...@redhat.com>
> >>>> ---
> >>>> hw/mem/memory-device.c | 54 ++++++++++++++++++++++++------------------
> >>>> 1 file changed, 31 insertions(+), 23 deletions(-)
> >>>>
> >>>> diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
> >>>> index 8be63c8032..28e871f562 100644
> >>>> --- a/hw/mem/memory-device.c
> >>>> +++ b/hw/mem/memory-device.c
> >>>> @@ -100,9 +100,8 @@ static uint64_t
> >>>> memory_device_get_free_addr(MachineState *ms,
> >>>> uint64_t align, uint64_t
> >>>> size,
> >>>> Error **errp)
> >>>> {
> >>>> - uint64_t address_space_start, address_space_end;
> >>>> GSList *list = NULL, *item;
> >>>> - uint64_t new_addr = 0;
> >>>> + Range as, new = range_empty;
> >>>>
> >>>> if (!ms->device_memory) {
> >>>> error_setg(errp, "memory devices (e.g. for memory hotplug) are
> >>>> not "
> >>>> @@ -115,13 +114,11 @@ static uint64_t
> >>>> memory_device_get_free_addr(MachineState *ms,
> >>>> "enabled, please specify the maxmem option");
> >>>> return 0;
> >>>> }
> >>>> - address_space_start = ms->device_memory->base;
> >>>> - address_space_end = address_space_start +
> >>>> - memory_region_size(&ms->device_memory->mr);
> >>>> - g_assert(address_space_end >= address_space_start);
> >>>> + range_init_nofail(&as, ms->device_memory->base,
> >>>> + memory_region_size(&ms->device_memory->mr));
> >>>>
> >>>> - /* address_space_start indicates the maximum alignment we expect */
> >>>> - if (!QEMU_IS_ALIGNED(address_space_start, align)) {
> >>>> + /* start of address space indicates the maximum alignment we expect
> >>>> */
> >>>> + if (!QEMU_IS_ALIGNED(range_lob(&as), align)) {
> >>>> error_setg(errp, "the alignment (0x%" PRIx64 ") is not
> >>>> supported",
> >>>> align);
> >>>> return 0;
> >>>> @@ -145,20 +142,25 @@ static uint64_t
> >>>> memory_device_get_free_addr(MachineState *ms,
> >>>> }
> >>>>
> >>>> if (hint) {
> >>>> - new_addr = *hint;
> >>>> - if (new_addr < address_space_start) {
> >>>> + if (range_init(&new, *hint, size)) {
> >>>> error_setg(errp, "can't add memory device [0x%" PRIx64
> >>>> ":0x%" PRIx64
> >>>> - "] before 0x%" PRIx64, new_addr, size,
> >>>> - address_space_start);
> >>>> + "], usable range for memory devices [0x%" PRIx64
> >>>> ":0x%"
> >>>> + PRIx64 "]", *hint, size, range_lob(&as),
> >>>> + range_size(&as));
> >>> this changes error message to be the same as the next one and looses
> >>> 'before' meaning
> >>> so if you'd like to have the same error message, then prbably merging
> >>> both branches would be better.
> >>
> >> I can do that, but I'll have to refer to "*hint" and "size" then instead
> >> of range_lob(&new) and range_size(&new), because the range might not be
> >> initialized.
> > either that or better make errors different to avoid confusion.
> >
>
> Will see what turns out better. As we indicate the ranges the user can
> figure out what is going wrong.
ok
>
> > [...]
> >>>> - new_addr = QEMU_ALIGN_UP(md_addr + md_size, align);
> >>>> +
> >>>> + next_addr = QEMU_ALIGN_UP(range_upb(&tmp) + 1, align);
> >>>> + if (!next_addr || range_init(&new, next_addr,
> >>>> range_size(&new))) {
> >>>> + range_make_empty(&new);
> >>>> + break;
> >>>> + }
> >>>> }
> >>>> }
> >>>>
> >>>> - if (new_addr + size > address_space_end) {
> >>>> + if (!range_contains_range(&as, &new)) {
> >>>> error_setg(errp, "could not find position in guest address
> >>>> space for "
> >>>> "memory device - memory fragmented due to
> >>>> alignments");
> >>> it could happen due to fragmentation but also in case remaining free
> >>> space is no enough
> >>
> >> That should be handled via memory_device_check_addable(), which is
> >> called at the beginning of the function. It checks for general size
> >> availability.
> >
> > I've meant
> > AS_LOB AS_UPB
> > 100 1000
> > MEM1_LOB MEM1_UPB
> > 100 900
> > then hotplugging MEM2 with size 200 would fail with this message,
> > which could be a bit confusing.
> > Maybe "not enough space to plug device of size %d" would be better?
>
>
> That should be covered by memory_device_check_addable() if I am not wrong.
>
> used_region_size + size > ms->maxram_size - ms->ram_size
>
> For your example (if I don't mess up the numbers):
>
> ms->maxram_size - ms->ram_size = 900
> used_region_size = 800
>
> So trying to add anything > 100 will bail out.
Thanks, I see it now.
>
>
> >
> >>
> >> Thanks!
> >>
> >
>
>
