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Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow cond
From: |
Bandan Das |
Subject: |
Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition |
Date: |
Mon, 21 Mar 2016 20:06:32 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Alex Williamson <address@hidden> writes:
> On Mon, 21 Mar 2016 18:00:50 -0400
> Bandan Das <address@hidden> wrote:
>
>> vfio_listener_region_add for a iommu mr results in
>> an overflow assert since emulated iommu memory region is initialized
>> with UINT64_MAX. Add a check just like memory_region_size()
>> does.
>>
>> Signed-off-by: Bandan Das <address@hidden>
>> ---
>> hw/vfio/common.c | 7 ++++++-
>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index fb588d8..269244b 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -349,7 +349,12 @@ static void vfio_listener_region_add(MemoryListener
>> *listener,
>> if (int128_ge(int128_make64(iova), llend)) {
>> return;
>> }
>> - end = int128_get64(llend);
>> +
>> + if (int128_eq(llend, int128_2_64())) {
>> + end = UINT64_MAX;
>> + } else {
>> + end = int128_get64(llend);
>> + }
>>
>> if ((iova < container->min_iova) || ((end - 1) > container->max_iova)) {
>> error_report("vfio: IOMMU container %p can't map guest IOVA region"
>
> But now all the calculations where we use end-1 are wrong. See the
> discussion with Pierre Morel in the January qemu-devel archives.
> There's a solution in there, but I never saw a follow-up from Pierre
> with a revised patch. Thanks,
I am missing something. When end < UIN64_MAX, end - 1 calculations are valid
because
the patch doesn't change that behavior. When end is UINT64_MAX, int128_get64()
doesn't know how
to calculate this value and we are just feeding it manually. The patch is just
the opposite
of what memory_region_init() did to init the mem region in the first place:
mr->size = int128_make64(size);
if (size == UINT64_MAX) {
mr->size = int128_2_64();
}
So, end - 1 is still valid for end = UINT64_MAX, no ?
> Alex
- [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition, Bandan Das, 2016/03/21
- Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition, Alex Williamson, 2016/03/21
- Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition,
Bandan Das <=
- Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition, Alex Williamson, 2016/03/21
- Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition, Bandan Das, 2016/03/21
- Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition, Alex Williamson, 2016/03/21
- Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition, Bandan Das, 2016/03/22
- Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition, Alex Williamson, 2016/03/22
- Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition, Bandan Das, 2016/03/22
Re: [Qemu-devel] [PATCH] vfio: add check for memory region overflow condition, Peter Xu, 2016/03/21