diff options
| author | Jiri Pirko <jiri@nvidia.com> | 2026-05-17 16:13:10 +0200 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@nvidia.com> | 2026-05-29 20:27:29 -0300 |
| commit | d7a40b519497fbee5644be4bd823b8d710bb8d55 (patch) | |
| tree | 3f8c704406630a96ab59af9022e7af9db9897da8 /include/uapi/rdma | |
| parent | 93ce776a5b0453314a5d1d6068762c9d646f5754 (diff) | |
RDMA/uverbs: Expose CoCo DMA bounce requirement to userspace
In CoCo guests, guest memory is encrypted and untrusted (T=0) devices
cannot DMA to it directly; such transfers must go through unencrypted
bounce buffers. RDMA registers user pages for direct device access,
bypassing the DMA layer and thus any bouncing, so registered memory does
not work in this configuration.
Until trusted (T=1) device detection is available, conservatively flag
every device attached to a CoCo guest. Expose the condition to userspace
as IB_UVERBS_DEVICE_CC_DMA_BOUNCE in device_cap_flags_ex so applications
can avoid memory registration and fall back to copying buffers through
send/recv.
Link: https://patch.msgid.link/r/20260517141311.2409230-2-jiri@resnulli.us
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Diffstat (limited to 'include/uapi/rdma')
| -rw-r--r-- | include/uapi/rdma/ib_user_verbs.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/uapi/rdma/ib_user_verbs.h b/include/uapi/rdma/ib_user_verbs.h index 3b7bd99813e9..d2aeadb6d2f9 100644 --- a/include/uapi/rdma/ib_user_verbs.h +++ b/include/uapi/rdma/ib_user_verbs.h @@ -1368,6 +1368,8 @@ enum ib_uverbs_device_cap_flags { IB_UVERBS_DEVICE_FLUSH_PERSISTENT = 1ULL << 39, /* Atomic write attributes */ IB_UVERBS_DEVICE_ATOMIC_WRITE = 1ULL << 40, + /* CoCo guest with DMA bounce buffering required */ + IB_UVERBS_DEVICE_CC_DMA_BOUNCE = 1ULL << 41, }; enum ib_uverbs_raw_packet_caps { |