hv_netvsc: Allocate send/receive buffers using vmbus_alloc_buffer()

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On CoCo VMs without confidential VMBus, the netvsc send and receive buffers
must be made host-visible by decrypting them. These buffers are vmalloc'ed,
but set_memory_decrypted()/encrypted() do not work on vmalloc'ed memory.
This use case is (so far) unique to netvsc, so solve it locally rather than
changing the set_memory() or allocation APIs.

Use vmbus_alloc_buffer() to allocate the send and receive buffers, which
will make them host-visible. Store the list of memory chunks in the
netvsc_device struct so they can be individually freed later. Use
vmbus_establish_gpadl_caller_decrypted() so there is no attempt to decrypt
the virtual address.

Appropriately free the buffers with vmbus_free_buffer(). Because vunmap()
and set_memory_encrypted() must run in process context, replace the
rcu_head/call_rcu() pair used to defer free_netvsc_device() with
rcu_work/queue_rcu_work(). This also fixes a small race condition where the
buffers may be accessed while being re-encrypted by moving the
re-encryption after the RCU grace period.

Signed-off-by: Kameron Carr <kameroncarr@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

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This commit is contained in:

Kameron Carr 2026-08-11 09:04:47 -07:00 • committed by Wei Liu

parent 73fe42af95

commit f85e1cc5ec

3 changed files with 83 additions and 34 deletions

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8

drivers/net/hyperv/hyperv_net.h

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103

drivers/net/hyperv/netvsc.c

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6

drivers/net/hyperv/netvsc_drv.c

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