linux.git/drivers/hv/connection.c, branch v5.19

Drivers: hv: vmbus: Remove support for Hyper-V 2008 and Hyper-V 2008R2/Win7

2022-05-11T17:49:49+00:00

The VMbus driver has special case code for running on the first released
versions of Hyper-V: 2008 and 2008 R2/Windows 7. These versions are now
out of support (except for extended security updates) and lack the
performance features needed for effective production usage of Linux
guests.

Simplify the code by removing the negotiation of the VMbus protocol
versions required for these releases of Hyper-V, and by removing the
special case code for handling these VMbus protocol versions.

Signed-off-by: Michael Kelley 
Reviewed-by: Andrea Parri (Microsoft) 
Link: https://lore.kernel.org/r/1651509391-2058-2-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu

Drivers: hv: vmbus: Add SNP support for VMbus channel initiate message

2021-10-28T11:22:55+00:00

The monitor pages in the CHANNELMSG_INITIATE_CONTACT msg are shared
with host in Isolation VM and so it's necessary to use hvcall to set
them visible to host. In Isolation VM with AMD SEV SNP, the access
address should be in the extra space which is above shared gpa
boundary. So remap these pages into the extra address(pa +
shared_gpa_boundary).

Introduce monitor_pages_original[] in the struct vmbus_connection
to store monitor page virtual address returned by hv_alloc_hyperv_
zeroed_page() and free monitor page via monitor_pages_original in
the vmbus_disconnect(). The monitor_pages[] is to used to access
monitor page and it is initialized to be equal with monitor_pages_
original. The monitor_pages[] will be overridden in the isolation VM
with va of extra address. Introduce monitor_pages_pa[] to store
monitor pages' physical address and use it to populate pa in the
initiate msg.

Reviewed-by: Michael Kelley 
Signed-off-by: Tianyu Lan 
Link: https://lore.kernel.org/r/20211025122116.264793-9-ltykernel@gmail.com
Signed-off-by: Wei Liu

x86/hyperv: Add ghcb hvcall support for SNP VM

2021-10-28T11:22:49+00:00

hyperv provides ghcb hvcall to handle VMBus
HVCALL_SIGNAL_EVENT and HVCALL_POST_MESSAGE
msg in SNP Isolation VM. Add such support.

Reviewed-by: Michael Kelley 
Signed-off-by: Tianyu Lan 
Link: https://lore.kernel.org/r/20211025122116.264793-8-ltykernel@gmail.com
Signed-off-by: Wei Liu

drivers: hv: Fix missing error code in vmbus_connect()

2021-06-02T15:16:36+00:00

Eliminate the follow smatch warning:

drivers/hv/connection.c:236 vmbus_connect() warn: missing error code
'ret'.

Reported-by: Abaci Robot 
Signed-off-by: Jiapeng Chong 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/1621940321-72353-1-git-send-email-jiapeng.chong@linux.alibaba.com
Signed-off-by: Wei Liu

Drivers: hv: vmbus: Initialize unload_event statically

2021-04-20T19:40:17+00:00

If a malicious or compromised Hyper-V sends a spurious message of type
CHANNELMSG_UNLOAD_RESPONSE, the function vmbus_unload_response() will
call complete() on an uninitialized event, and cause an oops.

Reported-by: Michael Kelley 
Signed-off-by: Andrea Parri (Microsoft) 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20210420014350.2002-1-parri.andrea@gmail.com
Signed-off-by: Wei Liu

Drivers: hv: vmbus: Introduce and negotiate VMBus protocol version 5.3

2021-04-18T13:03:11+00:00

Hyper-V has added VMBus protocol version 5.3.  Allow Linux guests to
negotiate the new version on version of Hyper-V that support it.

Signed-off-by: Andrea Parri (Microsoft) 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20210416143449.16185-2-parri.andrea@gmail.com
Signed-off-by: Wei Liu

drivers: hv: Fix whitespace errors

2021-03-08T17:32:58+00:00

Fixed checkpatch warning and errors on hv driver.

Signed-off-by: Vasanth Mathivanan 
Link: https://lore.kernel.org/r/20210219171311.421961-1-vasanth3g@gmail.com
Reviewed-by: Michael Kelley 
Signed-off-by: Wei Liu

Drivers: hv: vmbus: Enforce 'VMBus version >= 5.2' on isolated guests

2021-02-11T08:47:05+00:00

Restrict the protocol version(s) that will be negotiated with the host
to be 5.2 or greater if the guest is running isolated.  This reduces the
footprint of the code that will be exercised by Confidential VMs and
hence the exposure to bugs and vulnerabilities.

Signed-off-by: Andrea Parri (Microsoft) 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20210201144814.2701-4-parri.andrea@gmail.com
Signed-off-by: Wei Liu

Drivers: hv: vmbus: Replace the per-CPU channel lists with a global array of channels

2020-04-23T13:17:11+00:00

When Hyper-V sends an interrupt to the guest, the guest has to figure
out which channel the interrupt is associated with.  Hyper-V sets a bit
in a memory page that is shared with the guest, indicating a particular
"relid" that the interrupt is associated with.  The current Linux code
then uses a set of per-CPU linked lists to map a given "relid" to a
pointer to a channel structure.

This design introduces a synchronization problem if the CPU that Hyper-V
will interrupt for a certain channel is changed.  If the interrupt comes
on the "old CPU" and the channel was already moved to the per-CPU list
of the "new CPU", then the relid -> channel mapping will fail and the
interrupt is dropped.  Similarly, if the interrupt comes on the new CPU
but the channel was not moved to the per-CPU list of the new CPU, then
the mapping will fail and the interrupt is dropped.

Relids are integers ranging from 0 to 2047.  The mapping from relids to
channel structures can be done by setting up an array with 2048 entries,
each entry being a pointer to a channel structure (hence total size ~16K
bytes, which is not a problem).  The array is global, so there are no
per-CPU linked lists to update.  The array can be searched and updated
by loading from/storing to the array at the specified index.  With no
per-CPU data structures, the above mentioned synchronization problem is
avoided and the relid2channel() function gets simpler.

Suggested-by: Michael Kelley 
Signed-off-by: Andrea Parri (Microsoft) 
Link: https://lore.kernel.org/r/20200406001514.19876-4-parri.andrea@gmail.com
Reviewed-by: Michael Kelley 
Signed-off-by: Wei Liu

Drivers: hv: vmbus: Always handle the VMBus messages on CPU0

2020-04-23T13:17:11+00:00

A Linux guest have to pick a "connect CPU" to communicate with the
Hyper-V host.  This CPU can not be taken offline because Hyper-V does
not provide a way to change that CPU assignment.

Current code sets the connect CPU to whatever CPU ends up running the
function vmbus_negotiate_version(), and this will generate problems if
that CPU is taken offine.

Establish CPU0 as the connect CPU, and add logics to prevents the
connect CPU from being taken offline.   We could pick some other CPU,
and we could pick that "other CPU" dynamically if there was a reason to
do so at some point in the future.  But for now, #defining the connect
CPU to 0 is the most straightforward and least complex solution.

While on this, add inline comments explaining "why" offer and rescind
messages should not be handled by a same serialized work queue.

Suggested-by: Dexuan Cui 
Signed-off-by: Andrea Parri (Microsoft) 
Reviewed-by: Vitaly Kuznetsov 
Link: https://lore.kernel.org/r/20200406001514.19876-2-parri.andrea@gmail.com
Reviewed-by: Michael Kelley 
Signed-off-by: Wei Liu