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SubjectRE: [PATCH v5 0/3] Drivers: hv: vmbus: vmbus_requestor data structure for VMBus hardening
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From: Stephen Hemminger <stephen@networkplumber.org> Sent: Wednesday, July 22, 2020 11:41 AM
>
> On Wed, 22 Jul 2020 11:10:48 -0700
> "Andres Beltran" <lkmlabelt@gmail.com> wrote:
>
> > Currently, VMbus drivers use pointers into guest memory as request IDs
> > for interactions with Hyper-V. To be more robust in the face of errors
> > or malicious behavior from a compromised Hyper-V, avoid exposing
> > guest memory addresses to Hyper-V. Also avoid Hyper-V giving back a
> > bad request ID that is then treated as the address of a guest data
> > structure with no validation. Instead, encapsulate these memory
> > addresses and provide small integers as request IDs.
> >
> > The first patch creates the definitions for the data structure, provides
> > helper methods to generate new IDs and retrieve data, and
> > allocates/frees the memory needed for vmbus_requestor.
> >
> > The second and third patches make use of vmbus_requestor to send request
> > IDs to Hyper-V in storvsc and netvsc respectively.
> >
> > Thanks.
> > Andres Beltran
> >
> > Cc: James E.J. Bottomley <jejb@linux.ibm.com>
> > Cc: Martin K. Petersen <martin.petersen@oracle.com>
> > Cc: David S. Miller <davem@davemloft.net>
> >
> > Andres Beltran (3):
> > Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus
> > hardening
> > scsi: storvsc: Use vmbus_requestor to generate transaction IDs for
> > VMBus hardening
> > hv_netvsc: Use vmbus_requestor to generate transaction IDs for VMBus
> > hardening
> >
> > drivers/hv/channel.c | 175 ++++++++++++++++++++++++++++++
> > drivers/net/hyperv/hyperv_net.h | 13 +++
> > drivers/net/hyperv/netvsc.c | 79 +++++++++++---
> > drivers/net/hyperv/rndis_filter.c | 1 +
> > drivers/scsi/storvsc_drv.c | 85 +++++++++++++--
> > include/linux/hyperv.h | 22 ++++
> > 6 files changed, 350 insertions(+), 25 deletions(-)
> >
>
>
> What is the performance impact of this?
> It means keeping a global (bookkeeping) structure which should have
> noticeable impact on mult-queue performance.

The bookkeeping structure is per-VMbus channel. There's nothing
global. Andrea Parri previously did some testing and reported no
measurable impact.

Michael


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