On 05/03/2018 12:01 PM, Pierre Morel wrote:
On 03/05/2018 16:41, Tony Krowiak wrote:
On 05/02/2018 10:57 AM, Pierre Morel wrote:
On 25/04/2018 18:21, Tony Krowiak wrote:
On 04/23/2018 09:46 AM, Pierre Morel wrote:
On 15/04/2018 23:22, Tony Krowiak wrote:
Provides interfaces to assign AP adapters, usage domains
and control domains to a KVM guest.
...
The kvm_ap_configure_matrix(kvm, matrix) interface configures the
APM, AQM and ADM in the
guest's CRYCB which implies AP instructions are being interpreted.
There is nothing in SIE
precluding the sharing of AP queues between guests using SIE to
interpret AP instructions,
it is my opinion - along with several others - that this is not
advisable given the
results are not predictable, not to mention the security concerns. If
the protocol to access
queues changes, then we create a different interface. The other
option is to include a flag
on the kvm_ap_configure_matrix(kvm, matrix) interface to indicate
whether sharing is
allowed. I don't like this, because we have no way of knowing if the
caller has taken the
proper care to ensure the VM sharing the queue should be allowed
access. Besides, when
queue sharing is implemented, it is my opinion that we will intercept
the AP instructions
and the matrix will not be configured in the CRYCB. I stick by my
response above.
I mean, validating the queue sharing is a mater of the VFIO driver.
This code is not needed if the VFIO driver is not used.
But it is not very important.
Yes, this check could have been implemented in the VFIO driver, but as I
stated above, that
would require the driver to "know" the internals of KVM. I think the KVM
logic should
be encapsulated in KVM. If we want to allow sharing of interpreted AP
devices, then we
can always add a flag to the interface.
+static int kvm_ap_matrix_apm_create(struct kvm_ap_matrix
*ap_matrix,
+ struct ap_config_info *config)
+{
+ int apm_max = (config && config->apxa) ? config->Na + 1 : 16;
At this moment you already know the format of the crycb.
How?
you calculated this in kvm_ap_build_crycbd() which is called from
kvm_s390_crypto_init()
itself called from kvm_arch_init_vm().
It is when starting the VM.
This structure is used by the vfio_ap driver to store the mediated
matrix device's matrix
configuration as well as to configure the CRYCB. The mediated
device's matrix is
configured before the guest is started ... it is the means for
configuring the guest's
matrix after all. The bottom line is, this function will be called
long before the
kvm_ap_build_crycbd() function is called.
you are right, I was thinking about open, should have take more
attention.
Sorry.
Pierre
