Kernel commit 292a7d6fca33 ("KVM: s390: pv: fix asynchronous teardown
for small VMs") causes the KVM_PV_ASYNC_CLEANUP_PREPARE ioctl to fail
if the VM is not larger than 2GiB. QEMU would attempt it and fail,
print an error message, and then proceed with a normal teardown.
Avoid attempting to use asynchronous teardown altogether when the VM is
not larger than 2 GiB. This will avoid triggering the error message and
also avoid pointless overhead; normal teardown is fast enough for small
VMs.
Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Fixes: c3a073c610 ("s390x/pv: Add support for asynchronous teardown for reboot")
Link: https://lore.kernel.org/all/20230421085036.52511-2-imbrenda@linux.ibm.com/
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-Id: <20230510105531.30623-2-imbrenda@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
[thuth: Fix inline function parameter in pv.h]
Signed-off-by: Thomas Huth <thuth@redhat.com>
This patch adds support for the asynchronous teardown for reboot for
protected VMs.
When attempting to tear down a protected VM, try to use the new
asynchronous interface first. If that fails, fall back to the classic
synchronous one.
The asynchronous interface involves invoking the new
KVM_PV_ASYNC_DISABLE_PREPARE command for the KVM_S390_PV_COMMAND ioctl.
This will prepare the current protected VM for asynchronous teardown.
Once the protected VM is prepared for teardown, execution can continue
immediately.
Once the protected VM has been prepared, a new thread is started to
actually perform the teardown. The new thread uses the new
KVM_PV_ASYNC_DISABLE command for the KVM_S390_PV_COMMAND ioctl. The
previously prepared protected VM is torn down in the new thread.
Once KVM_PV_ASYNC_DISABLE is invoked, it is possible to use
KVM_PV_ASYNC_DISABLE_PREPARE again. If a protected VM has already been
prepared and its cleanup has not started, it will not be possible to
prepare a new VM. In that case the classic synchronous teardown has to
be performed.
The synchronous teardown will now also clean up any prepared VMs whose
asynchronous teardown has not been initiated yet.
This considerably speeds up the reboot of a protected VM; for large VMs
especially, it could take a long time to perform a reboot with the
traditional synchronous teardown, while with this patch it is almost
immediate.
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20230214163035.44104-3-imbrenda@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Let's add a few bits of code which hide the new KVM PV dump API from
us via new functions.
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
[ Marc-André: fix up for compilation issue ]
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20221017083822.43118-10-frankja@linux.ibm.com>
Introduce an interface over which we can get information about UV data.
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20221017083822.43118-8-frankja@linux.ibm.com>
At least some s390 cpu models support "Protected Virtualization" (PV),
a mechanism to protect guests from eavesdropping by a compromised
hypervisor.
This is similar in function to other mechanisms like AMD's SEV and
POWER's PEF, which are controlled by the "confidential-guest-support"
machine option. s390 is a slightly special case, because we already
supported PV, simply by using a CPU model with the required feature
(S390_FEAT_UNPACK).
To integrate this with the option used by other platforms, we
implement the following compromise:
- When the confidential-guest-support option is set, s390 will
recognize it, verify that the CPU can support PV (failing if not)
and set virtio default options necessary for encrypted or protected
guests, as on other platforms. i.e. if confidential-guest-support
is set, we will either create a guest capable of entering PV mode,
or fail outright.
- If confidential-guest-support is not set, guests might still be
able to enter PV mode, if the CPU has the right model. This may be
a little surprising, but shouldn't actually be harmful.
To start a guest supporting Protected Virtualization using the new
option use the command line arguments:
-object s390-pv-guest,id=pv0 -machine confidential-guest-support=pv0
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
s390_pv_perf_clear_reset() is not a very helpful name since that
function needs to be called for a normal and a clear reset via
diag308.
Let's instead name it s390_pv_prep_reset() which reflects the purpose
of the function a bit better.
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-Id: <20200505124159.24099-1-frankja@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
linux/kvm.h is not available on all platforms. Let us move
s390_machine_inject_pv_error into pv.c as it uses KVM structures.
Also rename the function to s390_pv_inject_reset_error.
While at it, ipl.h needs an include for "exec/address-spaces.h"
as it uses address_space_memory.
Fixes: c3347ed0d2 ("s390x: protvirt: Support unpack facility")
Reported-by: Bruce Rogers <brogers@suse.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Message-Id: <20200406100158.5940-2-borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
The unpack facility provides the means to setup a protected guest. A
protected guest cannot be introspected by the hypervisor or any
user/administrator of the machine it is running on.
Protected guests are encrypted at rest and need a special boot
mechanism via diag308 subcode 8 and 10.
Code 8 sets the PV specific IPLB which is retained separately from
those set via code 5.
Code 10 is used to unpack the VM into protected memory, verify its
integrity and start it.
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Co-developed-by: Christian Borntraeger <borntraeger@de.ibm.com> [Changes
to machine]
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200323083606.24520-1-frankja@linux.ibm.com>
[CH: fixed up KVM_PV_VM_ -> KVM_PV_]
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Claudio Imbrenda