When pulling or pushing an OS context from/to a CPU, we should
re-evaluate the state of the External interrupt signal. Otherwise, we
can end up catching the External interrupt exception in hypervisor
mode, which is unexpected.
The problem is best illustrated with the following scenario:
1. an External interrupt is raised while the guest is on the CPU.
2. before the guest can ack the External interrupt, an hypervisor
interrupt is raised, for example the Hypervisor Decrementer or
Hypervisor Virtualization interrupt. The hypervisor interrupt forces
the guest to exit while the External interrupt is still pending.
3. the hypervisor handles the hypervisor interrupt. At this point, the
External interrupt is still pending. So it's very likely to be
delivered while the hypervisor is running. That's unexpected and can
result in an infinite loop where the hypervisor catches the External
interrupt, looks for an interrupt in its hypervisor queue, doesn't
find any, exits the interrupt handler with the External interrupt
still raised, repeat...
The fix is simply to always lower the External interrupt signal when
pulling an OS context. It means it needs to be raised again when
re-pushing the OS context. Fortunately, it's already the case, as we
now always call xive_tctx_ipb_update(), which will raise the signal if
needed.
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Message-Id: <20220429071620.177142-3-fbarrat@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
The Post Interrupt Priority Register (PIPR) is not restored like the
other OS-context related fields of the TIMA when pushing an OS context
on the CPU. It's not needed because it can be calculated from the
Interrupt Pending Buffer (IPB), which is saved and restored. The PIPR
must therefore always be recomputed when pushing an OS context.
This patch fixes a path on P9 and P10 where it was not done. If there
was a pending interrupt when the OS context was pulled, the IPB was
saved correctly. When pushing back the context, the code in
xive_tctx_need_resend() was checking for a interrupt raised while the
context was not on the CPU, saved in the NVT. If one was found, then
it was merged with the saved IPB and the PIPR updated and everything
was fine. However, if there was no interrupt found in the NVT, then
xive_tctx_ipb_update() was not being called and the PIPR was not
updated. This patch fixes it by always calling xive_tctx_ipb_update().
Note that on P10 (xive2.c) and because of the above, there's no longer
any need to check the CPPR value so it can go away.
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Message-Id: <20220429071620.177142-2-fbarrat@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Xive2EndSource objects can only be instantiated through a Xive2Router
(PnvXive2).
Reported-by: Thomas Huth <thuth@redhat.com>
Fixes: f8a233dedf ("ppc/xive2: Introduce a XIVE2 core framework")
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
The XIVE interrupt controller on P10 can automatically save and
restore the state of the interrupt registers under the internal NVP
structure representing the VCPU. This saves a costly store/load in
guest entries and exits.
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Add GEN1 config even if we don't use it yet in the core framework.
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Only the CAM line updates done by the hypervisor are specific to
POWER10. Instead of duplicating the TM ops table, we handle these
commands locally under the PowerNV XIVE2 model.
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
The trigger message coming from a HW source contains a special bit
informing the XIVE interrupt controller that the PQ bits have been
checked at the source or not. Depending on the value, the IC can
perform the check and the state transition locally using its own PQ
state bits.
The following changes add new accessors to the XiveRouter required to
query and update the PQ state bits. This only applies to the PowerNV
machine. sPAPR accessors are provided but the pSeries machine should
not be concerned by such complex configuration for the moment.
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
This is an internal offset used to inject triggers when the PQ state
bits are not controlled locally. Such as for LSIs when the PHB5 are
using the Address-Based Interrupt Trigger mode and on the END.
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
The VP space is larger in XIVE2 (P10), 24 bits instead of 19bits on
XIVE (P9), and the CAM line can use a 7bits or 8bits thread id.
For now, we only use 7bits thread ids, same as P9, but because of the
change of the size of the VP space, the CAM matching routine is
different between P9 and P10. It is easier to duplicate the whole
routine than to add extra handlers in xive_presenter_tctx_match() used
for P9.
We might come with a better solution later on, after we have added
some more support for the XIVE2 controller.
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
The XIVE2 interrupt controller of the POWER10 processor as the same
logic as on POWER9 but its SW interface has been largely reworked. The
interrupt controller has a new register interface, different BARs,
extra VSDs. These will be described when we add the device model for
the baremetal machine.
The XIVE internal structures for the EAS, END, NVT have different
layouts which is a problem for the current core XIVE framework. To
avoid adding too much complexity in the XIVE models, a new XIVE2 core
framework is introduced. It duplicates the models which are closely
linked to the XIVE internal structures : Xive2Router and
Xive2ENDSource and reuses the XiveSource, XivePresenter, XiveTCTX
models, as they are more generic.
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
