| 17fd09c0 | 14-Jun-2021 |
Nicholas Piggin <npiggin@gmail.com> |
target/ppc/spapr: Update H_GET_CPU_CHARACTERISTICS L1D cache flush bits
There are several new L1D cache flush bits added to the hcall which reflect
hardware security features for speculative cache a
target/ppc/spapr: Update H_GET_CPU_CHARACTERISTICS L1D cache flush bits
There are several new L1D cache flush bits added to the hcall which reflect
hardware security features for speculative cache access issues.
These behaviours are now being specified as negative in order to simplify
patched kernel compatibility with older firmware (a new problem found in
existing systems would automatically be vulnerable).
[dwg: Technically this changes behaviour for existing machine types.
After discussion with Nick, we've determined this is safe, because
the worst that will happen if a guest gets the wrong information due
to a migration is that it will perform some unnecessary workarounds,
but will remain correct and secure (well, as secure as it was going
to be anyway). In addition the change only affects cap-cfpc=safe
which is not enabled by default, and in fact is not possible to set
on any current hardware (though it's expected it will be possible on
POWER10)]
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20210615044107.1481608-1-npiggin@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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| fc8c745d | 25-Jun-2021 |
Alexey Kardashevskiy <aik@ozlabs.ru> |
spapr: Implement Open Firmware client interface
The PAPR platform describes an OS environment that's presented by
a combination of a hypervisor and firmware. The features it specifies
require collab
spapr: Implement Open Firmware client interface
The PAPR platform describes an OS environment that's presented by
a combination of a hypervisor and firmware. The features it specifies
require collaboration between the firmware and the hypervisor.
Since the beginning, the runtime component of the firmware (RTAS) has
been implemented as a 20 byte shim which simply forwards it to
a hypercall implemented in qemu. The boot time firmware component is
SLOF - but a build that's specific to qemu, and has always needed to be
updated in sync with it. Even though we've managed to limit the amount
of runtime communication we need between qemu and SLOF, there's some,
and it has become increasingly awkward to handle as we've implemented
new features.
This implements a boot time OF client interface (CI) which is
enabled by a new "x-vof" pseries machine option (stands for "Virtual Open
Firmware). When enabled, QEMU implements the custom H_OF_CLIENT hcall
which implements Open Firmware Client Interface (OF CI). This allows
using a smaller stateless firmware which does not have to manage
the device tree.
The new "vof.bin" firmware image is included with source code under
pc-bios/. It also includes RTAS blob.
This implements a handful of CI methods just to get -kernel/-initrd
working. In particular, this implements the device tree fetching and
simple memory allocator - "claim" (an OF CI memory allocator) and updates
"/memory@0/available" to report the client about available memory.
This implements changing some device tree properties which we know how
to deal with, the rest is ignored. To allow changes, this skips
fdt_pack() when x-vof=on as not packing the blob leaves some room for
appending.
In absence of SLOF, this assigns phandles to device tree nodes to make
device tree traversing work.
When x-vof=on, this adds "/chosen" every time QEMU (re)builds a tree.
This adds basic instances support which are managed by a hash map
ihandle -> [phandle].
Before the guest started, the used memory is:
0..e60 - the initial firmware
8000..10000 - stack
400000.. - kernel
3ea0000.. - initramdisk
This OF CI does not implement "interpret".
Unlike SLOF, this does not format uninitialized nvram. Instead, this
includes a disk image with pre-formatted nvram.
With this basic support, this can only boot into kernel directly.
However this is just enough for the petitboot kernel and initradmdisk to
boot from any possible source. Note this requires reasonably recent guest
kernel with:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=df5be5be8735
The immediate benefit is much faster booting time which especially
crucial with fully emulated early CPU bring up environments. Also this
may come handy when/if GRUB-in-the-userspace sees light of the day.
This separates VOF and sPAPR in a hope that VOF bits may be reused by
other POWERPC boards which do not support pSeries.
This assumes potential support for booting from QEMU backends
such as blockdev or netdev without devices/drivers used.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-Id: <20210625055155.2252896-1-aik@ozlabs.ru>
Reviewed-by: BALATON Zoltan <balaton@eik.bme.hu>
[dwg: Adjusted some includes which broke compile in some more obscure
compilation setups]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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| f93c8f14 | 18-May-2021 |
Shivaprasad G Bhat <sbhat@linux.ibm.com> |
spapr: nvdimm: Forward declare and move the definitions
The subsequent patches add definitions which tend to get
the compilation to cyclic dependency. So, prepare with
forward declarations, move the
spapr: nvdimm: Forward declare and move the definitions
The subsequent patches add definitions which tend to get
the compilation to cyclic dependency. So, prepare with
forward declarations, move the definitions and clean up.
Signed-off-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Message-Id: <162133925415.610.11584121797866216417.stgit@4f1e6f2bd33e>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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| 962104f0 | 06-May-2021 |
Lucas Mateus Castro (alqotel) <lucas.araujo@eldorado.org.br> |
hw/ppc: moved hcalls that depend on softmmu
The hypercalls h_enter, h_remove, h_bulk_remove, h_protect, and h_read,
have been moved to spapr_softmmu.c with the functions they depend on. The
function
hw/ppc: moved hcalls that depend on softmmu
The hypercalls h_enter, h_remove, h_bulk_remove, h_protect, and h_read,
have been moved to spapr_softmmu.c with the functions they depend on. The
functions is_ram_address and push_sregs_to_kvm_pr are not static anymore
as functions on both spapr_hcall.c and spapr_softmmu.c depend on them.
The hypercalls h_resize_hpt_prepare and h_resize_hpt_commit have been
divided, the KVM part stayed in spapr_hcall.c while the softmmu part
was moved to spapr_softmmu.c
Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.araujo@eldorado.org.br>
Message-Id: <20210506163941.106984-2-lucas.araujo@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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| b7573092 | 08-Apr-2021 |
Daniel Henrique Barboza <danielhb413@gmail.com> |
spapr.h: increase FDT_MAX_SIZE
Certain SMP topologies stress, e.g. 1 thread/core, 2048 cores and
1 socket, stress the current maximum size of the pSeries FDT:
Calling ibm,client-architecture-suppor
spapr.h: increase FDT_MAX_SIZE
Certain SMP topologies stress, e.g. 1 thread/core, 2048 cores and
1 socket, stress the current maximum size of the pSeries FDT:
Calling ibm,client-architecture-support...qemu-system-ppc64: error
creating device tree: (fdt_setprop(fdt, offset,
"ibm,processor-segment-sizes", segs, sizeof(segs))): FDT_ERR_NOSPACE
2048 is the default NR_CPUS value for the pSeries kernel. It's expected
that users will want QEMU to be able to handle this kind of
configuration.
Bumping FDT_MAX_SIZE to 2MB is enough for these setups to be created.
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20210408204049.221802-3-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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| eb7f80fd | 02-Mar-2021 |
Daniel Henrique Barboza <danielhb413@gmail.com> |
spapr.c: send QAPI event when memory hotunplug fails
Recent changes allowed the pSeries machine to rollback the hotunplug
process for the DIMM when the guest kernel signals, via a
reconfiguration of
spapr.c: send QAPI event when memory hotunplug fails
Recent changes allowed the pSeries machine to rollback the hotunplug
process for the DIMM when the guest kernel signals, via a
reconfiguration of the DR connector, that it's not going to release the
LMBs.
Let's also warn QAPI listerners about it. One place to do it would be
right after the unplug state is cleaned up,
spapr_clear_pending_dimm_unplug_state(). This would mean that the
function is now doing more than cleaning up the pending dimm state
though.
This patch does the following changes in spapr.c:
- send a QAPI event to inform that we experienced a failure in the
hotunplug of the DIMM;
- rename spapr_clear_pending_dimm_unplug_state() to
spapr_memory_unplug_rollback(). This is a better fit for what the
function is now doing, and it makes callers care more about what the
function goal is and less about spapr.c internals such as clearing
the pending dimm unplug state.
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20210302141019.153729-3-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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| fe1831ef | 22-Feb-2021 |
Daniel Henrique Barboza <danielhb413@gmail.com> |
spapr_drc.c: use DRC reconfiguration to cleanup DIMM unplug state
Handling errors in memory hotunplug in the pSeries machine is more
complex than any other device type, because there are all the
com
spapr_drc.c: use DRC reconfiguration to cleanup DIMM unplug state
Handling errors in memory hotunplug in the pSeries machine is more
complex than any other device type, because there are all the
complications that other devices has, and more.
For instance, determining a timeout for a DIMM hotunplug must consider
if it's a Hash-MMU or a Radix-MMU guest, because Hash guests takes
longer to hotunplug DIMMs. The size of the DIMM is also a factor, given
that longer DIMMs naturally takes longer to be hotunplugged from the
kernel. And there's also the guest memory usage to be considered: if
there's a process that is consuming memory that would be lost by the
DIMM unplug, the kernel will postpone the unplug process until the
process finishes, and then initiate the regular hotunplug process. The
first two considerations are manageable, but the last one is a deal
breaker.
There is no sane way for the pSeries machine to determine the memory
load in the guest when attempting a DIMM hotunplug - and even if there
was a way, the guest can start using all the RAM in the middle of the
unplug process and invalidate our previous assumptions - and in result
we can't even begin to calculate a timeout for the operation. This means
that we can't implement a viable timeout mechanism for memory unplug in
pSeries.
Going back to why we would consider an unplug timeout, the reason is
that we can't know if the kernel is giving up the unplug. Turns out
that, sometimes, we can. Consider a failed memory hotunplug attempt
where the kernel will error out with the following message:
'pseries-hotplug-mem: Memory indexed-count-remove failed, adding any
removed LMBs'
This happens when there is a LMB that the kernel gave up in removing,
and the LMBs previously marked for removal are now being added back.
This happens in the pseries kernel in [1], dlpar_memory_remove_by_ic()
into dlpar_add_lmb(), and after that update_lmb_associativity_index().
In this function, the kernel is configuring the LMB DRC connector again.
Note that this is a valid usage in LOPAR, as stated in section
"ibm,configure-connector RTAS Call":
'A subsequent sequence of calls to ibm,configure-connector with the same
entry from the “ibm,drc-indexes” or “ibm,drc-info” property will restart
the configuration of devices which were not completely configured.'
We can use this kernel behavior in our favor. If a DRC connector
reconfiguration for a LMB that we marked as unplug pending happens, this
indicates that the kernel changed its mind about the unplug and is
reasserting that it will keep using all the LMBs of the DIMM. In this
case, it's safe to assume that the whole DIMM device unplug was
cancelled.
This patch hops into rtas_ibm_configure_connector() and, in the scenario
described above, clear the unplug state for the DIMM device. This will
not solve all the problems we still have with memory unplug, but it will
cover this case where the kernel reconfigures LMBs after a failed
unplug. We are a bit more resilient, without using an unreliable
timeout, and we didn't make the remaining error cases any worse.
[1] arch/powerpc/platforms/pseries/hotplug-memory.c
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20210222194531.62717-6-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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| d1c2e3ce | 22-Feb-2021 |
Daniel Henrique Barboza <danielhb413@gmail.com> |
spapr_drc.c: add hotunplug timeout for CPUs
There is a reliable way to make a CPU hotunplug fail in the pseries
machine. Hotplug a CPU A, then offline all other CPUs inside the guest
but A. When try
spapr_drc.c: add hotunplug timeout for CPUs
There is a reliable way to make a CPU hotunplug fail in the pseries
machine. Hotplug a CPU A, then offline all other CPUs inside the guest
but A. When trying to hotunplug A the guest kernel will refuse to do it,
because A is now the last online CPU of the guest. PAPR has no 'error
callback' in this situation to report back to the platform, so the guest
kernel will deny the unplug in silent and QEMU will never know what
happened. The unplug pending state of A will remain until the guest is
shutdown or rebooted.
Previous attempts of fixing it (see [1] and [2]) were aimed at trying to
mitigate the effects of the problem. In [1] we were trying to guess
which guest CPUs were online to forbid hotunplug of the last online CPU
in the QEMU layer, avoiding the scenario described above because QEMU is
now failing in behalf of the guest. This is not robust because the last
online CPU of the guest can change while we're in the middle of the
unplug process, and our initial assumptions are now invalid. In [2] we
were accepting that our unplug process is uncertain and the user should
be allowed to spam the IRQ hotunplug queue of the guest in case the CPU
hotunplug fails.
This patch presents another alternative, using the timeout
infrastructure introduced in the previous patch. CPU hotunplugs in the
pSeries machine will now timeout after 15 seconds. This is a long time
for a single CPU unplug to occur, regardless of guest load - although
the user is *strongly* encouraged to *not* hotunplug devices from a
guest under high load - and we can be sure that something went wrong if
it takes longer than that for the guest to release the CPU (the same
can't be said about memory hotunplug - more on that in the next patch).
Timing out the unplug operation will reset the unplug state of the CPU
and allow the user to try it again, regardless of the error situation
that prevented the hotunplug to occur. Of all the not so pretty
fixes/mitigations for CPU hotunplug errors in pSeries, timing out the
operation is an admission that we have no control in the process, and
must assume the worst case if the operation doesn't succeed in a
sensible time frame.
[1] https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg03353.html
[2] https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg04400.html
Reported-by: Xujun Ma <xuma@redhat.com>
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1911414
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20210222194531.62717-5-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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| 51254ffb | 22-Feb-2021 |
Daniel Henrique Barboza <danielhb413@gmail.com> |
spapr_drc.c: introduce unplug_timeout_timer
The LoPAR spec provides no way for the guest kernel to report failure of
hotplug/hotunplug events. This wouldn't be bad if those operations were
granted t
spapr_drc.c: introduce unplug_timeout_timer
The LoPAR spec provides no way for the guest kernel to report failure of
hotplug/hotunplug events. This wouldn't be bad if those operations were
granted to always succeed, but that's far for the reality.
What ends up happening is that, in the case of a failed hotunplug,
regardless of whether it was a QEMU error or a guest misbehavior, the
pSeries machine is retaining the unplug state of the device in the
running guest. This state is cleanup in machine reset, where it is
assumed that this state represents a device that is pending unplug, and
the device is hotunpluged from the board. Until the reset occurs, any
hotunplug operation of the same device is forbid because there is a
pending unplug state.
This behavior has at least one undesirable side effect. A long standing
pending unplug state is, more often than not, the result of a hotunplug
error. The user had to dealt with it, since retrying to unplug the
device is noy allowed, and then in the machine reset we're removing the
device from the guest. This means that we're failing the user twice -
failed to hotunplug when asked, then hotunplugged without notice.
Solutions to this problem range between trying to predict when the
hotunplug will fail and forbid the operation from the QEMU layer, from
opening up the IRQ queue to allow for multiple hotunplug attempts, from
telling the users to 'reboot the machine if something goes wrong'. The
first solution is flawed because we can't fully predict guest behavior
from QEMU, the second solution is a trial and error remediation that
counts on a hope that the unplug will eventually succeed, and the third
is ... well.
This patch introduces a crude, but effective solution to hotunplug
errors in the pSeries machine. For each unplug done, we'll timeout after
some time. If a certain amount of time passes, we'll cleanup the
hotunplug state from the machine. During the timeout period, any unplug
operations in the same device will still be blocked. After that, we'll
assume that the guest failed the operation, and allow the user to try
again. If the timeout is too short we'll prevent legitimate hotunplug
situations to occur, so we'll need to overestimate the regular time an
unplug operation takes to succeed to account that.
The true solution for the hotunplug errors in the pSeries machines is a
PAPR change to allow for the guest to warn the platform about it. For
now, the work done in this timeout design can be used for the new PAPR
'abort hcall' in the future, given that for both cases we'll need code
to cleanup the existing unplug states of the DRCs.
At this moment we're adding the basic wiring of the timer into the DRC.
Next patch will use the timer to timeout failed CPU hotunplugs.
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20210222194531.62717-4-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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| 66407069 | 28-Jan-2021 |
Daniel Henrique Barboza <danielhb413@gmail.com> |
spapr_numa.c: create spapr_numa_initial_nvgpu_numa_id() helper
We'll need to check the initial value given to spapr->gpu_numa_id when
building the rtas DT, so put it in a helper for easier access an
spapr_numa.c: create spapr_numa_initial_nvgpu_numa_id() helper
We'll need to check the initial value given to spapr->gpu_numa_id when
building the rtas DT, so put it in a helper for easier access and to
avoid repetition.
Tested-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20210128174213.1349181-3-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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