ppc/xive: Fix high prio group interrupt being preempted by low prio VP

xive_tctx_pipr_present() as implemented with xive_tctx_pipr_update()
causes VP-directed (group==0) interrupt to be presented in

ppc/xive: Fix high prio group interrupt being preempted by low prio VP

xive_tctx_pipr_present() as implemented with xive_tctx_pipr_update()
causes VP-directed (group==0) interrupt to be presented in PIPR and NSR
despite being a lower priority than the currently presented group
interrupt.

This must not happen. The IPB bit should record the low priority VP
interrupt, but PIPR and NSR must not present the lower priority
interrupt.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-32-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive: Add xive_tctx_pipr_present() to present new interrupt

xive_tctx_pipr_update() is used for multiple things. In an effort
to make things simpler and less overloaded, split out the function
t

ppc/xive: Add xive_tctx_pipr_present() to present new interrupt

xive_tctx_pipr_update() is used for multiple things. In an effort
to make things simpler and less overloaded, split out the function
that is used to present a new interrupt to the tctx.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-31-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Redistribute group interrupt preempted by higher priority interrupt

A group interrupt that gets preempted by a higher priority interrupt
delivery must be redistributed otherwise it would

ppc/xive2: Redistribute group interrupt preempted by higher priority interrupt

A group interrupt that gets preempted by a higher priority interrupt
delivery must be redistributed otherwise it would get lost.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-30-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive: Change presenter .match_nvt to match not present

Have the match_nvt method only perform a TCTX match but don't present
the interrupt, the caller presents. This has no functional change, bu

ppc/xive: Change presenter .match_nvt to match not present

Have the match_nvt method only perform a TCTX match but don't present
the interrupt, the caller presents. This has no functional change, but
allows for more complicated presentation logic after matching.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-29-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: redistribute irqs for pool and phys ctx pull

When disabling (pulling) an xive interrupt context, we need
to redistribute any active group interrupts to other threads
that can handle the i

ppc/xive2: redistribute irqs for pool and phys ctx pull

When disabling (pulling) an xive interrupt context, we need
to redistribute any active group interrupts to other threads
that can handle the interrupt if possible. This support had
already been added for the OS context but had not yet been
added to the pool or physical context.

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-28-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Redistribute group interrupt precluded by CPPR update

Add support for redistributing a presented group interrupt if it
is precluded as a result of changing the CPPR value. Without this,
g

ppc/xive2: Redistribute group interrupt precluded by CPPR update

Add support for redistributing a presented group interrupt if it
is precluded as a result of changing the CPPR value. Without this,
group interrupts can be lost.

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-27-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Implement "Ack OS IRQ to even report line" TIMA op

Booting AIX in a PowerVM partition requires the use of the "Acknowledge
O/S Interrupt to even O/S reporting line" special operation prov

ppc/xive2: Implement "Ack OS IRQ to even report line" TIMA op

Booting AIX in a PowerVM partition requires the use of the "Acknowledge
O/S Interrupt to even O/S reporting line" special operation provided by
the IBM XIVE interrupt controller. This operation is invoked by writing
a byte (data is irrelevant) to offset 0xC10 of the Thread Interrupt
Management Area (TIMA). It can be used by software to notify the XIVE
logic that the interrupt was received.

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-26-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Improve pool regs variable name

Change pregs to pool_regs, for clarity.

[npiggin: split from larger patch]

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin

ppc/xive2: Improve pool regs variable name

Change pregs to pool_regs, for clarity.

[npiggin: split from larger patch]

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-25-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive: Add more interrupt notification tracing

Add more tracing around notification, redistribution, and escalation.

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggi

ppc/xive: Add more interrupt notification tracing

Add more tracing around notification, redistribution, and escalation.

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-24-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Support redistribution of group interrupts

When an XIVE context is pulled while it has an active, unacknowledged
group interrupt, XIVE will check to see if a context on another thread
can

ppc/xive2: Support redistribution of group interrupts

When an XIVE context is pulled while it has an active, unacknowledged
group interrupt, XIVE will check to see if a context on another thread
can handle the interrupt and, if so, notify that context. If there
are no contexts that can handle the interrupt, then the interrupt is
added to a backlog and XIVE will attempt to escalate the interrupt,
if configured to do so, allowing the higher privileged handler to
activate a context that can handle the original interrupt.

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-23-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: add interrupt priority configuration flags

Adds support for extracting additional configuration flags from
the XIVE configuration register that are needed for redistribution
of group inte

ppc/xive2: add interrupt priority configuration flags

Adds support for extracting additional configuration flags from
the XIVE configuration register that are needed for redistribution
of group interrupts.

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-22-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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pnv/xive2: Permit valid writes to VC/PC Flush Control registers

Writes to the Flush Control registers were logged as invalid
when they are allowed. Clearing the unsupported want_cache_disable
featur

pnv/xive2: Permit valid writes to VC/PC Flush Control registers

Writes to the Flush Control registers were logged as invalid
when they are allowed. Clearing the unsupported want_cache_disable
feature is supported, so don't log an error in that case.

Signed-off-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-21-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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pnv/xive2: VC_ENDC_WATCH_SPEC regs should read back WATCH_FULL

Firmware expects to read back the WATCH_FULL bit from the VC_ENDC_WATCH_SPEC
register, so don't clear it on read.

Don't bother clearin

pnv/xive2: VC_ENDC_WATCH_SPEC regs should read back WATCH_FULL

Firmware expects to read back the WATCH_FULL bit from the VC_ENDC_WATCH_SPEC
register, so don't clear it on read.

Don't bother clearing the reads-as-zero CONFLICT bit because it's masked
at write already.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-20-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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pnv/xive2: Print value in invalid register write logging

This can make it easier to see what the target system is trying to
do.

[npiggin: split from larger patch]

Signed-off-by: Michael Kowal <kow

pnv/xive2: Print value in invalid register write logging

This can make it easier to see what the target system is trying to
do.

[npiggin: split from larger patch]

Signed-off-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-19-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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pnv/xive2: Support ESB Escalation

Add support for XIVE ESB Interrupt Escalation.

Suggested-by: Michael Kowal <kowal@linux.ibm.com>
[This change was taken from a patch provided by Michael Kowal.]
Si

pnv/xive2: Support ESB Escalation

Add support for XIVE ESB Interrupt Escalation.

Suggested-by: Michael Kowal <kowal@linux.ibm.com>
[This change was taken from a patch provided by Michael Kowal.]
Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-18-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive: Fix pulling pool and phys contexts

This improves the implementation of pulling pool and phys contexts in
XIVE1, by following closer the OS pulling code.

In particular, the old ring data i

ppc/xive: Fix pulling pool and phys contexts

This improves the implementation of pulling pool and phys contexts in
XIVE1, by following closer the OS pulling code.

In particular, the old ring data is returned rather than the modified,
and irq signals are reset on pull.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-17-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive: Move NSR decoding into helper functions

Rather than functions to return masks to test NSR bits, have functions
to test those bits directly. This should be no functional change, it
just mak

ppc/xive: Move NSR decoding into helper functions

Rather than functions to return masks to test NSR bits, have functions
to test those bits directly. This should be no functional change, it
just makes the code more readable.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-16-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive: Explicitly zero NSR after accepting

Have xive_tctx_accept clear NSR in one shot rather than masking out bits
as they are tested, which makes it clear it's reset to 0, and does not
have a p

ppc/xive: Explicitly zero NSR after accepting

Have xive_tctx_accept clear NSR in one shot rather than masking out bits
as they are tested, which makes it clear it's reset to 0, and does not
have a partial NSR value in the register.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-15-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive: tctx_notify should clear the precluded interrupt

If CPPR is lowered to preclude the pending interrupt, NSR should be
cleared and the qemu_irq should be lowered. This avoids some cases
of s

ppc/xive: tctx_notify should clear the precluded interrupt

If CPPR is lowered to preclude the pending interrupt, NSR should be
cleared and the qemu_irq should be lowered. This avoids some cases
of supurious interrupts.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-14-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Set CPPR delivery should account for group priority

The group interrupt delivery flow selects the group backlog scan if
LSMFB < IPB, but that scan may find an interrupt with a priority >=

ppc/xive2: Set CPPR delivery should account for group priority

The group interrupt delivery flow selects the group backlog scan if
LSMFB < IPB, but that scan may find an interrupt with a priority >=
IPB. In that case, the VP-direct interrupt should be chosen. This
extends to selecting the lowest prio between POOL and PHYS rings.

Implement this just by re-starting the selection logic if the
backlog irq was not found or priority did not match LSMFB (LSMFB
is updated so next time around it would see the right value and
not loop infinitely).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-13-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Do not present group interrupt on OS-push if precluded by CPPR

Group interrupts should not be taken from the backlog and presented
if they are precluded by CPPR.

Fixes: 855434b3b8 ("ppc/

ppc/xive2: Do not present group interrupt on OS-push if precluded by CPPR

Group interrupts should not be taken from the backlog and presented
if they are precluded by CPPR.

Fixes: 855434b3b8 ("ppc/xive2: Process group backlog when pushing an OS context")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-12-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Fix treatment of PIPR in CPPR update

According to the XIVE spec, updating the CPPR should also update the
PIPR. The final value of the PIPR depends on other factors, but it
should never b

ppc/xive2: Fix treatment of PIPR in CPPR update

According to the XIVE spec, updating the CPPR should also update the
PIPR. The final value of the PIPR depends on other factors, but it
should never be set to a value that is above the CPPR.

Also added support for redistributing an active group interrupt when it
is precluded as a result of changing the CPPR value.

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-11-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Fix irq preempted by lower priority group irq

A problem was seen where uart interrupts would be lost resulting in the
console hanging. Traces showed that a lower priority interrupt was
pr

ppc/xive2: Fix irq preempted by lower priority group irq

A problem was seen where uart interrupts would be lost resulting in the
console hanging. Traces showed that a lower priority interrupt was
preempting a higher priority interrupt, which would result in the higher
priority interrupt never being handled.

The new interrupt's priority was being compared against the CPPR
(Current Processor Priority Register) instead of the PIPR (Post
Interrupt Priority Register), as was required by the XIVE spec.
This allowed for a window between raising an interrupt and ACK'ing
the interrupt where a lower priority interrupt could slip in.

Fixes: 26c55b99418 ("ppc/xive2: Process group backlog when updating the CPPR")
Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-10-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Use fair irq target search algorithm

The current xive algorithm for finding a matching group vCPU
target always uses the first vCPU found. And, since it always
starts the search with thr

ppc/xive2: Use fair irq target search algorithm

The current xive algorithm for finding a matching group vCPU
target always uses the first vCPU found. And, since it always
starts the search with thread 0 of a core, thread 0 is almost
always used to handle group interrupts. This can lead to additional
interrupt latency and poor performance for interrupt intensive
work loads.

Changing this to use a simple round-robin algorithm for deciding which
thread number to use when starting a search, which leads to a more
distributed use of threads for handling group interrupts.

[npiggin: Also round-robin among threads, not just cores]

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-9-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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ppc/xive2: Reset Generation Flipped bit on END Cache Watch

When the END Event Queue wraps the END EQ Generation bit is flipped and the
Generation Flipped bit is set to one. On a END cache Watch rea

ppc/xive2: Reset Generation Flipped bit on END Cache Watch

When the END Event Queue wraps the END EQ Generation bit is flipped and the
Generation Flipped bit is set to one. On a END cache Watch read operation,
the Generation Flipped bit needs to be reset.

While debugging an error modified END not valid error messages to include
the method since all were the same.

Signed-off-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-8-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

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