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linux/arch/sparc/kernel/sun4v_ivec.S
Jane Chu 9d53caec84 sparc64: Measure receiver forward progress to avoid send mondo timeout 
A large sun4v SPARC system may have moments of intensive xcall activities,
usually caused by unmapping many pages on many CPUs concurrently. This can
flood receivers with CPU mondo interrupts for an extended period, causing
some unlucky senders to hit send-mondo timeout. This problem gets worse
as cpu count increases because sometimes mappings must be invalidated on
all CPUs, and sometimes all CPUs may gang up on a single CPU.

But a busy system is not a broken system. In the above scenario, as long
as the receiver is making forward progress processing mondo interrupts,
the sender should continue to retry.

This patch implements the receiver's forward progress meter by introducing
a per cpu counter 'cpu_mondo_counter[cpu]' where 'cpu' is in the range
of 0..NR_CPUS. The receiver increments its counter as soon as it receives
a mondo and the sender tracks the receiver's counter. If the receiver has
stopped making forward progress when the retry limit is reached, the sender
declares send-mondo-timeout and panic; otherwise, the receiver is allowed
to keep making forward progress.

In addition, it's been observed that PCIe hotplug events generate Correctable
Errors that are handled by hypervisor and then OS. Hypervisor 'borrows'
a guest cpu strand briefly to provide the service. If the cpu strand is
simultaneously the only cpu targeted by a mondo, it may not be available
for the mondo in 20msec, causing SUN4V mondo timeout. It appears that 1 second
is the agreed wait time between hypervisor and guest OS, this patch makes
the adjustment.

Orabug: 25476541
Orabug: 26417466

Signed-off-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Reviewed-by: Rob Gardner <rob.gardner@oracle.com>
Reviewed-by: Thomas Tai <thomas.tai@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-14 11:18:02 -07:00

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/* sun4v_ivec.S: Sun4v interrupt vector handling.
*
* Copyright (C) 2006 <davem@davemloft.net>
*/
#include <asm/cpudata.h>
#include <asm/intr_queue.h>
#include <asm/pil.h>
.text
.align 32
sun4v_cpu_mondo:
/* Head offset in %g2, tail offset in %g4.
* If they are the same, no work.
*/
mov INTRQ_CPU_MONDO_HEAD, %g2
ldxa [%g2] ASI_QUEUE, %g2
mov INTRQ_CPU_MONDO_TAIL, %g4
ldxa [%g4] ASI_QUEUE, %g4
cmp %g2, %g4
be,pn %xcc, sun4v_cpu_mondo_queue_empty
nop
/* Get &trap_block[smp_processor_id()] into %g4. */
ldxa [%g0] ASI_SCRATCHPAD, %g4
sub %g4, TRAP_PER_CPU_FAULT_INFO, %g4
/* Get smp_processor_id() into %g3 */
sethi %hi(trap_block), %g5
or %g5, %lo(trap_block), %g5
sub %g4, %g5, %g3
srlx %g3, TRAP_BLOCK_SZ_SHIFT, %g3
/* Increment cpu_mondo_counter[smp_processor_id()] */
sethi %hi(cpu_mondo_counter), %g5
or %g5, %lo(cpu_mondo_counter), %g5
sllx %g3, 3, %g3
add %g5, %g3, %g5
ldx [%g5], %g3
add %g3, 1, %g3
stx %g3, [%g5]
/* Get CPU mondo queue base phys address into %g7. */
ldx [%g4 + TRAP_PER_CPU_CPU_MONDO_PA], %g7
/* Now get the cross-call arguments and handler PC, same
* layout as sun4u:
*
* 1st 64-bit word: low half is 32-bit PC, put into %g3 and jmpl to it
* high half is context arg to MMU flushes, into %g5
* 2nd 64-bit word: 64-bit arg, load into %g1
* 3rd 64-bit word: 64-bit arg, load into %g7
*/
ldxa [%g7 + %g2] ASI_PHYS_USE_EC, %g3
add %g2, 0x8, %g2
srlx %g3, 32, %g5
ldxa [%g7 + %g2] ASI_PHYS_USE_EC, %g1
add %g2, 0x8, %g2
srl %g3, 0, %g3
ldxa [%g7 + %g2] ASI_PHYS_USE_EC, %g7
add %g2, 0x40 - 0x8 - 0x8, %g2
/* Update queue head pointer. */
lduw [%g4 + TRAP_PER_CPU_CPU_MONDO_QMASK], %g4
and %g2, %g4, %g2
mov INTRQ_CPU_MONDO_HEAD, %g4
stxa %g2, [%g4] ASI_QUEUE
membar #Sync
jmpl %g3, %g0
nop
sun4v_cpu_mondo_queue_empty:
retry
sun4v_dev_mondo:
/* Head offset in %g2, tail offset in %g4. */
mov INTRQ_DEVICE_MONDO_HEAD, %g2
ldxa [%g2] ASI_QUEUE, %g2
mov INTRQ_DEVICE_MONDO_TAIL, %g4
ldxa [%g4] ASI_QUEUE, %g4
cmp %g2, %g4
be,pn %xcc, sun4v_dev_mondo_queue_empty
nop
/* Get &trap_block[smp_processor_id()] into %g4. */
ldxa [%g0] ASI_SCRATCHPAD, %g4
sub %g4, TRAP_PER_CPU_FAULT_INFO, %g4
/* Get DEV mondo queue base phys address into %g5. */
ldx [%g4 + TRAP_PER_CPU_DEV_MONDO_PA], %g5
/* Load IVEC into %g3. */
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
add %g2, 0x40, %g2
/* XXX There can be a full 64-byte block of data here.
* XXX This is how we can get at MSI vector data.
* XXX Current we do not capture this, but when we do we'll
* XXX need to add a 64-byte storage area in the struct ino_bucket
* XXX or the struct irq_desc.
*/
/* Update queue head pointer, this frees up some registers. */
lduw [%g4 + TRAP_PER_CPU_DEV_MONDO_QMASK], %g4
and %g2, %g4, %g2
mov INTRQ_DEVICE_MONDO_HEAD, %g4
stxa %g2, [%g4] ASI_QUEUE
membar #Sync
TRAP_LOAD_IRQ_WORK_PA(%g1, %g4)
/* For VIRQs, cookie is encoded as ~bucket_phys_addr */
brlz,pt %g3, 1f
xnor %g3, %g0, %g4
/* Get __pa(&ivector_table[IVEC]) into %g4. */
sethi %hi(ivector_table_pa), %g4
ldx [%g4 + %lo(ivector_table_pa)], %g4
sllx %g3, 4, %g3
add %g4, %g3, %g4
1: ldx [%g1], %g2
stxa %g2, [%g4] ASI_PHYS_USE_EC
stx %g4, [%g1]
/* Signal the interrupt by setting (1 << pil) in %softint. */
wr %g0, 1 << PIL_DEVICE_IRQ, %set_softint
sun4v_dev_mondo_queue_empty:
retry
sun4v_res_mondo:
/* Head offset in %g2, tail offset in %g4. */
mov INTRQ_RESUM_MONDO_HEAD, %g2
ldxa [%g2] ASI_QUEUE, %g2
mov INTRQ_RESUM_MONDO_TAIL, %g4
ldxa [%g4] ASI_QUEUE, %g4
cmp %g2, %g4
be,pn %xcc, sun4v_res_mondo_queue_empty
nop
/* Get &trap_block[smp_processor_id()] into %g3. */
ldxa [%g0] ASI_SCRATCHPAD, %g3
sub %g3, TRAP_PER_CPU_FAULT_INFO, %g3
/* Get RES mondo queue base phys address into %g5. */
ldx [%g3 + TRAP_PER_CPU_RESUM_MONDO_PA], %g5
/* Get RES kernel buffer base phys address into %g7. */
ldx [%g3 + TRAP_PER_CPU_RESUM_KBUF_PA], %g7
/* If the first word is non-zero, queue is full. */
ldxa [%g7 + %g2] ASI_PHYS_USE_EC, %g1
brnz,pn %g1, sun4v_res_mondo_queue_full
nop
lduw [%g3 + TRAP_PER_CPU_RESUM_QMASK], %g4
/* Remember this entry's offset in %g1. */
mov %g2, %g1
/* Copy 64-byte queue entry into kernel buffer. */
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
/* Update queue head pointer. */
and %g2, %g4, %g2
mov INTRQ_RESUM_MONDO_HEAD, %g4
stxa %g2, [%g4] ASI_QUEUE
membar #Sync
/* Disable interrupts and save register state so we can call
* C code. The etrap handling will leave %g4 in %l4 for us
* when it's done.
*/
rdpr %pil, %g2
wrpr %g0, PIL_NORMAL_MAX, %pil
mov %g1, %g4
ba,pt %xcc, etrap_irq
rd %pc, %g7
#ifdef CONFIG_TRACE_IRQFLAGS
call trace_hardirqs_off
nop
#endif
/* Log the event. */
add %sp, PTREGS_OFF, %o0
call sun4v_resum_error
mov %l4, %o1
/* Return from trap. */
ba,pt %xcc, rtrap_irq
nop
sun4v_res_mondo_queue_empty:
retry
sun4v_res_mondo_queue_full:
/* The queue is full, consolidate our damage by setting
* the head equal to the tail. We'll just trap again otherwise.
* Call C code to log the event.
*/
mov INTRQ_RESUM_MONDO_HEAD, %g2
stxa %g4, [%g2] ASI_QUEUE
membar #Sync
rdpr %pil, %g2
wrpr %g0, PIL_NORMAL_MAX, %pil
ba,pt %xcc, etrap_irq
rd %pc, %g7
#ifdef CONFIG_TRACE_IRQFLAGS
call trace_hardirqs_off
nop
#endif
call sun4v_resum_overflow
add %sp, PTREGS_OFF, %o0
ba,pt %xcc, rtrap_irq
nop
sun4v_nonres_mondo:
/* Head offset in %g2, tail offset in %g4. */
mov INTRQ_NONRESUM_MONDO_HEAD, %g2
ldxa [%g2] ASI_QUEUE, %g2
mov INTRQ_NONRESUM_MONDO_TAIL, %g4
ldxa [%g4] ASI_QUEUE, %g4
cmp %g2, %g4
be,pn %xcc, sun4v_nonres_mondo_queue_empty
nop
/* Get &trap_block[smp_processor_id()] into %g3. */
ldxa [%g0] ASI_SCRATCHPAD, %g3
sub %g3, TRAP_PER_CPU_FAULT_INFO, %g3
/* Get RES mondo queue base phys address into %g5. */
ldx [%g3 + TRAP_PER_CPU_NONRESUM_MONDO_PA], %g5
/* Get RES kernel buffer base phys address into %g7. */
ldx [%g3 + TRAP_PER_CPU_NONRESUM_KBUF_PA], %g7
/* If the first word is non-zero, queue is full. */
ldxa [%g7 + %g2] ASI_PHYS_USE_EC, %g1
brnz,pn %g1, sun4v_nonres_mondo_queue_full
nop
lduw [%g3 + TRAP_PER_CPU_NONRESUM_QMASK], %g4
/* Remember this entry's offset in %g1. */
mov %g2, %g1
/* Copy 64-byte queue entry into kernel buffer. */
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
ldxa [%g5 + %g2] ASI_PHYS_USE_EC, %g3
stxa %g3, [%g7 + %g2] ASI_PHYS_USE_EC
add %g2, 0x08, %g2
/* Update queue head pointer. */
and %g2, %g4, %g2
mov INTRQ_NONRESUM_MONDO_HEAD, %g4
stxa %g2, [%g4] ASI_QUEUE
membar #Sync
/* Disable interrupts and save register state so we can call
* C code. The etrap handling will leave %g4 in %l4 for us
* when it's done.
*/
rdpr %pil, %g2
wrpr %g0, PIL_NORMAL_MAX, %pil
mov %g1, %g4
ba,pt %xcc, etrap_irq
rd %pc, %g7
#ifdef CONFIG_TRACE_IRQFLAGS
call trace_hardirqs_off
nop
#endif
/* Log the event. */
add %sp, PTREGS_OFF, %o0
call sun4v_nonresum_error
mov %l4, %o1
/* Return from trap. */
ba,pt %xcc, rtrap_irq
nop
sun4v_nonres_mondo_queue_empty:
retry
sun4v_nonres_mondo_queue_full:
/* The queue is full, consolidate our damage by setting
* the head equal to the tail. We'll just trap again otherwise.
* Call C code to log the event.
*/
mov INTRQ_NONRESUM_MONDO_HEAD, %g2
stxa %g4, [%g2] ASI_QUEUE
membar #Sync
rdpr %pil, %g2
wrpr %g0, PIL_NORMAL_MAX, %pil
ba,pt %xcc, etrap_irq
rd %pc, %g7
#ifdef CONFIG_TRACE_IRQFLAGS
call trace_hardirqs_off
nop
#endif
call sun4v_nonresum_overflow
add %sp, PTREGS_OFF, %o0
ba,pt %xcc, rtrap_irq
nop
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