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powerpc/rtas: Implement reentrant rtas call

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Implement rtas_call_reentrant() for reentrant rtas-calls:
"ibm,int-on", "ibm,int-off",ibm,get-xive" and  "ibm,set-xive".

On LoPAPR Version 1.1 (March 24, 2016), from 7.3.10.1 to 7.3.10.4,
items 2 and 3 say:

2 - For the PowerPC External Interrupt option: The * call must be
reentrant to the number of processors on the platform.
3 - For the PowerPC External Interrupt option: The * argument call
buffer for each simultaneous call must be physically unique.

So, these rtas-calls can be called in a lockless way, if using
a different buffer for each cpu doing such rtas call.

For this, it was suggested to add the buffer (struct rtas_args)
in the PACA struct, so each cpu can have it's own buffer.
The PACA struct received a pointer to rtas buffer, which is
allocated in the memory range available to rtas 32-bit.

Reentrant rtas calls are useful to avoid deadlocks in crashing,
where rtas-calls are needed, but some other thread crashed holding
the rtas.lock.

This is a backtrace of a deadlock from a kdump testing environment:

  #0 arch_spin_lock
  #1  lock_rtas ()
  #2  rtas_call (token=8204, nargs=1, nret=1, outputs=0x0)
  #3  ics_rtas_mask_real_irq (hw_irq=4100)
  #4  machine_kexec_mask_interrupts
  #5  default_machine_crash_shutdown
  #6  machine_crash_shutdown
  #7  __crash_kexec
  #8  crash_kexec
  #9  oops_end

Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
[mpe: Move under #ifdef PSERIES to avoid build breakage]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200518234245.200672-3-leobras.c@gmail.com
This commit is contained in:
Leonardo Bras
2020-05-18 20:42:45 -03:00
committed by Michael Ellerman
parent 783a015b74
commit b664db8e3f
5 changed files with 98 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
arch/powerpc/sysdev/xics/ics-rtas.c
View File

@@ -50,8 +50,8 @@ static void ics_rtas_unmask_irq(struct irq_data *d)
server = xics_get_irq_server(d->irq, irq_data_get_affinity_mask(d), 0);
call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq, server,
DEFAULT_PRIORITY);
call_status = rtas_call_reentrant(ibm_set_xive, 3, 1, NULL, hw_irq,
server, DEFAULT_PRIORITY);
if (call_status != 0) {
printk(KERN_ERR
"%s: ibm_set_xive irq %u server %x returned %d\n",
@@ -60,7 +60,7 @@ static void ics_rtas_unmask_irq(struct irq_data *d)
}
/* Now unmask the interrupt (often a no-op) */
call_status = rtas_call(ibm_int_on, 1, 1, NULL, hw_irq);
call_status = rtas_call_reentrant(ibm_int_on, 1, 1, NULL, hw_irq);
if (call_status != 0) {
printk(KERN_ERR "%s: ibm_int_on irq=%u returned %d\n",
__func__, hw_irq, call_status);
@@ -91,7 +91,7 @@ static void ics_rtas_mask_real_irq(unsigned int hw_irq)
if (hw_irq == XICS_IPI)
return;
call_status = rtas_call(ibm_int_off, 1, 1, NULL, hw_irq);
call_status = rtas_call_reentrant(ibm_int_off, 1, 1, NULL, hw_irq);
if (call_status != 0) {
printk(KERN_ERR "%s: ibm_int_off irq=%u returned %d\n",
__func__, hw_irq, call_status);
@@ -99,8 +99,8 @@ static void ics_rtas_mask_real_irq(unsigned int hw_irq)
}
/* Have to set XIVE to 0xff to be able to remove a slot */
call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq,
xics_default_server, 0xff);
call_status = rtas_call_reentrant(ibm_set_xive, 3, 1, NULL, hw_irq,
xics_default_server, 0xff);
if (call_status != 0) {
printk(KERN_ERR "%s: ibm_set_xive(0xff) irq=%u returned %d\n",
__func__, hw_irq, call_status);
@@ -131,7 +131,7 @@ static int ics_rtas_set_affinity(struct irq_data *d,
if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
return -1;
status = rtas_call(ibm_get_xive, 1, 3, xics_status, hw_irq);
status = rtas_call_reentrant(ibm_get_xive, 1, 3, xics_status, hw_irq);
if (status) {
printk(KERN_ERR "%s: ibm,get-xive irq=%u returns %d\n",
@@ -146,8 +146,8 @@ static int ics_rtas_set_affinity(struct irq_data *d,
return -1;
}
status = rtas_call(ibm_set_xive, 3, 1, NULL,
hw_irq, irq_server, xics_status[1]);
status = rtas_call_reentrant(ibm_set_xive, 3, 1, NULL,
hw_irq, irq_server, xics_status[1]);
if (status) {
printk(KERN_ERR "%s: ibm,set-xive irq=%u returns %d\n",
@@ -179,7 +179,7 @@ static int ics_rtas_map(struct ics *ics, unsigned int virq)
return -EINVAL;
/* Check if RTAS knows about this interrupt */
rc = rtas_call(ibm_get_xive, 1, 3, status, hw_irq);
rc = rtas_call_reentrant(ibm_get_xive, 1, 3, status, hw_irq);
if (rc)
return -ENXIO;
@@ -198,7 +198,7 @@ static long ics_rtas_get_server(struct ics *ics, unsigned long vec)
{
int rc, status[2];
rc = rtas_call(ibm_get_xive, 1, 3, status, vec);
rc = rtas_call_reentrant(ibm_get_xive, 1, 3, status, vec);
if (rc)
return -1;
return status[0];