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author | Leonardo Bras <leobras.c@gmail.com> | 2020-05-19 02:42:45 +0300 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-06-02 13:59:08 +0300 |
commit | b664db8e3f976d9233cc9ea5e3f8a8c0bcabeb48 (patch) | |
tree | 487ddb1404c7fd3029a5e72167fa4010d7ef002e /arch/powerpc/sysdev | |
parent | 783a015b747f606e803b798eb8b50c73c548691d (diff) | |
download | linux-b664db8e3f976d9233cc9ea5e3f8a8c0bcabeb48.tar.xz |
powerpc/rtas: Implement reentrant rtas call
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
Diffstat (limited to 'arch/powerpc/sysdev')
-rw-r--r-- | arch/powerpc/sysdev/xics/ics-rtas.c | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/arch/powerpc/sysdev/xics/ics-rtas.c b/arch/powerpc/sysdev/xics/ics-rtas.c index 6aabc74688a6..4cf18000f07c 100644 --- a/arch/powerpc/sysdev/xics/ics-rtas.c +++ b/arch/powerpc/sysdev/xics/ics-rtas.c @@ -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]; |