Revert "powerpc/rtas: Implement reentrant rtas call"

At the time this was submitted by Leonardo, I confirmed -- or thought
I had confirmed -- with PowerVM partition firmware development that
the following RTAS functions:

- ibm,get-xive
- ibm,int-off
- ibm,int-on
- ibm,set-xive

were safe to call on multiple CPUs simultaneously, not only with
respect to themselves as indicated by PAPR, but with arbitrary other
RTAS calls:

https://lore.kernel.org/linuxppc-dev/875zcy2v8o.fsf@linux.ibm.com/

Recent discussion with firmware development makes it clear that this
is not true, and that the code in commit b664db8e3f97 ("powerpc/rtas:
Implement reentrant rtas call") is unsafe, likely explaining several
strange bugs we've seen in internal testing involving DLPAR and
LPM. These scenarios use ibm,configure-connector, whose internal state
can be corrupted by the concurrent use of the "reentrant" functions,
leading to symptoms like endless busy statuses from RTAS.

Fixes: b664db8e3f97 ("powerpc/rtas: Implement reentrant rtas call")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Laurent Dufour <laurent.dufour@fr.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220907220111.223267-1-nathanl@linux.ibm.com

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 9e7007f9aca5..f8320f8e5bc7 100644
--- a/arch/powerpc/sysdev/xics/ics-rtas.c
+++ b/arch/powerpc/sysdev/xics/ics-rtas.c
@@ -36,8 +36,8 @@ 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_reentrant(ibm_set_xive, 3, 1, NULL, hw_irq,
-					  server, DEFAULT_PRIORITY);
+	call_status = rtas_call(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",
@@ -46,7 +46,7 @@ static void ics_rtas_unmask_irq(struct irq_data *d)
 	}
 
 	/* Now unmask the interrupt (often a no-op) */
-	call_status = rtas_call_reentrant(ibm_int_on, 1, 1, NULL, hw_irq);
+	call_status = rtas_call(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);
@@ -68,7 +68,7 @@ static void ics_rtas_mask_real_irq(unsigned int hw_irq)
 	if (hw_irq == XICS_IPI)
 		return;
 
-	call_status = rtas_call_reentrant(ibm_int_off, 1, 1, NULL, hw_irq);
+	call_status = rtas_call(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);
@@ -76,8 +76,8 @@ 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_reentrant(ibm_set_xive, 3, 1, NULL, hw_irq,
-					  xics_default_server, 0xff);
+	call_status = rtas_call(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);
@@ -108,7 +108,7 @@ 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_reentrant(ibm_get_xive, 1, 3, xics_status, hw_irq);
+	status = rtas_call(ibm_get_xive, 1, 3, xics_status, hw_irq);
 
 	if (status) {
 		printk(KERN_ERR "%s: ibm,get-xive irq=%u returns %d\n",
@@ -126,8 +126,8 @@ static int ics_rtas_set_affinity(struct irq_data *d,
 	pr_debug("%s: irq %d [hw 0x%x] server: 0x%x\n", __func__, d->irq,
 		 hw_irq, irq_server);
 
-	status = rtas_call_reentrant(ibm_set_xive, 3, 1, NULL,
-				     hw_irq, irq_server, xics_status[1]);
+	status = rtas_call(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",
@@ -158,7 +158,7 @@ static int ics_rtas_check(struct ics *ics, unsigned int hw_irq)
 		return -EINVAL;
 
 	/* Check if RTAS knows about this interrupt */
-	rc = rtas_call_reentrant(ibm_get_xive, 1, 3, status, hw_irq);
+	rc = rtas_call(ibm_get_xive, 1, 3, status, hw_irq);
 	if (rc)
 		return -ENXIO;
 
@@ -174,7 +174,7 @@ static long ics_rtas_get_server(struct ics *ics, unsigned long vec)
 {
 	int rc, status[2];
 
-	rc = rtas_call_reentrant(ibm_get_xive, 1, 3, status, vec);
+	rc = rtas_call(ibm_get_xive, 1, 3, status, vec);
 	if (rc)
 		return -1;
 	return status[0];