svn commit: r356896 - head/sys/powerpc/aim

[Justin Hibbits]

Author: jhibbits
Date: Sun Jan 19 21:17:57 2020
New Revision: 356896
URL: https://svnweb.freebsd.org/changeset/base/356896

Log:
  [PowerPC64] fix crash when using machdep.moea64_bpvo_pool_size tunable
  
  Summary:
  This fixes kernel crashing when tunable "machdep.moea64_bpvo_pool_size" is
  set to a value higher then 327680 (default value).  Function
  moea64_mid_bootstrap() relies on moea64_bpvo_pool_size, but at time of the
  use the variable wan't yet updated with the new value provided by user.
  
  Problem was detected after trying to use a VM with 64GB of RAM, and default
  moea64_bpvo_pool_size is insufficient (kernel boot used more than 470000) .
  I think default value must be discussed to address this use case, or find a
  way to calculate pool size automatically based on amount of memory detected.
  
  Test Plan: Tested on QEMU VM with 64GB of RAM using "set
  machdep.moea64_bpvo_pool_size=655360" on loader prompt
  
  Submitted by:	Alfredo Dal'Ava Júnior (alfredo.junior_eldorado.org.br)
  Differential Revision:	https://reviews.freebsd.org/D23233

Modified:
  head/sys/powerpc/aim/mmu_oea64.c

Modified: head/sys/powerpc/aim/mmu_oea64.c
==============================================================================
--- head/sys/powerpc/aim/mmu_oea64.c	Sun Jan 19 20:04:44 2020	(r356895)
+++ head/sys/powerpc/aim/mmu_oea64.c	Sun Jan 19 21:17:57 2020	(r356896)
@@ -185,7 +185,6 @@ uma_zone_t	moea64_pvo_zone; /* zone for pvo entries */
 static struct	pvo_entry *moea64_bpvo_pool;
 static int	moea64_bpvo_pool_index = 0;
 static int	moea64_bpvo_pool_size = 327680;
-TUNABLE_INT("machdep.moea64_bpvo_pool_size", &moea64_bpvo_pool_size);
 SYSCTL_INT(_machdep, OID_AUTO, moea64_allocated_bpvo_entries, CTLFLAG_RD, 
     &moea64_bpvo_pool_index, 0, "");
 
@@ -390,9 +389,11 @@ alloc_pvo_entry(int bootstrap)
 
 	if (!moea64_initialized || bootstrap) {
 		if (moea64_bpvo_pool_index >= moea64_bpvo_pool_size) {
-			panic("moea64_enter: bpvo pool exhausted, %d, %d, %zd",
-			      moea64_bpvo_pool_index, moea64_bpvo_pool_size,
-			      moea64_bpvo_pool_size * sizeof(struct pvo_entry));
+			panic("%s: bpvo pool exhausted, index=%d, size=%d, bytes=%zd."
+			    "Try setting machdep.moea64_bpvo_pool_size tunable",
+			    __func__, moea64_bpvo_pool_index,
+			    moea64_bpvo_pool_size,
+			    moea64_bpvo_pool_size * sizeof(struct pvo_entry));
 		}
 		pvo = &moea64_bpvo_pool[
 		    atomic_fetchadd_int(&moea64_bpvo_pool_index, 1)];
@@ -914,6 +915,7 @@ moea64_mid_bootstrap(mmu_t mmup, vm_offset_t kernelsta
 	/*
 	 * Initialise the bootstrap pvo pool.
 	 */
+	TUNABLE_INT_FETCH("machdep.moea64_bpvo_pool_size", &moea64_bpvo_pool_size);
 	moea64_bpvo_pool = (struct pvo_entry *)moea64_bootstrap_alloc(
 		moea64_bpvo_pool_size*sizeof(struct pvo_entry), PAGE_SIZE);
 	moea64_bpvo_pool_index = 0;