Re: [PATCH] pseries: Fix 64 bit logical memory block panic

On 7/16/20 7:00 AM, Paul Mackerras wrote:

On Wed, Jul 15, 2020 at 06:12:25PM +0530, Aneesh Kumar K.V wrote:

quoted

Anton Blanchard [off-list ref] writes:

quoted

Booting with a 4GB LMB size causes us to panic:

   qemu-system-ppc64: OS terminated: OS panic:
       Memory block size not suitable: 0x0

Fix pseries_memory_block_size() to handle 64 bit LMBs.

Cc: stable@vger.kernel.org
Signed-off-by: Anton Blanchard <redacted>
---
  arch/powerpc/platforms/pseries/hotplug-memory.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 5ace2f9a277e..6574ac33e887 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c

@@ -27,7 +27,7 @@ static bool rtas_hp_event;
  unsigned long pseries_memory_block_size(void)
  {
  	struct device_node *np;
-	unsigned int memblock_size = MIN_MEMORY_BLOCK_SIZE;
+	uint64_t memblock_size = MIN_MEMORY_BLOCK_SIZE;
  	struct resource r;
  
  	np = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");

We need similar changes at more places?

modified   arch/powerpc/include/asm/book3s/64/mmu.h

@@ -85,7 +85,7 @@ extern unsigned int mmu_base_pid;
  /*
   * memory block size used with radix translation.
   */
-extern unsigned int __ro_after_init radix_mem_block_size;
+extern unsigned long __ro_after_init radix_mem_block_size;
  
  #define PRTB_SIZE_SHIFT	(mmu_pid_bits + 4)
  #define PRTB_ENTRIES	(1ul << mmu_pid_bits)

modified   arch/powerpc/include/asm/drmem.h

@@ -21,7 +21,7 @@ struct drmem_lmb {
  struct drmem_lmb_info {
  	struct drmem_lmb        *lmbs;
  	int                     n_lmbs;
-	u32                     lmb_size;
+	u64                     lmb_size;
  };
  
  extern struct drmem_lmb_info *drmem_info;

modified   arch/powerpc/mm/book3s64/radix_pgtable.c

@@ -34,7 +34,7 @@
  
  unsigned int mmu_pid_bits;
  unsigned int mmu_base_pid;
-unsigned int radix_mem_block_size __ro_after_init;
+unsigned long radix_mem_block_size __ro_after_init;

These changes look fine.

quoted

  static __ref void *early_alloc_pgtable(unsigned long size, int nid,
  			unsigned long region_start, unsigned long region_end)
modified   arch/powerpc/mm/drmem.c

@@ -268,14 +268,15 @@ static void __init __walk_drmem_v2_lmbs(const __be32 *prop, const __be32 *usm,
  void __init walk_drmem_lmbs_early(unsigned long node,
  			void (*func)(struct drmem_lmb *, const __be32 **))
  {
+	const __be64 *lmb_prop;
  	const __be32 *prop, *usm;
  	int len;
  
-	prop = of_get_flat_dt_prop(node, "ibm,lmb-size", &len);
-	if (!prop || len < dt_root_size_cells * sizeof(__be32))
+	lmb_prop = of_get_flat_dt_prop(node, "ibm,lmb-size", &len);
+	if (!lmb_prop || len < sizeof(__be64))
  		return;
  
-	drmem_info->lmb_size = dt_mem_next_cell(dt_root_size_cells, &prop);
+	drmem_info->lmb_size = be64_to_cpup(lmb_prop);

This particular change shouldn't be necessary.  We already have
dt_mem_next_cell() returning u64, and it knows how to combine two
cells to give a u64 (for dt_root_size_cells == 2).

agreed. I added it here because in another patch i was confused about 
the usage of dt_root_size_cells. We don't generally use that in other 
device tree parsing code. I will move that to a separate patch as cleanup.

quoted

  	usm = of_get_flat_dt_prop(node, "linux,drconf-usable-memory", &len);
  

@@ -296,19 +297,19 @@ void __init walk_drmem_lmbs_early(unsigned long node,
  
  static int __init init_drmem_lmb_size(struct device_node *dn)
  {
-	const __be32 *prop;
+	const __be64 *prop;
  	int len;
  
  	if (drmem_info->lmb_size)
  		return 0;
  
  	prop = of_get_property(dn, "ibm,lmb-size", &len);
-	if (!prop || len < dt_root_size_cells * sizeof(__be32)) {
+	if (!prop || len < sizeof(__be64)) {
  		pr_info("Could not determine LMB size\n");
  		return -1;
  	}
  
-	drmem_info->lmb_size = dt_mem_next_cell(dt_root_size_cells, &prop);
+	drmem_info->lmb_size = be64_to_cpup(prop);

Same comment here.

-aneesh