ACPI / APEI: Make hest.c manage the estatus memory pool

ghes.c has a memory pool it uses for the estatus cache and the estatus
queue. The cache is initialised when registering the platform driver.
For the queue, an NMI-like notification has to grow/shrink the pool
as it is registered and unregistered.

This is all pretty noisy when adding new NMI-like notifications, it
would be better to replace this with a static pool size based on the
number of users.

As a precursor, move the call that creates the pool from ghes_init(),
into hest.c. Later this will take the number of ghes entries and
consolidate the queue allocations.
Remove ghes_estatus_pool_exit() as hest.c doesn't have anywhere to put
this.

The pool is now initialised as part of ACPI's subsys_initcall():
(acpi_init(), acpi_scan_init(), acpi_pci_root_init(), acpi_hest_init())
Before this patch it happened later as a GHES specific device_initcall().
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/apei/ghes.c

@@ -162,26 +162,16 @@ static void ghes_iounmap_irq(void)
 	clear_fixmap(FIX_APEI_GHES_IRQ);
 }
 
-static int ghes_estatus_pool_init(void)
+static int ghes_estatus_pool_expand(unsigned long len); //temporary
+
+int ghes_estatus_pool_init(void)
 {
 	ghes_estatus_pool = gen_pool_create(GHES_ESTATUS_POOL_MIN_ALLOC_ORDER, -1);
 	if (!ghes_estatus_pool)
 		return -ENOMEM;
-	return 0;
-}
 
-static void ghes_estatus_pool_free_chunk(struct gen_pool *pool,
-					      struct gen_pool_chunk *chunk,
-					      void *data)
-{
-	vfree((void *)chunk->start_addr);
-}
-
-static void ghes_estatus_pool_exit(void)
-{
-	gen_pool_for_each_chunk(ghes_estatus_pool,
-				ghes_estatus_pool_free_chunk, NULL);
-	gen_pool_destroy(ghes_estatus_pool);
+	return ghes_estatus_pool_expand(GHES_ESTATUS_CACHE_AVG_SIZE *
+					GHES_ESTATUS_CACHE_ALLOCED_MAX);
 }
 
 static int ghes_estatus_pool_expand(unsigned long len)
@@ -1227,18 +1217,9 @@ static int __init ghes_init(void)
 
 	ghes_nmi_init_cxt();
 
-	rc = ghes_estatus_pool_init();
-	if (rc)
-		goto err;
-
-	rc = ghes_estatus_pool_expand(GHES_ESTATUS_CACHE_AVG_SIZE *
-				      GHES_ESTATUS_CACHE_ALLOCED_MAX);
-	if (rc)
-		goto err_pool_exit;
-
 	rc = platform_driver_register(&ghes_platform_driver);
 	if (rc)
-		goto err_pool_exit;
+		goto err;
 
 	rc = apei_osc_setup();
 	if (rc == 0 && osc_sb_apei_support_acked)
@@ -1251,8 +1232,6 @@ static int __init ghes_init(void)
 		pr_info(GHES_PFX "Failed to enable APEI firmware first mode.\n");
 
 	return 0;
-err_pool_exit:
-	ghes_estatus_pool_exit();
 err:
 	return rc;
 }

drivers/acpi/apei/hest.c

@@ -32,6 +32,7 @@
 #include <linux/io.h>
 #include <linux/platform_device.h>
 #include <acpi/apei.h>
+#include <acpi/ghes.h>
 
 #include "apei-internal.h"
 
@@ -209,6 +210,11 @@ static int __init hest_ghes_dev_register(unsigned int ghes_count)
 	rc = apei_hest_parse(hest_parse_ghes, &ghes_arr);
 	if (rc)
 		goto err;
+
+	rc = ghes_estatus_pool_init();
+	if (rc)
+		goto err;
+
 out:
 	kfree(ghes_arr.ghes_devs);
 	return rc;
@@ -257,7 +263,9 @@ void __init acpi_hest_init(void)
 		rc = apei_hest_parse(hest_parse_ghes_count, &ghes_count);
 		if (rc)
 			goto err;
-		rc = hest_ghes_dev_register(ghes_count);
+
+		if (ghes_count)
+			rc = hest_ghes_dev_register(ghes_count);
 		if (rc)
 			goto err;
 	}

include/acpi/ghes.h

@@ -52,6 +52,8 @@ enum {
 	GHES_SEV_PANIC = 0x3,
 };
 
+int ghes_estatus_pool_init(void);
+
 /* From drivers/edac/ghes_edac.c */
 
 #ifdef CONFIG_EDAC_GHES