[PATCH v6 15/18] ACPI / APEI: Only use queued estatus entry during _in_nmi_notify_one()

James Morse
2018-09-21T22:18:57Z

Each struct ghes has an worst-case sized buffer for storing the
estatus. If an error is being processed by ghes_proc() in process
context this buffer will be in use. If the error source then triggers
an NMI-like notification, the same buffer will be used by
_in_nmi_notify_one() to stage the estatus data, before
__process_error() copys it into a queued estatus entry.

Merge __process_error()s work into _in_nmi_notify_one() so that
the queued estatus entry is used from the beginning. Use the
ghes_peek_estatus() so we know how much memory to allocate from
the ghes_estatus_pool before we read the records.

Reported-by: Borislav Petkov <bp@suse.de>
Signed-off-by: James Morse <james.morse@arm.com>
---
drivers/acpi/apei/ghes.c | 45 ++++++++++++++++++++--------------------
1 file changed, 22 insertions(+), 23 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 055176ed68ac..a0c10b60ad44 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -722,40 +722,32 @@ static void ghes_print_queued_estatus(void)
}
}

-/* Save estatus for further processing in IRQ context */
-static void __process_error(struct ghes *ghes,
- struct acpi_hest_generic_status *ghes_estatus)
+static int _in_nmi_notify_one(struct ghes *ghes, int fixmap_idx)
{
+ u64 buf_paddr;
+ int sev, rc = 0;
u32 len, node_len;
struct ghes_estatus_node *estatus_node;
struct acpi_hest_generic_status *estatus;

- if (ghes_estatus_cached(ghes_estatus))
- return;
+ rc = ghes_peek_estatus(ghes, fixmap_idx, &buf_paddr, &len);
+ if (rc)
+ return rc;

- len = cper_estatus_len(ghes_estatus);
node_len = GHES_ESTATUS_NODE_LEN(len);

estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool, node_len);
if (!estatus_node)
- return;
+ return -ENOMEM;

estatus_node->ghes = ghes;
estatus_node->generic = ghes->generic;
estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
- memcpy(estatus, ghes_estatus, len);
- llist_add(&estatus_node->llnode, &ghes_estatus_llist);
-}
-
-static int _in_nmi_notify_one(struct ghes *ghes, int fixmap_idx)
-{
- int sev;
- u64 buf_paddr;
- struct acpi_hest_generic_status *estatus = ghes->estatus;

- if (ghes_read_estatus(ghes, estatus, &buf_paddr, fixmap_idx)) {
+ if (__ghes_read_estatus(estatus, buf_paddr, len, fixmap_idx)) {
ghes_clear_estatus(estatus, buf_paddr, fixmap_idx);
- return -ENOENT;
+ rc = -ENOENT;
+ goto no_work;
}

sev = ghes_severity(estatus->error_severity);
@@ -764,13 +756,20 @@ static int _in_nmi_notify_one(struct ghes *ghes, int fixmap_idx)
__ghes_panic(ghes, estatus);
}

- if (!buf_paddr)
- return 0;
-
- __process_error(ghes, estatus);
ghes_clear_estatus(estatus, buf_paddr, fixmap_idx);

- return 0;
+ if (!buf_paddr || ghes_estatus_cached(estatus))
+ goto no_work;
+
+ llist_add(&estatus_node->llnode, &ghes_estatus_llist);
+
+ return rc;
+
+no_work:
+ gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node,
+ node_len);
+
+ return rc;
}

static int ghes_estatus_queue_notified(struct list_head *rcu_list,
--
2.19.0