[PATCH] arm64/apei: Filter the apei GAS address from the ECAM space

[Xuesong Chen]

ECAM configuration memory space is reserved during the initializaion of the
kernel, but sometimes the apei needs to access the GAS address within the
ECAM space, thus the request_mem_region(...) will be failed in this case,
the error message looks like:
...
APEI: Can not request [mem 0x50100000-0x50100003] for APEI EINJ Trigger registers
...

This patch provides an arm64 specific filter function to remove the GAS address
range from the reserved ECAM resource regions, which will make the apei's GAS
address can pass the check while not affecting the original reserved ECAM area.

Signed-off-by: Xuesong Chen <xuesong.chen at linux.alibaba.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Steve Capper <steve.capper at arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Cc: Mark Rutland <mark.rutland at arm.com>
---
 arch/arm64/kernel/pci.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index 1006ed2..6096165 100644
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c
@@ -19,6 +19,13 @@
 #include <linux/slab.h>
 
 #ifdef CONFIG_ACPI
+struct pci_mcfg_res_region {
+	struct list_head list;
+	struct resource res;
+};
+
+static LIST_HEAD(pci_mcfg_res_list);
+static DEFINE_MUTEX(pci_mcfg_lock);
 /*
  * Try to assign the IRQ number when probing a new device
  */
@@ -107,6 +114,58 @@ static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci)
 	return status;
 }
 
+#ifdef CONFIG_ACPI_APEI
+extern int (*arch_apei_filter_addr)(int (*func)(__u64 start, __u64 size,
+		void *data), void *data);
+
+static int pci_mcfg_for_each_region(int (*func)(__u64 start, __u64 size,
+		void *data), void *data)
+{
+	struct pci_mcfg_res_region *e;
+	int rc = 0;
+
+	if (list_empty(&pci_mcfg_res_list))
+		return 0;
+
+	list_for_each_entry(e, &pci_mcfg_res_list, list) {
+		rc = func(e->res.start, resource_size(&e->res), data);
+		if (rc)
+			return rc;
+	}
+
+	return 0;
+}
+
+#define set_apei_filter() \
+	do { \
+		if (!arch_apei_filter_addr) \
+			arch_apei_filter_addr = pci_mcfg_for_each_region; \
+	} while (0)
+#else
+#define set_apei_filter()
+#endif
+
+static int pci_mcfg_res_add(struct resource *res)
+{
+	struct pci_mcfg_res_region *new;
+
+	if (!res)
+		return -EINVAL;
+
+	new = kzalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	new->res.start = res->start;
+	new->res.end = res->end;
+
+	mutex_lock(&pci_mcfg_lock);
+	list_add(&new->list, &pci_mcfg_res_list);
+	mutex_unlock(&pci_mcfg_lock);
+
+	return 0;
+}
+
 /*
  * Lookup the bus range for the domain in MCFG, and set up config space
  * mapping.
@@ -144,6 +203,11 @@ static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci)
 		return NULL;
 	}
 
+	/* insert the mcfg resource region of current segment into the list */
+	ret = pci_mcfg_res_add(&cfgres);
+	if (ret)
+		dev_warn(dev, "add %pR into the mcfg res list failed\n", &cfgres);
+
 	return cfg;
 }
 
@@ -204,6 +268,8 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
 	list_for_each_entry(child, &bus->children, node)
 		pcie_bus_configure_settings(child);
 
+	set_apei_filter();
+
 	return bus;
 }
 
-- 
1.8.3.1