[PATCH v4 2/3] ACPI, APEI, EINJ: Add CXL 1.1 EINJ error type support

[Ben Cheatham <Benjamin.Cheatham@amd.com>]

Add support for CXL EINJ error types for CXL 1.1 hosts added in ACPI
v6.5. Because these error types target memory-mapped CXL 1.1 compliant
downstream ports and not physical (normal/persistent) memory, these
error types are not currently  allowed through the memory range
validation done by the EINJ driver.

The MMIO address of a CXL 1.1 downstream port can be found in the
cxl_rcrb_addr file in the corresponding dport directory under
/sys/bus/cxl/devices/portX. CXL 1.1 error types follow the same
procedure as a memory error type, but with param1 set to the
downstream port MMIO address.

Example usage:
$ cd /sys/kernel/debug/apei/einj
$ cat available_error_type
    0x00000008      Memory Correctable
    0x00000010      Memory Uncorrectable non-fatal
    0x00000020      Memory Uncorrectable fatal
    0x00000040      PCI Express Correctable
    0x00000080      PCI Express Uncorrectable non-fatal
    0x00000100      PCI Express Uncorrectable fatal
    0x00008000      CXL.mem Protocol Correctable
    0x00020000      CXL.mem Protocol Uncorrectable fatal
$ echo 0x8000 > error_type
$ echo 0xfffffffffffff000 > param2
$ echo 0x3 > flags
$ cat /sys/bus/cxl/devices/portX/dportY/cxl_rcrb_addr
0xb2f00000
$ echo 0xb2f00000 > param1
$ echo 1 > error_inject

Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
---
 drivers/acpi/apei/Kconfig |  2 ++
 drivers/acpi/apei/einj.c  | 24 +++++++++++++++++++++++-
 drivers/cxl/core/port.c   | 19 +++++++++++++++++++
 drivers/cxl/cxl.h         |  1 +
 include/linux/cxl.h       | 18 ++++++++++++++++++
 5 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 include/linux/cxl.h

diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
index 6b18f8bc7be3..eb9cc7157342 100644
--- a/drivers/acpi/apei/Kconfig
+++ b/drivers/acpi/apei/Kconfig
@@ -55,6 +55,8 @@ config ACPI_APEI_MEMORY_FAILURE
 config ACPI_APEI_EINJ
 	tristate "APEI Error INJection (EINJ)"
 	depends on ACPI_APEI && DEBUG_FS
+	imply CXL_BUS
+	imply CXL_ACPI
 	help
 	  EINJ provides a hardware error injection mechanism, it is
 	  mainly used for debugging and testing the other parts of
diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
index 013eb621dc92..8000417a5f26 100644
--- a/drivers/acpi/apei/einj.c
+++ b/drivers/acpi/apei/einj.c
@@ -21,6 +21,7 @@
 #include <linux/nmi.h>
 #include <linux/delay.h>
 #include <linux/mm.h>
+#include <linux/cxl.h>
 #include <asm/unaligned.h>
 
 #include "apei-internal.h"
@@ -36,6 +37,7 @@
 #define MEM_ERROR_MASK		(ACPI_EINJ_MEMORY_CORRECTABLE | \
 				ACPI_EINJ_MEMORY_UNCORRECTABLE | \
 				ACPI_EINJ_MEMORY_FATAL)
+#define CXL_ERROR_MASK		GENMASK(17, 12)
 
 /*
  * ACPI version 5 provides a SET_ERROR_TYPE_WITH_ADDRESS action.
@@ -512,6 +514,22 @@ static int __einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
 	return rc;
 }
 
+static int is_valid_cxl_addr(u64 addr)
+{
+	struct cxl_dport *dport;
+
+	if (IS_REACHABLE(CONFIG_CXL_ACPI))
+		dport = cxl_find_rch_dport_by_rcrb((resource_size_t) addr);
+	else
+		return 0;
+
+	if (!IS_ERR_OR_NULL(dport))
+		return 1;
+
+	pr_info("Could not find dport with rcrb 0x%llx\n", addr);
+	return 0;
+}
+
 /* Inject the specified hardware error */
 static int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
 			     u64 param3, u64 param4)
@@ -537,8 +555,11 @@ static int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
 	if (type & ACPI5_VENDOR_BIT) {
 		if (vendor_flags != SETWA_FLAGS_MEM)
 			goto inject;
-	} else if (!(type & MEM_ERROR_MASK) && !(flags & SETWA_FLAGS_MEM))
+	} else if (!(type & MEM_ERROR_MASK) && !(flags & SETWA_FLAGS_MEM)) {
 		goto inject;
+	} else if (type & CXL_ERROR_MASK && is_valid_cxl_addr(param1)) {
+		goto inject;
+	}
 
 	/*
 	 * Disallow crazy address masks that give BIOS leeway to pick
@@ -807,3 +828,4 @@ module_exit(einj_exit);
 MODULE_AUTHOR("Huang Ying");
 MODULE_DESCRIPTION("APEI Error INJection support");
 MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(CXL);
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 001ab8742e21..f8f300496140 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1122,6 +1122,25 @@ struct cxl_dport *devm_cxl_add_rch_dport(struct cxl_port *port,
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_add_rch_dport, CXL);
 
+#if IS_ENABLED(CONFIG_CXL_ACPI)
+struct cxl_dport *cxl_find_rch_dport_by_rcrb(resource_size_t rcrb_base)
+{
+	struct cxl_dport *dport;
+	unsigned long index;
+
+	if (!cxl_root)
+		return ERR_PTR(-ENODEV);
+
+	xa_for_each(&cxl_root->dports, index, dport)
+		if ((dport->rch && dport->rcrb.base != CXL_RESOURCE_NONE)
+		    && dport->rcrb.base == rcrb_base)
+			return dport;
+
+	return NULL;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_find_rch_dport_by_rcrb, CXL);
+#endif
+
 static int add_ep(struct cxl_ep *new)
 {
 	struct cxl_port *port = new->dport->port;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 4d5bce4bae7e..3e6779dbcd23 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -8,6 +8,7 @@
 #include <linux/bitfield.h>
 #include <linux/bitops.h>
 #include <linux/log2.h>
+#include <linux/cxl.h>
 #include <linux/io.h>
 
 /**
diff --git a/include/linux/cxl.h b/include/linux/cxl.h
new file mode 100644
index 000000000000..b57a4cc85005
--- /dev/null
+++ b/include/linux/cxl.h
@@ -0,0 +1,18 @@
+#ifndef _LINUX_CXL_H
+#define _LINUX_CXL_H
+
+#include <linux/xarray.h>
+#include <linux/errno.h>
+
+struct cxl_dport;
+
+#if IS_ENABLED(CONFIG_CXL_ACPI)
+struct cxl_dport *cxl_find_rch_dport_by_rcrb(resource_size_t rcrb_base);
+#else
+static inline struct cxl_dport *cxl_find_rch_dport_by_rcrb(resource_size_t rcrb_base)
+{
+	return NULL;
+}
+#endif
+
+#endif
-- 
2.34.1