[PATCH v5 0/9] Add RAS support for RISC-V architecture

[PATCH v5 0/9] Add RAS support for RISC-V architecture

[Himanshu Chauhan]

RAS stands for Reliability, Availability and Serviceability.

This series implements the RAS support for RISC-V architecture using
RISC-V RERI specification. It is conformant to ACPI platform error
interfaces (APEI). It uses the highest priority Supervisor Software
Events (SSE)[2] to deliver the hardware error events to the kernel.
The SSE implementation has already been merged in OpenSBI. Clement/Zhanpeng Zhang
have sent a patch series for its implemenation in Linux kernel.[6]

The GHES driver framework is used as is with the following changes for RISC-V:
	1. Register each ghes entry with SSE layer. Ghes notification vector is SSE event.
	2. Add RISC-V specific entries for processor type and ISA string
	3. Add fixmap indices GHES SSE Low and High Priority to help map and read from
	   physical addresses present in GHES entry.
	4. Other changes to build/configure the RAS support

Changes in v5:
 - Rebased to 7.3-rc3
 - Based on SSE v10 Patch series
 - Notificate type patch is generated from acpica gen-patch.sh script since the review request in v4 is now merged.
 - Since 7bfd21e828504, takes care of conditionally compiling ghes_in_nmi_spool_from_list, 5th patch in v4 is dropped.
 - Moved from kzalloc to kzalloc_obj for sse event allocation

Changes in v4:
 - Rebased to Linux v7.1-rc3
 - Changed RISCV to RISC-V
 - RISCV32 and RISCV64 to RV32/RV32E and RV64 respectively
 - Raised a review request for patch "Introduce SSE in HEST notification types" in ACPICA
   https://github.com/acpica/acpica/pull/1170
   Keeping the patch here for complete functionality

Changes in v3:
 - Dropped RFC tag because the related ECRs are now approved [6][7][8][9]
 - Changes to be conformant with SSE v8 patches

Changes in v2:
 - Made changes to be conformant with SSE v7 patches
 - Fixed some bot warnings

How to Use:
----------
This RAS stack consists of Qemu[3], OpenSBI, EDK2[4], Linux kernel and devmem utility to inject and trigger
errors. Qemu [Ref.] has support to emulate RISC-V RERI. The RAS agent is implemented in OpenSBI which
creates CPER records. EDK2 generates HEST table and populates it with GHES entries with the help of
OpenSBI.

Qemu Command:
------------
<qemu-dir>/build/qemu-system-riscv64 \
    -s -accel tcg -m 4096 -smp 2 \
    -cpu rv64,smepmp=false \
    -serial mon:stdio \
    -d guest_errors -D ./qemu.log \
    -bios <opensbi-dir>/build/platform/generic/firmware/fw_dynamic.bin \
    -monitor telnet:127.0.0.1:55555,server,nowait \
    -device virtio-gpu-pci -full-screen \ 
    -device qemu-xhci \
    -device usb-kbd \
    -blockdev node-name=pflash0,driver=file,read-only=on,filename=<edk2-build-dir>/RiscVVirtQemu/RELEASE_GCC5/FV/RISCV_VIRT_CODE.fd \
    -blockdev node-name=pflash1,driver=file,filename=<edk2-build-dir>/RiscVVirtQemu/RELEASE_GCC5/FV/RISCV_VIRT_VARS.fd \
    -M virt,pflash0=pflash0,pflash1=pflash1,rpmi=true,reri=true,aia=aplic-imsic \
    -kernel <kernel image> \
    -initrd <rootfs image> \
    -append "root=/dev/ram rw console=ttyS0 earlycon=uart8250,mmio,0x10000000"

Error Injection & Triggering:
----------------------------
devmem 0x4010040 32 0x2a1
devmem 0x4010048 32 0x9001404
devmem 0x4010044 8 1

The above commands injects a TLB error on CPU 0.

Sample Output (CPU 0):
---------------------
[   34.370282] {1}[Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 1
[   34.371375] {1}[Hardware Error]: event severity: recoverable
[   34.372149] {1}[Hardware Error]:  Error 0, type: recoverable
[   34.372756] {1}[Hardware Error]:   section_type: general processor error
[   34.373357] {1}[Hardware Error]:   processor_type: 3, RISCV
[   34.373806] {1}[Hardware Error]:   processor_isa: 6, RISCV64
[   34.374294] {1}[Hardware Error]:   error_type: 0x02
[   34.374845] {1}[Hardware Error]:   TLB error
[   34.375448] {1}[Hardware Error]:   operation: 1, data read
[   34.376100] {1}[Hardware Error]:   target_address: 0x0000000000000000

References:
----------
[1] [RERI Specification          ]: https://github.com/riscv-non-isa/riscv-ras-eri/releases/download/v1.0/riscv-reri.pdf
[2] [Chap-19 SSE RISC-V SBI v3.0 ]: https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v3.0/riscv-sbi.pdf
[3] [Qemu source (RERI Support)  ]: https://github.com/ventanamicro/qemu.git (branch: dev-upstream)
[4] [EDK2                        ]: https://github.com/ventanamicro/edk2.git (branch: dev-upstream)
[5] [SSE Kernel Patches (v8)     ]: https://lore.kernel.org/all/20251105082639.342973-1-cleger@rivosinc.com/
[6] [SSE Kernel Patches (v10)    ]: https://lore.kernel.org/all/cover.1789974241.git.zhangzhanpeng.jasper@bytedance.com/
[7] [ACPI ECR for HEST changes   ]: https://mantis.uefi.org/mantis/view.php?id=2522
[8] [RISC-V CPER Table ECR       ]: https://mantis.uefi.org/mantis/view.php?id=2551
[9] [RISC-V CPER Proposed Changes]:
	[PART 1] https://docs.google.com/document/d/1-Dd-T_QIUqjq3muyjfK8IUeXWr9QWkFAkFyzweXQL30/edit?tab=t.0
	[PART 2] https://docs.google.com/document/d/13y8kQqbVtCAPCMI4oJ80MtcUS5FL4xuO914NmfCi5vI/edit?tab=t.0
[10] [RISC-V APEI Proposed Changes]: https://docs.google.com/document/d/18rxA6JTyFTelEj0aiKdSFzxPgwyHyThj8EP8lXqWZdY/edit?tab=t.0

Himanshu Chauhan (9):
  riscv: Define ioremap_cache for RISC-V
  riscv: Define arch_apei_get_mem_attribute for RISC-V
  Introduce a new HEST notification type for RISC-V SSE events.
  riscv: Add fixmap indices for GHES IRQ and SSE contexts
  riscv: Add functions to register ghes having SSE notification
  riscv: Add RISC-V entries in processor type and ISA strings
  riscv: Introduce HEST SSE notification handlers
  riscv: Select HAVE_ACPI_APEI required for RAS
  riscv: Enable APEI GHES driver in defconfig

 arch/riscv/Kconfig                     |   1 +
 arch/riscv/configs/defconfig           |   3 +
 arch/riscv/include/asm/acpi.h          |  16 +++
 arch/riscv/include/asm/fixmap.h        |   8 ++
 arch/riscv/include/asm/io.h            |   3 +
 arch/riscv/kernel/acpi.c               |  12 ++
 drivers/acpi/apei/Kconfig              |   5 +
 drivers/acpi/apei/ghes.c               |  99 +++++++++++++++--
 drivers/firmware/efi/cper.c            |   3 +
 drivers/firmware/riscv/riscv_sbi_sse.c | 146 +++++++++++++++++++++++++
 include/acpi/actbl1.h                  |   3 +-
 include/linux/riscv_sbi_sse.h          |  16 +++
 12 files changed, 303 insertions(+), 12 deletions(-)

-- 
2.43.0

[PATCH v5 1/9] riscv: Define ioremap_cache for RISC-V

[Himanshu Chauhan]

bert and einj drivers use ioremap_cache for mapping entries
but ioremap_cache is not defined for RISC-V.

Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
---
 arch/riscv/include/asm/io.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index 92d5f831f349..a51904a6c79b 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -150,6 +150,9 @@ __io_writes_outs(outs, u64, q, __io_pbr(), __io_paw())
 #ifdef CONFIG_MMU
 #define arch_memremap_wb(addr, size, flags)	\
 	((__force void *)ioremap_prot((addr), (size), __pgprot(_PAGE_KERNEL)))
+
+#define ioremap_cache(addr, size)					\
+	((__force void *)ioremap_prot((addr), (size), PAGE_KERNEL))
 #endif
 
 #endif /* _ASM_RISCV_IO_H */
-- 
2.43.0

[PATCH v5 2/9] riscv: Define arch_apei_get_mem_attribute for RISC-V

[Himanshu Chauhan]

ghes_map function uses arch_apei_get_mem_attribute to get the
protection bits for a given physical address. These protection
bits are then used to map the physical address.

Reviewed-by: Sunil V L <sunilvl@oss.qualcomm.com>
Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
---
 arch/riscv/include/asm/acpi.h | 16 ++++++++++++++++
 arch/riscv/kernel/acpi.c      | 12 ++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
index cdefa1f2d67d..c7dee956cdb1 100644
--- a/arch/riscv/include/asm/acpi.h
+++ b/arch/riscv/include/asm/acpi.h
@@ -16,6 +16,7 @@
 
 /* Basic configuration for ACPI */
 #ifdef CONFIG_ACPI
+pgprot_t __acpi_get_mem_attribute(phys_addr_t addr);
 
 typedef u64 phys_cpuid_t;
 #define PHYS_CPUID_INVALID INVALID_HARTID
@@ -29,6 +30,21 @@ extern int acpi_disabled;
 extern int acpi_noirq;
 extern int acpi_pci_disabled;
 
+#ifdef	CONFIG_ACPI_APEI
+/*
+ * acpi_disable_cmcff to disable IA-32 Corrected Machine Check (CMC)
+ * Firmware-First mode. It is not required in RISC-V architecture
+ * and is present for compatibility
+ */
+#define acpi_disable_cmcff 1
+static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
+{
+	return  __acpi_get_mem_attribute(addr);
+}
+#else /* CONFIG_ACPI_APEI */
+#define acpi_disable_cmcff 0
+#endif /* !CONFIG_ACPI_APEI */
+
 static inline void disable_acpi(void)
 {
 	acpi_disabled = 1;
diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
index efd52a5d05b5..d1e472ce0878 100644
--- a/arch/riscv/kernel/acpi.c
+++ b/arch/riscv/kernel/acpi.c
@@ -204,6 +204,18 @@ struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)
 	return &cpu_madt_rintc[cpu];
 }
 
+pgprot_t __acpi_get_mem_attribute(phys_addr_t addr)
+{
+	u64 attr;
+
+	attr = efi_mem_attributes(addr);
+	if (attr & EFI_MEMORY_WB)
+		return PAGE_KERNEL;
+	if ((attr & EFI_MEMORY_WC) || (attr & EFI_MEMORY_WT))
+		return pgprot_writecombine(PAGE_KERNEL);
+	return PAGE_KERNEL;
+}
+
 /*
  * __acpi_map_table() will be called before paging_init(), so early_ioremap()
  * or early_memremap() should be called here to for ACPI table mapping.
-- 
2.43.0

[PATCH v5 3/9] Introduce a new HEST notification type for RISC-V SSE events.

[Himanshu Chauhan]

The GHES entry's notification structure contains the notification
to be used for a given error source. For error sources delivering
events over SSE, it should contain the new SSE notification type.
acpi: Introduce SSE in HEST notification types

ACPICA commit f73f39352c1170464afe812cc96b20cc9db1d822

Link: https://github.com/open-acpica/acpica/commit/f73f3935
Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
---
 include/acpi/actbl1.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/acpi/actbl1.h b/include/acpi/actbl1.h
index d824838cb7af..105fd51f83ec 100644
--- a/include/acpi/actbl1.h
+++ b/include/acpi/actbl1.h
@@ -1798,7 +1798,8 @@ enum acpi_hest_notify_types {
 	ACPI_HEST_NOTIFY_SEI = 9,	/* ACPI 6.1 */
 	ACPI_HEST_NOTIFY_GSIV = 10,	/* ACPI 6.1 */
 	ACPI_HEST_NOTIFY_SOFTWARE_DELEGATED = 11,	/* ACPI 6.2 */
-	ACPI_HEST_NOTIFY_RESERVED = 12	/* 12 and greater are reserved */
+	ACPI_HEST_NOTIFY_SSE = 12, /* RISCV SSE */
+	ACPI_HEST_NOTIFY_RESERVED = 13	/* 13 and greater are reserved */
 };
 
 /* Values for config_write_enable bitfield above */
-- 
2.43.0

[PATCH v5 4/9] riscv: Add fixmap indices for GHES IRQ and SSE contexts

[Himanshu Chauhan]

GHES error handling requires fixmap entries for IRQ notifications.
Add fixmap indices for IRQ, SSE Low and High priority notifications.

Reviewed-by: Clément Léger <cleger@rivosinc.com>
Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
---
 arch/riscv/include/asm/fixmap.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
index a81823c5ee4a..3a775b8d0cdd 100644
--- a/arch/riscv/include/asm/fixmap.h
+++ b/arch/riscv/include/asm/fixmap.h
@@ -38,6 +38,14 @@ enum fixed_addresses {
 	FIX_TEXT_POKE0,
 	FIX_EARLYCON_MEM_BASE,
 
+#ifdef CONFIG_ACPI_APEI_GHES
+	/* Used for GHES mapping from assorted contexts */
+	FIX_APEI_GHES_IRQ,
+#ifdef CONFIG_RISCV_SBI_SSE
+	FIX_APEI_GHES_SSE_LOW_PRIORITY,
+	FIX_APEI_GHES_SSE_HIGH_PRIORITY,
+#endif /* CONFIG_RISCV_SBI_SSE */
+#endif /* CONFIG_ACPI_APEI_GHES */
 	__end_of_permanent_fixed_addresses,
 	/*
 	 * Temporary boot-time mappings, used by early_ioremap(),
-- 
2.43.0

[PATCH v5 5/9] riscv: Add functions to register ghes having SSE notification

[Himanshu Chauhan]

Add functions to register the ghes entries which have SSE as
notification type. The vector inside the ghes is the SSE event
ID that should be registered.

Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
---
 drivers/firmware/riscv/riscv_sbi_sse.c | 146 +++++++++++++++++++++++++
 include/linux/riscv_sbi_sse.h          |  16 +++
 2 files changed, 162 insertions(+)

diff --git a/drivers/firmware/riscv/riscv_sbi_sse.c b/drivers/firmware/riscv/riscv_sbi_sse.c
index 69ce98380331..d4a8691fdf8f 100644
--- a/drivers/firmware/riscv/riscv_sbi_sse.c
+++ b/drivers/firmware/riscv/riscv_sbi_sse.c
@@ -6,6 +6,8 @@
 #define pr_fmt(fmt) "sse: " fmt
 
 #include <linux/atomic.h>
+#include <acpi/ghes.h>
+#include <linux/acpi.h>
 #include <linux/cpu.h>
 #include <linux/cpuhotplug.h>
 #include <linux/cpu_pm.h>
@@ -1226,3 +1228,147 @@ static int __init sse_init(void)
 	return ret;
 }
 arch_initcall(sse_init);
+
+struct sse_ghes_callback {
+	struct list_head head;
+	struct ghes *ghes;
+	sse_event_handler_fn *callback;
+};
+
+struct sse_ghes_event_data {
+	struct list_head head;
+	u32 event_num;
+	struct list_head callback_list;
+	struct sse_event *event;
+};
+
+static DEFINE_SPINLOCK(sse_ghes_event_list_lock);
+static LIST_HEAD(sse_ghes_event_list);
+
+static int sse_ghes_handler(u32 event_num, void *arg, struct pt_regs *regs)
+{
+	struct sse_ghes_event_data *ev_data = arg;
+	struct sse_ghes_callback *cb = NULL;
+
+	list_for_each_entry(cb, &ev_data->callback_list, head) {
+		if (cb && cb->ghes && cb->callback)
+			cb->callback(ev_data->event_num, cb->ghes, regs);
+	}
+
+	return 0;
+}
+
+int sse_register_ghes(struct ghes *ghes, sse_event_handler_fn *lo_cb,
+		      sse_event_handler_fn *hi_cb)
+{
+	struct sse_ghes_event_data *ev_data, *evd;
+	struct sse_ghes_callback *cb;
+	u32 ev_num;
+	int err;
+
+	if (!sse_available)
+		return -EOPNOTSUPP;
+	if (!ghes || !lo_cb || !hi_cb)
+		return -EINVAL;
+
+	ev_num = ghes->generic->notify.vector;
+
+	ev_data = NULL;
+	spin_lock(&sse_ghes_event_list_lock);
+	list_for_each_entry(evd, &sse_ghes_event_list, head) {
+		if (evd->event_num == ev_num) {
+			ev_data = evd;
+			break;
+		}
+	}
+	spin_unlock(&sse_ghes_event_list_lock);
+
+	if (!ev_data) {
+		ev_data = kzalloc_obj(*ev_data, GFP_KERNEL);
+		if (!ev_data)
+			return -ENOMEM;
+
+		INIT_LIST_HEAD(&ev_data->head);
+		ev_data->event_num = ev_num;
+
+		INIT_LIST_HEAD(&ev_data->callback_list);
+
+		ev_data->event = sse_event_register(ev_num, ev_num,
+						    sse_ghes_handler, ev_data);
+		if (IS_ERR(ev_data->event)) {
+			pr_err("%s: Couldn't register event 0x%x\n", __func__, ev_num);
+			kfree(ev_data);
+			return -ENOMEM;
+		}
+
+		err = sse_event_enable(ev_data->event);
+		if (err) {
+			pr_err("%s: Couldn't enable event 0x%x\n", __func__, ev_num);
+			sse_event_unregister(ev_data->event);
+			kfree(ev_data);
+			return err;
+		}
+
+		spin_lock(&sse_ghes_event_list_lock);
+		list_add_tail(&ev_data->head, &sse_ghes_event_list);
+		spin_unlock(&sse_ghes_event_list_lock);
+	}
+
+	list_for_each_entry(cb, &ev_data->callback_list, head) {
+		if (cb->ghes == ghes)
+			return -EALREADY;
+	}
+
+	cb = kzalloc_obj(*cb, GFP_KERNEL);
+	if (!cb)
+		return -ENOMEM;
+	INIT_LIST_HEAD(&cb->head);
+	cb->ghes = ghes;
+	cb->callback = lo_cb;
+	list_add_tail(&cb->head, &ev_data->callback_list);
+
+	return 0;
+}
+
+int sse_unregister_ghes(struct ghes *ghes)
+{
+	struct sse_ghes_event_data *ev_data, *tmp;
+	struct sse_ghes_callback *cb;
+	int free_ev_data = 0;
+
+	if (!ghes)
+		return -EINVAL;
+
+	spin_lock(&sse_ghes_event_list_lock);
+
+	list_for_each_entry_safe(ev_data, tmp, &sse_ghes_event_list, head) {
+		list_for_each_entry(cb, &ev_data->callback_list, head) {
+			if (cb->ghes != ghes)
+				continue;
+
+			list_del(&cb->head);
+			kfree(cb);
+			break;
+		}
+
+		if (list_empty(&ev_data->callback_list))
+			free_ev_data = 1;
+
+		if (free_ev_data) {
+			spin_unlock(&sse_ghes_event_list_lock);
+
+			sse_event_disable(ev_data->event);
+			sse_event_unregister(ev_data->event);
+			ev_data->event = NULL;
+
+			spin_lock(&sse_ghes_event_list_lock);
+
+			list_del(&ev_data->head);
+			kfree(ev_data);
+		}
+	}
+
+	spin_unlock(&sse_ghes_event_list_lock);
+
+	return 0;
+}
diff --git a/include/linux/riscv_sbi_sse.h b/include/linux/riscv_sbi_sse.h
index f6b3881c8884..b470abd61b92 100644
--- a/include/linux/riscv_sbi_sse.h
+++ b/include/linux/riscv_sbi_sse.h
@@ -13,6 +13,7 @@
 
 struct sse_event;
 struct pt_regs;
+struct ghes;
 
 typedef int (sse_event_handler_fn)(u32 event_num, void *arg,
 				   struct pt_regs *regs);
@@ -37,6 +38,10 @@ void sse_event_cleanup(struct sse_event *evt);
 
 int sse_event_set_target_cpu(struct sse_event *sse_evt, unsigned int cpu);
 
+int sse_register_ghes(struct ghes *ghes, sse_event_handler_fn *lo_cb,
+		      sse_event_handler_fn *hi_cb);
+int sse_unregister_ghes(struct ghes *ghes);
+
 int sse_event_enable(struct sse_event *sse_evt);
 
 int sse_event_disable(struct sse_event *sse_evt);
@@ -67,6 +72,17 @@ static inline int sse_event_set_target_cpu(struct sse_event *sse_evt,
 	return -EOPNOTSUPP;
 }
 
+static inline int sse_register_ghes(struct ghes *ghes, sse_event_handler_fn *lo_cb,
+				    sse_event_handler_fn *hi_cb)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int sse_unregister_ghes(struct ghes *ghes)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline int sse_event_enable(struct sse_event *sse_evt)
 {
 	return -EOPNOTSUPP;
-- 
2.43.0

[PATCH v5 6/9] riscv: Add RISC-V entries in processor type and ISA strings

[Himanshu Chauhan]

Add RISCV and RISCV32/64 strings in the in processor type and ISA strings
respectively. These are defined for cper records.

Reviewed-by: Sunil V L <sunilvl@oss.qualcomm.com>
Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
---
 drivers/firmware/efi/cper.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/cper.c b/drivers/firmware/efi/cper.c
index 06b4fdb59917..1b1ab2f1355b 100644
--- a/drivers/firmware/efi/cper.c
+++ b/drivers/firmware/efi/cper.c
@@ -170,6 +170,7 @@ static const char * const proc_type_strs[] = {
 	"IA32/X64",
 	"IA64",
 	"ARM",
+	"RISC-V",
 };
 
 static const char * const proc_isa_strs[] = {
@@ -178,6 +179,8 @@ static const char * const proc_isa_strs[] = {
 	"X64",
 	"ARM A32/T32",
 	"ARM A64",
+	"RV32/RV32E",
+	"RV64",
 };
 
 const char * const cper_proc_error_type_strs[] = {
-- 
2.43.0

[PATCH v5 7/9] riscv: Introduce HEST SSE notification handlers

[Himanshu Chauhan]

Add config option to enable SSE in APEI. When it is enabled, functions
to register/unregister a ghes entry with SSE are avilable along with
low and high priority event handers. If a SSE notification type is
determined, a ghes common handler to handle an error event is registered.

Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
---
 drivers/acpi/apei/Kconfig |  5 ++
 drivers/acpi/apei/ghes.c  | 99 ++++++++++++++++++++++++++++++++++-----
 2 files changed, 93 insertions(+), 11 deletions(-)

diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
index 428458c623f0..895a843d0e36 100644
--- a/drivers/acpi/apei/Kconfig
+++ b/drivers/acpi/apei/Kconfig
@@ -46,6 +46,11 @@ config ACPI_APEI_SEA
 	depends on ARM64 && ACPI_APEI_GHES
 	default y
 
+config ACPI_APEI_SSE
+	bool
+	depends on RISCV && RISCV_SBI_SSE && ACPI_APEI_GHES
+	default y
+
 config ACPI_APEI_MEMORY_FAILURE
 	bool "APEI memory error recovering support"
 	depends on ACPI_APEI && MEMORY_FAILURE
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index fe10ab0e02f6..1a6d21f7992b 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -17,6 +17,8 @@
  *   Author: Huang Ying <ying.huang@intel.com>
  */
 
+#include <linux/err.h>
+#include <linux/riscv_sbi_sse.h>
 #include <linux/arm_sdei.h>
 #include <linux/kernel.h>
 #include <linux/moduleparam.h>
@@ -100,6 +102,11 @@
 #define FIX_APEI_GHES_SDEI_CRITICAL	__end_of_fixed_addresses
 #endif
 
+#ifndef CONFIG_RISCV_SBI_SSE
+#define FIX_APEI_GHES_SSE_LOW_PRIORITY	__end_of_fixed_addresses
+#define FIX_APEI_GHES_SSE_HIGH_PRIORITY	__end_of_fixed_addresses
+#endif
+
 static ATOMIC_NOTIFIER_HEAD(ghes_report_chain);
 
 static inline bool is_hest_type_generic_v2(struct ghes *ghes)
@@ -1682,6 +1689,63 @@ static int apei_sdei_unregister_ghes(struct ghes *ghes)
 	return sdei_unregister_ghes(ghes);
 }
 
+#if defined(CONFIG_ACPI_APEI_SSE)
+/* SSE Handlers */
+static int __ghes_sse_callback(struct ghes *ghes,
+			       enum fixed_addresses fixmap_idx)
+{
+	if (!ghes_in_nmi_queue_one_entry(ghes, fixmap_idx)) {
+		irq_work_queue(&ghes_proc_irq_work);
+
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+/* Low priority */
+static int ghes_sse_lo_callback(u32 event_num, void *arg, struct pt_regs *regs)
+{
+	static DEFINE_RAW_SPINLOCK(ghes_notify_lock_sse_lo);
+	struct ghes *ghes = arg;
+	int err;
+
+	raw_spin_lock(&ghes_notify_lock_sse_lo);
+	err = __ghes_sse_callback(ghes, FIX_APEI_GHES_SSE_LOW_PRIORITY);
+	raw_spin_unlock(&ghes_notify_lock_sse_lo);
+
+	return err;
+}
+
+/* High priority */
+static int ghes_sse_hi_callback(u32 event_num, void *arg, struct pt_regs *regs)
+{
+	static DEFINE_RAW_SPINLOCK(ghes_notify_lock_sse_hi);
+	struct ghes *ghes = arg;
+	int err;
+
+	raw_spin_lock(&ghes_notify_lock_sse_hi);
+	err = __ghes_sse_callback(ghes, FIX_APEI_GHES_SSE_HIGH_PRIORITY);
+	raw_spin_unlock(&ghes_notify_lock_sse_hi);
+
+	return err;
+}
+
+static int apei_sse_register_ghes(struct ghes *ghes)
+{
+	return sse_register_ghes(ghes, ghes_sse_lo_callback,
+				 ghes_sse_hi_callback);
+}
+
+static int apei_sse_unregister_ghes(struct ghes *ghes)
+{
+	return sse_unregister_ghes(ghes);
+}
+#else /* CONFIG_ACPI_APEI_SSE */
+static int apei_sse_register_ghes(struct ghes *ghes) { return -EOPNOTSUPP; }
+static int apei_sse_unregister_ghes(struct ghes *ghes) { return -EOPNOTSUPP; }
+#endif
+
 static int ghes_probe(struct platform_device *ghes_dev)
 {
 	struct acpi_hest_generic *generic;
@@ -1728,6 +1792,14 @@ static int ghes_probe(struct platform_device *ghes_dev)
 		pr_warn(GHES_PFX "Generic hardware error source: %d notified via local interrupt is not supported!\n",
 			generic->header.source_id);
 		goto err;
+	case ACPI_HEST_NOTIFY_SSE:
+		if (!IS_ENABLED(CONFIG_ACPI_APEI_SSE)) {
+			pr_warn(GHES_PFX "Generic hardware error source: %d notified via SSE is not supported\n",
+				generic->header.source_id);
+			rc = -EOPNOTSUPP;
+			goto err;
+		}
+		break;
 	default:
 		pr_warn(FW_WARN GHES_PFX "Unknown notification type: %u for generic hardware error source: %d\n",
 			generic->notify.type, generic->header.source_id);
@@ -1795,6 +1867,17 @@ static int ghes_probe(struct platform_device *ghes_dev)
 		if (rc)
 			goto err;
 		break;
+
+	case ACPI_HEST_NOTIFY_SSE:
+		rc = apei_sse_register_ghes(ghes);
+		if (rc) {
+			pr_err(GHES_PFX "Failed to register for SSE notification on vector %d\n",
+			       generic->notify.vector);
+			goto err;
+		}
+		pr_err(GHES_PFX "Registered SSE notification on vector %d\n",
+		       generic->notify.vector);
+		break;
 	default:
 		BUG();
 	}
@@ -1824,7 +1907,6 @@ static int ghes_probe(struct platform_device *ghes_dev)
 
 static void ghes_remove(struct platform_device *ghes_dev)
 {
-	int rc;
 	struct ghes *ghes;
 	struct acpi_hest_generic *generic;
 
@@ -1858,16 +1940,11 @@ static void ghes_remove(struct platform_device *ghes_dev)
 		ghes_nmi_remove(ghes);
 		break;
 	case ACPI_HEST_NOTIFY_SOFTWARE_DELEGATED:
-		rc = apei_sdei_unregister_ghes(ghes);
-		if (rc) {
-			/*
-			 * Returning early results in a resource leak, but we're
-			 * only here if stopping the hardware failed.
-			 */
-			dev_err(&ghes_dev->dev, "Failed to unregister ghes (%pe)\n",
-				ERR_PTR(rc));
-			return;
-		}
+		apei_sdei_unregister_ghes(ghes);
+		break;
+
+	case ACPI_HEST_NOTIFY_SSE:
+		apei_sse_unregister_ghes(ghes);
 		break;
 	default:
 		BUG();
-- 
2.43.0

[PATCH v5 8/9] riscv: Select HAVE_ACPI_APEI required for RAS

[Himanshu Chauhan]

Select the HAVE_ACPI_APEI option so that APEI GHES config options
are visible.

Reviewed-by: Sunil V L <sunilvl@oss.qualcomm.com>
Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d6c2dbf8455c..9608abe126a0 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -191,6 +191,7 @@ config RISCV
 	select HAVE_MOVE_PUD
 	select HAVE_PAGE_SIZE_4KB
 	select HAVE_PCI
+	select HAVE_ACPI_APEI if ACPI
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
-- 
2.43.0

[PATCH v5 9/9] riscv: Enable APEI GHES driver in defconfig

[Himanshu Chauhan]

The APEI GHES driver is very important for error handling on ACPI
based platforms so enable it in defconfig.

Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
---
 arch/riscv/configs/defconfig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
index 04ae305d5511..66353b22298f 100644
--- a/arch/riscv/configs/defconfig
+++ b/arch/riscv/configs/defconfig
@@ -48,6 +48,9 @@ CONFIG_ACPI_CPPC_CPUFREQ=m
 CONFIG_VIRTUALIZATION=y
 CONFIG_KVM=m
 CONFIG_ACPI=y
+CONFIG_ACPI_APEI=y
+CONFIG_ACPI_APEI_GHES=y
+CONFIG_ACPI_APEI_ERST_DEBUG=y
 CONFIG_JUMP_LABEL=y
 CONFIG_MODULES=y
 CONFIG_MODULE_UNLOAD=y
-- 
2.43.0

Re: [PATCH v5 2/9] riscv: Define arch_apei_get_mem_attribute for RISC-V

[Rui Qi]

On 9/24/26 3:37 PM, Himanshu Chauhan wrote:
> ghes_map function uses arch_apei_get_mem_attribute to get the
> protection bits for a given physical address. These protection
> bits are then used to map the physical address.
> 
> Reviewed-by: Sunil V L <sunilvl@oss.qualcomm.com>
> Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
> ---
>  arch/riscv/include/asm/acpi.h | 16 ++++++++++++++++
>  arch/riscv/kernel/acpi.c      | 12 ++++++++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
> index cdefa1f2d67d..c7dee956cdb1 100644
> --- a/arch/riscv/include/asm/acpi.h
> +++ b/arch/riscv/include/asm/acpi.h
> @@ -16,6 +16,7 @@
>  
>  /* Basic configuration for ACPI */
>  #ifdef CONFIG_ACPI
> +pgprot_t __acpi_get_mem_attribute(phys_addr_t addr);
>  
>  typedef u64 phys_cpuid_t;
>  #define PHYS_CPUID_INVALID INVALID_HARTID
> @@ -29,6 +30,21 @@ extern int acpi_disabled;
>  extern int acpi_noirq;
>  extern int acpi_pci_disabled;
>  
> +#ifdef	CONFIG_ACPI_APEI
> +/*
> + * acpi_disable_cmcff to disable IA-32 Corrected Machine Check (CMC)
> + * Firmware-First mode. It is not required in RISC-V architecture
> + * and is present for compatibility
> + */
> +#define acpi_disable_cmcff 1
> +static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
> +{
> +	return  __acpi_get_mem_attribute(addr);
> +}
> +#else /* CONFIG_ACPI_APEI */
> +#define acpi_disable_cmcff 0
> +#endif /* !CONFIG_ACPI_APEI */
> +
>  static inline void disable_acpi(void)
>  {
>  	acpi_disabled = 1;
> diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
> index efd52a5d05b5..d1e472ce0878 100644
> --- a/arch/riscv/kernel/acpi.c
> +++ b/arch/riscv/kernel/acpi.c
> @@ -204,6 +204,18 @@ struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)
>  	return &cpu_madt_rintc[cpu];
>  }
>  
> +pgprot_t __acpi_get_mem_attribute(phys_addr_t addr)
> +{
> +	u64 attr;
> +
> +	attr = efi_mem_attributes(addr);
> +	if (attr & EFI_MEMORY_WB)
> +		return PAGE_KERNEL;
> +	if ((attr & EFI_MEMORY_WC) || (attr & EFI_MEMORY_WT))
> +		return pgprot_writecombine(PAGE_KERNEL);
> +	return PAGE_KERNEL;
> +}


Hi Himanshu,



Could you clarify why PAGE_KERNEL is used as the fallback here?

When none of EFI_MEMORY_WB, EFI_MEMORY_WC or EFI_MEMORY_WT is
present, including the case where only EFI_MEMORY_UC is advertised,
this returns PAGE_KERNEL.

With standard Svpbmt, PAGE_KERNEL leaves PBMT at zero and therefore
relies on the underlying PMA. In comparison, the existing RISC-V
acpi_os_ioremap() starts with PAGE_KERNEL_IO and retains it when none
of WB/WC/WT is present.

Is relying on the platform PMA intentional for the GHES error status
block mapped by ghes_map()? If so, is there a platform guarantee that
the PMA provides the appropriate memory type for every address reaching
this path?

Otherwise, would PAGE_KERNEL_IO be a more appropriate fallback here,
consistent with acpi_os_ioremap()? A comment documenting the intended
PMA dependency would also help clarify the difference between the two
mapping paths.

Thanks,
Qirui

> +
>  /*
>   * __acpi_map_table() will be called before paging_init(), so early_ioremap()
>   * or early_memremap() should be called here to for ACPI table mapping.

Re: [PATCH v5 3/9] Introduce a new HEST notification type for RISC-V SSE events.

[Himanshu Chauhan]

On Thu, Sep 24, 2026 at 01:07:08PM +0530, Himanshu Chauhan wrote:
> The GHES entry's notification structure contains the notification
> to be used for a given error source. For error sources delivering
> events over SSE, it should contain the new SSE notification type.
> acpi: Introduce SSE in HEST notification types
> 
> ACPICA commit f73f39352c1170464afe812cc96b20cc9db1d822

Hi Rafael,

This is merged in ACPICA. Could you please pick it up for Linux kernel?
Once you do that I will drop this patch from here.

Regards
Himanshu

> 
> Link: https://github.com/open-acpica/acpica/commit/f73f3935
> Signed-off-by: Himanshu Chauhan <himanshu.chauhan@oss.qualcomm.com>
> ---
>  include/acpi/actbl1.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/include/acpi/actbl1.h b/include/acpi/actbl1.h
> index d824838cb7af..105fd51f83ec 100644
> --- a/include/acpi/actbl1.h
> +++ b/include/acpi/actbl1.h
> @@ -1798,7 +1798,8 @@ enum acpi_hest_notify_types {
>  	ACPI_HEST_NOTIFY_SEI = 9,	/* ACPI 6.1 */
>  	ACPI_HEST_NOTIFY_GSIV = 10,	/* ACPI 6.1 */
>  	ACPI_HEST_NOTIFY_SOFTWARE_DELEGATED = 11,	/* ACPI 6.2 */
> -	ACPI_HEST_NOTIFY_RESERVED = 12	/* 12 and greater are reserved */
> +	ACPI_HEST_NOTIFY_SSE = 12, /* RISCV SSE */
> +	ACPI_HEST_NOTIFY_RESERVED = 13	/* 13 and greater are reserved */
>  };
>  
>  /* Values for config_write_enable bitfield above */
> -- 
> 2.43.0
> 

Re: [PATCH v5 5/9] riscv: Add functions to register ghes having SSE notification

[Conor Dooley]

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Acked-by: Conor Dooley <conor.dooley@microchip.com>

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