[RFC PATCH v1 00/10] Add RAS support for RISC-V architecture

[RFC PATCH v1 00/10] Add RAS support for RISC-V architecture

[Himanshu Chauhan]

This series implements the RAS (Reliability, Availability and Serviceability)
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 implemetation has already been merged in OpenSBI. Clement has sent a patch series for
its implemenation in Linux kernel.[5]

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

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] SSE Section in OpenSBI v3.0: https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v3.0-rc3/riscv-sbi.pdf
[3] Qemu source (with RERI emulation 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: https://lore.kernel.org/linux-riscv/649fdead-09b0-4f94-a6ff-099fc970d890@rivosinc.com/T/

Himanshu Chauhan (10):
  riscv: Define ioremap_cache for RISC-V
  riscv: Define arch_apei_get_mem_attribute for RISC-V
  acpi: Introduce SSE in HEST notification types
  riscv: Add fixmap indices for GHES IRQ and SSE contexts
  riscv: conditionally compile GHES NMI spool function
  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: Add config option to enable APEI SSE handler
  riscv: Enable APEI and NMI safe cmpxchg options required for RAS

 arch/riscv/Kconfig                 |   2 +
 arch/riscv/include/asm/acpi.h      |  20 ++++
 arch/riscv/include/asm/fixmap.h    |   8 ++
 arch/riscv/include/asm/io.h        |   3 +
 drivers/acpi/apei/Kconfig          |   5 +
 drivers/acpi/apei/ghes.c           | 102 +++++++++++++++++---
 drivers/firmware/efi/cper.c        |   3 +
 drivers/firmware/riscv/riscv_sse.c | 147 +++++++++++++++++++++++++++++
 include/acpi/actbl1.h              |   3 +-
 include/linux/riscv_sse.h          |  15 +++
 10 files changed, 296 insertions(+), 12 deletions(-)

-- 
2.43.0

[RFC PATCH v1 01/10] 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 <hchauhan@ventanamicro.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 1c5c641075d2..e23a4901e928 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -30,6 +30,9 @@
 #define PCI_IOBASE		((void __iomem *)PCI_IO_START)
 #endif /* CONFIG_MMU */
 
+#define ioremap_cache(addr, size)					\
+	((__force void *)ioremap_prot((addr), (size), _PAGE_KERNEL))
+
 /*
  * Emulation routines for the port-mapped IO space used by some PCI drivers.
  * These are defined as being "fully synchronous", but also "not guaranteed to
-- 
2.43.0

Re: [RFC PATCH v1 01/10] riscv: Define ioremap_cache for RISC-V

[Anup Patel]

On Thu, Feb 27, 2025 at 6:08 PM Himanshu Chauhan
<hchauhan@ventanamicro.com> wrote:
>
> bert and einj drivers use ioremap_cache for mapping entries
> but ioremap_cache is not defined for RISC-V.
>
> Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.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 1c5c641075d2..e23a4901e928 100644
> --- a/arch/riscv/include/asm/io.h
> +++ b/arch/riscv/include/asm/io.h
> @@ -30,6 +30,9 @@
>  #define PCI_IOBASE             ((void __iomem *)PCI_IO_START)
>  #endif /* CONFIG_MMU */
>
> +#define ioremap_cache(addr, size)                                      \
> +       ((__force void *)ioremap_prot((addr), (size), _PAGE_KERNEL))
> +

There is a compile error observed with this patch applied
on the latest Linux-6.15-rcX kernel.

To fix compile error, we need the following change:
s/_PAGE_KERNEL/PAGE_KERNEL/

Regards,
Anup

[RFC PATCH v1 02/10] 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.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
---
 arch/riscv/include/asm/acpi.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
index 6e13695120bc..0c599452ef48 100644
--- a/arch/riscv/include/asm/acpi.h
+++ b/arch/riscv/include/asm/acpi.h
@@ -27,6 +27,26 @@ extern int acpi_disabled;
 extern int acpi_noirq;
 extern int acpi_pci_disabled;
 
+#ifdef	CONFIG_ACPI_APEI
+/*
+ * acpi_disable_cmcff is used in drivers/acpi/apei/hest.c for disabling
+ * IA-32 Architecture Corrected Machine Check (CMC) Firmware-First mode
+ * with a kernel command line parameter "acpi=nocmcoff". But we don't
+ * have this IA-32 specific feature on ARM64, this definition is only
+ * for compatibility.
+ */
+#define acpi_disable_cmcff 1
+static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
+{
+	/*
+	 * Until we have a way to look for EFI memory attributes.
+	 */
+	return PAGE_KERNEL;
+}
+#else /* CONFIG_ACPI_APEI */
+#define acpi_disable_cmcff 0
+#endif /* !CONFIG_ACPI_APEI */
+
 static inline void disable_acpi(void)
 {
 	acpi_disabled = 1;
-- 
2.43.0

Re: [RFC PATCH v1 02/10] riscv: Define arch_apei_get_mem_attribute for RISC-V

[Clément Léger]

On 27/02/2025 13:36, 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.
> 
> Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
> ---
>  arch/riscv/include/asm/acpi.h | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
> index 6e13695120bc..0c599452ef48 100644
> --- a/arch/riscv/include/asm/acpi.h
> +++ b/arch/riscv/include/asm/acpi.h
> @@ -27,6 +27,26 @@ extern int acpi_disabled;
>  extern int acpi_noirq;
>  extern int acpi_pci_disabled;
>  
> +#ifdef	CONFIG_ACPI_APEI
> +/*
> + * acpi_disable_cmcff is used in drivers/acpi/apei/hest.c for disabling
> + * IA-32 Architecture Corrected Machine Check (CMC) Firmware-First mode
> + * with a kernel command line parameter "acpi=nocmcoff". But we don't
> + * have this IA-32 specific feature on ARM64, this definition is only

Hi Himanshu

s/ARM/RISC-V

Thanks,

Clément

> + * for compatibility.
> + */
> +#define acpi_disable_cmcff 1
> +static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
> +{
> +	/*
> +	 * Until we have a way to look for EFI memory attributes.
> +	 */
> +	return PAGE_KERNEL;
> +}
> +#else /* CONFIG_ACPI_APEI */
> +#define acpi_disable_cmcff 0
> +#endif /* !CONFIG_ACPI_APEI */
> +
>  static inline void disable_acpi(void)
>  {
>  	acpi_disabled = 1;

[RFC PATCH v1 03/10] acpi: Introduce SSE in HEST notification types

[Himanshu Chauhan]

Introduce a new HEST notification type for RISC-V SSE events.
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.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.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 387fc821703a..df577bf25423 100644
--- a/include/acpi/actbl1.h
+++ b/include/acpi/actbl1.h
@@ -1515,7 +1515,8 @@ 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

[RFC PATCH v1 04/10] 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.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.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 0a55099bb734..fa3a0ec0c55c 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_SSE
+	FIX_APEI_GHES_SSE_LOW_PRIORITY,
+	FIX_APEI_GHES_SSE_HIGH_PRIORITY,
+#endif /* CONFIG_RISCV_SSE */
+#endif /* CONFIG_ACPI_APEI_GHES */
 	__end_of_permanent_fixed_addresses,
 	/*
 	 * Temporary boot-time mappings, used by early_ioremap(),
-- 
2.43.0

[RFC PATCH v1 05/10] riscv: conditionally compile GHES NMI spool function

[Himanshu Chauhan]

Compile ghes_in_nmi_spool_from_list only when NMI and SEA
is enabled. Otherwise compilation fails with "defined but
not used" error.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
---
 drivers/acpi/apei/ghes.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index b72772494655..8a1029163799 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -1231,6 +1231,7 @@ static int ghes_in_nmi_queue_one_entry(struct ghes *ghes,
 	return rc;
 }
 
+#if defined(CONFIG_HAVE_ACPI_APEI_NMI) || defined(CONFIG_ACPI_APEI_SEA)
 static int ghes_in_nmi_spool_from_list(struct list_head *rcu_list,
 				       enum fixed_addresses fixmap_idx)
 {
@@ -1249,6 +1250,7 @@ static int ghes_in_nmi_spool_from_list(struct list_head *rcu_list,
 
 	return ret;
 }
+#endif
 
 #ifdef CONFIG_ACPI_APEI_SEA
 static LIST_HEAD(ghes_sea);
-- 
2.43.0

[RFC PATCH v1 06/10] 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 <hchauhan@ventanamicro.com>
---
 drivers/firmware/riscv/riscv_sse.c | 147 +++++++++++++++++++++++++++++
 include/linux/riscv_sse.h          |  15 +++
 2 files changed, 162 insertions(+)

diff --git a/drivers/firmware/riscv/riscv_sse.c b/drivers/firmware/riscv/riscv_sse.c
index c165e32cc9a5..511db9ad7a9e 100644
--- a/drivers/firmware/riscv/riscv_sse.c
+++ b/drivers/firmware/riscv/riscv_sse.c
@@ -5,6 +5,8 @@
 
 #define pr_fmt(fmt) "sse: " fmt
 
+#include <acpi/ghes.h>
+#include <linux/acpi.h>
 #include <linux/cpu.h>
 #include <linux/cpuhotplug.h>
 #include <linux/cpu_pm.h>
@@ -689,3 +691,148 @@ 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 *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 *lo_cb,
+		      sse_event_handler *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(sizeof(*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(sizeof(*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_sse.h b/include/linux/riscv_sse.h
index c73184074b8c..16700677f1e8 100644
--- a/include/linux/riscv_sse.h
+++ b/include/linux/riscv_sse.h
@@ -12,6 +12,8 @@
 struct sse_event;
 struct pt_regs;
 
+struct ghes;
+
 typedef int (sse_event_handler)(u32 event_num, void *arg, struct pt_regs *regs);
 
 #ifdef CONFIG_RISCV_SSE
@@ -27,6 +29,9 @@ int sse_event_enable(struct sse_event *sse_evt);
 
 void sse_event_disable(struct sse_event *sse_evt);
 
+int sse_register_ghes(struct ghes *ghes, sse_event_handler *lo_cb,
+		      sse_event_handler *hi_cb);
+int sse_unregister_ghes(struct ghes *ghes);
 #else
 static inline struct sse_event *sse_event_register(u32 event_num, u32 priority,
 						   sse_event_handler *handler,
@@ -50,6 +55,16 @@ static inline int sse_event_enable(struct sse_event *sse_evt)
 
 static inline void sse_event_disable(struct sse_event *sse_evt) {}
 
+static inline int sse_register_ghes(struct ghes *ghes, sse_event_handler *lo_cb,
+				    sse_event_handler *hi_cb)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int sse_unregister_ghes(struct ghes *ghes)
+{
+	return -EOPNOTSUPP;
+}
 
 #endif
 
-- 
2.43.0

[RFC PATCH v1 07/10] riscv: Add RISC-V entries in processor type and ISA strings

[Himanshu Chauhan]

- Add RISCV in processor type
- Add RISCV32/64 in ISA

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.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 b69e68ef3f02..f2908296a48f 100644
--- a/drivers/firmware/efi/cper.c
+++ b/drivers/firmware/efi/cper.c
@@ -110,6 +110,7 @@ static const char * const proc_type_strs[] = {
 	"IA32/X64",
 	"IA64",
 	"ARM",
+	"RISCV",
 };
 
 static const char * const proc_isa_strs[] = {
@@ -118,6 +119,8 @@ static const char * const proc_isa_strs[] = {
 	"X64",
 	"ARM A32/T32",
 	"ARM A64",
+	"RISCV32",
+	"RISCV64",
 };
 
 const char * const cper_proc_error_type_strs[] = {
-- 
2.43.0

[RFC PATCH v1 08/10] riscv: Introduce HEST SSE notification handlers

[Himanshu Chauhan]

- Functions to register a ghes entry with SSE
- Add Handlers for low/high priority events
- Call ghes common handler to handle an error event

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
---
 drivers/acpi/apei/ghes.c | 100 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 89 insertions(+), 11 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 8a1029163799..59abb89d3547 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -17,6 +17,7 @@
  *   Author: Huang Ying <ying.huang@intel.com>
  */
 
+#include <linux/riscv_sse.h>
 #include <linux/arm_sdei.h>
 #include <linux/kernel.h>
 #include <linux/moduleparam.h>
@@ -97,6 +98,11 @@
 #define FIX_APEI_GHES_SDEI_CRITICAL	__end_of_fixed_addresses
 #endif
 
+#ifndef CONFIG_RISCV_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)
@@ -1405,6 +1411,63 @@ 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 -ENOTSUPP; }
+static int apei_sse_unregister_ghes(struct ghes *ghes) { return -ENOTSUPP; }
+#endif
+
 static int ghes_probe(struct platform_device *ghes_dev)
 {
 	struct acpi_hest_generic *generic;
@@ -1451,6 +1514,15 @@ 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 = -ENOTSUPP;
+			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);
@@ -1514,6 +1586,18 @@ 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();
 	}
@@ -1543,7 +1627,6 @@ 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;
 
@@ -1577,16 +1660,11 @@ 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

[RFC PATCH v1 09/10] riscv: Add config option to enable APEI SSE handler

[Himanshu Chauhan]

APEI SSE handlers can be enabled/disabled with this config
option. When enabled, the SSE registration is done for GHES
entries having notification type set to SSE. When disabled,
registration function return not supported error.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
---
 drivers/acpi/apei/Kconfig | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
index 3cfe7e7475f2..be1eaba9b093 100644
--- a/drivers/acpi/apei/Kconfig
+++ b/drivers/acpi/apei/Kconfig
@@ -45,6 +45,11 @@ config ACPI_APEI_SEA
 	depends on ARM64 && ACPI_APEI_GHES
 	default y
 
+config ACPI_APEI_SSE
+	bool
+	depends on RISCV && RISCV_SSE && ACPI_APEI_GHES
+	default y
+
 config ACPI_APEI_MEMORY_FAILURE
 	bool "APEI memory error recovering support"
 	depends on ACPI_APEI && MEMORY_FAILURE
-- 
2.43.0

[RFC PATCH v1 10/10] riscv: Enable APEI and NMI safe cmpxchg options required for RAS

[Himanshu Chauhan]

Enable the APEI option so that APEI GHES options are visible.
Enable SAFE_CMPXCHG option required for GHES error handling.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
---
 arch/riscv/Kconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 7612c52e9b1e..baf97a4f6830 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -54,6 +54,7 @@ config RISCV
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UBSAN
 	select ARCH_HAS_VDSO_TIME_DATA
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_KEEP_MEMBLOCK if ACPI
 	select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE	if 64BIT && MMU
 	select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
@@ -175,6 +176,7 @@ 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

Re: [RFC PATCH v1 00/10] Add RAS support for RISC-V architecture

[Ruidong Tian]

在 2025/2/27 20:36, Himanshu Chauhan 写道:
> This series implements the RAS (Reliability, Availability and Serviceability)
> 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 implemetation has already been merged in OpenSBI. Clement has sent a patch series for
> its implemenation in Linux kernel.[5]
>
> 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
>
> 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] SSE Section in OpenSBI v3.0: https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v3.0-rc3/riscv-sbi.pdf
> [3] Qemu source (with RERI emulation 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: https://lore.kernel.org/linux-riscv/649fdead-09b0-4f94-a6ff-099fc970d890@rivosinc.com/T/

Hi,

Thanks for this series.

I'm doing some work related to your patch. Besides SSE, I'm working on support
for another notification type for synchronous hardware errors (e.g., on a poison
read), which called Hardware Error Exception (HEE) in Dhaval Sharma's UEFI
proposal[0] in PRS-TG.  I have a patch for HEE support which I've sent out
separately[1].

Perhaps we could merge my work into your patchset to bringing a complete RAS
solution to the RISC-V architecture? Or, I'm also happy to wait for your patches
to land and then continue my work on top.

Let me know what you think would be best.

Cheers,
Ruidong Tian

[0]: https://lists.riscv.org/g/tech-prs/topic/risc_v_ras_related_ecrs/113685653
[1]: https://lore.kernel.org/all/20250910093347.75822-6-tianruidong@linux.alibaba.com/

> Himanshu Chauhan (10):
>    riscv: Define ioremap_cache for RISC-V
>    riscv: Define arch_apei_get_mem_attribute for RISC-V
>    acpi: Introduce SSE in HEST notification types
>    riscv: Add fixmap indices for GHES IRQ and SSE contexts
>    riscv: conditionally compile GHES NMI spool function
>    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: Add config option to enable APEI SSE handler
>    riscv: Enable APEI and NMI safe cmpxchg options required for RAS
>
>   arch/riscv/Kconfig                 |   2 +
>   arch/riscv/include/asm/acpi.h      |  20 ++++
>   arch/riscv/include/asm/fixmap.h    |   8 ++
>   arch/riscv/include/asm/io.h        |   3 +
>   drivers/acpi/apei/Kconfig          |   5 +
>   drivers/acpi/apei/ghes.c           | 102 +++++++++++++++++---
>   drivers/firmware/efi/cper.c        |   3 +
>   drivers/firmware/riscv/riscv_sse.c | 147 +++++++++++++++++++++++++++++
>   include/acpi/actbl1.h              |   3 +-
>   include/linux/riscv_sse.h          |  15 +++
>   10 files changed, 296 insertions(+), 12 deletions(-)
>