diff mbox

[V15,06/11] acpi: apei: handle SEA notification type for ARMv8

Message ID 1492556723-9189-7-git-send-email-tbaicar@codeaurora.org (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Tyler Baicar April 18, 2017, 11:05 p.m. UTC
ARM APEI extension proposal added SEA (Synchronous External Abort)
notification type for ARMv8.
Add a new GHES error source handling function for SEA. If an error
source's notification type is SEA, then this function can be registered
into the SEA exception handler. That way GHES will parse and report
SEA exceptions when they occur.
An SEA can interrupt code that had interrupts masked and is treated as
an NMI. To aid this the page of address space for mapping APEI buffers
while in_nmi() is always reserved, and ghes_ioremap_pfn_nmi() is
changed to use the helper methods to find the prot_t to map with in
the same way as ghes_ioremap_pfn_irq().

Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org>
CC: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
Reviewed-by: James Morse <james.morse@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/Kconfig        |  2 ++
 arch/arm64/mm/fault.c     | 13 +++++++++
 drivers/acpi/apei/Kconfig | 15 ++++++++++
 drivers/acpi/apei/ghes.c  | 70 +++++++++++++++++++++++++++++++++++++++++++----
 include/acpi/ghes.h       |  7 +++++
 5 files changed, 101 insertions(+), 6 deletions(-)

Comments

Borislav Petkov April 25, 2017, 5:21 p.m. UTC | #1
On Tue, Apr 18, 2017 at 05:05:18PM -0600, Tyler Baicar wrote:
> ARM APEI extension proposal added SEA (Synchronous External Abort)
> notification type for ARMv8.
> Add a new GHES error source handling function for SEA. If an error
> source's notification type is SEA, then this function can be registered
> into the SEA exception handler. That way GHES will parse and report
> SEA exceptions when they occur.
> An SEA can interrupt code that had interrupts masked and is treated as
> an NMI. To aid this the page of address space for mapping APEI buffers
> while in_nmi() is always reserved, and ghes_ioremap_pfn_nmi() is
> changed to use the helper methods to find the prot_t to map with in
> the same way as ghes_ioremap_pfn_irq().

...

> @@ -518,6 +520,17 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>  	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
>  		inf->name, esr, addr);
>  
> +	/*
> +	 * Synchronous aborts may interrupt code which had interrupts masked.
> +	 * Before calling out into the wider kernel tell the interested
> +	 * subsystems.
> +	 */
> +	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
> +		nmi_enter();
> +		ghes_notify_sea();
> +		nmi_exit();
> +	}

Well, the other GHES notification methods use a notifier:
ghes_notify_sci, ghes_notify_nmi. You probably should do that too
instead of calling straight into a driver from arch code.
Tyler Baicar April 25, 2017, 5:41 p.m. UTC | #2
On 4/25/2017 11:21 AM, Borislav Petkov wrote:
> On Tue, Apr 18, 2017 at 05:05:18PM -0600, Tyler Baicar wrote:
>> ARM APEI extension proposal added SEA (Synchronous External Abort)
>> notification type for ARMv8.
>> Add a new GHES error source handling function for SEA. If an error
>> source's notification type is SEA, then this function can be registered
>> into the SEA exception handler. That way GHES will parse and report
>> SEA exceptions when they occur.
>> An SEA can interrupt code that had interrupts masked and is treated as
>> an NMI. To aid this the page of address space for mapping APEI buffers
>> while in_nmi() is always reserved, and ghes_ioremap_pfn_nmi() is
>> changed to use the helper methods to find the prot_t to map with in
>> the same way as ghes_ioremap_pfn_irq().
> ...
>
>> @@ -518,6 +520,17 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>>   	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
>>   		inf->name, esr, addr);
>>   
>> +	/*
>> +	 * Synchronous aborts may interrupt code which had interrupts masked.
>> +	 * Before calling out into the wider kernel tell the interested
>> +	 * subsystems.
>> +	 */
>> +	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
>> +		nmi_enter();
>> +		ghes_notify_sea();
>> +		nmi_exit();
>> +	}
> Well, the other GHES notification methods use a notifier:
> ghes_notify_sci, ghes_notify_nmi. You probably should do that too
> instead of calling straight into a driver from arch code.
I originally had this as a notifier, but Will requested to remove the 
notifier. That conversation is here: https://lkml.org/lkml/2017/1/18/1018

Thanks,
Tyler
Borislav Petkov April 25, 2017, 5:46 p.m. UTC | #3
On Tue, Apr 25, 2017 at 11:41:39AM -0600, Baicar, Tyler wrote:
> I originally had this as a notifier, but Will requested to remove the
> notifier. That conversation is here: https://lkml.org/lkml/2017/1/18/1018

Yeah, he mentioned on IRC. I just think notifiers would be the cleaner
thing but whatever you guys say.

Just we had a nasty hack on x86 which I got rid of recently:

https://lkml.kernel.org/r/20170406090634.30950-1-bp@alien8.de

and I wouldn't want you guys to have the same "fun". :)
James Morse May 8, 2017, 5:28 p.m. UTC | #4
Hi Tyler,

On 19/04/17 00:05, Tyler Baicar wrote:
> ARM APEI extension proposal added SEA (Synchronous External Abort)
> notification type for ARMv8.
> Add a new GHES error source handling function for SEA. If an error
> source's notification type is SEA, then this function can be registered
> into the SEA exception handler. That way GHES will parse and report
> SEA exceptions when they occur.
> An SEA can interrupt code that had interrupts masked and is treated as
> an NMI. To aid this the page of address space for mapping APEI buffers
> while in_nmi() is always reserved, and ghes_ioremap_pfn_nmi() is
> changed to use the helper methods to find the prot_t to map with in
> the same way as ghes_ioremap_pfn_irq().

> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index b74d8b7..10013ff 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -518,6 +520,17 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>  	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
>  		inf->name, esr, addr);
>  
> +	/*
> +	 * Synchronous aborts may interrupt code which had interrupts masked.
> +	 * Before calling out into the wider kernel tell the interested
> +	 * subsystems.
> +	 */
> +	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
> +		nmi_enter();
> +		ghes_notify_sea();
> +		nmi_exit();
> +	}
> +
>  	info.si_signo = SIGBUS;
>  	info.si_errno = 0;
>  	info.si_code  = 0;


I was tidying up the masking/unmasking in entry.S, something I wasn't aware of
that leads to a bug:
entry.S will unmask interrupts for instruction/data aborts that came from a
context with interrupts enabled. This makes sense for get_user() and friends...
For do_sea() we pull nmi_enter() as this can interrupt interrupts-masked code,
such as APEI, but if we end up in here with interrupts unmasked we can take an
IRQ from this 'NMI' context, which will inherit the in_nmi() and could lead to
the deadlock we were originally trying to avoid.

Teaching entry.S to spot external aborts is messy. I think the two choices are
to either mask interrupts when calling nmi_enter() (as these things should be
mutually exclusive), or to conditionally call nmi_enter() based on
interrupts_enabled(regs). I prefer the second one as it matches the notify_sea()
while interruptible that happens when KVM takes one of these.



Thanks,

James
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Tyler Baicar May 8, 2017, 7:59 p.m. UTC | #5
On 5/8/2017 11:28 AM, James Morse wrote:
> Hi Tyler,
>
> On 19/04/17 00:05, Tyler Baicar wrote:
>> ARM APEI extension proposal added SEA (Synchronous External Abort)
>> notification type for ARMv8.
>> Add a new GHES error source handling function for SEA. If an error
>> source's notification type is SEA, then this function can be registered
>> into the SEA exception handler. That way GHES will parse and report
>> SEA exceptions when they occur.
>> An SEA can interrupt code that had interrupts masked and is treated as
>> an NMI. To aid this the page of address space for mapping APEI buffers
>> while in_nmi() is always reserved, and ghes_ioremap_pfn_nmi() is
>> changed to use the helper methods to find the prot_t to map with in
>> the same way as ghes_ioremap_pfn_irq().
>> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
>> index b74d8b7..10013ff 100644
>> --- a/arch/arm64/mm/fault.c
>> +++ b/arch/arm64/mm/fault.c
>> @@ -518,6 +520,17 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>>   	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
>>   		inf->name, esr, addr);
>>   
>> +	/*
>> +	 * Synchronous aborts may interrupt code which had interrupts masked.
>> +	 * Before calling out into the wider kernel tell the interested
>> +	 * subsystems.
>> +	 */
>> +	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
>> +		nmi_enter();
>> +		ghes_notify_sea();
>> +		nmi_exit();
>> +	}
>> +
>>   	info.si_signo = SIGBUS;
>>   	info.si_errno = 0;
>>   	info.si_code  = 0;
>
> I was tidying up the masking/unmasking in entry.S, something I wasn't aware of
> that leads to a bug:
> entry.S will unmask interrupts for instruction/data aborts that came from a
> context with interrupts enabled. This makes sense for get_user() and friends...
> For do_sea() we pull nmi_enter() as this can interrupt interrupts-masked code,
> such as APEI, but if we end up in here with interrupts unmasked we can take an
> IRQ from this 'NMI' context, which will inherit the in_nmi() and could lead to
> the deadlock we were originally trying to avoid.
>
> Teaching entry.S to spot external aborts is messy. I think the two choices are
> to either mask interrupts when calling nmi_enter() (as these things should be
> mutually exclusive), or to conditionally call nmi_enter() based on
> interrupts_enabled(regs). I prefer the second one as it matches the notify_sea()
> while interruptible that happens when KVM takes one of these.
Hello James,

So it would need to be like this?

         if(interrupts_enabled(regs))
             nmi_enter();
         ghes_notify_sea();
         if(interrupts_enabled(regs))
             nmi_exit();

Thanks,
Tyler
James Morse May 12, 2017, 4:45 p.m. UTC | #6
Hi Tyler,

On 08/05/17 20:59, Baicar, Tyler wrote:
> On 5/8/2017 11:28 AM, James Morse wrote:
>> I was tidying up the masking/unmasking in entry.S, something I wasn't aware of
>> that leads to a bug:
>> entry.S will unmask interrupts for instruction/data aborts that came from a
>> context with interrupts enabled. This makes sense for get_user() and friends...
>> For do_sea() we pull nmi_enter() as this can interrupt interrupts-masked code,
>> such as APEI, but if we end up in here with interrupts unmasked we can take an
>> IRQ from this 'NMI' context, which will inherit the in_nmi() and could lead to
>> the deadlock we were originally trying to avoid.
>>
>> Teaching entry.S to spot external aborts is messy. I think the two choices are
>> to either mask interrupts when calling nmi_enter() (as these things should be
>> mutually exclusive), or to conditionally call nmi_enter() based on
>> interrupts_enabled(regs). I prefer the second one as it matches the notify_sea()
>> while interruptible that happens when KVM takes one of these.

Thinking about this some more: the KVM case is different as we know it was a
guest that triggered the external abort. Nothing the host kernel does is likely
to trigger either the same error or a related one.

But I can't think of a way this would trip twice on the host... yes your
suggestion looks fine.

(When we add SError/SEI support too we will need to change it as SEA may
interrupt SEI, and nmi_enter() has a BUG_ON(in_nmi()), so this nesting will need
explicitly checking.)


Thanks,

James

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Xiongfeng Wang Aug. 14, 2017, 7:55 a.m. UTC | #7
Hi Tyler,

On 2017/4/19 7:05, Tyler Baicar wrote:
> ARM APEI extension proposal added SEA (Synchronous External Abort)
> notification type for ARMv8.
> Add a new GHES error source handling function for SEA. If an error
> source's notification type is SEA, then this function can be registered
> into the SEA exception handler. That way GHES will parse and report
> SEA exceptions when they occur.
> An SEA can interrupt code that had interrupts masked and is treated as
> an NMI. To aid this the page of address space for mapping APEI buffers
> while in_nmi() is always reserved, and ghes_ioremap_pfn_nmi() is
> changed to use the helper methods to find the prot_t to map with in
> the same way as ghes_ioremap_pfn_irq().
> 
> Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org>
> CC: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
> Reviewed-by: James Morse <james.morse@arm.com>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> ---

> @@ -518,6 +520,17 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>  	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
>  		inf->name, esr, addr);
>  
> +	/*
> +	 * Synchronous aborts may interrupt code which had interrupts masked.
> +	 * Before calling out into the wider kernel tell the interested
> +	 * subsystems.
> +	 */
> +	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
> +		nmi_enter();
> +		ghes_notify_sea();
> +		nmi_exit();
> +	}
> +
>  	info.si_signo = SIGBUS;
>  	info.si_errno = 0;
>  	info.si_code  = 0;
For instruction abort, if there exists memory section in ghes, we will call memory_failure() in ghes_notify_sea()
and reread the instruction from the disk. In this case, we don't have to send SIGBUS to the application.
But memory_failure() is scheduled in a work queue, we don't what the result of memory_failure will be when ghes_notify_sea() returned.
Do you have any idea about how to fix this, so we don't have to kill the application in the instruction abort case.

Thanks,
Wang Xiongfeng


> diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
> index b0140c8..de14d49 100644
> --- a/drivers/acpi/apei/Kconfig
> +++ b/drivers/acpi/apei/Kconfig
> @@ -39,6 +39,21 @@ config ACPI_APEI_PCIEAER
>  	  PCIe AER errors may be reported via APEI firmware first mode.
>  	  Turn on this option to enable the corresponding support.
>  
> +config ACPI_APEI_SEA
> +	bool "APEI Synchronous External Abort logging/recovering support"
> +	depends on ARM64 && ACPI_APEI_GHES
> +	default y
> +	help
> +	  This option should be enabled if the system supports
> +	  firmware first handling of SEA (Synchronous External Abort).
> +	  SEA happens with certain faults of data abort or instruction
> +	  abort synchronous exceptions on ARMv8 systems. If a system
> +	  supports firmware first handling of SEA, the platform analyzes
> +	  and handles hardware error notifications from SEA, and it may then
> +	  form a HW error record for the OS to parse and handle. This
> +	  option allows the OS to look for such hardware error record, and
> +	  take appropriate action.
> +
>  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 dfb7dd2..2d387f8 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -115,11 +115,7 @@
>   * Two virtual pages are used, one for IRQ/PROCESS context, the other for
>   * NMI context (optionally).
>   */
> -#ifdef CONFIG_HAVE_ACPI_APEI_NMI
>  #define GHES_IOREMAP_PAGES           2
> -#else
> -#define GHES_IOREMAP_PAGES           1
> -#endif
>  #define GHES_IOREMAP_IRQ_PAGE(base)	(base)
>  #define GHES_IOREMAP_NMI_PAGE(base)	((base) + PAGE_SIZE)
>  
> @@ -158,10 +154,14 @@ static void ghes_ioremap_exit(void)
>  static void __iomem *ghes_ioremap_pfn_nmi(u64 pfn)
>  {
>  	unsigned long vaddr;
> +	phys_addr_t paddr;
> +	pgprot_t prot;
>  
>  	vaddr = (unsigned long)GHES_IOREMAP_NMI_PAGE(ghes_ioremap_area->addr);
> -	ioremap_page_range(vaddr, vaddr + PAGE_SIZE,
> -			   pfn << PAGE_SHIFT, PAGE_KERNEL);
> +
> +	paddr = pfn << PAGE_SHIFT;
> +	prot = arch_apei_get_mem_attribute(paddr);
> +	ioremap_page_range(vaddr, vaddr + PAGE_SIZE, paddr, prot);
>  
>  	return (void __iomem *)vaddr;
>  }
> @@ -771,6 +771,50 @@ static int ghes_notify_sci(struct notifier_block *this,
>  	.notifier_call = ghes_notify_sci,
>  };
>  
> +#ifdef CONFIG_ACPI_APEI_SEA
> +static LIST_HEAD(ghes_sea);
> +
> +void ghes_notify_sea(void)
> +{
> +	struct ghes *ghes;
> +
> +	/*
> +	 * synchronize_rcu() will wait for nmi_exit(), so no need to
> +	 * rcu_read_lock().
> +	 */
> +	list_for_each_entry_rcu(ghes, &ghes_sea, list) {
> +		ghes_proc(ghes);
> +	}
> +}
> +
> +static void ghes_sea_add(struct ghes *ghes)
> +{
> +	mutex_lock(&ghes_list_mutex);
> +	list_add_rcu(&ghes->list, &ghes_sea);
> +	mutex_unlock(&ghes_list_mutex);
> +}
> +
> +static void ghes_sea_remove(struct ghes *ghes)
> +{
> +	mutex_lock(&ghes_list_mutex);
> +	list_del_rcu(&ghes->list);
> +	mutex_unlock(&ghes_list_mutex);
> +	synchronize_rcu();
> +}
> +#else /* CONFIG_ACPI_APEI_SEA */
> +static inline void ghes_sea_add(struct ghes *ghes)
> +{
> +	pr_err(GHES_PFX "ID: %d, trying to add SEA notification which is not supported\n",
> +	       ghes->generic->header.source_id);
> +}
> +
> +static inline void ghes_sea_remove(struct ghes *ghes)
> +{
> +	pr_err(GHES_PFX "ID: %d, trying to remove SEA notification which is not supported\n",
> +	       ghes->generic->header.source_id);
> +}
> +#endif /* CONFIG_ACPI_APEI_SEA */
> +
>  #ifdef CONFIG_HAVE_ACPI_APEI_NMI
>  /*
>   * printk is not safe in NMI context.  So in NMI handler, we allocate
> @@ -1016,6 +1060,14 @@ static int ghes_probe(struct platform_device *ghes_dev)
>  	case ACPI_HEST_NOTIFY_EXTERNAL:
>  	case ACPI_HEST_NOTIFY_SCI:
>  		break;
> +	case ACPI_HEST_NOTIFY_SEA:
> +		if (!IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
> +			pr_warn(GHES_PFX "Generic hardware error source: %d notified via SEA is not supported\n",
> +				generic->header.source_id);
> +			rc = -ENOTSUPP;
> +			goto err;
> +		}
> +		break;
>  	case ACPI_HEST_NOTIFY_NMI:
>  		if (!IS_ENABLED(CONFIG_HAVE_ACPI_APEI_NMI)) {
>  			pr_warn(GHES_PFX "Generic hardware error source: %d notified via NMI interrupt is not supported!\n",
> @@ -1081,6 +1133,9 @@ static int ghes_probe(struct platform_device *ghes_dev)
>  		list_add_rcu(&ghes->list, &ghes_sci);
>  		mutex_unlock(&ghes_list_mutex);
>  		break;
> +	case ACPI_HEST_NOTIFY_SEA:
> +		ghes_sea_add(ghes);
> +		break;
>  	case ACPI_HEST_NOTIFY_NMI:
>  		ghes_nmi_add(ghes);
>  		break;
> @@ -1124,6 +1179,9 @@ static int ghes_remove(struct platform_device *ghes_dev)
>  		mutex_unlock(&ghes_list_mutex);
>  		synchronize_rcu();
>  		break;
> +	case ACPI_HEST_NOTIFY_SEA:
> +		ghes_sea_remove(ghes);
> +		break;
>  	case ACPI_HEST_NOTIFY_NMI:
>  		ghes_nmi_remove(ghes);
>  		break;
> diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
> index b89361a..ef0040893 100644
> --- a/include/acpi/ghes.h
> +++ b/include/acpi/ghes.h
> @@ -1,3 +1,6 @@
> +#ifndef GHES_H
> +#define GHES_H
> +
>  #include <acpi/apei.h>
>  #include <acpi/hed.h>
>  
> @@ -95,3 +98,7 @@ static inline void *acpi_hest_get_payload(struct acpi_hest_generic_data *gdata)
>  
>  	return gdata + 1;
>  }
> +
> +void ghes_notify_sea(void);
> +
> +#endif /* GHES_H */
> 

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diff mbox

Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 3741859..36226c2 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -18,6 +18,7 @@  config ARM64
 	select ARCH_HAS_STRICT_KERNEL_RWX
 	select ARCH_HAS_STRICT_MODULE_RWX
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG if ACPI_APEI_SEA
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_SUPPORTS_NUMA_BALANCING
@@ -92,6 +93,7 @@  config ARM64
 	select HAVE_IRQ_TIME_ACCOUNTING
 	select HAVE_MEMBLOCK
 	select HAVE_MEMBLOCK_NODE_MAP if NUMA
+	select HAVE_NMI if ACPI_APEI_SEA
 	select HAVE_PATA_PLATFORM
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index b74d8b7..10013ff 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -42,6 +42,8 @@ 
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 
+#include <acpi/ghes.h>
+
 struct fault_info {
 	int	(*fn)(unsigned long addr, unsigned int esr,
 		      struct pt_regs *regs);
@@ -518,6 +520,17 @@  static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
 		inf->name, esr, addr);
 
+	/*
+	 * Synchronous aborts may interrupt code which had interrupts masked.
+	 * Before calling out into the wider kernel tell the interested
+	 * subsystems.
+	 */
+	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
+		nmi_enter();
+		ghes_notify_sea();
+		nmi_exit();
+	}
+
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code  = 0;
diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
index b0140c8..de14d49 100644
--- a/drivers/acpi/apei/Kconfig
+++ b/drivers/acpi/apei/Kconfig
@@ -39,6 +39,21 @@  config ACPI_APEI_PCIEAER
 	  PCIe AER errors may be reported via APEI firmware first mode.
 	  Turn on this option to enable the corresponding support.
 
+config ACPI_APEI_SEA
+	bool "APEI Synchronous External Abort logging/recovering support"
+	depends on ARM64 && ACPI_APEI_GHES
+	default y
+	help
+	  This option should be enabled if the system supports
+	  firmware first handling of SEA (Synchronous External Abort).
+	  SEA happens with certain faults of data abort or instruction
+	  abort synchronous exceptions on ARMv8 systems. If a system
+	  supports firmware first handling of SEA, the platform analyzes
+	  and handles hardware error notifications from SEA, and it may then
+	  form a HW error record for the OS to parse and handle. This
+	  option allows the OS to look for such hardware error record, and
+	  take appropriate action.
+
 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 dfb7dd2..2d387f8 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -115,11 +115,7 @@ 
  * Two virtual pages are used, one for IRQ/PROCESS context, the other for
  * NMI context (optionally).
  */
-#ifdef CONFIG_HAVE_ACPI_APEI_NMI
 #define GHES_IOREMAP_PAGES           2
-#else
-#define GHES_IOREMAP_PAGES           1
-#endif
 #define GHES_IOREMAP_IRQ_PAGE(base)	(base)
 #define GHES_IOREMAP_NMI_PAGE(base)	((base) + PAGE_SIZE)
 
@@ -158,10 +154,14 @@  static void ghes_ioremap_exit(void)
 static void __iomem *ghes_ioremap_pfn_nmi(u64 pfn)
 {
 	unsigned long vaddr;
+	phys_addr_t paddr;
+	pgprot_t prot;
 
 	vaddr = (unsigned long)GHES_IOREMAP_NMI_PAGE(ghes_ioremap_area->addr);
-	ioremap_page_range(vaddr, vaddr + PAGE_SIZE,
-			   pfn << PAGE_SHIFT, PAGE_KERNEL);
+
+	paddr = pfn << PAGE_SHIFT;
+	prot = arch_apei_get_mem_attribute(paddr);
+	ioremap_page_range(vaddr, vaddr + PAGE_SIZE, paddr, prot);
 
 	return (void __iomem *)vaddr;
 }
@@ -771,6 +771,50 @@  static int ghes_notify_sci(struct notifier_block *this,
 	.notifier_call = ghes_notify_sci,
 };
 
+#ifdef CONFIG_ACPI_APEI_SEA
+static LIST_HEAD(ghes_sea);
+
+void ghes_notify_sea(void)
+{
+	struct ghes *ghes;
+
+	/*
+	 * synchronize_rcu() will wait for nmi_exit(), so no need to
+	 * rcu_read_lock().
+	 */
+	list_for_each_entry_rcu(ghes, &ghes_sea, list) {
+		ghes_proc(ghes);
+	}
+}
+
+static void ghes_sea_add(struct ghes *ghes)
+{
+	mutex_lock(&ghes_list_mutex);
+	list_add_rcu(&ghes->list, &ghes_sea);
+	mutex_unlock(&ghes_list_mutex);
+}
+
+static void ghes_sea_remove(struct ghes *ghes)
+{
+	mutex_lock(&ghes_list_mutex);
+	list_del_rcu(&ghes->list);
+	mutex_unlock(&ghes_list_mutex);
+	synchronize_rcu();
+}
+#else /* CONFIG_ACPI_APEI_SEA */
+static inline void ghes_sea_add(struct ghes *ghes)
+{
+	pr_err(GHES_PFX "ID: %d, trying to add SEA notification which is not supported\n",
+	       ghes->generic->header.source_id);
+}
+
+static inline void ghes_sea_remove(struct ghes *ghes)
+{
+	pr_err(GHES_PFX "ID: %d, trying to remove SEA notification which is not supported\n",
+	       ghes->generic->header.source_id);
+}
+#endif /* CONFIG_ACPI_APEI_SEA */
+
 #ifdef CONFIG_HAVE_ACPI_APEI_NMI
 /*
  * printk is not safe in NMI context.  So in NMI handler, we allocate
@@ -1016,6 +1060,14 @@  static int ghes_probe(struct platform_device *ghes_dev)
 	case ACPI_HEST_NOTIFY_EXTERNAL:
 	case ACPI_HEST_NOTIFY_SCI:
 		break;
+	case ACPI_HEST_NOTIFY_SEA:
+		if (!IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
+			pr_warn(GHES_PFX "Generic hardware error source: %d notified via SEA is not supported\n",
+				generic->header.source_id);
+			rc = -ENOTSUPP;
+			goto err;
+		}
+		break;
 	case ACPI_HEST_NOTIFY_NMI:
 		if (!IS_ENABLED(CONFIG_HAVE_ACPI_APEI_NMI)) {
 			pr_warn(GHES_PFX "Generic hardware error source: %d notified via NMI interrupt is not supported!\n",
@@ -1081,6 +1133,9 @@  static int ghes_probe(struct platform_device *ghes_dev)
 		list_add_rcu(&ghes->list, &ghes_sci);
 		mutex_unlock(&ghes_list_mutex);
 		break;
+	case ACPI_HEST_NOTIFY_SEA:
+		ghes_sea_add(ghes);
+		break;
 	case ACPI_HEST_NOTIFY_NMI:
 		ghes_nmi_add(ghes);
 		break;
@@ -1124,6 +1179,9 @@  static int ghes_remove(struct platform_device *ghes_dev)
 		mutex_unlock(&ghes_list_mutex);
 		synchronize_rcu();
 		break;
+	case ACPI_HEST_NOTIFY_SEA:
+		ghes_sea_remove(ghes);
+		break;
 	case ACPI_HEST_NOTIFY_NMI:
 		ghes_nmi_remove(ghes);
 		break;
diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
index b89361a..ef0040893 100644
--- a/include/acpi/ghes.h
+++ b/include/acpi/ghes.h
@@ -1,3 +1,6 @@ 
+#ifndef GHES_H
+#define GHES_H
+
 #include <acpi/apei.h>
 #include <acpi/hed.h>
 
@@ -95,3 +98,7 @@  static inline void *acpi_hest_get_payload(struct acpi_hest_generic_data *gdata)
 
 	return gdata + 1;
 }
+
+void ghes_notify_sea(void);
+
+#endif /* GHES_H */