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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 88F0F80003 X-Stat-Signature: 39yfzkjqttwqrqx5t49gdt6dmntkdthb X-Rspam-User: X-HE-Tag: 1701408157-613426 X-HE-Meta: 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 J3/r0AFf kVZDYpPiJtU4qgw3dulerEevP+2ayo75NU/uvLYM8zhD0DKZmWWXMDghjlNsxHUxCQxPB/+ar5C35b7/yuPxos8KHL6er78hcW9ubFT+6VCqUl1OSRfsue4JmjBoOi6sq8JDk2be6Pw9wRZ+VEJ2WEALdh7xJGJGPHmjl16WqJ8xSJdnc4t+gIUZ0RP0ViHVHUJuvowGmkiPl3LE6o1Wr5Hg2Uw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2023/12/1 01:39, James Morse wrote: > Hi Shuai, > > On 07/10/2023 08:28, Shuai Xue wrote: >> There are two major types of uncorrected recoverable (UCR) errors : > > Is UCR a well known x86 acronym? It's best to just spell this out each time, > there is enough jargon in this area already. Quite agreed, will replace the commit log with "uncorrected recoverable error". > >> >> - Action Required (AR): The error is detected and the processor already >> consumes the memory. OS requires to take action (for example, offline >> failure page/kill failure thread) to recover this uncorrectable error. >> >> - Action Optional (AO): The error is detected out of processor execution >> context. Some data in the memory are corrupted. But the data have not >> been consumed. OS is optional to take action to recover this >> uncorrectable error. > > As elsewhere, please don't think of errors as 'action required', this is how > things get reported to user-space. Action-required for one thread may be > action-optional for another that has the same page mapped - its really not a > property of the error. > It would be better to describe this as synchronous and asynchronous, or in-band > and out-of-band. Thank you for explanation. I will change to "synchronous and asynchronous". > > >> The essential difference between AR and AO errors is that AR is a >> synchronous event, while AO is an asynchronous event. The hardware will >> signal a synchronous exception (Machine Check Exception on X86 and >> Synchronous External Abort on Arm64) when an error is detected and the >> memory access has been architecturally executed. > >> When APEI firmware first is enabled, a platform may describe one error >> source for the handling of synchronous errors (e.g. MCE or SEA notification >> ), or for handling asynchronous errors (e.g. SCI or External Interrupt >> notification). In other words, we can distinguish synchronous errors by >> APEI notification. For AR errors, kernel will kill current process >> accessing the poisoned page by sending SIGBUS with BUS_MCEERR_AR. In >> addition, for AO errors, kernel will notify the process who owns the >> poisoned page by sending SIGBUS with BUS_MCEERR_AO in early kill mode. >> However, the GHES driver always sets mf_flags to 0 so that all UCR errors >> are handled as AO errors in memory failure. > > To make this easier to read: > UCR and AR -> synchronous > AO -> asynchronous > Will do that. > >> To this end, set memory failure flags as MF_ACTION_REQUIRED on synchronous >> events. > >> Fixes: ba61ca4aab47 ("ACPI, APEI, GHES: Add hardware memory error recovery support")' > > Erm, this predates arm64 support, and what you have here doesn't change the behaviour on x86. > > You can blame 7f17b4a121d0d50 ("ACPI: APEI: Kick the memory_failure() queue for > synchronous errors"), which should have covered this. Do you mean just drop the "Fixes" tags? > >> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c >> index ef59d6ea16da..88178aa6222d 100644 >> --- a/drivers/acpi/apei/ghes.c >> +++ b/drivers/acpi/apei/ghes.c >> @@ -101,6 +101,20 @@ static inline bool is_hest_type_generic_v2(struct ghes *ghes) >> return ghes->generic->header.type == ACPI_HEST_TYPE_GENERIC_ERROR_V2; >> } >> >> +/* >> + * A platform may describe one error source for the handling of synchronous >> + * errors (e.g. MCE or SEA), or for handling asynchronous errors (e.g. SCI >> + * or External Interrupt). On x86, the HEST notifications are always >> + * asynchronous, so only SEA on ARM is delivered as a synchronous >> + * notification. >> + */ >> +static inline bool is_hest_sync_notify(struct ghes *ghes) >> +{ >> + u8 notify_type = ghes->generic->notify.type; >> + >> + return notify_type == ACPI_HEST_NOTIFY_SEA; >> +} > > and as you had in earlier versions, sometimes SDEI. > SDEI can report by synchronous and asynchronous errors, I wouldn't too surprised if the > hardware NMI can be used for the same. It would be good to chase up having a hint of this > in the CPER records and pass that in here as a hint.> > Unfortunately, its not safe to assume either way for SDEI. For SDEI notification, only x0-x17 has preserved by firmware. As SDEI TRM[1] describes "the dispatcher can simulate an exception-like entry into the client, **with the client providing an additional asynchronous entry point similar to an interrupt entry point**". The client (kernel) lacks complete synchronous context, e.g. system register (ELR, ESR, etc). So I think SDEI notification should not be used for asynchronous error, can you help to confirm this? For NMI notification, as far as I know, AArch64 (aka arm64 in the Linux tree) does not provide architected NMIs. > > Reviewed-by: James Morse > Thank you for valuable comments. Best Regards, Shuai [1] https://developer.arm.com/documentation/den0054/latest/