linux-kernel - Re: [BUG] kernel side can NOT trigger memory error with einj

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Message-ID: <78cefd4c-f735-2ec4-0c09-35c8191280c5@linux.alibaba.com>
Date:   Sun, 20 Mar 2022 21:11:58 +0800
From:   Shuai Xue <xueshuai@...ux.alibaba.com>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "james.morse@....com" <james.morse@....com>,
        "bp@...en8.de" <bp@...en8.de>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "graeme.gregory@...aro.org" <graeme.gregory@...aro.org>,
        "will.deacon@....com" <will.deacon@....com>,
        "myron.stowe@...hat.com" <myron.stowe@...hat.com>,
        "Brown, Len" <len.brown@...el.com>,
        "Huang, Ying" <ying.huang@...el.com>
Subject: Re: [BUG] kernel side can NOT trigger memory error with einj

在 2022/3/18 AM12:57, Luck, Tony 写道:
>> -       rc = apei_exec_run(&trigger_ctx, ACPI_EINJ_TRIGGER_ERROR);
>> +       ptr = kmap(pfn_to_page(pfn));
>> +       tmp = *(ptr + (param1 & ~ PAGE_MASK));
> 
> That hack works when the trigger action is just trying to access the injected
> location. But on Intel platforms the trigger "kicks" the patrol scrubber in the
> memory controller to access the address. So the error is triggered not by
> an access from the core, but by internal memory controller access.
> 
> This results in a different error signature (for an uncorrected error injection
> it will be a UCNA or SRAO in Intel acronym-speak).

As far as I know, APEI only defines five injection instructions, ACPI_EINJ_READ_REGISTER,
ACPI_EINJ_READ_REGISTER_VALUE, ACPI_EINJ_WRITE_REGISTER, ACPI_EINJ_WRITE_REGISTER_VALUE and
ACPI_EINJ_NOOP. ACPI_EINJ_TRIGGER_ERROR action should run one of them, I don't see
any of them will kick the patrol scrubber. For example, trigger with ACPI_EINJ_READ_REGISTER:

apei_exec_run(&trigger_ctx, ACPI_EINJ_TRIGGER_ERROR)
    __apei_exec_run	// ins=0
        => apei_exec_read_register
            => apei_read
                => acpi_os_read_memory
                    => acpi_map_vaddr_lookup    /* lookup VA of PA from acpi_ioremap */
                    => acpi_os_ioremap
		    => acpi_os_read_iomem
			=> *(u32 *) value = readl(virt_addr);

As we can see, the error is triggered by access from the core. However, the physical
address can NOT be mapped by acpi_os_ioremap.

If I missed anything, please let me know. Thank you very much.

Best Regards,
Shuai