Commit 22cda7c1 authored by Oliver O'Halloran's avatar Oliver O'Halloran Committed by Michael Ellerman
Browse files

powerpc/eeh: Add debugfs interface to run an EEH check 



Detecting an frozen EEH PE usually occurs when an MMIO load returns a 0xFFs
response. When performing EEH testing using the EEH error injection feature
available on some platforms there is no simple way to kick-off the kernel's
recovery process since any accesses from userspace (usually /dev/mem) will
bypass the MMIO helpers in the kernel which check if a 0xFF response is due
to an EEH freeze or not.

If a device contains a 0xFF byte in it's config space it's possible to
trigger the recovery process via config space read from userspace, but this
is not a reliable method. If a driver is bound to the device an in use it
will frequently trigger the MMIO check, but this is also inconsistent.

To solve these problems this patch adds a debugfs file called
"eeh_dev_check" which accepts a <domain>:<bus>:<dev>.<fn> string and runs
eeh_dev_check_failure() on it. This is the same check that's done when the
kernel gets a 0xFF result from an config or MMIO read with the added
benifit that it can be reliably triggered from userspace.

Signed-off-by: default avatarOliver O'Halloran <oohall@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190903101605.2890-13-oohall@gmail.com
parent aeff27c1

arch/powerpc/kernel/eeh.c

+61 −0
Original line number Diff line number Diff line
@@ -1871,6 +1871,64 @@ static const struct file_operations eeh_force_recover_fops = { 
	.llseek	= no_llseek,

	.write	= eeh_force_recover_write,

};



static ssize_t eeh_debugfs_dev_usage(struct file *filp,

				char __user *user_buf,

				size_t count, loff_t *ppos)

{

	static const char usage[] = "input format: <domain>:<bus>:<dev>.<fn>\n";



	return simple_read_from_buffer(user_buf, count, ppos,

				       usage, sizeof(usage) - 1);

}



static ssize_t eeh_dev_check_write(struct file *filp,

				const char __user *user_buf,

				size_t count, loff_t *ppos)

{

	uint32_t domain, bus, dev, fn;

	struct pci_dev *pdev;

	struct eeh_dev *edev;

	char buf[20];

	int ret;



	ret = simple_write_to_buffer(buf, sizeof(buf), ppos, user_buf, count);

	if (!ret)

		return -EFAULT;



	ret = sscanf(buf, "%x:%x:%x.%x", &domain, &bus, &dev, &fn);

	if (ret != 4) {

		pr_err("%s: expected 4 args, got %d\n", __func__, ret);

		return -EINVAL;

	}



	pdev = pci_get_domain_bus_and_slot(domain, bus, (dev << 3) | fn);

	if (!pdev)

		return -ENODEV;



	edev = pci_dev_to_eeh_dev(pdev);

	if (!edev) {

		pci_err(pdev, "No eeh_dev for this device!\n");

		pci_dev_put(pdev);

		return -ENODEV;

	}



	ret = eeh_dev_check_failure(edev);

	pci_info(pdev, "eeh_dev_check_failure(%04x:%02x:%02x.%01x) = %d\n",

			domain, bus, dev, fn, ret);



	pci_dev_put(pdev);



	return count;

}



static const struct file_operations eeh_dev_check_fops = {

	.open	= simple_open,

	.llseek	= no_llseek,

	.write	= eeh_dev_check_write,

	.read   = eeh_debugfs_dev_usage,

};



#endif



static int __init eeh_init_proc(void)
@@ -1886,6 +1944,9 @@ static int __init eeh_init_proc(void) 
		debugfs_create_bool("eeh_disable_recovery", 0600,

				powerpc_debugfs_root,

				&eeh_debugfs_no_recover);

		debugfs_create_file_unsafe("eeh_dev_check", 0600,

				powerpc_debugfs_root, NULL,

				&eeh_dev_check_fops);

		debugfs_create_file_unsafe("eeh_force_recover", 0600,

				powerpc_debugfs_root, NULL,

				&eeh_force_recover_fops);

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