Re: [PATCH 12/14] powerpc/eeh: Add debugfs interface to run an EEH check
From: Sam Bobroff <hidden>
Date: 2019-09-17 03:18:20
On Tue, Sep 03, 2019 at 08:16:03PM +1000, Oliver O'Halloran wrote:
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: Oliver O'Halloran <oohall@gmail.com>
Looks good, and I tested it with the next patch and it seems to work. But I think you should make it clear that this does not work with the hardware "EEH error injection" facility accessible via debugfs in err_injct (that doesn't seem clear to me from the commit message). Tested-by: Sam Bobroff <redacted> Reviewed-by: Sam Bobroff <redacted>
quoted hunk ↗ jump to hunk
--- arch/powerpc/kernel/eeh.c | 61 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+)diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c index 46d17817b438..ace1c5a6b8ed 100644 --- a/arch/powerpc/kernel/eeh.c +++ b/arch/powerpc/kernel/eeh.c@@ -1873,6 +1873,64 @@ 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)@@ -1888,6 +1946,9 @@ 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);-- 2.21.0
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