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 <ooh...@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 <sbobr...@linux.ibm.com>
Reviewed-by: Sam Bobroff <sbobr...@linux.ibm.com>
> ---
> 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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