On Tue, Sep 03, 2019 at 08:16:04PM +1000, Oliver O'Halloran wrote: > Add an interface to debugfs for generating an EEH event on a given device. > This works by disabling memory accesses to and from the device by setting > the PCI_COMMAND register (or the VF Memory Space Enable on the parent PF). > > This is a somewhat portable alternative to using the platform specific > error injection mechanisms since those tend to be either hard to use, or > straight up broken. For pseries the interfaces also requires the use of > /dev/mem which is probably going to go away in a post-LOCKDOWN world > (and it's a horrific hack to begin with) so moving to a kernel-provided > interface makes sense and provides a sane, cross-platform interface for > userspace so we can write more generic testing scripts. > > Signed-off-by: Oliver O'Halloran <ooh...@gmail.com>
Looks good to me. Tested with the previous patch.
Tested-by: Sam Bobroff <sbobr...@linux.ibm.com>
Reviewed-by: Sam Bobroff <sbobr...@linux.ibm.com>
> ---
> arch/powerpc/kernel/eeh.c | 139 +++++++++++++++++++++++++++++++++++++-
> 1 file changed, 138 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
> index ace1c5a6b8ed..a55d2f01da1d 100644
> --- a/arch/powerpc/kernel/eeh.c
> +++ b/arch/powerpc/kernel/eeh.c
> @@ -1894,7 +1894,8 @@ static ssize_t eeh_dev_check_write(struct file *filp,
> char buf[20];
> int ret;
>
> - ret = simple_write_to_buffer(buf, sizeof(buf), ppos, user_buf, count);
> + memset(buf, 0, sizeof(buf));
> + ret = simple_write_to_buffer(buf, sizeof(buf)-1, ppos, user_buf, count);
> if (!ret)
> return -EFAULT;
>
> @@ -1931,6 +1932,139 @@ static const struct file_operations
> eeh_dev_check_fops = {
> .read = eeh_debugfs_dev_usage,
> };
>
> +static int eeh_debugfs_break_device(struct pci_dev *pdev)
> +{
> + struct resource *bar = NULL;
> + void __iomem *mapped;
> + u16 old, bit;
> + int i, pos;
> +
> + /* Do we have an MMIO BAR to disable? */
> + for (i = 0; i <= PCI_STD_RESOURCE_END; i++) {
> + struct resource *r = &pdev->resource[i];
> +
> + if (!r->flags || !r->start)
> + continue;
> + if (r->flags & IORESOURCE_IO)
> + continue;
> + if (r->flags & IORESOURCE_UNSET)
> + continue;
> +
> + bar = r;
> + break;
> + }
> +
> + if (!bar) {
> + pci_err(pdev, "Unable to find Memory BAR to cause EEH with\n");
> + return -ENXIO;
> + }
> +
> + pci_err(pdev, "Going to break: %pR\n", bar);
> +
> + if (pdev->is_virtfn) {
> +#ifndef CONFIG_IOV
> + return -ENXIO;
> +#else
> + /*
> + * VFs don't have a per-function COMMAND register, so the best
> + * we can do is clear the Memory Space Enable bit in the PF's
> + * SRIOV control reg.
> + *
> + * Unfortunately, this requires that we have a PF (i.e doesn't
> + * work for a passed-through VF) and it has the potential side
> + * effect of also causing an EEH on every other VF under the
> + * PF. Oh well.
> + */
> + pdev = pdev->physfn;
> + if (!pdev)
> + return -ENXIO; /* passed through VFs have no PF */
> +
> + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_SRIOV);
> + pos += PCI_SRIOV_CTRL;
> + bit = PCI_SRIOV_CTRL_MSE;
> +#endif /* !CONFIG_IOV */
> + } else {
> + bit = PCI_COMMAND_MEMORY;
> + pos = PCI_COMMAND;
> + }
> +
> + /*
> + * Process here is:
> + *
> + * 1. Disable Memory space.
> + *
> + * 2. Perform an MMIO to the device. This should result in an error
> + * (CA / UR) being raised by the device which results in an EEH
> + * PE freeze. Using the in_8() accessor skips the eeh detection hook
> + * so the freeze hook so the EEH Detection machinery won't be
> + * triggered here. This is to match the usual behaviour of EEH
> + * where the HW will asyncronously freeze a PE and it's up to
> + * the kernel to notice and deal with it.
> + *
> + * 3. Turn Memory space back on. This is more important for VFs
> + * since recovery will probably fail if we don't. For normal
> + * the COMMAND register is reset as a part of re-initialising
> + * the device.
> + *
> + * Breaking stuff is the point so who cares if it's racy ;)
> + */
> + pci_read_config_word(pdev, pos, &old);
> +
> + mapped = ioremap(bar->start, PAGE_SIZE);
> + if (!mapped) {
> + pci_err(pdev, "Unable to map MMIO BAR %pR\n", bar);
> + return -ENXIO;
> + }
> +
> + pci_write_config_word(pdev, pos, old & ~bit);
> + in_8(mapped);
> + pci_write_config_word(pdev, pos, old);
> +
> + iounmap(mapped);
> +
> + return 0;
> +}
> +
> +static ssize_t eeh_dev_break_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;
> + char buf[20];
> + int ret;
> +
> + memset(buf, 0, sizeof(buf));
> + ret = simple_write_to_buffer(buf, sizeof(buf)-1, 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;
> +
> + ret = eeh_debugfs_break_device(pdev);
> + pci_dev_put(pdev);
> +
> + if (ret < 0)
> + return ret;
> +
> + return count;
> +}
> +
> +static const struct file_operations eeh_dev_break_fops = {
> + .open = simple_open,
> + .llseek = no_llseek,
> + .write = eeh_dev_break_write,
> + .read = eeh_debugfs_dev_usage,
> +};
> +
> #endif
>
> static int __init eeh_init_proc(void)
> @@ -1949,6 +2083,9 @@ static int __init eeh_init_proc(void)
> debugfs_create_file_unsafe("eeh_dev_check", 0600,
> powerpc_debugfs_root, NULL,
> &eeh_dev_check_fops);
> + debugfs_create_file_unsafe("eeh_dev_break", 0600,
> + powerpc_debugfs_root, NULL,
> + &eeh_dev_break_fops);
> debugfs_create_file_unsafe("eeh_force_recover", 0600,
> powerpc_debugfs_root, NULL,
> &eeh_force_recover_fops);
> --
> 2.21.0
>
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