Date:	Mon, 16 May 2011 15:33:01 -0400
From:	Don Zickus <dzickus@...hat.com>
To:	Huang Ying <ying.huang@...el.com>
Cc:	Len Brown <lenb@...nel.org>, linux-kernel@...r.kernel.org,
	Andi Kleen <andi@...stfloor.org>,
	Tony Luck <tony.luck@...el.com>, linux-acpi@...r.kernel.org
Subject: Re: [RFC] ACPI, APEI, Generic Hardware Error Source (GHES) injecting
 support

On Tue, May 10, 2011 at 11:08:41AM +0800, Huang Ying wrote:
> The testing of Generic Hardware Error Source (GHES) is quite
> difficult, because special hardware is needed to trigger the hardware
> error. So a software based hardware error injector for GHES is
> implemented.
> 
> Error notification is not provided in this patch.  So you still need
> some NMI/SCI/IRQ injecting support to make it work.

Should we add that to this patch, otherwise it seems like the injection
isn't very useful or intuitive from the end-user perspective that they
have to provide their own notification source (ie NMI/SCI/MCE/IRQ).

Cheers,
Don

> 
> Signed-off-by: Huang Ying <ying.huang@...el.com>
> ---
>  drivers/acpi/apei/Kconfig         |   10 ++
>  drivers/acpi/apei/Makefile        |    1 
>  drivers/acpi/apei/apei-internal.h |    8 ++
>  drivers/acpi/apei/ghes-inj.c      |  132 ++++++++++++++++++++++++++++++++++++++
>  drivers/acpi/apei/ghes.c          |   15 ++++
>  5 files changed, 165 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/acpi/apei/ghes-inj.c
> 
> --- a/drivers/acpi/apei/Kconfig
> +++ b/drivers/acpi/apei/Kconfig
> @@ -54,3 +54,13 @@ config ACPI_APEI_ERST_DEBUG
>  	  error information to and from a persistent store. Enable this
>  	  if you want to debugging and testing the ERST kernel support
>  	  and firmware implementation.
> +
> +config ACPI_APEI_GHES_INJ
> +	tristate "APEI Generic Hardware Error Source (GHES) Injecting Support"
> +	depends on ACPI_APEI_GHES
> +	help
> +	  GHES provides a way to report platform hardware errors (such
> +	  as that from chipset).
> +
> +	  The injector can inject fake hardware error record. This is
> +	  used for GHES debugging/testing.
> --- a/drivers/acpi/apei/Makefile
> +++ b/drivers/acpi/apei/Makefile
> @@ -2,5 +2,6 @@ obj-$(CONFIG_ACPI_APEI)		+= apei.o
>  obj-$(CONFIG_ACPI_APEI_GHES)	+= ghes.o
>  obj-$(CONFIG_ACPI_APEI_EINJ)	+= einj.o
>  obj-$(CONFIG_ACPI_APEI_ERST_DEBUG) += erst-dbg.o
> +obj-$(CONFIG_ACPI_APEI_GHES_INJ) += ghes-inj.o
>  
>  apei-y := apei-base.o hest.o cper.o erst.o
> --- a/drivers/acpi/apei/apei-internal.h
> +++ b/drivers/acpi/apei/apei-internal.h
> @@ -33,6 +33,14 @@ struct apei_exec_context {
>  	u32 entries;
>  };
>  
> +struct ghes_inject_data {
> +	unsigned long error_status_address;
> +	u16 source_id;
> +	unsigned short valid : 1;
> +};
> +
> +extern struct ghes_inject_data ghes_inject_data;
> +
>  void apei_exec_ctx_init(struct apei_exec_context *ctx,
>  			struct apei_exec_ins_type *ins_table,
>  			u32 instructions,
> --- /dev/null
> +++ b/drivers/acpi/apei/ghes-inj.c
> @@ -0,0 +1,132 @@
> +/*
> + * APEI Generic Hardware Error Source (GHES) injector support
> + *
> + * Fake hardware error record can be injected. This is used for for
> + * GHES debugging/testing.
> + *
> + * Copyright 2010,2011 Intel Corp.
> + *   Author: Huang Ying <ying.huang@...el.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version
> + * 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/uaccess.h>
> +#include <linux/debugfs.h>
> +#include <acpi/apei.h>
> +
> +#include "apei-internal.h"
> +
> +#define GHES_INJ_PFX		"GHES-INJ: "
> +
> +#define GHES_INJ_BUF_LEN_MAX	4096
> +
> +static void *ghes_inj_buf;
> +static unsigned int ghes_inj_buf_len;
> +
> +/* Prevent erst_inj_buf from being accessed concurrently */
> +static DEFINE_MUTEX(ghes_inj_mutex);
> +
> +static ssize_t ghes_inj_write(struct file *filp, const char __user *ubuf,
> +			      size_t usize, loff_t *off)
> +{
> +	int rc;
> +
> +	if (!capable(CAP_SYS_ADMIN))
> +		return -EPERM;
> +
> +	if (*off != 0)
> +		return -EINVAL;
> +
> +	if (usize > GHES_INJ_BUF_LEN_MAX)
> +		return -EINVAL;
> +
> +	if (mutex_lock_interruptible(&ghes_inj_mutex))
> +		return -EINTR;
> +	ghes_inject_data.valid = 0;
> +	/* Wait for all consumers finish using the injecting buffer */
> +	synchronize_rcu();
> +	if (usize > ghes_inj_buf_len) {
> +		void *p;
> +		rc = -ENOMEM;
> +		p = kmalloc(usize, GFP_KERNEL);
> +		if (!p)
> +			goto out;
> +		kfree(ghes_inj_buf);
> +		ghes_inj_buf = p;
> +		ghes_inj_buf_len = usize;
> +	}
> +	rc = copy_from_user(ghes_inj_buf, ubuf, usize);
> +	if (rc) {
> +		rc = -EFAULT;
> +		goto out;
> +	}
> +	ghes_inject_data.error_status_address = __pa(ghes_inj_buf);
> +	/*
> +	 * ghes_injiect_data.valid must be set after other fields are
> +	 * written
> +	 */
> +	smp_wmb();
> +	ghes_inject_data.valid = 1;
> +out:
> +	mutex_unlock(&ghes_inj_mutex);
> +	return rc ? rc : usize;
> +}
> +
> +static const struct file_operations ghes_inj_fops = {
> +	.owner		= THIS_MODULE,
> +	.write		= ghes_inj_write,
> +};
> +
> +static struct dentry *ghes_debug_dir;
> +
> +static __init int ghes_inj_init(void)
> +{
> +	struct dentry *f;
> +	int rc = -ENOMEM;
> +
> +	ghes_debug_dir = debugfs_create_dir("ghes", apei_get_debugfs_dir());
> +	if (!ghes_debug_dir)
> +		return rc;
> +	f = debugfs_create_file("inject", S_IWUSR, ghes_debug_dir,
> +				NULL, &ghes_inj_fops);
> +	if (!f)
> +		goto err_cleanup;
> +	f = debugfs_create_u16("inject_source_id", S_IRUSR | S_IWUSR,
> +			       ghes_debug_dir, &ghes_inject_data.source_id);
> +	if (!f)
> +		goto err_cleanup;
> +
> +	return 0;
> +err_cleanup:
> +	debugfs_remove_recursive(ghes_debug_dir);
> +	return rc;
> +}
> +
> +static __exit void ghes_inj_exit(void)
> +{
> +	debugfs_remove_recursive(ghes_debug_dir);
> +	ghes_inject_data.valid = 0;
> +	/* Wait for all consumers finish using the injecting buffer */
> +	synchronize_rcu();
> +	kfree(ghes_inj_buf);
> +}
> +
> +module_init(ghes_inj_init);
> +module_exit(ghes_inj_exit);
> +
> +MODULE_AUTHOR("Huang Ying");
> +MODULE_DESCRIPTION("APEI Generic Hardware Error Source (GHES) injecting support");
> +MODULE_LICENSE("GPL");
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -153,6 +153,9 @@ static unsigned long ghes_estatus_pool_s
>  static struct llist_head ghes_estatus_llist;
>  static struct irq_work ghes_proc_irq_work;
>  
> +struct ghes_inject_data ghes_inject_data;
> +EXPORT_SYMBOL_GPL(ghes_inject_data);
> +
>  static int ghes_ioremap_init(void)
>  {
>  	ghes_ioremap_area = __get_vm_area(PAGE_SIZE * GHES_IOREMAP_PAGES,
> @@ -371,7 +374,13 @@ static int ghes_read_estatus(struct ghes
>  	u32 len;
>  	int rc;
>  
> -	rc = acpi_atomic_read(&buf_paddr, &g->error_status_address);
> +	if (!ghes_inject_data.valid ||
> +	    ghes_inject_data.source_id != g->header.source_id)
> +		rc = acpi_atomic_read(&buf_paddr, &g->error_status_address);
> +	else {
> +		buf_paddr = ghes_inject_data.error_status_address;
> +		rc = 0;
> +	}
>  	if (rc) {
>  		if (!silent && printk_ratelimit())
>  			pr_warning(FW_WARN GHES_PFX
> @@ -420,6 +429,10 @@ static void ghes_clear_estatus(struct gh
>  	ghes_copy_tofrom_phys(ghes->estatus, ghes->buffer_paddr,
>  			      sizeof(ghes->estatus->block_status), 0);
>  	ghes->flags &= ~GHES_TO_CLEAR;
> +
> +	if (ghes_inject_data.valid &&
> +	    ghes_inject_data.source_id == ghes->generic->header.source_id)
> +		ghes_inject_data.valid = 0;
>  }
>  
>  static void ghes_do_proc(const struct acpi_hest_generic_status *estatus)
--
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