Re: [PATCH] More Sanity checks for DMAR

mark gross
2007-11-20T19:02:17Z

On Mon, Nov 19, 2007 at 03:03:48PM -0800, Fenghua Yu wrote:
>
> This patch adds and changes a few sanity checks in dmar.c.
>
> 1. The haw field in ACPI DMAR table in VT-d spec doesn't describe the range of
> haw. But since DMA page size is 4KB in DMA remapping, haw should be at least
> 4KB. The current VT-d code in dmar.c returns failure when haw==0. This sanity
> check is not accurate and execution can pass when haw is less than one page
> size 4KB. This patch changes the haw sanity check to validate if haw is less
> than 4KB.
> 2. Add dmar_rmrr_units verification.
> 3. Add parse_dmar_table() verification.
>
> Thanks.
>
> -Fenghua
>
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
>
> ---
>
> dmar.c | 20 +++++++++++++++++---
> 1 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
> index 5dfdfda..a5b6ed0 100644
> --- a/drivers/pci/dmar.c
> +++ b/drivers/pci/dmar.c
> @@ -25,6 +25,7 @@
>
> #include <linux/pci.h>
> #include <linux/dmar.h>
> +#include "iova.h"
>
> #undef PREFIX
> #define PREFIX "DMAR:"
> @@ -263,8 +264,8 @@ parse_dmar_table(void)
> if (!dmar)
> return -ENODEV;
>
> - if (!dmar->width) {
> - printk (KERN_WARNING PREFIX "Zero: Invalid DMAR haw\n");
> + if (dmar->width < PAGE_SHIFT_4K - 1) {
> + printk (KERN_WARNING PREFIX "Invalid DMAR haw\n");
> return -EINVAL;
> }
>
> @@ -301,11 +302,24 @@ parse_dmar_table(void)
> int __init dmar_table_init(void)
> {
>
> - parse_dmar_table();
> + int ret;
> +
> + ret = parse_dmar_table();
> + if (ret) {
> + printk(KERN_INFO PREFIX "parse DMAR table failure.\n");
> + return ret;
> + }
> +
> if (list_empty(&dmar_drhd_units)) {
> printk(KERN_INFO PREFIX "No DMAR devices found\n");
> return -ENODEV;
> }
> +
> + if (list_empty(&dmar_rmrr_units)) {
> + printk(KERN_INFO PREFIX "No RMRR found\n");
> + return -ENODEV;
> + }
> +
> return 0;
> }
>
> -
Ack : mark gross <mgross@linux.intel.com>

Thanks,

--mgross