ACK: [PATCH][V3] bios: mtrr: check MTRR default memory type

[Colin Ian King]

On 15/07/16 16:31, Alex Hung wrote:
> IA32_MTRR_DEF_TYPE MSR sets the default properties of the regions
> of physical memory that are not encompassed by MTRRs. Especially,
> Bit 0 to 7 indicates the default memory type.
> 
> Signed-off-by: Alex Hung <alex.hung at canonical.com>
> ---
>  src/bios/mtrr/mtrr.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/src/bios/mtrr/mtrr.c b/src/bios/mtrr/mtrr.c
> index 18e1a29..08ce90b 100644
> --- a/src/bios/mtrr/mtrr.c
> +++ b/src/bios/mtrr/mtrr.c
> @@ -49,6 +49,8 @@ static fwts_cpuinfo_x86 *fwts_cpuinfo;
>  #define DISABLED	0x0040
>  #define UNKNOWN		0x0080
>  
> +#define MTRR_DEF_TYPE_MSR	0x2FF
> +
>  struct mtrr_entry {
>  	uint8_t  reg;
>  	uint64_t start;
> @@ -170,6 +172,7 @@ static int cache_types(uint64_t start, uint64_t end)
>  	fwts_list_link *item;
>  	struct mtrr_entry *entry;
>  	int type = 0;
> +	uint64_t mtrr_default = UNCACHED;
>  
>  	fwts_list_foreach(item, mtrr_list) {
>  		entry = fwts_list_data(struct mtrr_entry*, item);
> @@ -198,6 +201,35 @@ restart:
>  	/* if there is no full coverage it's also uncached */
>  	if (start != end)
>  		type |= DEFAULT;
> +
> +	if (fwts_cpu_readmsr(0, MTRR_DEF_TYPE_MSR, &mtrr_default) == FWTS_OK) {
> +		switch (mtrr_default & 0xFF) {
> +			case 0:
> +				mtrr_default = UNCACHED;
> +				break;
> +			case 1:
> +				mtrr_default = WRITE_COMBINING;
> +				break;
> +			case 4:
> +				mtrr_default = WRITE_THROUGH;
> +				break;
> +			case 5:
> +				mtrr_default = WRITE_PROTECT;
> +				break;
> +			case 6:
> +				mtrr_default = WRITE_BACK;
> +				break;
> +			default:
> +				mtrr_default = UNKNOWN;
> +				break;
> +		}
> +
> +		if ((type & DEFAULT) && mtrr_default != UNCACHED) {
> +			type &= ~DEFAULT;
> +			type |= mtrr_default;
> +		}
> +	}
> +
>  	return type;
>  }
>  
> 
Thanks Alex!

Acked-by: Colin Ian King <colin.king at canonical.com>