Re: [PATCH v4 4/7] platform/x86/amd/hsmp: Source metric-table size from firmware

[Ilpo Järvinen]

On Thu, 28 May 2026, Muralidhara M K wrote:

> The driver hard-codes the metric-table region size to
> sizeof(struct hsmp_metric_table). That is correct for HSMP protocol
> version 6 but mis-sizes the ioremap of the SMU DRAM region on newer
> platforms: Family 1Ah Model 50h-5Fh exposes a ~13 KB
> hsmp_metric_table_zen6, and the table is expected to keep growing
> on future firmware. The same hard-coded value also forces
> hsmp_metric_tbl_read() to reject any read that follows the actual
> firmware layout.
> 
> Pick up the table size from firmware instead. SMU on Family 1Ah
> Model 50h and later populates HSMP_GET_METRIC_TABLE_DRAM_ADDR's
> args[2] with the DRAM region size in bytes; older firmware leaves
> it 0. Bump the descriptor's response_sz to 3 so the field is read,
> store the value in hsmp_pdev.hsmp_table_size at probe time, and
> fall back to sizeof(struct hsmp_metric_table) when firmware reports
> 0. Use hsmp_table_size both for the devm_ioremap() of the region
> and as the upper bound for hsmp_metric_tbl_read().
> 
> Behaviour on existing protocol-version-6 hardware is unchanged:
> firmware returns 0, the fallback yields the same value as the
> previous hard-coded one, and both the ioremap and the size check
> produce the same result as before.
> 
> The ioctl interface added later in this series uses the same
> hsmp_table_size to validate the userspace request and to copy out
> the full firmware-reported region.
> 
> Co-developed-by: Muthusamy Ramalingam <muthusamy.ramalingam@xxxxxxx>
> Signed-off-by: Muthusamy Ramalingam <muthusamy.ramalingam@xxxxxxx>
> Signed-off-by: Muralidhara M K <muralidhara.mk@xxxxxxx>
> ---
>  arch/x86/include/uapi/asm/amd_hsmp.h |  5 +++--
>  drivers/platform/x86/amd/hsmp/hsmp.c | 11 ++++++++---
>  drivers/platform/x86/amd/hsmp/hsmp.h |  1 +
>  3 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/include/uapi/asm/amd_hsmp.h b/arch/x86/include/uapi/asm/amd_hsmp.h
> index fce271282348..438ac38d0dc8 100644
> --- a/arch/x86/include/uapi/asm/amd_hsmp.h
> +++ b/arch/x86/include/uapi/asm/amd_hsmp.h
> @@ -365,11 +365,12 @@ static const struct hsmp_msg_desc hsmp_msg_desc_table[]
>  	{0, 0, HSMP_GET},
>  
>  	/*
> -	 * HSMP_GET_METRIC_TABLE_DRAM_ADDR, num_args = 0, response_sz = 2
> +	 * HSMP_GET_METRIC_TABLE_DRAM_ADDR, num_args = 0, response_sz = 3
>  	 * output: args[0] = lower 32 bits of the address
>  	 * output: args[1] = upper 32 bits of the address
> +	 * output: args[2] = DRAM region size in bytes
>  	 */
> -	{0, 2, HSMP_GET},
> +	{0, 3, HSMP_GET},
>  
>  	/*
>  	 * HSMP_SET_XGMI_PSTATE_RANGE, num_args = 1, response_sz = 0
> diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c
> index 9bad58fef304..cf9392f99298 100644
> --- a/drivers/platform/x86/amd/hsmp/hsmp.c
> +++ b/drivers/platform/x86/amd/hsmp/hsmp.c
> @@ -356,8 +356,7 @@ ssize_t hsmp_metric_tbl_read(struct hsmp_socket *sock, char *buf, size_t size)
>  		return -ENOMEM;
>  	}
>  
> -	/* Do not support lseek(), also don't allow more than the size of metric table */
> -	if (size != sizeof(struct hsmp_metric_table)) {
> +	if (size != hsmp_pdev.hsmp_table_size) {
>  		dev_err(sock->dev, "Wrong buffer size\n");
>  		return -EINVAL;
>  	}
> @@ -398,8 +397,14 @@ int hsmp_get_tbl_dram_base(u16 sock_ind)
>  		dev_err(sock->dev, "Invalid DRAM address for metric table\n");
>  		return -ENOMEM;
>  	}
> +	/* SMU returns table size from Family 1Ah Model 50h and forward */
> +	if (msg.args[2])
> +		hsmp_pdev.hsmp_table_size = msg.args[2];
> +	else
> +		hsmp_pdev.hsmp_table_size = sizeof(struct hsmp_metric_table);
> +
>  	sock->metric_tbl_addr = devm_ioremap(sock->dev, dram_addr,
> -					     sizeof(struct hsmp_metric_table));
> +					     hsmp_pdev.hsmp_table_size);
>  	if (!sock->metric_tbl_addr) {
>  		dev_err(sock->dev, "Failed to ioremap metric table addr\n");
>  		return -ENOMEM;
> diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h
> index b153527e0a0d..e7f051475728 100644
> --- a/drivers/platform/x86/amd/hsmp/hsmp.h
> +++ b/drivers/platform/x86/amd/hsmp/hsmp.h
> @@ -55,6 +55,7 @@ struct hsmp_plat_device {
>  	u32 proto_ver;
>  	u16 num_sockets;
>  	bool is_probed;
> +	size_t hsmp_table_size;

Please add types.h include.

>  };
>  
>  int hsmp_cache_proto_ver(u16 sock_ind);
> 

-- 
 i.