Re: [PATCH 3/7] iommu/s390: add basic routines for region 1st and 2nd tables

[Thomas Huth <thuth@redhat.com>]

On 09/12/2024 20.25, Matthew Rosato wrote:
> Add common routines for region first and region second tables, similar
> to what already exists for region third tables.  Routines added are
> for determining an index value based on address, getting and setting
> origin flags, and validating entries.
> These routines are not yet used, but will be in subsequent commits.
> 
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
>   arch/s390/include/asm/pci_dma.h |  2 ++
>   drivers/iommu/s390-iommu.c      | 56 +++++++++++++++++++++++++++++++++
>   2 files changed, 58 insertions(+)
> 
> diff --git a/arch/s390/include/asm/pci_dma.h b/arch/s390/include/asm/pci_dma.h
> index 42d7cc4262ca..8d8962e4fd58 100644
> --- a/arch/s390/include/asm/pci_dma.h
> +++ b/arch/s390/include/asm/pci_dma.h
> @@ -55,6 +55,8 @@ enum zpci_ioat_dtype {
>   #define ZPCI_PT_BITS			8
>   #define ZPCI_ST_SHIFT			(ZPCI_PT_BITS + PAGE_SHIFT)
>   #define ZPCI_RT_SHIFT			(ZPCI_ST_SHIFT + ZPCI_TABLE_BITS)
> +#define ZPCI_RS_SHIFT			(ZPCI_RT_SHIFT + ZPCI_TABLE_BITS)
> +#define ZPCI_RF_SHIFT			(ZPCI_RS_SHIFT + ZPCI_TABLE_BITS)
>   
>   #define ZPCI_RTE_FLAG_MASK		0x3fffUL
>   #define ZPCI_RTE_ADDR_MASK		(~ZPCI_RTE_FLAG_MASK)
> diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
> index f6c27b6ab4c6..fcebc7415fb3 100644
> --- a/drivers/iommu/s390-iommu.c
> +++ b/drivers/iommu/s390-iommu.c
> @@ -36,6 +36,16 @@ struct s390_domain {
>   
>   static struct iommu_domain blocking_domain;
>   
> +static inline unsigned int calc_rfx(dma_addr_t ptr)
> +{
> +	return ((unsigned long)ptr >> ZPCI_RF_SHIFT) & ZPCI_INDEX_MASK;
> +}

  Hi Matthew!

Correct me if I'm wrong, but IIRC Clang will barf at you when you declare a 
"static inline" function in a .c file without using it? So this might break 
bisection later when using Clang and -Werror ... maybe it's better to 
introduce the functions just when they are also used?

  Thomas