Re: [PATCH v9 4/7] arm64: realm: Move Realm memory encryption ops to RSI code

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 05/08/2026 07:32, Aneesh Kumar K.V (Arm) wrote:
> Realm memory encryption callbacks are CCA-specific. Keep the Realm callback
> registration with the RSI initialization code instead of pageattr.c, which
> only needs to provide the low-level page-attribute transition helper.
> 
> Export __set_memory_enc_dec() within arm64 so the RSI code can wrap it with
> the Realm-specific encrypt/decrypt callbacks and warning policy.
> 
> No functional changes in this patch.
> 
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
> ---
>   arch/arm64/include/asm/mem_encrypt.h |  3 +--
>   arch/arm64/mm/pageattr.c             | 38 +---------------------------
>   drivers/firmware/arm_rmm/rsi.c       | 34 +++++++++++++++++++++++++
>   3 files changed, 36 insertions(+), 39 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/mem_encrypt.h b/arch/arm64/include/asm/mem_encrypt.h
> index f03b9d7b83b4..ef8b8463e52b 100644
> --- a/arch/arm64/include/asm/mem_encrypt.h
> +++ b/arch/arm64/include/asm/mem_encrypt.h
> @@ -16,8 +16,7 @@ int arm64_mem_crypt_ops_register(const struct arm64_mem_crypt_ops *ops);
>   
>   int set_memory_encrypted(unsigned long addr, int numpages);
>   int set_memory_decrypted(unsigned long addr, int numpages);
> -
> -int realm_register_memory_enc_ops(void);
> +int __set_memory_enc_dec(unsigned long addr, int numpages, bool encrypt);
>   
>   static inline bool force_dma_unencrypted(struct device *dev)
>   {
> diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
> index bbe98ac9ad8c..14b2a3801f40 100644
> --- a/arch/arm64/mm/pageattr.c
> +++ b/arch/arm64/mm/pageattr.c
> @@ -275,9 +275,7 @@ int set_direct_map_default_noflush(struct page *page)
>   				 PAGE_SIZE, set_mask, clear_mask);
>   }
>   
> -static int __set_memory_enc_dec(unsigned long addr,
> -				int numpages,
> -				bool encrypt)
> +int __set_memory_enc_dec(unsigned long addr, int numpages, bool encrypt)
>   {
>   	unsigned long set_prot = 0, clear_prot = 0;
>   	phys_addr_t start, end;
> @@ -321,40 +319,6 @@ static int __set_memory_enc_dec(unsigned long addr,
>   				      __pgprot(PTE_PRESENT_INVALID));
>   }

This calls "rsi_set_memory_range_protected/shared(). Should we add call 
backs for those too in the arm64_mem_crypt_ops and take those away too ?

something like :

	pre_enc_dec_phys_range(start, end, bool encrypt) ?

and implement that in firmware/arm_rmm/rsi.c ?

Suzuki




>   
> -static int realm_set_memory_encrypted(unsigned long addr, int numpages)
> -{
> -	int ret = __set_memory_enc_dec(addr, numpages, true);
> -
> -	/*
> -	 * If the request to change state fails, then the only sensible cause
> -	 * of action for the caller is to leak the memory
> -	 */
> -	WARN(ret, "Failed to encrypt memory, %d pages will be leaked",
> -	     numpages);
> -
> -	return ret;
> -}
> -
> -static int realm_set_memory_decrypted(unsigned long addr, int numpages)
> -{
> -	int ret = __set_memory_enc_dec(addr, numpages, false);
> -
> -	WARN(ret, "Failed to decrypt memory, %d pages will be leaked",
> -	     numpages);
> -
> -	return ret;
> -}
> -
> -static const struct arm64_mem_crypt_ops realm_crypt_ops = {
> -	.encrypt = realm_set_memory_encrypted,
> -	.decrypt = realm_set_memory_decrypted,
> -};
> -
> -int realm_register_memory_enc_ops(void)
> -{
> -	return arm64_mem_crypt_ops_register(&realm_crypt_ops);
> -}
> -
>   int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
>   {
>   	unsigned long addr = (unsigned long)page_address(page);
> diff --git a/drivers/firmware/arm_rmm/rsi.c b/drivers/firmware/arm_rmm/rsi.c
> index 8e716f1c1e31..ada139d0e344 100644
> --- a/drivers/firmware/arm_rmm/rsi.c
> +++ b/drivers/firmware/arm_rmm/rsi.c
> @@ -127,6 +127,40 @@ static int realm_ioremap_hook(phys_addr_t phys, size_t size, pgprot_t *prot)
>   	return 0;
>   }
>   
> +static int realm_set_memory_encrypted(unsigned long addr, int numpages)
> +{
> +	int ret = __set_memory_enc_dec(addr, numpages, true);
> +
> +	/*
> +	 * If the request to change state fails, then the only sensible cause
> +	 * of action for the caller is to leak the memory
> +	 */
> +	WARN(ret, "Failed to encrypt memory, %d pages will be leaked",
> +	     numpages);
> +
> +	return ret;
> +}
> +
> +static int realm_set_memory_decrypted(unsigned long addr, int numpages)
> +{
> +	int ret = __set_memory_enc_dec(addr, numpages, false);
> +
> +	WARN(ret, "Failed to decrypt memory, %d pages will be leaked",
> +	     numpages);
> +
> +	return ret;
> +}
> +
> +static const struct arm64_mem_crypt_ops realm_crypt_ops = {
> +	.encrypt = realm_set_memory_encrypted,
> +	.decrypt = realm_set_memory_decrypted,
> +};
> +
> +static int realm_register_memory_enc_ops(void)
> +{
> +	return arm64_mem_crypt_ops_register(&realm_crypt_ops);
> +}
> +
>   void __init arm64_rsi_init(void)
>   {
>   	if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_SMC)