Subject: Re: linux-next: manual merge of the arm64 tree with the mm tree

From: Stephen Rothwell <[email-masked]>
Date: Wed, 20 Nov 2024 11:58:55 +1100

Hi all,

On Thu, 24 Oct 2024 10:37:09 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> Today's linux-next merge of the arm64 tree got a conflict in:
> 
>   arch/arm64/mm/pageattr.c
> 
> between commit:
> 
>   040ee4186d6c ("arch: introduce set_direct_map_valid_noflush()")
> 
> from the mm-unstable branch of the mm tree and commit:
> 
>   42be24a4178f ("arm64: Enable memory encrypt for Realms")
> 
> from the arm64 tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
> 
> -- 
> Cheers,
> Stephen Rothwell
> 
> diff --cc arch/arm64/mm/pageattr.c
> index 01225900293a,6ae6ae806454..000000000000
> --- a/arch/arm64/mm/pageattr.c
> +++ b/arch/arm64/mm/pageattr.c
> @@@ -192,16 -202,86 +202,96 @@@ int set_direct_map_default_noflush(stru
>   				   PAGE_SIZE, change_page_range, &data);
>   }
>   
>  +int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
>  +{
>  +	unsigned long addr = (unsigned long)page_address(page);
>  +
>  +	if (!can_set_direct_map())
>  +		return 0;
>  +
>  +	return set_memory_valid(addr, nr, valid);
>  +}
>  +
> + static 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;
> + 	int ret;
> + 
> + 	if (!is_realm_world())
> + 		return 0;
> + 
> + 	if (!__is_lm_address(addr))
> + 		return -EINVAL;
> + 
> + 	start = __virt_to_phys(addr);
> + 	end = start + numpages * PAGE_SIZE;
> + 
> + 	if (encrypt)
> + 		clear_prot = PROT_NS_SHARED;
> + 	else
> + 		set_prot = PROT_NS_SHARED;
> + 
> + 	/*
> + 	 * Break the mapping before we make any changes to avoid stale TLB
> + 	 * entries or Synchronous External Aborts caused by RIPAS_EMPTY
> + 	 */
> + 	ret = __change_memory_common(addr, PAGE_SIZE * numpages,
> + 				     __pgprot(set_prot),
> + 				     __pgprot(clear_prot | PTE_VALID));
> + 
> + 	if (ret)
> + 		return ret;
> + 
> + 	if (encrypt)
> + 		ret = rsi_set_memory_range_protected(start, end);
> + 	else
> + 		ret = rsi_set_memory_range_shared(start, end);
> + 
> + 	if (ret)
> + 		return ret;
> + 
> + 	return __change_memory_common(addr, PAGE_SIZE * numpages,
> + 				      __pgprot(PTE_VALID),
> + 				      __pgprot(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,
> + };
> + 
> + int realm_register_memory_enc_ops(void)
> + {
> + 	return arm64_mem_crypt_ops_register(&realm_crypt_ops);
> + }
> + 
>   #ifdef CONFIG_DEBUG_PAGEALLOC
>   void __kernel_map_pages(struct page *page, int numpages, int enable)
>   {

This is now a conflict between the mm-stable tree and Linus' tree.

-- 
Cheers,
Stephen Rothwell