Re: [PATCH v2 3/5] x86/e820: Tag e820_entry with crypto capabilities

[Dov Murik <dovmurik@linux.ibm.com>]

On 24/11/2021 22:34, Martin Fernandez wrote:
> Add a new member in e820_entry to hold whether an entry is able to do
> hardware memory encryption or not.
> 
> Add a new argument to __e820__range_add to accept this new
> crypto_capable.
> 
> Add a new argument to __e820__update_range to be able to change a
> region's crypto_capable member. Also, change its behavior a little,
> before if you wanted to update a region with its same type it was a
> BUG_ON; now if you call it with both old_type and new_type equals,
> then the function won't change the types, just crypto_capable.
> 
> Change e820__update_table to handle merging and overlap problems
> taking into account crypto_capable.
> 
> Add a function to mark a range as crypto, using __e820__range_update
> in the background. This will be called when initializing EFI.
> 
> Signed-off-by: Martin Fernandez <martin.fernandez@eclypsium.com>
> ---
>  arch/x86/include/asm/e820/api.h   |  1 +
>  arch/x86/include/asm/e820/types.h |  1 +
>  arch/x86/kernel/e820.c            | 58 +++++++++++++++++++++++++------
>  3 files changed, 49 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h
> index e8f58ddd06d9..fdfe1c37dcfc 100644
> --- a/arch/x86/include/asm/e820/api.h
> +++ b/arch/x86/include/asm/e820/api.h
> @@ -17,6 +17,7 @@ extern bool e820__mapped_all(u64 start, u64 end, enum e820_type type);
>  extern void e820__range_add   (u64 start, u64 size, enum e820_type type);
>  extern u64  e820__range_update(u64 start, u64 size, enum e820_type old_type, enum e820_type new_type);
>  extern u64  e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool check_type);
> +extern u64  e820__range_mark_as_crypto(u64 start, u64 size);

I suggest: e820__range_mark_as_crypto_capable
(as you do in other function and field names)

>  
>  extern void e820__print_table(char *who);
>  extern int  e820__update_table(struct e820_table *table);
> diff --git a/arch/x86/include/asm/e820/types.h b/arch/x86/include/asm/e820/types.h
> index 314f75d886d0..7b510dffd3b9 100644
> --- a/arch/x86/include/asm/e820/types.h
> +++ b/arch/x86/include/asm/e820/types.h
> @@ -56,6 +56,7 @@ struct e820_entry {
>  	u64			addr;
>  	u64			size;
>  	enum e820_type		type;
> +	u8			crypto_capable;
>  } __attribute__((packed));
>  
>  /*
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index bc0657f0deed..4581598690a9 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -163,7 +163,7 @@ int e820__get_entry_type(u64 start, u64 end)
>  /*
>   * Add a memory region to the kernel E820 map.
>   */
> -static void __init __e820__range_add(struct e820_table *table, u64 start, u64 size, enum e820_type type)
> +static void __init __e820__range_add(struct e820_table *table, u64 start, u64 size, enum e820_type type, u8 crypto_capable)
>  {
>  	int x = table->nr_entries;
>  
> @@ -176,12 +176,13 @@ static void __init __e820__range_add(struct e820_table *table, u64 start, u64 si
>  	table->entries[x].addr = start;
>  	table->entries[x].size = size;
>  	table->entries[x].type = type;
> +	table->entries[x].crypto_capable = crypto_capable;
>  	table->nr_entries++;
>  }
>  
>  void __init e820__range_add(u64 start, u64 size, enum e820_type type)
>  {
> -	__e820__range_add(e820_table, start, size, type);
> +	__e820__range_add(e820_table, start, size, type, 0);
>  }
>  
>  static void __init e820_print_type(enum e820_type type)
> @@ -211,6 +212,8 @@ void __init e820__print_table(char *who)
>  			e820_table->entries[i].addr + e820_table->entries[i].size - 1);
>  
>  		e820_print_type(e820_table->entries[i].type);
> +		if (e820_table->entries[i].crypto_capable)
> +			pr_cont("; crypto-capable");
>  		pr_cont("\n");
>  	}
>  }
> @@ -327,6 +330,7 @@ int __init e820__update_table(struct e820_table *table)
>  	unsigned long long last_addr;
>  	u32 new_nr_entries, overlap_entries;
>  	u32 i, chg_idx, chg_nr;
> +	u8 current_crypto, last_crypto;
>  
>  	/* If there's only one memory region, don't bother: */
>  	if (table->nr_entries < 2)
> @@ -367,6 +371,7 @@ int __init e820__update_table(struct e820_table *table)
>  	new_nr_entries = 0;	 /* Index for creating new map entries */
>  	last_type = 0;		 /* Start with undefined memory type */
>  	last_addr = 0;		 /* Start with 0 as last starting address */
> +	last_crypto = 0;
>  
>  	/* Loop through change-points, determining effect on the new map: */
>  	for (chg_idx = 0; chg_idx < chg_nr; chg_idx++) {
> @@ -388,13 +393,17 @@ int __init e820__update_table(struct e820_table *table)
>  		 * 1=usable, 2,3,4,4+=unusable)
>  		 */
>  		current_type = 0;
> +		current_crypto = 1;
>  		for (i = 0; i < overlap_entries; i++) {
> +			current_crypto = current_crypto && overlap_list[i]->crypto_capable;
>  			if (overlap_list[i]->type > current_type)
>  				current_type = overlap_list[i]->type;
>  		}
>  
>  		/* Continue building up new map based on this information: */
> -		if (current_type != last_type || e820_nomerge(current_type)) {
> +		if (current_type != last_type ||
> +		    current_crypto != last_crypto ||
> +		    e820_nomerge(current_type)) {
>  			if (last_type != 0)	 {
>  				new_entries[new_nr_entries].size = change_point[chg_idx]->addr - last_addr;
>  				/* Move forward only if the new size was non-zero: */
> @@ -406,9 +415,12 @@ int __init e820__update_table(struct e820_table *table)
>  			if (current_type != 0)	{
>  				new_entries[new_nr_entries].addr = change_point[chg_idx]->addr;
>  				new_entries[new_nr_entries].type = current_type;
> +				new_entries[new_nr_entries].crypto_capable = current_crypto;
> +
>  				last_addr = change_point[chg_idx]->addr;
>  			}
>  			last_type = current_type;
> +			last_crypto = current_crypto;
>  		}
>  	}
>  
> @@ -459,14 +471,20 @@ static int __init append_e820_table(struct boot_e820_entry *entries, u32 nr_entr
>  	return __append_e820_table(entries, nr_entries);
>  }
>  
> +/*
> + * Update a memory range.
> + *
> + * If old_type and new_type are the same then ignore the types and
> + * just change crypto_capable.
> + */
>  static u64 __init
> -__e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_type old_type, enum e820_type new_type)
> +__e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_type old_type, enum e820_type new_type, u8 crypto_capable)
>  {
>  	u64 end;
>  	unsigned int i;
>  	u64 real_updated_size = 0;
>  
> -	BUG_ON(old_type == new_type);
> +	bool update_crypto = new_type == old_type;
>  
>  	if (size > (ULLONG_MAX - start))
>  		size = ULLONG_MAX - start;
> @@ -476,6 +494,8 @@ __e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_ty
>  	e820_print_type(old_type);
>  	pr_cont(" ==> ");
>  	e820_print_type(new_type);
> +	if (crypto_capable)
> +		pr_cont("; crypto-capable");
>  	pr_cont("\n");
>  
>  	for (i = 0; i < table->nr_entries; i++) {
> @@ -483,22 +503,27 @@ __e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_ty
>  		u64 final_start, final_end;
>  		u64 entry_end;
>  
> -		if (entry->type != old_type)
> +		if (entry->type != old_type && !update_crypto)
>  			continue;
>  
> +		if (update_crypto)
> +			new_type = entry->type;
> +
>  		entry_end = entry->addr + entry->size;
>  
>  		/* Completely covered by new range? */
>  		if (entry->addr >= start && entry_end <= end) {
>  			entry->type = new_type;
> +			entry->crypto_capable = crypto_capable;
>  			real_updated_size += entry->size;
>  			continue;
>  		}
>  
>  		/* New range is completely covered? */
>  		if (entry->addr < start && entry_end > end) {
> -			__e820__range_add(table, start, size, new_type);
> -			__e820__range_add(table, end, entry_end - end, entry->type);
> +			__e820__range_add(table, start, size, new_type, crypto_capable);
> +			__e820__range_add(table, end, entry_end - end,
> +					  entry->type, entry->crypto_capable);
>  			entry->size = start - entry->addr;
>  			real_updated_size += size;
>  			continue;
> @@ -510,7 +535,8 @@ __e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_ty
>  		if (final_start >= final_end)
>  			continue;
>  
> -		__e820__range_add(table, final_start, final_end - final_start, new_type);
> +		__e820__range_add(table, final_start, final_end - final_start,
> +				  new_type, crypto_capable);
>  
>  		real_updated_size += final_end - final_start;
>  
> @@ -527,14 +553,19 @@ __e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_ty
>  	return real_updated_size;
>  }
>  
> +u64 __init e820__range_mark_as_crypto(u64 start, u64 size)
> +{
> +	return __e820__range_update(e820_table, start, size, 0, 0, true);
> +}
> +
>  u64 __init e820__range_update(u64 start, u64 size, enum e820_type old_type, enum e820_type new_type)
>  {
> -	return __e820__range_update(e820_table, start, size, old_type, new_type);
> +	return __e820__range_update(e820_table, start, size, old_type, new_type, false);
>  }
>  
>  static u64 __init e820__range_update_kexec(u64 start, u64 size, enum e820_type old_type, enum e820_type  new_type)
>  {
> -	return __e820__range_update(e820_table_kexec, start, size, old_type, new_type);
> +	return __e820__range_update(e820_table_kexec, start, size, old_type, new_type, false);
>  }
>  
>  /* Remove a range of memory from the E820 table: */
> @@ -573,6 +604,9 @@ u64 __init e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool
>  		/* Is the new range completely covered? */
>  		if (entry->addr < start && entry_end > end) {
>  			e820__range_add(end, entry_end - end, entry->type);
> +			if (entry->crypto_capable)
> +				e820__range_mark_as_crypto(end, entry_end - end);
> +

Why introduce this new function call instead of adding an extra
'crypto_capable' argument to e820__range_add() ?

-Dov


>  			entry->size = start - entry->addr;
>  			real_removed_size += size;
>  			continue;
> @@ -1322,6 +1356,8 @@ void __init e820__memblock_setup(void)
>  			continue;
>  
>  		memblock_add(entry->addr, entry->size);
> +		if (entry->crypto_capable)
> +			memblock_mark_crypto_capable(entry->addr, entry->size);
>  	}
>  
>  	/* Throw away partial pages: */
>