On 11/5/21 2:27 PM, Martin Fernandez wrote:
> Add a new member in e820_entry to hold whether an entry is able to do
> hardware memory encryption or not.
That's a bit sparse for what this is doing. It covers the first hunk at
best.
> diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h
> index e8f58ddd06d9..f3a09b6afca1 100644
> --- a/arch/x86/include/asm/e820/api.h
> +++ b/arch/x86/include/asm/e820/api.h
> @@ -18,6 +18,8 @@ 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 void e820__mark_regions_as_crypto_capable(u64 start, u64 size);
> +
> extern void e820__print_table(char *who);
> extern int e820__update_table(struct e820_table *table);
> extern void e820__update_table_print(void);
> diff --git a/arch/x86/include/asm/e820/types.h b/arch/x86/include/asm/e820/types.h
> index 314f75d886d0..231c9ad9a9c3 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;
> + bool crypto_capable;
> } __attribute__((packed));
>
> /*
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index bc0657f0deed..3e0aaa5525e0 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -176,6 +176,7 @@ 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 = false;
> table->nr_entries++;
> }
>
> @@ -184,6 +185,19 @@ void __init e820__range_add(u64 start, u64 size, enum e820_type type)
> __e820__range_add(e820_table, start, size, type);
> }
>
> +void __init e820__mark_regions_as_crypto_capable(u64 start, u64 size)
> +{
> + int i;
> + u64 end = start + size;
> +
> + for (i = 0; i < e820_table->nr_entries; i++) {
> + struct e820_entry *const entry = &e820_table->entries[i];
> +
> + if (entry->addr >= start && entry->addr + entry->size <= end)
> + entry->crypto_capable = true;
> + }
> +}
Looking at this in isolation, this is really tricky. I have no idea
what this is _supposed_ to or expected to be doing. It also makes me
wonder what happens when start/size don't line up exactly on an e820 entry.
> static void __init e820_print_type(enum e820_type type)
> {
> switch (type) {
> @@ -211,6 +225,8 @@ 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);
> + pr_cont("%s",
> + e820_table->entries[i].crypto_capable ? "; crypto-capable" : "");
Am I missing something or should this just be:
if (e820_table->entries[i].crypto_capable)
pr_cont("; crypto-capable");
In general, I find code that retreats to the ternary form is almost
always doing something nasty.
> pr_cont("\n");
> }
> }
> @@ -327,6 +343,8 @@ 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;
> + bool current_crypto;
> + bool last_crypto = false;
>
> /* If there's only one memory region, don't bother: */
> if (table->nr_entries < 2)
> @@ -388,13 +406,17 @@ int __init e820__update_table(struct e820_table *table)
> * 1=usable, 2,3,4,4+=unusable)
> */
> current_type = 0;
> + current_crypto = false;
> for (i = 0; i < overlap_entries; i++) {
> + current_crypto = current_crypto || overlap_list[i]->crypto_capable;
No comment, eh?
This seems backwards to me. If there are overlapping region and only
one is crypto-capable, shouldn't the whole thing become non-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: */
> @@ -406,6 +428,9 @@ 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_crypto = current_crypto;
> last_addr = change_point[chg_idx]->addr;
> }
> last_type = current_type;
The "current_crypto != last_crypto" checks seem to go with the
current_type/last_type checks. I'm naively surprised that the
last_crypto assignment wasn't paired with the last_type assignment.
I kinda get the impression this was just quickly hacked in here. It
seems like "crypto" and "type" are very closely related in how they are
being handled. It's a shame they're not being managed in a common way.
> @@ -1321,7 +1346,10 @@ void __init e820__memblock_setup(void)
> if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN)
> continue;
>
> - memblock_add(entry->addr, entry->size);
> + if (entry->crypto_capable)
> + memblock_add_crypto_capable(entry->addr, entry->size);
> + else
> + memblock_add(entry->addr, entry->size);
Having a different memblock_add_foo() doesn't seem to be the way this is
done. See:
memblock_mark_hotplug();
or
memblock_mark_mirror();
Shouldn't this be: memblock_mark_crypto()
By the way, how was this tested?
