Re: [RFC 04/12] x86/mm: Add helper functions to manage memory encryption keys

["Sakkinen, Jarkko" <jarkko.sakkinen@intel.com>]

On Fri, 2018-09-07 at 15:36 -0700, Alison Schofield wrote:
> Define a global mapping structure to track the mapping of userspace
> keys to hardware keyids in MKTME (Multi-Key Total Memory Encryption).
> This data will be used for the memory encryption system call and the
> kernel key service API.

This is also for earlier patches. I kind of feel uncomfortable because
I can neither TME nor MKTME how they reside in the chipset/board. Are
they inside the CPU package? Or is it perhaps a separate chip outside
the CPU? I would guess not but the problem is that I have to guess in
the first place.

> Implement helper functions to access this mapping structure and make
> them visible to the MKTME Kernel Key Service: security/keys/mktme_keys
> 
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> ---
>  arch/x86/include/asm/mktme.h | 11 ++++++
>  arch/x86/mm/mktme.c          | 85
> ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 96 insertions(+)
> 
> diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h
> index dbfbd955da98..f6acd551457f 100644
> --- a/arch/x86/include/asm/mktme.h
> +++ b/arch/x86/include/asm/mktme.h
> @@ -13,6 +13,17 @@ extern phys_addr_t mktme_keyid_mask;
>  extern int mktme_nr_keyids;
>  extern int mktme_keyid_shift;
>  
> +/* Manage mappings between hardware keyids and userspace keys */
> +extern int mktme_map_alloc(void);
> +extern void mktme_map_free(void);
> +extern void mktme_map_lock(void);
> +extern void mktme_map_unlock(void);
> +extern int mktme_map_get_free_keyid(void);
> +extern void mktme_map_clear_keyid(int keyid);
> +extern void mktme_map_set_keyid(int keyid, unsigned int serial);
> +extern int mktme_map_keyid_from_serial(unsigned int serial);
> +extern unsigned int mktme_map_serial_from_keyid(int keyid);
> +
>  extern struct page_ext_operations page_mktme_ops;
>  
>  #define page_keyid page_keyid
> diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c
> index 660caf6a5ce1..5246d8323359 100644
> --- a/arch/x86/mm/mktme.c
> +++ b/arch/x86/mm/mktme.c
> @@ -63,6 +63,91 @@ int vma_keyid(struct vm_area_struct *vma)
>  	return (prot & mktme_keyid_mask) >> mktme_keyid_shift;
>  }
>  
> +/*
> + * struct mktme_mapping and the mktme_map_* functions manage the mapping
> + * of userspace keys to hardware keyids in MKTME. They are used by the
> + * the encrypt_mprotect system call and the MKTME Key Service API.
> + */
> +struct mktme_mapping {
> +	struct mutex	lock;		/* protect this map & HW
> state */
> +	unsigned int	mapped_keyids;
> +	unsigned int	serial[];
> +};
> +
> +struct mktme_mapping *mktme_map;
> +
> +static inline long mktme_map_size(void)
> +{
> +	long size = 0;
> +
> +	size += sizeof(mktme_map);
> +	size += sizeof(mktme_map->serial[0]) * mktme_nr_keyids;
> +	return size;
> +}
> +
> +int mktme_map_alloc(void)
> +{
> +	mktme_map = kzalloc(mktme_map_size(), GFP_KERNEL);
> +	if (!mktme_map)
> +		return 0;
> +	mutex_init(&mktme_map->lock);
> +	return 1;
> +}
> +
> +void mktme_map_free(void)
> +{
> +	kfree(mktme_map);
> +}
> +
> +void mktme_map_lock(void)
> +{
> +	mutex_lock(&mktme_map->lock);
> +}
> +
> +void mktme_map_unlock(void)
> +{
> +	mutex_unlock(&mktme_map->lock);
> +}
> +
> +void mktme_map_set_keyid(int keyid, unsigned int serial)
> +{
> +	mktme_map->serial[keyid] = serial;
> +	mktme_map->mapped_keyids++;
> +}
> +
> +void mktme_map_clear_keyid(int keyid)
> +{
> +	mktme_map->serial[keyid] = 0;
> +	mktme_map->mapped_keyids--;
> +}
> +
> +unsigned int mktme_map_serial_from_keyid(int keyid)
> +{
> +	return mktme_map->serial[keyid];
> +}
> +
> +int mktme_map_keyid_from_serial(unsigned int serial)
> +{
> +	int i;
> +
> +	for (i = 1; i < mktme_nr_keyids; i++)
> +		if (mktme_map->serial[i] == serial)
> +			return i;
> +	return 0;
> +}
> +
> +int mktme_map_get_free_keyid(void)
> +{
> +	int i;
> +
> +	if (mktme_map->mapped_keyids < mktme_nr_keyids) {
> +		for (i = 1; i < mktme_nr_keyids; i++)
> +			if (mktme_map->serial[i] == 0)
> +				return i;
> +	}
> +	return 0;
> +}


The kdoc header is missing from all above.

/Jarkko