Re: [RFC PATCH v3 13/27] x86/sgx: Add helper to update SGX_LEPUBKEYHASHn MSRs

[Jarkko Sakkinen <jarkko@kernel.org>]

On Tue, Jan 26, 2021 at 10:31:05PM +1300, Kai Huang wrote:
> Add a helper to update SGX_LEPUBKEYHASHn MSRs.  SGX virtualization also
> needs to update those MSRs based on guest's "virtual" SGX_LEPUBKEYHASHn
> before EINIT from guest.
> 
> Signed-off-by: Kai Huang <kai.huang@intel.com>


Acked-by: Jarkko Sakkinen <jarkko@kernel.org>

/Jarkko

> ---
> v2->v3:
> 
>  - Added comment for sgx_update_lepubkeyhash(), per Jarkko and Dave.
> 
> ---
>  arch/x86/kernel/cpu/sgx/ioctl.c |  5 ++---
>  arch/x86/kernel/cpu/sgx/main.c  | 15 +++++++++++++++
>  arch/x86/kernel/cpu/sgx/sgx.h   |  2 ++
>  3 files changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> index e5977752c7be..1bae754268d1 100644
> --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> @@ -495,7 +495,7 @@ static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,
>  			 void *token)
>  {
>  	u64 mrsigner[4];
> -	int i, j, k;
> +	int i, j;
>  	void *addr;
>  	int ret;
>  
> @@ -544,8 +544,7 @@ static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,
>  
>  			preempt_disable();
>  
> -			for (k = 0; k < 4; k++)
> -				wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + k, mrsigner[k]);
> +			sgx_update_lepubkeyhash(mrsigner);
>  
>  			ret = __einit(sigstruct, token, addr);
>  
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 93d249f7bff3..b456899a9532 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -697,6 +697,21 @@ static bool __init sgx_page_cache_init(void)
>  	return true;
>  }
>  
> +
> +/*
> + * Update the SGX_LEPUBKEYHASH MSRs to the values specified by caller.
> + * Bare-metal driver requires to update them to hash of enclave's signer
> + * before EINIT. KVM needs to update them to guest's virtual MSR values
> + * before doing EINIT from guest.
> + */
> +void sgx_update_lepubkeyhash(u64 *lepubkeyhash)
> +{
> +	int i;
> +
> +	for (i = 0; i < 4; i++)
> +		wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + i, lepubkeyhash[i]);
> +}
> +
>  static int __init sgx_init(void)
>  {
>  	int ret;
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index 509f2af33e1d..ccd4f145c464 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -83,4 +83,6 @@ void sgx_mark_page_reclaimable(struct sgx_epc_page *page);
>  int sgx_unmark_page_reclaimable(struct sgx_epc_page *page);
>  struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim);
>  
> +void sgx_update_lepubkeyhash(u64 *lepubkeyhash);
> +
>  #endif /* _X86_SGX_H */
> -- 
> 2.29.2
> 
>