Re: [RFC PATCH 02/20] x86/sgx: Store EPC page owner as a 'void *' to handle multiple users

Dave Hansen
2022-09-22T18:54:23Z

On 9/22/22 10:10, Kristen Carlson Accardi wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> A future patch will use the owner field for either a pointer to
> a struct sgx_encl, or a struct sgx_encl_page.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
> Cc: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kernel/cpu/sgx/sgx.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index 0f2020653fba..5a7e858a8f98 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -33,7 +33,7 @@ struct sgx_epc_page {
> unsigned int section;
> u16 flags;
> u16 poison;
> - struct sgx_encl_page *owner;
> + void *owner;
> struct list_head list;
> };
>

We normally handle these with a union. I'd probably do something like
this instead:

- struct sgx_encl_page *owner;
+ union owner {
+ struct sgx_encl *o_encl;
+ struct sgx_encl_page *o_page;
+ }