Re: [PATCH v5 3/9] x86/sgx: Keep record for SGX VA and Guest page type

[Jarkko Sakkinen <jarkko@kernel.org>]

On Fri, May 20, 2022 at 06:38:58PM +0800, Cathy Zhang wrote:
> Regular enclave EPC pages have sgx_encl_page as their owner, but
> SGX VA page and KVM guest EPC page are maintained by different
> owner structures.
> 
> SGX CPUSVN update requires to know the EPC page owner's status
> and then decide how to handle the page.
> 
> Keep a record of page type for SGX VA and KVM guest page while
> the other EPC pages already have their type tracked, so that
> CPUSVN update can get EPC page's owner by type and handle it then.
> 
> Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>
> 
> ---
> Changes since v3:
>  - Rename SGX_EPC_PAGE_GUEST as SGX_EPC_PAGE_KVM_GUEST. (Suggested by
>    Jarkko, Sakkinen)
> ---
>  arch/x86/kernel/cpu/sgx/sgx.h  | 4 ++++
>  arch/x86/kernel/cpu/sgx/encl.c | 2 ++
>  arch/x86/kernel/cpu/sgx/virt.c | 2 ++
>  3 files changed, 8 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index f8ed9deac18b..4ad0e5396eef 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -28,6 +28,10 @@
>  
>  /* Pages on free list */
>  #define SGX_EPC_PAGE_IS_FREE		BIT(1)
> +/* VA page */
> +#define SGX_EPC_PAGE_VA			BIT(2)
> +/* Pages allocated for KVM guest */
> +#define SGX_EPC_PAGE_KVM_GUEST		BIT(3)
>  
>  struct sgx_epc_page {
>  	unsigned int section;
> diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> index 08f39fa03a39..383abd538ac9 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.c
> +++ b/arch/x86/kernel/cpu/sgx/encl.c
> @@ -912,6 +912,8 @@ struct sgx_epc_page *sgx_alloc_va_page(struct sgx_va_page *va_page)
>  		return ERR_PTR(-EFAULT);
>  	}
>  
> +	epc_page->flags |= SGX_EPC_PAGE_VA;
> +
>  	return epc_page;
>  }
>  
> diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
> index e953816d7c8b..104487b72fb8 100644
> --- a/arch/x86/kernel/cpu/sgx/virt.c
> +++ b/arch/x86/kernel/cpu/sgx/virt.c
> @@ -50,6 +50,8 @@ static int __sgx_vepc_fault(struct sgx_vepc *vepc,
>  	if (IS_ERR(epc_page))
>  		return PTR_ERR(epc_page);
>  
> +	epc_page->flags |= SGX_EPC_PAGE_KVM_GUEST;

This would need to be synced up with SGX_EPC_IS_VEPC:

https://lore.kernel.org/linux-sgx/694234d7-6a0d-e85f-f2f9-e52b4a61e1ec@intel.com/T/#t

Otherwise, we have a chaos.

Can you sync up with Zhiquan Li and find some common approach. IMHO,
it might even sense to merge these patch sets into one. Then it would
be easier to review them as a whole.

BR, Jarkko