Re: [PATCH v3 2/2] x86/sgx: Implement EUPDATESVN and opportunistically call it during first EPC page alloc

[Dave Hansen <dave.hansen@intel.com>]

On 4/25/25 12:29, Sean Christopherson wrote:
> --- a/arch/x86/kernel/cpu/sgx/virt.c
> +++ b/arch/x86/kernel/cpu/sgx/virt.c
> @@ -255,6 +255,7 @@ static int sgx_vepc_release(struct inode *inode, struct file *file)
>  	xa_destroy(&vepc->page_array);
>  	kfree(vepc);
>  
> +	sgx_dec_usage_count();
>  	return 0;
>  }

->release() is not close(). Userspace doesn't have control over when
release() gets called, so it's a poor thing to say: "wait until all SGX
struct files have been released, then do EUPDATESVN". At least that's
what folks have always told me when I went poking around the VFS.

That alone would make this a non-starter.