Re: [PATCH v5 03/26] hostmem: Add hostmem-epc as a backend for SGX EPC

[Philippe Mathieu-Daudé]

On 9/24/21 13:24, Paolo Bonzini wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> EPC (Enclave Page Cahe) is a specialized type of memory used by Intel

Typo "Enclave Page Cache".

> SGX (Software Guard Extensions).  The SDM desribes EPC as:
> 
>     The Enclave Page Cache (EPC) is the secure storage used to store
>     enclave pages when they are a part of an executing enclave. For an
>     EPC page, hardware performs additional access control checks to
>     restrict access to the page. After the current page access checks
>     and translations are performed, the hardware checks that the EPC
>     page is accessible to the program currently executing. Generally an
>     EPC page is only accessed by the owner of the executing enclave or
>     an instruction which is setting up an EPC page.
> 
> Because of its unique requirements, Linux manages EPC separately from
> normal memory.  Similar to memfd, the device /dev/sgx_vepc can be
> opened to obtain a file descriptor which can in turn be used to mmap()
> EPC memory.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Yang Zhong <yang.zhong@intel.com>
> Message-Id: <20210719112136.57018-3-yang.zhong@intel.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  backends/hostmem-epc.c        | 82 +++++++++++++++++++++++++++++++++++
>  backends/meson.build          |  1 +
>  include/hw/i386/hostmem-epc.h | 28 ++++++++++++
>  3 files changed, 111 insertions(+)
>  create mode 100644 backends/hostmem-epc.c
>  create mode 100644 include/hw/i386/hostmem-epc.h