Tested-by: Jethro Beekman <jethro@xxxxxxxxxxxx>
--
Jethro Beekman | Fortanix
On 2020-08-18 06:24, Sean Christopherson wrote:
> Allow userspace to exit the vDSO on interrupts that are acknowledged
> while the enclave is active. This allows the user's runtime to switch
> contexts at opportune times without additional overhead, e.g. when using
> an M:N threading model (where M user threads run N TCSs, with N > M).
>
> Suggested-by: Jethro Beekman <jethro@xxxxxxxxxxxx>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
> arch/x86/entry/vdso/vsgx_enter_enclave.S | 27 ++++++++++++++++++++----
> arch/x86/include/uapi/asm/sgx.h | 3 +++
> 2 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/entry/vdso/vsgx_enter_enclave.S b/arch/x86/entry/vdso/vsgx_enter_enclave.S
> index b09e87dbe9334..33428c0f94b0d 100644
> --- a/arch/x86/entry/vdso/vsgx_enter_enclave.S
> +++ b/arch/x86/entry/vdso/vsgx_enter_enclave.S
> @@ -21,6 +21,9 @@
>
> #define SGX_SYNCHRONOUS_EXIT 0
> #define SGX_EXCEPTION_EXIT 1
> +#define SGX_INTERRUPT_EXIT 2
> +
> +#define SGX_EXIT_ON_INTERRUPTS 1
>
> /* Offsets into sgx_enter_enclave.exception. */
> #define EX_TRAPNR 0*8
> @@ -51,12 +54,17 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave)
>
> mov RUN_OFFSET(%rbp), %rcx
>
> - /* No flags are currently defined/supported. */
> - cmpq $0, FLAGS_OFFSET(%rcx)
> - jne .Linvalid_input
> -
> /* Load TCS and AEP */
> mov TCS_OFFEST(%rcx), %rbx
> +
> + /* Use the alternate AEP if the user wants to exit on interrupts. */
> + mov FLAGS_OFFSET(%rcx), %rcx
> + cmpq $SGX_EXIT_ON_INTERRUPTS, %rcx
> + je .Lload_interrupts_aep
> +
> + /* All other flags are reserved. */
> + test %rcx, %rcx
> + jne .Linvalid_input
> lea .Lasync_exit_pointer(%rip), %rcx
>
> /* Single ENCLU serving as both EENTER and AEP (ERESUME) */
> @@ -93,6 +101,17 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave)
> mov $(-EINVAL), %eax
> jmp .Lout
>
> +.Lload_interrupts_aep:
> + lea .Lhandle_interrupt(%rip), %rcx
> + jmp .Lenclu_eenter_eresume
> +
> +.Lhandle_interrupt:
> + mov RUN_OFFSET(%rbp), %rbx
> +
> + /* Set the exit_reason and exception info. */
> + movl $SGX_INTERRUPT_EXIT, EXIT_REASON_OFFSET(%rbx)
> + jmp .Lhandle_exit
> +
> .Lhandle_exception:
> mov RUN_OFFSET(%rbp), %rbx
>
> diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
> index 80a8b7a949a23..beeabfad6eb81 100644
> --- a/arch/x86/include/uapi/asm/sgx.h
> +++ b/arch/x86/include/uapi/asm/sgx.h
> @@ -76,6 +76,7 @@ struct sgx_enclave_set_attribute {
>
> #define SGX_SYNCHRONOUS_EXIT 0
> #define SGX_EXCEPTION_EXIT 1
> +#define SGX_INTERRUPT_EXIT 2
>
> struct sgx_enclave_run;
>
> @@ -116,6 +117,8 @@ struct sgx_enclave_exception {
> __u64 address;
> };
>
> +#define SGX_EXIT_ON_INTERRUPTS (1ULL << 0)
> +
> /**
> * struct sgx_enclave_run - Control structure for __vdso_sgx_enter_enclave()
> *
>
Attachment:
smime.p7s
Description: S/MIME Cryptographic Signature
