On Thu, Nov 03, 2022 at 08:23:53PM -0700, Kuppuswamy Sathyanarayanan wrote:
> To support TDX attestation, the TDX guest driver exposes an IOCTL
> interface to allow userspace to get the TDREPORT from the TDX module
> via TDG.MR.TDREPORT TDCALL.
>
> In order to get the TDREPORT in the TDX guest driver, instead of using
> a low level function like __tdx_module_call(), add a
> tdx_mcall_get_report() wrapper function to handle it.
>
> This is a preparatory patch for adding attestation support.
>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> ---
>
> Changes since v16
> * Added invalid operand error code support.
> * Removed subtype param in tdx_mcall_get_report().
>
> Changes since v15:
> * None
>
> Changes since v14:
> * Instead of exporting __tdx_module_call(), added a new wrapper.
> * Rebased on top of v6.1-rc1
>
> arch/x86/coco/tdx/tdx.c | 38 ++++++++++++++++++++++++++++++++++++++
> arch/x86/include/asm/tdx.h | 2 ++
> 2 files changed, 40 insertions(+)
>
> diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
> index 928dcf7a20d9..17cf2e9d5849 100644
> --- a/arch/x86/coco/tdx/tdx.c
> +++ b/arch/x86/coco/tdx/tdx.c
> @@ -5,6 +5,8 @@
> #define pr_fmt(fmt) "tdx: " fmt
>
> #include <linux/cpufeature.h>
> +#include <linux/export.h>
> +#include <linux/io.h>
> #include <asm/coco.h>
> #include <asm/tdx.h>
> #include <asm/vmx.h>
> @@ -15,6 +17,7 @@
> /* TDX module Call Leaf IDs */
> #define TDX_GET_INFO 1
> #define TDX_GET_VEINFO 3
> +#define TDX_GET_REPORT 4
> #define TDX_ACCEPT_PAGE 6
>
> /* TDX hypercall Leaf IDs */
> @@ -34,6 +37,10 @@
> #define VE_GET_PORT_NUM(e) ((e) >> 16)
> #define VE_IS_IO_STRING(e) ((e) & BIT(4))
>
> +/* TDX Module call error codes */
> +#define TDCALL_RETURN_CODE(a) ((a) >> 32)
> +#define TDCALL_INVALID_OPERAND 0xc0000100
> +
> /*
> * Wrapper for standard use of __tdx_hypercall with no output aside from
> * return code.
> @@ -98,6 +105,37 @@ static inline void tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
> panic("TDCALL %lld failed (Buggy TDX module!)\n", fn);
> }
>
> +/**
> + * tdx_mcall_get_report() - Wrapper for TDG.MR.REPORT TDCALL.
> + * @reportdata: Address of the input buffer which contains
> + * user-defined REPORTDATA to be included into
> + * TDREPORT.
> + * @tdreport: Address of the output buffer to store TDREPORT.
> + *
> + * Generate TDREPORT using "TDG.MR.REPORT" TDCALL. Refer to section
> + * titled "TDG.MR.REPORT leaf" in the TDX Module 1.0 specification
> + * for detailed information. It is used in the TDX guest driver
> + * module to get the TDREPORT.
> + *
> + * Return 0 on success, -EINVAL for invalid operands, or -EIO on
> + * other TDCALL failures.
> + */
> +int tdx_mcall_get_report(u8 *reportdata, u8 *tdreport)
> +{
> + u64 ret;
> +
> + ret = __tdx_module_call(TDX_GET_REPORT, virt_to_phys(tdreport),
> + virt_to_phys(reportdata), 0, 0, NULL);
> + if (ret) {
> + if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND)
> + return -EINVAL;
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(tdx_mcall_get_report);
> +
> static u64 get_cc_mask(void)
> {
> struct tdx_module_output out;
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index 020c81a7c729..eef9c0b7880e 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -67,6 +67,8 @@ void tdx_safe_halt(void);
>
> bool tdx_early_handle_ve(struct pt_regs *regs);
>
> +int tdx_mcall_get_report(u8 *reportdata, u8 *tdreport);
> +
> #else
>
> static inline void tdx_early_init(void) { };
> --
> 2.34.1
>
>
Acked-by: Wander Lairson Costa <wander@xxxxxxxxxx>
