Re: [PATCH v9 05/18] x86/virt/tdx: Add SEAMCALL infrastructure

Peter Zijlstra
2023-02-14T15:27:21Z

On Tue, Feb 14, 2023 at 12:59:12AM +1300, Kai Huang wrote:
> +/*
> + * Wrapper of __seamcall() to convert SEAMCALL leaf function error code
> + * to kernel error code. @seamcall_ret and @out contain the SEAMCALL
> + * leaf function return code and the additional output respectively if
> + * not NULL.
> + */
> +static int __always_unused seamcall(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
> + u64 *seamcall_ret,
> + struct tdx_module_output *out)
> +{
> + int cpu, ret = 0;
> + u64 sret;
> +
> + /* Need a stable CPU id for printing error message */
> + cpu = get_cpu();
> +
> + sret = __seamcall(fn, rcx, rdx, r8, r9, out);
> +
> + /* Save SEAMCALL return code if the caller wants it */
> + if (seamcall_ret)
> + *seamcall_ret = sret;
> +
> + /* SEAMCALL was successful */
> + if (!sret)
> + goto out;

I'm thinking you want if (likely(!sret)), here. That whole switch thing
should end up in cold storage.

> +
> + switch (sret) {
> + case TDX_SEAMCALL_GP:
> + /*
> + * tdx_enable() has already checked that BIOS has
> + * enabled TDX at the very beginning before going
> + * forward. It's likely a firmware bug if the
> + * SEAMCALL still caused #GP.
> + */
> + pr_err_once("[firmware bug]: TDX is not enabled by BIOS.\n");
> + ret = -ENODEV;
> + break;
> + case TDX_SEAMCALL_VMFAILINVALID:
> + pr_err_once("TDX module is not loaded.\n");
> + ret = -ENODEV;
> + break;
> + case TDX_SEAMCALL_UD:
> + pr_err_once("SEAMCALL failed: CPU %d is not in VMX operation.\n",
> + cpu);
> + ret = -EINVAL;
> + break;
> + default:
> + pr_err_once("SEAMCALL failed: CPU %d: leaf %llu, error 0x%llx.\n",
> + cpu, fn, sret);
> + if (out)
> + pr_err_once("additional output: rcx 0x%llx, rdx 0x%llx, r8 0x%llx, r9 0x%llx, r10 0x%llx, r11 0x%llx.\n",
> + out->rcx, out->rdx, out->r8,
> + out->r9, out->r10, out->r11);
> + ret = -EIO;
> + }
> +out:
> + put_cpu();
> + return ret;
> +}