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

["Huang, Kai" <kai.huang@intel.com>]

On Tue, 2023-02-14 at 13:42 +0100, Peter Zijlstra wrote:
> 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.
> 

Thanks Peter.  Will do.

> > +
> > +	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;
> > +}
>