Re: [PATCH v5 04/22] x86/virt/tdx: Prevent ACPI CPU hotplug and ACPI memory hotplug

From: Kai Huang
Date: Fri Jun 24 2022 - 07:22:09 EST


On Fri, 2022-06-24 at 09:41 +0800, Chao Gao wrote:
> On Wed, Jun 22, 2022 at 11:16:07PM +1200, Kai Huang wrote:
> > -static bool intel_cc_platform_has(enum cc_attr attr)
> > +#ifdef CONFIG_INTEL_TDX_GUEST
> > +static bool intel_tdx_guest_has(enum cc_attr attr)
> > {
> > switch (attr) {
> > case CC_ATTR_GUEST_UNROLL_STRING_IO:
> > @@ -28,6 +31,33 @@ static bool intel_cc_platform_has(enum cc_attr attr)
> > return false;
> > }
> > }
> > +#endif
> > +
> > +#ifdef CONFIG_INTEL_TDX_HOST
> > +static bool intel_tdx_host_has(enum cc_attr attr)
> > +{
> > + switch (attr) {
> > + case CC_ATTR_ACPI_CPU_HOTPLUG_DISABLED:
> > + case CC_ATTR_ACPI_MEMORY_HOTPLUG_DISABLED:
> > + return true;
> > + default:
> > + return false;
> > + }
> > +}
> > +#endif
> > +
> > +static bool intel_cc_platform_has(enum cc_attr attr)
> > +{
> > +#ifdef CONFIG_INTEL_TDX_GUEST
> > + if (boot_cpu_has(X86_FEATURE_TDX_GUEST))
> > + return intel_tdx_guest_has(attr);
> > +#endif
> > +#ifdef CONFIG_INTEL_TDX_HOST
> > + if (platform_tdx_enabled())
> > + return intel_tdx_host_has(attr);
> > +#endif
> > + return false;
> > +}
>
> how about:
>
> static bool intel_cc_platform_has(enum cc_attr attr)
> {
> switch (attr) {
> /* attributes applied to TDX guest only */
> case CC_ATTR_GUEST_UNROLL_STRING_IO:
> ...
> return boot_cpu_has(X86_FEATURE_TDX_GUEST);
>
> /* attributes applied to TDX host only */
> case CC_ATTR_ACPI_CPU_HOTPLUG_DISABLED:
> case CC_ATTR_ACPI_MEMORY_HOTPLUG_DISABLED:
> return platform_tdx_enabled();
>
> default:
> return false;
> }
> }
>
> so that we can get rid of #ifdef/endif.

Personally I don't quite like this way. To me having separate function for host
and guest is more clear and more flexible. And I don't think having
#ifdef/endif has any problem. I would like to leave to maintainers.

--
Thanks,
-Kai