On Tue, Jun 8, 2021 at 4:38 PM Dave Hansen <dave.hansen@xxxxxxxxx> wrote: > > On 6/8/21 4:32 PM, Dan Williams wrote: > >> Persistent memory is also currently not supported. Another code > >> path that uses WBINVD is the MTRR driver, but EPT/virtualization > >> always disables MTRRs so those are not needed. This all implies > >> WBINVD is not needed with current TDX. > > Let's drop the last three paragraphs and just say something like: > > "This is one of a series of patches to usages of wbinvd for protected > > guests. For now this just addresses the one known path that TDX > > executes, ACPI reboot. Its usage can be elided because FOO reason and > > all the other ACPI_FLUSH_CPU_CACHE usages can be elided because BAR > > reason" > > A better effort at transparency can be made here: > > This patches the one WBINVD instance which has been encountered > in practice: ACPI reboot. Assume no other instance will be > encountered. > That works too, but I assume if ACPI_FLUSH_CPU_CACHE() itself is going to be changed rather than sprinkling protected_guest_has() checks in a few places it will need to assert why changing all of those at once is correct. Otherwise I expect Rafael to ask why this global change of the ACPI_FLUSH_CPU_CACHE() policy is ok.
