Re: [PATCH v3 6/6] KVM: TDX: Explicitly do WBINVD upon reboot notifier

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

> > --- a/arch/x86/include/asm/tdx.h
> > +++ b/arch/x86/include/asm/tdx.h
> > @@ -221,6 +221,8 @@ u64 tdh_mem_page_remove(struct tdx_td *td, u64 gpa, u64 level, u64 *ext_err1, u6
> >  u64 tdh_phymem_cache_wb(bool resume);
> >  u64 tdh_phymem_page_wbinvd_tdr(struct tdx_td *td);
> >  u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page);
> > +
> 
> Nit: There is a new line here, but not below. I guess it's ok.

I will remove.


[...]

> > +	if (enable_tdx)
> > +		/*
> > +		 * Ignore the return value.  @tdx_reboot_nb is used to flush
> > +		 * cache for all CPUs upon rebooting to avoid having to do
> > +		 * WBINVD in kexec while the kexec-ing CPU stops all remote
> > +		 * CPUs.  Failure to register isn't fatal, because if KVM
> > +		 * doesn't flush cache explicitly upon rebooting the kexec
> > +		 * will do it anyway.
> > +		 */
> > +		register_reboot_notifier(&tdx_reboot_nb);
> > +
> 
> The comment should be inside a {}.

Will do.

> 
> >  	return r;
> >  
> >  success_disable_tdx:
> > diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> > index c7a9a087ccaf..73425e9bee39 100644
> > --- a/arch/x86/virt/vmx/tdx/tdx.c
> > +++ b/arch/x86/virt/vmx/tdx/tdx.c
> > @@ -1870,3 +1870,12 @@ u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page)
> >  	return seamcall(TDH_PHYMEM_PAGE_WBINVD, &args);
> >  }
> >  EXPORT_SYMBOL_GPL(tdh_phymem_page_wbinvd_hkid);
> > +
> > +void tdx_cpu_flush_cache(void)
> > +{
> > +	lockdep_assert_preemption_disabled();
> > +
> > +	wbinvd();
> > +	this_cpu_write(cache_state_incoherent, false);
> > +}
> > +EXPORT_SYMBOL_GPL(tdx_cpu_flush_cache);
> 
> Does this need to be here? Why not in KVM?

Otherwise the 'cache_state_incoherent' variable needs to be exported.  It's
good to hide the details in TDX core code too.