RE: [PATCH v2 6/6] Drivers: hv: vmbus: Support TDX guests

[Dexuan Cui <decui@microsoft.com>]

> From: Michael Kelley (LINUX) <mikelley@microsoft.com>
> Sent: Monday, December 12, 2022 9:02 AM
> > [...]
> > @@ -225,6 +275,10 @@ void hv_synic_enable_regs(unsigned int cpu)
> >  	} else {
> >  		simp.base_simp_gpa = virt_to_phys(hv_cpu->synic_message_page)
> >  			>> HV_HYP_PAGE_SHIFT;
> > +
> > +		if (hv_isolation_type_tdx())
> > +			simp.base_simp_gpa |= ms_hyperv.shared_gpa_boundary
> > +				>> HV_HYP_PAGE_SHIFT;
> 
> Since we're using cc_mkdec() in hv_do_hypercall() to set the SHARED bit,
> perhaps the same could be done here to simplify the code and avoid the
> explicit call to hv_isolation_type_tdx():

Good idea! Will do.

> 		simp.base_simp_gpa =
> cc_mkdec(virt_to_phys(hv_cpu->synic_message))
> 			>> HV_HYP_PAGE_SHIFT;
> 
> cc_mkdec() does nothing in a normal VM, and vTOM VMs are already
> special-cased.

This should work for C-bit SNP as well (clearing cc_mask from the GPA
doesn't really change the GPA since the GPA doesn't have the bit in the
first place).

> >  	hv_set_register(HV_REGISTER_SIMP, simp.as_uint64);
> > @@ -243,6 +297,10 @@ void hv_synic_enable_regs(unsigned int cpu)
> >  	} else {
> >  		siefp.base_siefp_gpa = virt_to_phys(hv_cpu->synic_event_page)
> >  			>> HV_HYP_PAGE_SHIFT;
> > +
> > +		if (hv_isolation_type_tdx())
> > +			siefp.base_siefp_gpa |= ms_hyperv.shared_gpa_boundary
> > +				>> HV_HYP_PAGE_SHIFT;
> 
> Same here.

Will do.