Re: [PATCH Part2 RFC v4 25/40] KVM: SVM: Reclaim the guest pages when SEV-SNP VM terminates

[Brijesh Singh]

On 7/19/21 12:18 PM, Sean Christopherson wrote:
> > Okay, I will add helper to make things easier. One case where we will
> > need to directly call the rmpupdate() is during the LAUNCH_UPDATE
> > command. In that case the page is private and its immutable bit is also
> > set. This is because the firmware makes change to the page, and we are
> > required to set the immutable bit before the call.
>
> Or do "int rmp_make_firmware(u64 pfn, bool immutable)"?

That's not what we need.

We need 'rmp_make_private() + immutable' all in one RMPUPDATE.  Here is 
the snippet from SNP_LAUNCH_UPDATE.


+	/* Transition the page state to pre-guest */
+	memset(&e, 0, sizeof(e));
+	e.assigned = 1;
+	e.gpa = gpa;
+	e.asid = sev_get_asid(kvm);
+	e.immutable = true;
+	e.pagesize = X86_TO_RMP_PG_LEVEL(level);
+	ret = rmpupdate(inpages[i], &e);

thanks