Re: [PATCH Part2 RFC v4 26/40] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command

From: Brijesh Singh
Date: Mon Jul 19 2021 - 15:12:50 EST

On 7/19/21 11:54 AM, Sean Christopherson wrote:
As I said in previous comments that by default all the memory is in the
hypervisor state. if the rmpupdate() failed that means nothing is changed in
the RMP and there is no need to reclaim. The reclaim is required only if the
pages are assigned in the RMP table.

I wasn't referring to RMPUPDATE failing here (or anywhere). This is the vCPU free
path, which I think means the svm->vmsa page was successfully updated in the RMP
during LAUNCH_UPDATE. snp_launch_update_vmsa() goes through snp_page_reclaim()
on LAUNCH_UPDATE failure, whereas this happy path does not. Is there some other
transition during teardown that obviastes the need for reclaim? If so, a comment
to explain that would be very helpful.

In this patch, the sev_free_vcpu() hunk takes care of reclaiming the vmsa pages before releasing it. I think it will make it more obvious after I add a helper so that we don't depend on user reading the comment block to see what its doing.