On Tue, Jan 21, 2025, Dionna Amalie Glaze wrote:
> On Mon, Jan 20, 2025 at 1:58 PM Melody Wang <huibo.wang@xxxxxxx> wrote:
> > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> > index 943bd074a5d3..4896c34ed318 100644
> > --- a/arch/x86/kvm/svm/sev.c
> > +++ b/arch/x86/kvm/svm/sev.c
> > @@ -4064,6 +4064,30 @@ static int snp_handle_guest_req(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t resp_
> > return ret;
> > }
> >
> > +static int snp_complete_req_certs(struct kvm_vcpu *vcpu)
> > +{
> > + struct vcpu_svm *svm = to_svm(vcpu);
> > + struct vmcb_control_area *control = &svm->vmcb->control;
> > +
> > + if (vcpu->run->snp_req_certs.ret) {
> > + if (vcpu->run->snp_req_certs.ret == ENOSPC) {
> > + vcpu->arch.regs[VCPU_REGS_RBX] = vcpu->run->snp_req_certs.npages;
> > + ghcb_set_sw_exit_info_2(svm->sev_es.ghcb,
> > + SNP_GUEST_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN, 0));
> > + } else if (vcpu->run->snp_req_certs.ret == EAGAIN) {
> > + ghcb_set_sw_exit_info_2(svm->sev_es.ghcb,
> > + SNP_GUEST_ERR(SNP_GUEST_VMM_ERR_BUSY, 0));
>
> Discussion, not a change request: given that my proposed patch [1] to
> add rate-limiting for guest messages to the PSP generally was
> rejected,
For the record, it wasn't rejected outright. I pointed out flaws in the proposed
behavior[*], and AFAICT no one ever responded. If I fully reject something, I
promise I will make it abundantly clear :-)
[*] https://lore.kernel.org/all/Y8rEFpbMV58yJIKy@xxxxxxxxxx
> do we think it'd be proper to add a KVM_EXIT_SNP_REQ_MSG or
> some such for the VMM to decide if the guest should have access to the
> globally shared resource (PSP) via EAGAIN or 0?
Can you elaborate? I don't quite understand what you're suggesting.
> [1] https://patchwork.kernel.org/project/kvm/cover/20230119213426.379312-1-dionnaglaze@xxxxxxxxxx/
>
> > + } else {
> > + ghcb_set_sw_exit_info_2(svm->sev_es.ghcb,
> > + SNP_GUEST_ERR(SNP_GUEST_VMM_ERR_GENERIC, 0));
> > + }
> > +
> > + return 1; /* resume guest */
> > + }
> > +
> > + return snp_handle_guest_req(svm, control->exit_info_1, control->exit_info_2);
> > +}
