Subject: Re: [PATCH v3 4/6] KVM: PPC: Book3s HV: Hold LPIDs in an unsigned long

From: Michael Ellerman <[email-masked]>
Date: Thu, 17 Aug 2023 22:21:08 +1000

Jordan Niethe <[email-masked]> writes:
> The LPID register is 32 bits long. The host keeps the lpids for each
> guest in an unsigned word struct kvm_arch. Currently, LPIDs are already
> limited by mmu_lpid_bits and KVM_MAX_NESTED_GUESTS_SHIFT.
>
> The nestedv2 API returns a 64 bit "Guest ID" to be used be the L1 host
> for each L2 guest. This value is used as an lpid, e.g. it is the
> parameter used by H_RPT_INVALIDATE. To minimize needless special casing
> it makes sense to keep this "Guest ID" in struct kvm_arch::lpid.
>
> This means that struct kvm_arch::lpid is too small so prepare for this
> and make it an unsigned long. This is not a problem for the KVM-HV and
> nestedv1 cases as their lpid values are already limited to valid ranges
> so in those contexts the lpid can be used as an unsigned word safely as
> needed.
>
> In the PAPR, the H_RPT_INVALIDATE pid/lpid parameter is already
> specified as an unsigned long so change pseries_rpt_invalidate() to
> match that.  Update the callers of pseries_rpt_invalidate() to also take
> an unsigned long if they take an lpid value.
>
> Signed-off-by: Jordan Niethe <[email-masked]>
> ---

This needs:

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 709ebd578394..08e32b44ee32 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -857,7 +857,7 @@ unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)
        }

        kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE;
-       pr_info("LPID %d went secure\n", kvm->arch.lpid);
+       pr_info("LPID %lu went secure\n", kvm->arch.lpid);

 out:
        srcu_read_unlock(&kvm->srcu, srcu_idx);

cheers