Hi. I discovered after upgrading to kernel 5.4 on my Talos II (Power9 Nimbus DD2.2) that KVM didn't work anymore. The guest would crash already in SLOF. After bisecting, I found that the culprit was this commit: | From 6c85b7bc637b64e681760f62c0eafba2f56745c6 Mon Sep 17 00:00:00 2001 | From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx> | Date: Thu, 22 Aug 2019 00:48:38 -0300 | Subject: powerpc/kvm: Use UV_RETURN ucall to return to ultravisor | | When an SVM makes an hypercall or incurs some other exception, the | Ultravisor usually forwards (a.k.a. reflects) the exceptions to the | Hypervisor. After processing the exception, Hypervisor uses the | UV_RETURN ultracall to return control back to the SVM. Looking at the diff, this change caught my eye: - ld r6, VCPU_CR(r4) + lwz r0, VCPU_CR(r4) So the loading of VPU_CR has changed from ld to lwz. This seems wrong. ccr is an unsigned long, and the store to VCPU_CR in the same file uses std, not stw. So loading VCPU_CR must be done with ld, otherwise the result will be wrong (truncated on LE, truncated and left shifted by 16 bits on BE)... // Marcus
