+Anup and Will On Fri, Apr 08, 2022, Peter Gonda wrote: > On Thu, Apr 7, 2022 at 8:55 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > > > On Thu, Apr 07, 2022, Peter Gonda wrote: > > > If an SEV-ES guest requests termination, exit to userspace with > > > KVM_EXIT_SYSTEM_EVENT and a dedicated SEV_TERM type instead of -EINVAL > > > so that userspace can take appropriate action. > > > > > > See AMD's GHCB spec section '4.1.13 Termination Request' for more details. > > > > Maybe it'll be obvious by the lack of compilation errors, but the changelog should > > call out the flags => ndata+data shenanigans, otherwise this looks like ABI breakage. > > Hmm I am not sure we can do this change anymore given that we have two > call sites using 'flags' > > arch/arm64/kvm/psci.c:184 > arch/riscv/kvm/vcpu_sbi.c:97 > > I am not at all familiar with ARM and RISC-V but some quick reading > tells me these archs also require 64-bit alignment on their 64-bit > accesses. If thats correct, should I fix this call sites up by > proceeding with this ndata + data[] change and move whatever they are > assigning to flags into data[0] like I am doing here? It looks like > both of these changes are not in a kernel release so IIUC we can still > fix the ABI here? Yeah, both came in for v5.18. Given that there will be multiple paths that need to set data, it's worth adding a common helper to the dirty work. Anup and Will, system_event.flags is broken (at least on x86) due to the prior 'type' field not being propery padded, e.g. userspace will read/write garbage if the userspace and kernel compilers pad structs differently. struct { __u32 type; __u64 flags; } system_event; Our plan to unhose this is to change the struct as follows and use bit 31 in the 'type' to indicate that ndata+data are valid. struct { __u32 type; __u32 ndata; __u64 data[16]; } system_event; Any objection to updating your architectures to use a helper to set the bit and populate ndata+data accordingly? It'll require a userspace update, but v5.18 hasn't officially released yet so it's not kinda sort not ABI breakage.