On 25/05/2018 14:54, Greg Kurz wrote: > Since the kernel commit "dbfcf3cb9c68 powerpc/64: Call H_REGISTER_PROC_TBL > when running as a HPT guest on POWER9", a nested guest running with PR KVM > hangs at boot: > > Preparing to boot Linux version 4.16.0-kvm-pr-hang-gku+ > (greg@qemu2222.boston16) (gcc version 8.1.1 20180502 (Red Hat 8.1.1-1) (GCC)) > #19 SMP Fri May 25 08:41:55 CEST 2018 > Detected machine type: 0000000000000101 > command line: root=UUID=22128c5c-30b1-4e0a-ac16-95853df31131 ro rhgb > console=hvc0 early_printk disable-radix=on > Max number of cores passed to firmware: 1024 (NR_CPUS = 1024) > Calling ibm,client-architecture-support... done > memory layout at init: > memory_limit : 0000000000000000 (16 MB aligned) > alloc_bottom : 0000000001b80000 > alloc_top : 0000000030000000 > alloc_top_hi : 0000000100000000 > rmo_top : 0000000030000000 > ram_top : 0000000100000000 > instantiating rtas at 0x000000002fff0000... done > prom_hold_cpus: skipped > copying OF device tree... > Building dt strings... > Building dt structure... > Device tree strings 0x0000000003d90000 -> 0x0000000003d90abb > Device tree struct 0x0000000003da0000 -> 0x0000000003db0000 > Quiescing Open Firmware ... > Booting Linux via __start() @ 0x0000000000400000 ... > > This happens because the H_REGISTER_PROC_TBL implementation in QEMU > always call KVM_PPC_CONFIGURE_V3_MMU when KVM is present. This fails > in the case of PR KVM, which doesn't implement it, and QEMU returns > H_PARAMETER to the guest, which is a BUG() condition in linux. > > In the case of PR, the HPT is allocated in userspace by QEMU, so it > doesn't make sense to call KVM_PPC_CONFIGURE_V3_MMU in the first > place. So, skip it in this case and let the guest boot. > > Signed-off-by: Greg Kurz <gr...@kaod.org> > --- > > Note that PR KVM requires this patch from Paul to work on POWER9: > > https://patchwork.ozlabs.org/patch/916766/ > > The original request was coming from people who want to run openQA in > fedora28 under PowerVM on a POWER9 system. This requires PR KVM, which > will be running in HPT-mode since pHyp doesn't do radix. > > Cc'ing stable because fedora28 ships QEMU 2.11.x. > --- > hw/ppc/spapr_hcall.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c > index 022f6d810182..12cbb317e5e8 100644 > --- a/hw/ppc/spapr_hcall.c > +++ b/hw/ppc/spapr_hcall.c > @@ -1420,7 +1420,7 @@ static target_ulong h_register_process_table(PowerPCCPU > *cpu, > ((flags & FLAG_GTSE) ? LPCR_GTSE : 0), > LPCR_UPRT | LPCR_GTSE); > > - if (kvm_enabled()) { > + if (kvm_enabled() && !spapr->htab) { > return kvmppc_configure_v3_mmu(cpu, flags & FLAG_RADIX, > flags & FLAG_GTSE, cproc); > } >
Reviewed-by: Laurent Vivier <lviv...@redhat.com>
