From 95912ce1ebe4303d17118219691573ae6227b0e2 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Mon, 22 Jan 2024 16:21:15 +1000 Subject: [PATCH] ppc/spapr: Add ibm,pi-features The ibm,pi-features property has a bit to say whether or not msgsndp should be used. Linux checks if it is being run under KVM and avoids msgsndp anyway, but it would be preferable to rely on this bit. Reviewed-by: Harsh Prateek Bora Signed-off-by: Nicholas Piggin --- hw/ppc/spapr.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index d2d1e310a3..4345764bce 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -353,6 +353,32 @@ static void spapr_dt_pa_features(SpaprMachineState *spapr, _FDT((fdt_setprop(fdt, offset, "ibm,pa-features", pa_features, pa_size))); } +static void spapr_dt_pi_features(SpaprMachineState *spapr, + PowerPCCPU *cpu, + void *fdt, int offset) +{ + uint8_t pi_features[] = { 1, 0, + 0x00 }; + + if (kvm_enabled() && ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_3_00, + 0, cpu->compat_pvr)) { + /* + * POWER9 and later CPUs with KVM run in LPAR-per-thread mode where + * all threads are essentially independent CPUs, and msgsndp does not + * work (because it is physically-addressed) and therefore is + * emulated by KVM, so disable it here to ensure XIVE will be used. + * This is both KVM and CPU implementation-specific behaviour so a KVM + * cap would be cleanest, but for now this works. If KVM ever permits + * native msgsndp execution by guests, a cap could be added at that + * time. + */ + pi_features[2] |= 0x08; /* 4: No msgsndp */ + } + + _FDT((fdt_setprop(fdt, offset, "ibm,pi-features", pi_features, + sizeof(pi_features)))); +} + static hwaddr spapr_node0_size(MachineState *machine) { if (machine->numa_state->num_nodes) { @@ -815,6 +841,8 @@ static void spapr_dt_cpu(CPUState *cs, void *fdt, int offset, spapr_dt_pa_features(spapr, cpu, fdt, offset); + spapr_dt_pi_features(spapr, cpu, fdt, offset); + _FDT((fdt_setprop_cell(fdt, offset, "ibm,chip-id", cs->cpu_index / vcpus_per_socket)));