On Monday 25 March 2019 12:02 PM, David Gibson wrote:
> On Fri, Mar 22, 2019 at 12:04:16PM +0530, Aravinda Prasad wrote:
>> Enable the KVM capability KVM_CAP_PPC_FWNMI so that
>> the KVM causes guest exit with NMI as exit reason
>> when it encounters a machine check exception on the
>> address belonging to a guest. Without this capability
>> enabled, KVM redirects machine check exceptions to
>> guest's 0x200 vector.
>>
>> Signed-off-by: Aravinda Prasad <aravi...@linux.vnet.ibm.com>
>> ---
>> hw/ppc/spapr_rtas.c | 15 +++++++++++++++
>> target/ppc/kvm.c | 14 ++++++++++++++
>> target/ppc/kvm_ppc.h | 6 ++++++
>> 3 files changed, 35 insertions(+)
>>
>> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
>> index fb594a4..939f428 100644
>> --- a/hw/ppc/spapr_rtas.c
>> +++ b/hw/ppc/spapr_rtas.c
>> @@ -49,6 +49,7 @@
>> #include "hw/ppc/fdt.h"
>> #include "target/ppc/mmu-hash64.h"
>> #include "target/ppc/mmu-book3s-v3.h"
>> +#include "kvm_ppc.h"
>>
>> static void rtas_display_character(PowerPCCPU *cpu, SpaprMachineState
>> *spapr,
>> uint32_t token, uint32_t nargs,
>> @@ -354,6 +355,20 @@ static void rtas_ibm_nmi_register(PowerPCCPU *cpu,
>> target_ulong args,
>> uint32_t nret, target_ulong rets)
>> {
>> + int ret;
>> +
>> + ret = kvmppc_fwnmi_enable(cpu);
>> +
>> + if (ret == 1) {
>> + rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
>
> Urgh, we're here making a guest visible different to the environment
> depending on a host (KVM) capability. What happens if you start a
> guest and it registers fwnmi support, then migrate it to a host that
> lacks the necessary KVM support?
I just checked how such scenarios are handled for other KVM
capabilities. Should I need to add an Spapr cap for this?
Regards,
Aravinda
>
>> + return;
>> + }
>> +
>> + if (ret < 0) {
>> + rtas_st(rets, 0, RTAS_OUT_HW_ERROR);
>> + return;
>> + }
>> +
>> spapr->mc_reset = 0;
>> spapr->guest_machine_check_addr = rtas_ld(args, 1);
>> rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
>> index a593448..161b45e 100644
>> --- a/target/ppc/kvm.c
>> +++ b/target/ppc/kvm.c
>> @@ -93,6 +93,7 @@ static int cap_ppc_safe_indirect_branch;
>> static int cap_ppc_count_cache_flush_assist;
>> static int cap_ppc_nested_kvm_hv;
>> static int cap_large_decr;
>> +static int cap_ppc_fwnmi;
>>
>> static uint32_t debug_inst_opcode;
>>
>> @@ -155,6 +156,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
>> kvmppc_get_cpu_characteristics(s);
>> cap_ppc_nested_kvm_hv = kvm_vm_check_extension(s,
>> KVM_CAP_PPC_NESTED_HV);
>> cap_large_decr = kvmppc_get_dec_bits();
>> + cap_ppc_fwnmi = kvm_check_extension(s, KVM_CAP_PPC_FWNMI);
>> /*
>> * Note: setting it to false because there is not such capability
>> * in KVM at this moment.
>> @@ -2091,6 +2093,18 @@ void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int
>> mpic_proxy)
>> }
>> }
>>
>> +int kvmppc_fwnmi_enable(PowerPCCPU *cpu)
>> +{
>> + CPUState *cs = CPU(cpu);
>> +
>> + if (!cap_ppc_fwnmi) {
>> + return 1;
>> + }
>> +
>> + return kvm_vcpu_enable_cap(cs, KVM_CAP_PPC_FWNMI, 0);
>> +}
>> +
>> +
>> int kvmppc_smt_threads(void)
>> {
>> return cap_ppc_smt ? cap_ppc_smt : 1;
>> diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
>> index df5e85f..cf7b24f 100644
>> --- a/target/ppc/kvm_ppc.h
>> +++ b/target/ppc/kvm_ppc.h
>> @@ -27,6 +27,7 @@ void kvmppc_enable_h_page_init(void);
>> void kvmppc_set_papr(PowerPCCPU *cpu);
>> int kvmppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr);
>> void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy);
>> +int kvmppc_fwnmi_enable(PowerPCCPU *cpu);
>> int kvmppc_smt_threads(void);
>> void kvmppc_hint_smt_possible(Error **errp);
>> int kvmppc_set_smt_threads(int smt);
>> @@ -158,6 +159,11 @@ static inline void kvmppc_set_mpic_proxy(PowerPCCPU
>> *cpu, int mpic_proxy)
>> {
>> }
>>
>> +int kvmppc_fwnmi_enable(PowerPCCPU *cpu)
>> +{
>> + return 1;
>> +}
>> +
>> static inline int kvmppc_smt_threads(void)
>> {
>> return 1;
>>
>
--
Regards,
Aravinda
