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Re: [PATCH 2/2] target/ppc/kvm: Use KVM_CAP_PPC_AIL_MODE_3 to determine
From: |
Nicholas Piggin |
Subject: |
Re: [PATCH 2/2] target/ppc/kvm: Use KVM_CAP_PPC_AIL_MODE_3 to determine cap-ail-mode-3 support |
Date: |
Tue, 15 Feb 2022 08:54:48 +1000 |
Excerpts from Fabiano Rosas's message of February 14, 2022 11:13 pm:
> Nicholas Piggin <npiggin@gmail.com> writes:
>
>> Use KVM_CAP_PPC_AIL_MODE_3 to determine cap-ail-mode-3 support for KVM
>> guests. Keep the fallback heuristic for KVM hosts that pre-date this
>> CAP.
>>
>> This is only proposed the KVM CAP has not yet been allocated. I will
>> ask to merge the new KVM cap when there are no objections on the QEMU
>> side.
>>
>> not-yet-Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>> ---
>> hw/ppc/spapr_caps.c | 2 +-
>> linux-headers/linux/kvm.h | 1 +
>> target/ppc/kvm.c | 18 +++++++++++++++++-
>> target/ppc/kvm_ppc.h | 4 ++--
>> 4 files changed, 21 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
>> index 5fd4a53c33..5cc80776d0 100644
>> --- a/hw/ppc/spapr_caps.c
>> +++ b/hw/ppc/spapr_caps.c
>> @@ -619,7 +619,7 @@ static void cap_ail_mode_3_apply(SpaprMachineState
>> *spapr,
>> ERRP_GUARD();
>>
>> if (kvm_enabled()) {
>> - if (!kvmppc_supports_ail_3()) {
>> + if (!kvmppc_has_cap_ail_3()) {
>> error_setg(errp, "KVM implementation does not support
>> cap-ail-mode-3");
>> error_append_hint(errp, "Try appending -machine
>> cap-ail-mode-3=off\n");
>> return;
>> diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h
>> index 02c5e7b7bb..d91f578200 100644
>> --- a/linux-headers/linux/kvm.h
>> +++ b/linux-headers/linux/kvm.h
>> @@ -1130,6 +1130,7 @@ struct kvm_ppc_resize_hpt {
>> #define KVM_CAP_BINARY_STATS_FD 203
>> #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204
>> #define KVM_CAP_ARM_MTE 205
>> +#define KVM_CAP_PPC_AIL_MODE_3 210
>>
>> #ifdef KVM_CAP_IRQ_ROUTING
>>
>> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
>> index 128bc530d4..d0d0bdaac4 100644
>> --- a/target/ppc/kvm.c
>> +++ b/target/ppc/kvm.c
>> @@ -90,6 +90,7 @@ static int cap_ppc_nested_kvm_hv;
>> static int cap_large_decr;
>> static int cap_fwnmi;
>> static int cap_rpt_invalidate;
>> +static int cap_ail_mode_3;
>>
>> static uint32_t debug_inst_opcode;
>>
>> @@ -154,6 +155,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
>> }
>>
>> cap_rpt_invalidate = kvm_vm_check_extension(s,
>> KVM_CAP_PPC_RPT_INVALIDATE);
>> + cap_ail_mode_3 = kvm_vm_check_extension(s, KVM_CAP_PPC_AIL_MODE_3);
>> kvm_ppc_register_host_cpu_type();
>>
>> return 0;
>> @@ -2563,10 +2565,24 @@ int kvmppc_has_cap_rpt_invalidate(void)
>> return cap_rpt_invalidate;
>> }
>>
>> -int kvmppc_supports_ail_3(void)
>> +int kvmppc_has_cap_ail_3(void)
>> {
>> PowerPCCPUClass *pcc = kvm_ppc_get_host_cpu_class();
>>
>> + if (cap_ail_mode_3) {
>> + return 1;
>> + }
>> +
>> + if (kvm_ioctl(kvm_state, KVM_CHECK_EXTENSION, KVM_CAP_PPC_AIL_MODE_3)
>> == 0) {
>> + return 0;
>> + }
>
> This is not needed here it seems.
This is to test whether the capability is recognised by the HV.
kvm_vm_check_extension() treats ioctl error as 0 capability but we want
to do this extra heuristic.
I'm not sure if there's a better standard way to do this.
Thanks,
Nick
Re: [PATCH 1/2] spapr: Add SPAPR_CAP_AIL_MODE_3 for AIL mode 3 support for H_SET_MODE hcall, David Gibson, 2022/02/14