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Re: [PATCH 2/2] target/ppc/kvm: Use KVM_CAP_PPC_AIL_MODE_3 to determine
From: |
Fabiano Rosas |
Subject: |
Re: [PATCH 2/2] target/ppc/kvm: Use KVM_CAP_PPC_AIL_MODE_3 to determine cap-ail-mode-3 support |
Date: |
Mon, 14 Feb 2022 10:13:56 -0300 |
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.
> +
> + /*
> + * For KVM hosts that pre-date this cap, special-case the test because
> + * the performance cost for disabling the feature unconditionally is
> + * prohibitive.
> + */
> +
> /*
> * KVM PR only supports AIL-0
> */
> diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
> index d9d1c54955..efafa67b83 100644
> --- a/target/ppc/kvm_ppc.h
> +++ b/target/ppc/kvm_ppc.h
> @@ -73,7 +73,7 @@ int kvmppc_set_cap_nested_kvm_hv(int enable);
> int kvmppc_get_cap_large_decr(void);
> int kvmppc_enable_cap_large_decr(PowerPCCPU *cpu, int enable);
> int kvmppc_has_cap_rpt_invalidate(void);
> -int kvmppc_supports_ail_3(void);
> +int kvmppc_has_cap_ail_3(void);
> int kvmppc_enable_hwrng(void);
> int kvmppc_put_books_sregs(PowerPCCPU *cpu);
> PowerPCCPUClass *kvm_ppc_get_host_cpu_class(void);
> @@ -394,7 +394,7 @@ static inline int kvmppc_has_cap_rpt_invalidate(void)
> return false;
> }
>
> -static inline int kvmppc_supports_ail_3(void)
> +static inline int kvmppc_has_cap_ail_3(void)
> {
> return false;
> }
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