| Message ID | 20220216063903.1782281-3-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/3] target/ppc: Fix POWER9 DD2.0 PVR, add DD2.1 | expand |
On Wed, Feb 16, 2022 at 04:39:03PM +1000, Nicholas Piggin wrote: > 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> LGTM, once the kernel side work is done. > --- > Since v1: > - Remove incorrect test for unsupported cap query. Add comment instead. > > linux-headers/linux/kvm.h | 1 + > target/ppc/kvm.c | 18 ++++++++++++++++++ > 2 files changed, 19 insertions(+) > > 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 You may be aware of this already, but once the cap is allocated on the kernel side, you should do a full update of the kernel headers as a separate patch. A direct hack to the headers copy is fine for a preliminary posting, though. > > #ifdef KVM_CAP_IRQ_ROUTING > > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > index 1338c41f8f..7f71f78253 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; > @@ -2567,6 +2569,17 @@ bool kvmppc_supports_ail_3(void) > { > PowerPCCPUClass *pcc = kvm_ppc_get_host_cpu_class(); > > + if (cap_ail_mode_3) { > + return 1; > + } > + > + /* > + * cap-ail-mode-3 is disabled, but it may be because the KVM host pre-dates > + * the cap. Special-case the test because the performance cost for > + * disabling the feature unconditionally is prohibitive until updated > + * KVM is widely in use. > + */ > + > /* > * KVM PR only supports AIL-0 > */ > @@ -2589,6 +2602,11 @@ bool kvmppc_supports_ail_3(void) > return 0; > } > > + /* > + * Beyond ISA v3.1 (POWER10), this could return 0, because all KVM > + * implementations for such hosts would support the cap. > + */ > + > return 1; > } >
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 1338c41f8f..7f71f78253 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; @@ -2567,6 +2569,17 @@ bool kvmppc_supports_ail_3(void) { PowerPCCPUClass *pcc = kvm_ppc_get_host_cpu_class(); + if (cap_ail_mode_3) { + return 1; + } + + /* + * cap-ail-mode-3 is disabled, but it may be because the KVM host pre-dates + * the cap. Special-case the test because the performance cost for + * disabling the feature unconditionally is prohibitive until updated + * KVM is widely in use. + */ + /* * KVM PR only supports AIL-0 */ @@ -2589,6 +2602,11 @@ bool kvmppc_supports_ail_3(void) return 0; } + /* + * Beyond ISA v3.1 (POWER10), this could return 0, because all KVM + * implementations for such hosts would support the cap. + */ + return 1; }