From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>,
Fabiano Rosas <farosas@linux.ibm.com>
Subject: [PATCH v4 36/53] KVM: PPC: Book3S HV P9: Demand fault EBB facility registers
Date: Tue, 23 Nov 2021 19:52:14 +1000 [thread overview]
Message-ID: <20211123095231.1036501-37-npiggin@gmail.com> (raw)
In-Reply-To: <20211123095231.1036501-1-npiggin@gmail.com>
Use HFSCR facility disabling to implement demand faulting for EBB, with
a hysteresis counter similar to the load_fp etc counters in context
switching that implement the equivalent demand faulting for userspace
facilities.
This speeds up guest entry/exit by avoiding the register save/restore
when a guest is not frequently using them. When a guest does use them
often, there will be some additional demand fault overhead, but these
are not commonly used facilities.
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/kvm_host.h | 1 +
arch/powerpc/kvm/book3s_hv.c | 16 +++++++++++++--
arch/powerpc/kvm/book3s_hv_p9_entry.c | 28 +++++++++++++++++++++------
3 files changed, 37 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 21ca15c3bc0b..7a55b19eb6c0 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -579,6 +579,7 @@ struct kvm_vcpu_arch {
ulong cfar;
ulong ppr;
u32 pspb;
+ u8 load_ebb;
ulong fscr;
ulong shadow_fscr;
ulong ebbhr;
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 3795080d5403..da29cf9236c8 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1436,6 +1436,16 @@ static int kvmppc_pmu_unavailable(struct kvm_vcpu *vcpu)
return RESUME_GUEST;
}
+static int kvmppc_ebb_unavailable(struct kvm_vcpu *vcpu)
+{
+ if (!(vcpu->arch.hfscr_permitted & HFSCR_EBB))
+ return EMULATE_FAIL;
+
+ vcpu->arch.hfscr |= HFSCR_EBB;
+
+ return RESUME_GUEST;
+}
+
static int kvmppc_handle_exit_hv(struct kvm_vcpu *vcpu,
struct task_struct *tsk)
{
@@ -1727,6 +1737,8 @@ static int kvmppc_handle_exit_hv(struct kvm_vcpu *vcpu,
r = kvmppc_emulate_doorbell_instr(vcpu);
if (cause == FSCR_PM_LG)
r = kvmppc_pmu_unavailable(vcpu);
+ if (cause == FSCR_EBB_LG)
+ r = kvmppc_ebb_unavailable(vcpu);
}
if (r == EMULATE_FAIL) {
kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
@@ -2771,9 +2783,9 @@ static int kvmppc_core_vcpu_create_hv(struct kvm_vcpu *vcpu)
vcpu->arch.hfscr_permitted = vcpu->arch.hfscr;
/*
- * PM is demand-faulted so start with it clear.
+ * PM, EBB is demand-faulted so start with it clear.
*/
- vcpu->arch.hfscr &= ~HFSCR_PM;
+ vcpu->arch.hfscr &= ~(HFSCR_PM | HFSCR_EBB);
kvmppc_mmu_book3s_hv_init(vcpu);
diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c b/arch/powerpc/kvm/book3s_hv_p9_entry.c
index a23f09fa7d2d..929a7c336b09 100644
--- a/arch/powerpc/kvm/book3s_hv_p9_entry.c
+++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c
@@ -232,9 +232,12 @@ static void load_spr_state(struct kvm_vcpu *vcpu,
struct p9_host_os_sprs *host_os_sprs)
{
mtspr(SPRN_TAR, vcpu->arch.tar);
- mtspr(SPRN_EBBHR, vcpu->arch.ebbhr);
- mtspr(SPRN_EBBRR, vcpu->arch.ebbrr);
- mtspr(SPRN_BESCR, vcpu->arch.bescr);
+
+ if (vcpu->arch.hfscr & HFSCR_EBB) {
+ mtspr(SPRN_EBBHR, vcpu->arch.ebbhr);
+ mtspr(SPRN_EBBRR, vcpu->arch.ebbrr);
+ mtspr(SPRN_BESCR, vcpu->arch.bescr);
+ }
if (cpu_has_feature(CPU_FTR_P9_TIDR))
mtspr(SPRN_TIDR, vcpu->arch.tid);
@@ -265,9 +268,22 @@ static void load_spr_state(struct kvm_vcpu *vcpu,
static void store_spr_state(struct kvm_vcpu *vcpu)
{
vcpu->arch.tar = mfspr(SPRN_TAR);
- vcpu->arch.ebbhr = mfspr(SPRN_EBBHR);
- vcpu->arch.ebbrr = mfspr(SPRN_EBBRR);
- vcpu->arch.bescr = mfspr(SPRN_BESCR);
+
+ if (vcpu->arch.hfscr & HFSCR_EBB) {
+ vcpu->arch.ebbhr = mfspr(SPRN_EBBHR);
+ vcpu->arch.ebbrr = mfspr(SPRN_EBBRR);
+ vcpu->arch.bescr = mfspr(SPRN_BESCR);
+ /*
+ * This is like load_fp in context switching, turn off the
+ * facility after it wraps the u8 to try avoiding saving
+ * and restoring the registers each partition switch.
+ */
+ if (!vcpu->arch.nested) {
+ vcpu->arch.load_ebb++;
+ if (!vcpu->arch.load_ebb)
+ vcpu->arch.hfscr &= ~HFSCR_EBB;
+ }
+ }
if (cpu_has_feature(CPU_FTR_P9_TIDR))
vcpu->arch.tid = mfspr(SPRN_TIDR);
--
2.23.0
next prev parent reply other threads:[~2021-11-23 10:16 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 9:51 [PATCH v4 00/53] KVM: PPC: Book3S HV P9: entry/exit optimisations Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 01/53] powerpc/64s: Remove WORT SPR from POWER9/10 (take 2) Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 02/53] powerpc/64s: guard optional TIDR SPR with CPU ftr test Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 03/53] KMV: PPC: Book3S HV P9: Use set_dec to set decrementer to host Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 04/53] KVM: PPC: Book3S HV P9: Use host timer accounting to avoid decrementer read Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 05/53] KVM: PPC: Book3S HV P9: Use large decrementer for HDEC Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 06/53] KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 07/53] powerpc/time: add API for KVM to re-arm the host timer/decrementer Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 08/53] KVM: PPC: Book3S HV: POWER10 enable HAIL when running radix guests Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 09/53] powerpc/64s: Keep AMOR SPR a constant ~0 at runtime Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 10/53] KVM: PPC: Book3S HV: Don't always save PMU for guest capable of nesting Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 11/53] powerpc/64s: Always set PMU control registers to frozen/disabled when not in use Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 12/53] powerpc/64s: Implement PMU override command line option Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 13/53] KVM: PPC: Book3S HV P9: Implement PMU save/restore in C Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 14/53] KVM: PPC: Book3S HV P9: Factor PMU save/load into context switch functions Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 15/53] KVM: PPC: Book3S HV P9: Demand fault PMU SPRs when marked not inuse Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 16/53] KVM: PPC: Book3S HV P9: Factor out yield_count increment Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 17/53] KVM: PPC: Book3S HV: CTRL SPR does not require read-modify-write Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 18/53] KVM: PPC: Book3S HV P9: Move SPRG restore to restore_p9_host_os_sprs Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 19/53] KVM: PPC: Book3S HV P9: Reduce mtmsrd instructions required to save host SPRs Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 20/53] KVM: PPC: Book3S HV P9: Improve mtmsrd scheduling by delaying MSR[EE] disable Nicholas Piggin
2021-11-23 9:51 ` [PATCH v4 21/53] KVM: PPC: Book3S HV P9: Add kvmppc_stop_thread to match kvmppc_start_thread Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 22/53] KVM: PPC: Book3S HV: Change dec_expires to be relative to guest timebase Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 23/53] KVM: PPC: Book3S HV P9: Move TB updates Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 24/53] KVM: PPC: Book3S HV P9: Optimise timebase reads Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 25/53] KVM: PPC: Book3S HV P9: Avoid SPR scoreboard stalls Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 26/53] KVM: PPC: Book3S HV P9: Only execute mtSPR if the value changed Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 27/53] KVM: PPC: Book3S HV P9: Juggle SPR switching around Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 28/53] KVM: PPC: Book3S HV P9: Move vcpu register save/restore into functions Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 29/53] KVM: PPC: Book3S HV P9: Move host OS save/restore functions to built-in Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 30/53] KVM: PPC: Book3S HV P9: Move nested guest entry into its own function Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 31/53] KVM: PPC: Book3S HV P9: Move remaining SPR and MSR access into low level entry Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 32/53] KVM: PPC: Book3S HV P9: Implement TM fastpath for guest entry/exit Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 33/53] KVM: PPC: Book3S HV P9: Switch PMU to guest as late as possible Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 34/53] KVM: PPC: Book3S HV P9: Restrict DSISR canary workaround to processors that require it Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 35/53] KVM: PPC: Book3S HV P9: More SPR speed improvements Nicholas Piggin
2021-11-23 9:52 ` Nicholas Piggin [this message]
2021-11-23 9:52 ` [PATCH v4 37/53] KVM: PPC: Book3S HV P9: Demand fault TM facility registers Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 38/53] KVM: PPC: Book3S HV P9: Use Linux SPR save/restore to manage some host SPRs Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 39/53] KVM: PPC: Book3S HV P9: Comment and fix MMU context switching code Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 40/53] KVM: PPC: Book3S HV P9: Test dawr_enabled() before saving host DAWR SPRs Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 41/53] KVM: PPC: Book3S HV P9: Don't restore PSSCR if not needed Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 42/53] KVM: PPC: Book3S HV: Split P8 from P9 path guest vCPU TLB flushing Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 43/53] KVM: PPC: Book3S HV P9: Avoid tlbsync sequence on radix guest exit Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 44/53] KVM: PPC: Book3S HV Nested: Avoid extra mftb() in nested entry Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 45/53] KVM: PPC: Book3S HV P9: Improve mfmsr performance on entry Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 46/53] KVM: PPC: Book3S HV P9: Optimise hash guest SLB saving Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 47/53] KVM: PPC: Book3S HV P9: Avoid changing MSR[RI] in entry and exit Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 48/53] KVM: PPC: Book3S HV P9: Add unlikely annotation for !mmu_ready Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 49/53] KVM: PPC: Book3S HV P9: Avoid cpu_in_guest atomics on entry and exit Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 50/53] KVM: PPC: Book3S HV P9: Remove most of the vcore logic Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 51/53] KVM: PPC: Book3S HV P9: Tidy kvmppc_create_dtl_entry Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 52/53] KVM: PPC: Book3S HV P9: Stop using vc->dpdes Nicholas Piggin
2021-11-23 9:52 ` [PATCH v4 53/53] KVM: PPC: Book3S HV P9: Remove subcore HMI handling Nicholas Piggin
2021-11-25 9:38 ` [PATCH v4 00/53] KVM: PPC: Book3S HV P9: entry/exit optimisations Michael Ellerman
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