From 19ccb76a1938ab364a412253daec64613acbf3df Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Sat, 23 Jul 2011 17:42:46 +1000 Subject: KVM: PPC: Implement H_CEDE hcall for book3s_hv in real-mode code With a KVM guest operating in SMT4 mode (i.e. 4 hardware threads per core), whenever a CPU goes idle, we have to pull all the other hardware threads in the core out of the guest, because the H_CEDE hcall is handled in the kernel. This is inefficient. This adds code to book3s_hv_rmhandlers.S to handle the H_CEDE hcall in real mode. When a guest vcpu does an H_CEDE hcall, we now only exit to the kernel if all the other vcpus in the same core are also idle. Otherwise we mark this vcpu as napping, save state that could be lost in nap mode (mainly GPRs and FPRs), and execute the nap instruction. When the thread wakes up, because of a decrementer or external interrupt, we come back in at kvm_start_guest (from the system reset interrupt vector), find the `napping' flag set in the paca, and go to the resume path. This has some other ramifications. First, when starting a core, we now start all the threads, both those that are immediately runnable and those that are idle. This is so that we don't have to pull all the threads out of the guest when an idle thread gets a decrementer interrupt and wants to start running. In fact the idle threads will all start with the H_CEDE hcall returning; being idle they will just do another H_CEDE immediately and go to nap mode. This required some changes to kvmppc_run_core() and kvmppc_run_vcpu(). These functions have been restructured to make them simpler and clearer. We introduce a level of indirection in the wait queue that gets woken when external and decrementer interrupts get generated for a vcpu, so that we can have the 4 vcpus in a vcore using the same wait queue. We need this because the 4 vcpus are being handled by one thread. Secondly, when we need to exit from the guest to the kernel, we now have to generate an IPI for any napping threads, because an HDEC interrupt doesn't wake up a napping thread. Thirdly, we now need to be able to handle virtual external interrupts and decrementer interrupts becoming pending while a thread is napping, and deliver those interrupts to the guest when the thread wakes. This is done in kvmppc_cede_reentry, just before fast_guest_return. Finally, since we are not using the generic kvm_vcpu_block for book3s_hv, and hence not calling kvm_arch_vcpu_runnable, we can remove the #ifdef from kvm_arch_vcpu_runnable. Signed-off-by: Paul Mackerras Signed-off-by: Alexander Graf --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 297 ++++++++++++++++++++++++++++---- 1 file changed, 263 insertions(+), 34 deletions(-) (limited to 'arch/powerpc/kvm/book3s_hv_rmhandlers.S') diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index bc6ade933089..f422231d9235 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -52,7 +52,7 @@ kvmppc_skip_Hinterrupt: b . /* - * Call kvmppc_handler_trampoline_enter in real mode. + * Call kvmppc_hv_entry in real mode. * Must be called with interrupts hard-disabled. * * Input Registers: @@ -92,6 +92,12 @@ _GLOBAL(kvmppc_hv_entry_trampoline) kvm_start_guest: ld r1,PACAEMERGSP(r13) subi r1,r1,STACK_FRAME_OVERHEAD + ld r2,PACATOC(r13) + + /* were we napping due to cede? */ + lbz r0,HSTATE_NAPPING(r13) + cmpwi r0,0 + bne kvm_end_cede /* get vcpu pointer */ ld r4, HSTATE_KVM_VCPU(r13) @@ -279,15 +285,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_201) cmpwi r0,0 beq 20b - /* Set LPCR. Set the MER bit if there is a pending external irq. */ + /* Set LPCR and RMOR. */ 10: ld r8,KVM_LPCR(r9) - ld r0,VCPU_PENDING_EXC(r4) - li r7,(1 << BOOK3S_IRQPRIO_EXTERNAL) - oris r7,r7,(1 << BOOK3S_IRQPRIO_EXTERNAL_LEVEL)@h - and. r0,r0,r7 - beq 11f - ori r8,r8,LPCR_MER -11: mtspr SPRN_LPCR,r8 + mtspr SPRN_LPCR,r8 ld r8,KVM_RMOR(r9) mtspr SPRN_RMOR,r8 isync @@ -451,19 +451,50 @@ toc_tlbie_lock: mtctr r6 mtxer r7 - /* Move SRR0 and SRR1 into the respective regs */ +kvmppc_cede_reentry: /* r4 = vcpu, r13 = paca */ ld r6, VCPU_SRR0(r4) ld r7, VCPU_SRR1(r4) - mtspr SPRN_SRR0, r6 - mtspr SPRN_SRR1, r7 - ld r10, VCPU_PC(r4) + ld r11, VCPU_MSR(r4) /* r11 = vcpu->arch.msr & ~MSR_HV */ - ld r11, VCPU_MSR(r4) /* r10 = vcpu->arch.msr & ~MSR_HV */ rldicl r11, r11, 63 - MSR_HV_LG, 1 rotldi r11, r11, 1 + MSR_HV_LG ori r11, r11, MSR_ME + /* Check if we can deliver an external or decrementer interrupt now */ + ld r0,VCPU_PENDING_EXC(r4) + li r8,(1 << BOOK3S_IRQPRIO_EXTERNAL) + oris r8,r8,(1 << BOOK3S_IRQPRIO_EXTERNAL_LEVEL)@h + and r0,r0,r8 + cmpdi cr1,r0,0 + andi. r0,r11,MSR_EE + beq cr1,11f +BEGIN_FTR_SECTION + mfspr r8,SPRN_LPCR + ori r8,r8,LPCR_MER + mtspr SPRN_LPCR,r8 + isync +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_206) + beq 5f + li r0,BOOK3S_INTERRUPT_EXTERNAL +12: mr r6,r10 + mr r10,r0 + mr r7,r11 + li r11,(MSR_ME << 1) | 1 /* synthesize MSR_SF | MSR_ME */ + rotldi r11,r11,63 + b 5f +11: beq 5f + mfspr r0,SPRN_DEC + cmpwi r0,0 + li r0,BOOK3S_INTERRUPT_DECREMENTER + blt 12b + + /* Move SRR0 and SRR1 into the respective regs */ +5: mtspr SPRN_SRR0, r6 + mtspr SPRN_SRR1, r7 + li r0,0 + stb r0,VCPU_CEDED(r4) /* cancel cede */ + fast_guest_return: mtspr SPRN_HSRR0,r10 mtspr SPRN_HSRR1,r11 @@ -577,21 +608,20 @@ kvmppc_interrupt: /* See if this is something we can handle in real mode */ cmpwi r12,BOOK3S_INTERRUPT_SYSCALL beq hcall_try_real_mode -hcall_real_cont: /* Check for mediated interrupts (could be done earlier really ...) */ BEGIN_FTR_SECTION cmpwi r12,BOOK3S_INTERRUPT_EXTERNAL bne+ 1f - ld r5,VCPU_KVM(r9) - ld r5,KVM_LPCR(r5) andi. r0,r11,MSR_EE beq 1f + mfspr r5,SPRN_LPCR andi. r0,r5,LPCR_MER bne bounce_ext_interrupt 1: END_FTR_SECTION_IFSET(CPU_FTR_ARCH_206) +hcall_real_cont: /* r9 = vcpu, r12 = trap, r13 = paca */ /* Save DEC */ mfspr r5,SPRN_DEC mftb r6 @@ -685,7 +715,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_201) slbia ptesync -hdec_soon: +hdec_soon: /* r9 = vcpu, r12 = trap, r13 = paca */ BEGIN_FTR_SECTION b 32f END_FTR_SECTION_IFSET(CPU_FTR_ARCH_201) @@ -703,6 +733,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_201) addi r0,r3,0x100 stwcx. r0,0,r6 bne 41b + lwsync /* * At this point we have an interrupt that we have to pass @@ -716,18 +747,39 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_201) * interrupt, since the other threads will already be on their * way here in that case. */ + cmpwi r3,0x100 /* Are we the first here? */ + bge 43f + cmpwi r3,1 /* Are any other threads in the guest? */ + ble 43f cmpwi r12,BOOK3S_INTERRUPT_HV_DECREMENTER beq 40f - cmpwi r3,0x100 /* Are we the first here? */ - bge 40f - cmpwi r3,1 - ble 40f li r0,0 mtspr SPRN_HDEC,r0 40: + /* + * Send an IPI to any napping threads, since an HDEC interrupt + * doesn't wake CPUs up from nap. + */ + lwz r3,VCORE_NAPPING_THREADS(r5) + lwz r4,VCPU_PTID(r9) + li r0,1 + sldi r0,r0,r4 + andc. r3,r3,r0 /* no sense IPI'ing ourselves */ + beq 43f + mulli r4,r4,PACA_SIZE /* get paca for thread 0 */ + subf r6,r4,r13 +42: andi. r0,r3,1 + beq 44f + ld r8,HSTATE_XICS_PHYS(r6) /* get thread's XICS reg addr */ + li r0,IPI_PRIORITY + li r7,XICS_QIRR + stbcix r0,r7,r8 /* trigger the IPI */ +44: srdi. r3,r3,1 + addi r6,r6,PACA_SIZE + bne 42b /* Secondary threads wait for primary to do partition switch */ - ld r4,VCPU_KVM(r9) /* pointer to struct kvm */ +43: ld r4,VCPU_KVM(r9) /* pointer to struct kvm */ ld r5,HSTATE_KVM_VCORE(r13) lwz r3,VCPU_PTID(r9) cmpwi r3,0 @@ -1080,7 +1132,6 @@ hcall_try_real_mode: hcall_real_fallback: li r12,BOOK3S_INTERRUPT_SYSCALL ld r9, HSTATE_KVM_VCPU(r13) - ld r11, VCPU_MSR(r9) b hcall_real_cont @@ -1142,7 +1193,7 @@ hcall_real_table: .long 0 /* 0xd4 */ .long 0 /* 0xd8 */ .long 0 /* 0xdc */ - .long 0 /* 0xe0 */ + .long .kvmppc_h_cede - hcall_real_table .long 0 /* 0xe4 */ .long 0 /* 0xe8 */ .long 0 /* 0xec */ @@ -1171,7 +1222,8 @@ bounce_ext_interrupt: mtspr SPRN_SRR0,r10 mtspr SPRN_SRR1,r11 li r10,BOOK3S_INTERRUPT_EXTERNAL - LOAD_REG_IMMEDIATE(r11,MSR_SF | MSR_ME); + li r11,(MSR_ME << 1) | 1 /* synthesize MSR_SF | MSR_ME */ + rotldi r11,r11,63 b fast_guest_return _GLOBAL(kvmppc_h_set_dabr) @@ -1180,6 +1232,178 @@ _GLOBAL(kvmppc_h_set_dabr) li r3,0 blr +_GLOBAL(kvmppc_h_cede) + ori r11,r11,MSR_EE + std r11,VCPU_MSR(r3) + li r0,1 + stb r0,VCPU_CEDED(r3) + sync /* order setting ceded vs. testing prodded */ + lbz r5,VCPU_PRODDED(r3) + cmpwi r5,0 + bne 1f + li r0,0 /* set trap to 0 to say hcall is handled */ + stw r0,VCPU_TRAP(r3) + li r0,H_SUCCESS + std r0,VCPU_GPR(r3)(r3) +BEGIN_FTR_SECTION + b 2f /* just send it up to host on 970 */ +END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206) + + /* + * Set our bit in the bitmask of napping threads unless all the + * other threads are already napping, in which case we send this + * up to the host. + */ + ld r5,HSTATE_KVM_VCORE(r13) + lwz r6,VCPU_PTID(r3) + lwz r8,VCORE_ENTRY_EXIT(r5) + clrldi r8,r8,56 + li r0,1 + sld r0,r0,r6 + addi r6,r5,VCORE_NAPPING_THREADS +31: lwarx r4,0,r6 + or r4,r4,r0 + popcntw r7,r4 + cmpw r7,r8 + bge 2f + stwcx. r4,0,r6 + bne 31b + li r0,1 + stb r0,HSTATE_NAPPING(r13) + /* order napping_threads update vs testing entry_exit_count */ + lwsync + mr r4,r3 + lwz r7,VCORE_ENTRY_EXIT(r5) + cmpwi r7,0x100 + bge 33f /* another thread already exiting */ + +/* + * Although not specifically required by the architecture, POWER7 + * preserves the following registers in nap mode, even if an SMT mode + * switch occurs: SLB entries, PURR, SPURR, AMOR, UAMOR, AMR, SPRG0-3, + * DAR, DSISR, DABR, DABRX, DSCR, PMCx, MMCRx, SIAR, SDAR. + */ + /* Save non-volatile GPRs */ + std r14, VCPU_GPR(r14)(r3) + std r15, VCPU_GPR(r15)(r3) + std r16, VCPU_GPR(r16)(r3) + std r17, VCPU_GPR(r17)(r3) + std r18, VCPU_GPR(r18)(r3) + std r19, VCPU_GPR(r19)(r3) + std r20, VCPU_GPR(r20)(r3) + std r21, VCPU_GPR(r21)(r3) + std r22, VCPU_GPR(r22)(r3) + std r23, VCPU_GPR(r23)(r3) + std r24, VCPU_GPR(r24)(r3) + std r25, VCPU_GPR(r25)(r3) + std r26, VCPU_GPR(r26)(r3) + std r27, VCPU_GPR(r27)(r3) + std r28, VCPU_GPR(r28)(r3) + std r29, VCPU_GPR(r29)(r3) + std r30, VCPU_GPR(r30)(r3) + std r31, VCPU_GPR(r31)(r3) + + /* save FP state */ + bl .kvmppc_save_fp + + /* + * Take a nap until a decrementer or external interrupt occurs, + * with PECE1 (wake on decr) and PECE0 (wake on external) set in LPCR + */ + li r0,0x80 + stb r0,PACAPROCSTART(r13) + mfspr r5,SPRN_LPCR + ori r5,r5,LPCR_PECE0 | LPCR_PECE1 + mtspr SPRN_LPCR,r5 + isync + li r0, 0 + std r0, HSTATE_SCRATCH0(r13) + ptesync + ld r0, HSTATE_SCRATCH0(r13) +1: cmpd r0, r0 + bne 1b + nap + b . + +kvm_end_cede: + /* Woken by external or decrementer interrupt */ + ld r1, HSTATE_HOST_R1(r13) + ld r2, PACATOC(r13) + + /* If we're a secondary thread and we got here by an IPI, ack it */ + ld r4,HSTATE_KVM_VCPU(r13) + lwz r3,VCPU_PTID(r4) + cmpwi r3,0 + beq 27f + mfspr r3,SPRN_SRR1 + rlwinm r3,r3,44-31,0x7 /* extract wake reason field */ + cmpwi r3,4 /* was it an external interrupt? */ + bne 27f + ld r5, HSTATE_XICS_PHYS(r13) + li r0,0xff + li r6,XICS_QIRR + li r7,XICS_XIRR + lwzcix r8,r5,r7 /* ack the interrupt */ + sync + stbcix r0,r5,r6 /* clear it */ + stwcix r8,r5,r7 /* EOI it */ +27: + /* load up FP state */ + bl kvmppc_load_fp + + /* Load NV GPRS */ + ld r14, VCPU_GPR(r14)(r4) + ld r15, VCPU_GPR(r15)(r4) + ld r16, VCPU_GPR(r16)(r4) + ld r17, VCPU_GPR(r17)(r4) + ld r18, VCPU_GPR(r18)(r4) + ld r19, VCPU_GPR(r19)(r4) + ld r20, VCPU_GPR(r20)(r4) + ld r21, VCPU_GPR(r21)(r4) + ld r22, VCPU_GPR(r22)(r4) + ld r23, VCPU_GPR(r23)(r4) + ld r24, VCPU_GPR(r24)(r4) + ld r25, VCPU_GPR(r25)(r4) + ld r26, VCPU_GPR(r26)(r4) + ld r27, VCPU_GPR(r27)(r4) + ld r28, VCPU_GPR(r28)(r4) + ld r29, VCPU_GPR(r29)(r4) + ld r30, VCPU_GPR(r30)(r4) + ld r31, VCPU_GPR(r31)(r4) + + /* clear our bit in vcore->napping_threads */ +33: ld r5,HSTATE_KVM_VCORE(r13) + lwz r3,VCPU_PTID(r4) + li r0,1 + sld r0,r0,r3 + addi r6,r5,VCORE_NAPPING_THREADS +32: lwarx r7,0,r6 + andc r7,r7,r0 + stwcx. r7,0,r6 + bne 32b + li r0,0 + stb r0,HSTATE_NAPPING(r13) + + /* see if any other thread is already exiting */ + lwz r0,VCORE_ENTRY_EXIT(r5) + cmpwi r0,0x100 + blt kvmppc_cede_reentry /* if not go back to guest */ + + /* some threads are exiting, so go to the guest exit path */ + b hcall_real_fallback + + /* cede when already previously prodded case */ +1: li r0,0 + stb r0,VCPU_PRODDED(r3) + sync /* order testing prodded vs. clearing ceded */ + stb r0,VCPU_CEDED(r3) + li r3,H_SUCCESS + blr + + /* we've ceded but we want to give control to the host */ +2: li r3,H_TOO_HARD + blr + secondary_too_late: ld r5,HSTATE_KVM_VCORE(r13) HMT_LOW @@ -1197,14 +1421,20 @@ secondary_too_late: slbmte r6,r5 1: addi r11,r11,16 .endr - b 50f secondary_nap: - /* Clear any pending IPI */ -50: ld r5, HSTATE_XICS_PHYS(r13) + /* Clear any pending IPI - assume we're a secondary thread */ + ld r5, HSTATE_XICS_PHYS(r13) + li r7, XICS_XIRR + lwzcix r3, r5, r7 /* ack any pending interrupt */ + rlwinm. r0, r3, 0, 0xffffff /* any pending? */ + beq 37f + sync li r0, 0xff li r6, XICS_QIRR - stbcix r0, r5, r6 + stbcix r0, r5, r6 /* clear the IPI */ + stwcix r3, r5, r7 /* EOI it */ +37: sync /* increment the nap count and then go to nap mode */ ld r4, HSTATE_KVM_VCORE(r13) @@ -1214,13 +1444,12 @@ secondary_nap: addi r3, r3, 1 stwcx. r3, 0, r4 bne 51b - isync + li r3, LPCR_PECE0 mfspr r4, SPRN_LPCR - li r0, LPCR_PECE - andc r4, r4, r0 - ori r4, r4, LPCR_PECE0 /* exit nap on interrupt */ + rlwimi r4, r3, 0, LPCR_PECE0 | LPCR_PECE1 mtspr SPRN_LPCR, r4 + isync li r0, 0 std r0, HSTATE_SCRATCH0(r13) ptesync -- cgit v1.2.3