On 08.01.2014, at 11:25, Paul Mackerras <paulus@xxxxxxxxx> wrote: > Currently in book3s_hv_rmhandlers.S we have three places where we > have woken up from nap mode and we check the reason field in SRR1 > to see what event woke us up. This consolidates them into a new > function, kvmppc_check_wake_reason. It looks at the wake reason > field in SRR1, and if it indicates that an external interrupt caused > the wakeup, calls kvmppc_read_intr to check what sort of interrupt > it was. > > This also consolidates the two places where we synthesize an external > interrupt (0x500 vector) for the guest. Now, if the guest exit code > finds that there was an external interrupt which has been handled > (i.e. it was an IPI indicating that there is now an interrupt pending > for the guest), it jumps to deliver_guest_interrupt, which is in the > last part of the guest entry code, where we synthesize guest external > and decrementer interrupts. That code has been streamlined a little > and now clears LPCR[MER] when appropriate as well as setting it. > > The extra clearing of any pending IPI on a secondary, offline CPU > thread before going back to nap mode has been removed. It is no longer > necessary now that we have code to read and acknowledge IPIs in the > guest exit path. > > This fixes a minor bug in the H_CEDE real-mode handling - previously, > if we found that other threads were already exiting the guest when we > were about to go to nap mode, we would branch to the cede wakeup path > and end up looking in SRR1 for a wakeup reason. Now we branch to a > point after we have checked the wakeup reason. > > This also fixes a minor bug in kvmppc_read_intr - previously it could > return 0xff rather than 1, in the case where we find that a host IPI > is pending after we have cleared the IPI. Now it returns 1. > > Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> > --- > arch/powerpc/kvm/book3s_hv_rmhandlers.S | 192 +++++++++++++------------------- > 1 file changed, 77 insertions(+), 115 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > index c0a5d8a..61125426 100644 > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > @@ -192,8 +192,10 @@ kvm_novcpu_wakeup: > stb r0, HSTATE_NAPPING(r13) > stb r0, HSTATE_HWTHREAD_REQ(r13) > > + /* check the wake reason */ > + bl kvmppc_check_wake_reason > + > /* see if any other thread is already exiting */ > - li r12, 0 > lwz r0, VCORE_ENTRY_EXIT(r5) > cmpwi r0, 0x100 > bge kvm_novcpu_exit > @@ -203,23 +205,14 @@ kvm_novcpu_wakeup: > li r0, 1 > sld r0, r0, r7 > addi r6, r5, VCORE_NAPPING_THREADS > -4: lwarx r3, 0, r6 > - andc r3, r3, r0 > - stwcx. r3, 0, r6 > +4: lwarx r7, 0, r6 > + andc r7, r7, r0 > + stwcx. r7, 0, r6 > bne 4b > > - /* Check the wake reason in SRR1 to see why we got here */ > - mfspr r3, SPRN_SRR1 > - rlwinm r3, r3, 44-31, 0x7 /* extract wake reason field */ > - cmpwi r3, 4 /* was it an external interrupt? */ > - bne kvm_novcpu_exit /* if not, exit the guest */ > - > - /* extern interrupt - read and handle it */ > - li r12, BOOK3S_INTERRUPT_EXTERNAL > - bl kvmppc_read_intr > + /* See if the wake reason means we need to exit */ > cmpdi r3, 0 > bge kvm_novcpu_exit > - li r12, 0 > > /* Got an IPI but other vcpus aren't yet exiting, must be a latecomer */ > ld r4, HSTATE_KVM_VCPU(r13) > @@ -263,40 +256,16 @@ kvm_start_guest: > */ > > /* Check the wake reason in SRR1 to see why we got here */ > - mfspr r3,SPRN_SRR1 > - rlwinm r3,r3,44-31,0x7 /* extract wake reason field */ > - cmpwi r3,4 /* was it an external interrupt? */ > - bne 27f /* if not */ > - ld r5,HSTATE_XICS_PHYS(r13) > - li r7,XICS_XIRR /* if it was an external interrupt, */ > - lwzcix r8,r5,r7 /* get and ack the interrupt */ > - sync > - clrldi. r9,r8,40 /* get interrupt source ID. */ > - beq 28f /* none there? */ > - cmpwi r9,XICS_IPI /* was it an IPI? */ > - bne 29f > - li r0,0xff > - li r6,XICS_MFRR > - stbcix r0,r5,r6 /* clear IPI */ > - stwcix r8,r5,r7 /* EOI the interrupt */ > - sync /* order loading of vcpu after that */ > + bl kvmppc_check_wake_reason > + cmpdi r3, 0 > + bge kvm_no_guest > > /* get vcpu pointer, NULL if we have no vcpu to run */ > ld r4,HSTATE_KVM_VCPU(r13) > cmpdi r4,0 > /* if we have no vcpu to run, go back to sleep */ > beq kvm_no_guest > - b 30f > > -27: /* XXX should handle hypervisor maintenance interrupts etc. here */ > - b kvm_no_guest > -28: /* SRR1 said external but ICP said nope?? */ > - b kvm_no_guest > -29: /* External non-IPI interrupt to offline secondary thread? help?? */ > - stw r8,HSTATE_SAVED_XIRR(r13) > - b kvm_no_guest > - > -30: > /* Set HSTATE_DSCR(r13) to something sensible */ > LOAD_REG_ADDR(r6, dscr_default) > ld r6, 0(r6) > @@ -314,18 +283,6 @@ kvm_start_guest: > * visible we could be given another vcpu. > */ > lwsync > - /* Clear any pending IPI - we're an offline 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_MFRR > - 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) > @@ -821,47 +778,46 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_206) > mtctr r6 > mtxer r7 > > +kvmppc_cede_reentry: /* r4 = vcpu, r13 = paca */ > ld r10, VCPU_PC(r4) > ld r11, VCPU_MSR(r4) > -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 > > +deliver_guest_interrupt: > /* r11 = 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) > - lis r8,(1 << BOOK3S_IRQPRIO_EXTERNAL_LEVEL)@h > - and r0,r0,r8 > - cmpdi cr1,r0,0 > - andi. r0,r11,MSR_EE > - beq cr1,11f > + ld r0, VCPU_PENDING_EXC(r4) > + rldicl r0, r0, 64 - BOOK3S_IRQPRIO_EXTERNAL_LEVEL, 63 > + cmpdi cr1, r0, 0 > + andi. r8, r11, MSR_EE > BEGIN_FTR_SECTION > - mfspr r8,SPRN_LPCR > - ori r8,r8,LPCR_MER > - mtspr SPRN_LPCR,r8 > + mfspr r8, SPRN_LPCR > + /* Insert EXTERNAL_LEVEL bit into LPCR at the MER bit position */ > + rldimi r8, r0, LPCR_MER_SH, 63 - LPCR_MER_SH > + mtspr SPRN_LPCR, r8 > isync > END_FTR_SECTION_IFSET(CPU_FTR_ARCH_206) > beq 5f > - li r0,BOOK3S_INTERRUPT_EXTERNAL > -12: mr r6,r10 > + li r0, BOOK3S_INTERRUPT_EXTERNAL > + bne cr1, 12f > + mfspr r0, SPRN_DEC > + cmpwi r0, 0 > + li r0, BOOK3S_INTERRUPT_DECREMENTER > + bge 5f > + > +12: mtspr SPRN_SRR0, r10 > mr r10,r0 > - mr r7,r11 > + mtspr SPRN_SRR1, 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 > +5: > > /* > * Required state: > @@ -1049,39 +1005,19 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206) > /* External interrupt, first check for host_ipi. If this is > * set, we know the host wants us out so let's do it now > */ > -do_ext_interrupt: > bl kvmppc_read_intr > cmpdi r3, 0 > bgt ext_interrupt_to_host > > - /* Allright, looks like an IPI for the guest, we need to set MER */ > /* Check if any CPU is heading out to the host, if so head out too */ > ld r5, HSTATE_KVM_VCORE(r13) > lwz r0, VCORE_ENTRY_EXIT(r5) > cmpwi r0, 0x100 > bge ext_interrupt_to_host > > - /* See if there is a pending interrupt for the guest */ > - mfspr r8, SPRN_LPCR > - ld r0, VCPU_PENDING_EXC(r9) > - /* Insert EXTERNAL_LEVEL bit into LPCR at the MER bit position */ > - rldicl. r0, r0, 64 - BOOK3S_IRQPRIO_EXTERNAL_LEVEL, 63 > - rldimi r8, r0, LPCR_MER_SH, 63 - LPCR_MER_SH > - beq 2f > - > - /* And if the guest EE is set, we can deliver immediately, else > - * we return to the guest with MER set > - */ > - andi. r0, r11, MSR_EE > - beq 2f > - mtspr SPRN_SRR0, r10 > - mtspr SPRN_SRR1, r11 > - li r10, BOOK3S_INTERRUPT_EXTERNAL > - li r11, (MSR_ME << 1) | 1 /* synthesize MSR_SF | MSR_ME */ > - rotldi r11, r11, 63 > -2: mr r4, r9 > - mtspr SPRN_LPCR, r8 > - b fast_guest_return > + /* Return to guest after delivering any pending interrupt */ > + mr r4, r9 > + b deliver_guest_interrupt > > ext_interrupt_to_host: > > @@ -1890,7 +1826,6 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206) > isync > li r0,NAPPING_CEDE > stb r0,HSTATE_NAPPING(r13) > - mr r4,r3 > lwz r7,VCORE_ENTRY_EXIT(r5) > cmpwi r7,0x100 > bge 33f /* another thread already exiting */ > @@ -1943,6 +1878,11 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206) > nap > b . > > +33: mr r4, r3 > + li r3, 0 > + li r12, 0 > + b 34f > + > kvm_end_cede: > /* get vcpu pointer */ > ld r4, HSTATE_KVM_VCPU(r13) > @@ -1972,12 +1912,15 @@ kvm_end_cede: > ld r29, VCPU_GPR(R29)(r4) > ld r30, VCPU_GPR(R30)(r4) > ld r31, VCPU_GPR(R31)(r4) > + > + /* Check the wake reason in SRR1 to see why we got here */ > + bl kvmppc_check_wake_reason > > /* clear our bit in vcore->napping_threads */ > -33: ld r5,HSTATE_KVM_VCORE(r13) > - lbz r3,HSTATE_PTID(r13) > +34: ld r5,HSTATE_KVM_VCORE(r13) > + lbz r7,HSTATE_PTID(r13) > li r0,1 > - sld r0,r0,r3 > + sld r0,r0,r7 > addi r6,r5,VCORE_NAPPING_THREADS > 32: lwarx r7,0,r6 > andc r7,r7,r0 > @@ -1986,23 +1929,18 @@ kvm_end_cede: > li r0,0 > stb r0,HSTATE_NAPPING(r13) > > - /* Check the wake reason in SRR1 to see why we got here */ > - mfspr r3, SPRN_SRR1 > - rlwinm r3, r3, 44-31, 0x7 /* extract wake reason field */ > - cmpwi r3, 4 /* was it an external interrupt? */ > - li r12, BOOK3S_INTERRUPT_EXTERNAL > + /* See if the wake reason means we need to exit */ > + stw r12, VCPU_TRAP(r4) > mr r9, r4 > - ld r10, VCPU_PC(r9) > - ld r11, VCPU_MSR(r9) > - beq do_ext_interrupt /* if so */ > + cmpdi r3, 0 > + bgt guest_exit_cont > > /* 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 */ > + bge guest_exit_cont > > - /* some threads are exiting, so go to the guest exit path */ > - b hcall_real_fallback > + b kvmppc_cede_reentry /* if not go back to guest */ > > /* cede when already previously prodded case */ > kvm_cede_prodded: > @@ -2033,6 +1971,29 @@ machine_check_realmode: > b fast_interrupt_c_return > > /* > + * Check the reason we woke from nap, and take appropriate action. > + * Returns: > + * 0 if nothing needs to be done > + * 1 if something happened that needs to be handled by the host > + * -1 if there was a guest wakeup (IPI) > + * > + * Also sets r12 to the interrupt vector for any interrupt that needs > + * to be handled now by the host (0x500 for external interrupt), or zero. > + */ > +kvmppc_check_wake_reason: > + mfspr r6, SPRN_SRR1 > + rlwinm r6, r6, 44-31, 0x7 /* extract wake reason field */ > + cmpwi r6, 4 /* was it an external interrupt? */ > + li r12, BOOK3S_INTERRUPT_EXTERNAL > + beq kvmppc_read_intr /* if so, see what it was */ > + li r3, 0 > + li r12, 0 > + cmpwi r6, 6 /* was it the decrementer? */ > + beq 0f > + li r3, 1 /* anything else, return 1 */ > +0: blr Tricky :). Please document somewhere (in a follow-up patch) which registers this function actually uses. Up there you assume that it doesn't modify r5 for example. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
