[PATCH v4 06/32] KVM: PPC: Book3S HV: Simplify real-mode interrupt handling
David Gibson
david at gibson.dropbear.id.au
Fri Oct 5 14:18:35 AEST 2018
On Thu, Oct 04, 2018 at 09:55:43PM +1000, Paul Mackerras wrote:
> This streamlines the first part of the code that handles a hypervisor
> interrupt that occurred in the guest. With this, all of the real-mode
> handling that occurs is done before the "guest_exit_cont" label; once
> we get to that label we are committed to exiting to host virtual mode.
> Thus the machine check and HMI real-mode handling is moved before that
> label.
>
> Also, the code to handle external interrupts is moved out of line, as
> is the code that calls kvmppc_realmode_hmi_handler().
>
> Signed-off-by: Paul Mackerras <paulus at ozlabs.org>
Reviewed-by: David Gibson <david at gibson.dropbear.id.au>
> ---
> arch/powerpc/kvm/book3s_hv_ras.c | 8 ++
> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 220 ++++++++++++++++----------------
> 2 files changed, 119 insertions(+), 109 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_ras.c b/arch/powerpc/kvm/book3s_hv_ras.c
> index b11043b..ee564b6 100644
> --- a/arch/powerpc/kvm/book3s_hv_ras.c
> +++ b/arch/powerpc/kvm/book3s_hv_ras.c
> @@ -331,5 +331,13 @@ long kvmppc_realmode_hmi_handler(void)
> } else {
> wait_for_tb_resync();
> }
> +
> + /*
> + * Reset tb_offset_applied so the guest exit code won't try
> + * to subtract the previous timebase offset from the timebase.
> + */
> + if (local_paca->kvm_hstate.kvm_vcore)
> + local_paca->kvm_hstate.kvm_vcore->tb_offset_applied = 0;
> +
> return 0;
> }
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 5b2ae34..772740d 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -1018,8 +1018,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
> no_xive:
> #endif /* CONFIG_KVM_XICS */
>
> -deliver_guest_interrupt:
> -kvmppc_cede_reentry: /* r4 = vcpu, r13 = paca */
> +deliver_guest_interrupt: /* r4 = vcpu, r13 = paca */
> /* Check if we can deliver an external or decrementer interrupt now */
> ld r0, VCPU_PENDING_EXC(r4)
> BEGIN_FTR_SECTION
> @@ -1269,18 +1268,26 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
> std r3, VCPU_CTR(r9)
> std r4, VCPU_XER(r9)
>
> -#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> - /* For softpatch interrupt, go off and do TM instruction emulation */
> - cmpwi r12, BOOK3S_INTERRUPT_HV_SOFTPATCH
> - beq kvmppc_tm_emul
> -#endif
> + /* Save more register state */
> + mfdar r6
> + mfdsisr r7
> + std r6, VCPU_DAR(r9)
> + stw r7, VCPU_DSISR(r9)
>
> /* If this is a page table miss then see if it's theirs or ours */
> cmpwi r12, BOOK3S_INTERRUPT_H_DATA_STORAGE
> beq kvmppc_hdsi
> + std r6, VCPU_FAULT_DAR(r9)
> + stw r7, VCPU_FAULT_DSISR(r9)
> cmpwi r12, BOOK3S_INTERRUPT_H_INST_STORAGE
> beq kvmppc_hisi
>
> +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> + /* For softpatch interrupt, go off and do TM instruction emulation */
> + cmpwi r12, BOOK3S_INTERRUPT_HV_SOFTPATCH
> + beq kvmppc_tm_emul
> +#endif
> +
> /* See if this is a leftover HDEC interrupt */
> cmpwi r12,BOOK3S_INTERRUPT_HV_DECREMENTER
> bne 2f
> @@ -1303,7 +1310,7 @@ BEGIN_FTR_SECTION
> END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
> lbz r0, HSTATE_HOST_IPI(r13)
> cmpwi r0, 0
> - beq 4f
> + beq maybe_reenter_guest
> b guest_exit_cont
> 3:
> /* If it's a hypervisor facility unavailable interrupt, save HFSCR */
> @@ -1315,82 +1322,16 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
> 14:
> /* External interrupt ? */
> cmpwi r12, BOOK3S_INTERRUPT_EXTERNAL
> - bne+ guest_exit_cont
> -
> - /* External interrupt, first check for host_ipi. If this is
> - * set, we know the host wants us out so let's do it now
> - */
> - bl kvmppc_read_intr
> -
> - /*
> - * Restore the active volatile registers after returning from
> - * a C function.
> - */
> - ld r9, HSTATE_KVM_VCPU(r13)
> - li r12, BOOK3S_INTERRUPT_EXTERNAL
> -
> - /*
> - * kvmppc_read_intr return codes:
> - *
> - * Exit to host (r3 > 0)
> - * 1 An interrupt is pending that needs to be handled by the host
> - * Exit guest and return to host by branching to guest_exit_cont
> - *
> - * 2 Passthrough that needs completion in the host
> - * Exit guest and return to host by branching to guest_exit_cont
> - * However, we also set r12 to BOOK3S_INTERRUPT_HV_RM_HARD
> - * to indicate to the host to complete handling the interrupt
> - *
> - * Before returning to guest, we check if any CPU is heading out
> - * to the host and if so, we head out also. If no CPUs are heading
> - * check return values <= 0.
> - *
> - * Return to guest (r3 <= 0)
> - * 0 No external interrupt is pending
> - * -1 A guest wakeup IPI (which has now been cleared)
> - * In either case, we return to guest to deliver any pending
> - * guest interrupts.
> - *
> - * -2 A PCI passthrough external interrupt was handled
> - * (interrupt was delivered directly to guest)
> - * Return to guest to deliver any pending guest interrupts.
> - */
> -
> - cmpdi r3, 1
> - ble 1f
> -
> - /* Return code = 2 */
> - li r12, BOOK3S_INTERRUPT_HV_RM_HARD
> - stw r12, VCPU_TRAP(r9)
> - b guest_exit_cont
> -
> -1: /* Return code <= 1 */
> - cmpdi r3, 0
> - bgt guest_exit_cont
> -
> - /* Return code <= 0 */
> -4: ld r5, HSTATE_KVM_VCORE(r13)
> - lwz r0, VCORE_ENTRY_EXIT(r5)
> - cmpwi r0, 0x100
> - mr r4, r9
> - blt deliver_guest_interrupt
> -
> -guest_exit_cont: /* r9 = vcpu, r12 = trap, r13 = paca */
> - /* Save more register state */
> - mfdar r6
> - mfdsisr r7
> - std r6, VCPU_DAR(r9)
> - stw r7, VCPU_DSISR(r9)
> - /* don't overwrite fault_dar/fault_dsisr if HDSI */
> - cmpwi r12,BOOK3S_INTERRUPT_H_DATA_STORAGE
> - beq mc_cont
> - std r6, VCPU_FAULT_DAR(r9)
> - stw r7, VCPU_FAULT_DSISR(r9)
> -
> + beq kvmppc_guest_external
> /* See if it is a machine check */
> cmpwi r12, BOOK3S_INTERRUPT_MACHINE_CHECK
> beq machine_check_realmode
> -mc_cont:
> + /* Or a hypervisor maintenance interrupt */
> + cmpwi r12, BOOK3S_INTERRUPT_HMI
> + beq hmi_realmode
> +
> +guest_exit_cont: /* r9 = vcpu, r12 = trap, r13 = paca */
> +
> #ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
> addi r3, r9, VCPU_TB_RMEXIT
> mr r4, r9
> @@ -1821,24 +1762,6 @@ BEGIN_FTR_SECTION
> mtspr SPRN_DPDES, r8
> END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
>
> - /* If HMI, call kvmppc_realmode_hmi_handler() */
> - lwz r12, STACK_SLOT_TRAP(r1)
> - cmpwi r12, BOOK3S_INTERRUPT_HMI
> - bne 27f
> - bl kvmppc_realmode_hmi_handler
> - nop
> - cmpdi r3, 0
> - /*
> - * At this point kvmppc_realmode_hmi_handler may have resync-ed
> - * the TB, and if it has, we must not subtract the guest timebase
> - * offset from the timebase. So, skip it.
> - *
> - * Also, do not call kvmppc_subcore_exit_guest() because it has
> - * been invoked as part of kvmppc_realmode_hmi_handler().
> - */
> - beq 30f
> -
> -27:
> /* Subtract timebase offset from timebase */
> ld r8, VCORE_TB_OFFSET_APPL(r5)
> cmpdi r8,0
> @@ -1856,7 +1779,16 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> addis r8,r8,0x100 /* if so, increment upper 40 bits */
> mtspr SPRN_TBU40,r8
>
> -17: bl kvmppc_subcore_exit_guest
> +17:
> + /*
> + * If this is an HMI, we called kvmppc_realmode_hmi_handler
> + * above, which may or may not have already called
> + * kvmppc_subcore_exit_guest. Fortunately, all that
> + * kvmppc_subcore_exit_guest does is clear a flag, so calling
> + * it again here is benign even if kvmppc_realmode_hmi_handler
> + * has already called it.
> + */
> + bl kvmppc_subcore_exit_guest
> nop
> 30: ld r5,HSTATE_KVM_VCORE(r13)
> ld r4,VCORE_KVM(r5) /* pointer to struct kvm */
> @@ -1910,6 +1842,67 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
> mtlr r0
> blr
>
> +kvmppc_guest_external:
> + /* External interrupt, first check for host_ipi. If this is
> + * set, we know the host wants us out so let's do it now
> + */
> + bl kvmppc_read_intr
> +
> + /*
> + * Restore the active volatile registers after returning from
> + * a C function.
> + */
> + ld r9, HSTATE_KVM_VCPU(r13)
> + li r12, BOOK3S_INTERRUPT_EXTERNAL
> +
> + /*
> + * kvmppc_read_intr return codes:
> + *
> + * Exit to host (r3 > 0)
> + * 1 An interrupt is pending that needs to be handled by the host
> + * Exit guest and return to host by branching to guest_exit_cont
> + *
> + * 2 Passthrough that needs completion in the host
> + * Exit guest and return to host by branching to guest_exit_cont
> + * However, we also set r12 to BOOK3S_INTERRUPT_HV_RM_HARD
> + * to indicate to the host to complete handling the interrupt
> + *
> + * Before returning to guest, we check if any CPU is heading out
> + * to the host and if so, we head out also. If no CPUs are heading
> + * check return values <= 0.
> + *
> + * Return to guest (r3 <= 0)
> + * 0 No external interrupt is pending
> + * -1 A guest wakeup IPI (which has now been cleared)
> + * In either case, we return to guest to deliver any pending
> + * guest interrupts.
> + *
> + * -2 A PCI passthrough external interrupt was handled
> + * (interrupt was delivered directly to guest)
> + * Return to guest to deliver any pending guest interrupts.
> + */
> +
> + cmpdi r3, 1
> + ble 1f
> +
> + /* Return code = 2 */
> + li r12, BOOK3S_INTERRUPT_HV_RM_HARD
> + stw r12, VCPU_TRAP(r9)
> + b guest_exit_cont
> +
> +1: /* Return code <= 1 */
> + cmpdi r3, 0
> + bgt guest_exit_cont
> +
> + /* Return code <= 0 */
> +maybe_reenter_guest:
> + ld r5, HSTATE_KVM_VCORE(r13)
> + lwz r0, VCORE_ENTRY_EXIT(r5)
> + cmpwi r0, 0x100
> + mr r4, r9
> + blt deliver_guest_interrupt
> + b guest_exit_cont
> +
> #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> /*
> * Softpatch interrupt for transactional memory emulation cases
> @@ -2685,13 +2678,7 @@ END_FTR_SECTION(CPU_FTR_TM | CPU_FTR_P9_TM_HV_ASSIST, 0)
> mr r9, r4
> cmpdi r3, 0
> bgt guest_exit_cont
> -
> - /* see if any other thread is already exiting */
> - lwz r0,VCORE_ENTRY_EXIT(r5)
> - cmpwi r0,0x100
> - bge guest_exit_cont
> -
> - b kvmppc_cede_reentry /* if not go back to guest */
> + b maybe_reenter_guest
>
> /* cede when already previously prodded case */
> kvm_cede_prodded:
> @@ -2758,12 +2745,12 @@ machine_check_realmode:
> */
> ld r11, VCPU_MSR(r9)
> rldicl. r0, r11, 64-MSR_HV_LG, 63 /* check if it happened in HV mode */
> - bne mc_cont /* if so, exit to host */
> + bne guest_exit_cont /* if so, exit to host */
> /* Check if guest is capable of handling NMI exit */
> ld r10, VCPU_KVM(r9)
> lbz r10, KVM_FWNMI(r10)
> cmpdi r10, 1 /* FWNMI capable? */
> - beq mc_cont /* if so, exit with KVM_EXIT_NMI. */
> + beq guest_exit_cont /* if so, exit with KVM_EXIT_NMI. */
>
> /* if not, fall through for backward compatibility. */
> andi. r10, r11, MSR_RI /* check for unrecoverable exception */
> @@ -2777,6 +2764,21 @@ machine_check_realmode:
> 2: b fast_interrupt_c_return
>
> /*
> + * Call C code to handle a HMI in real mode.
> + * Only the primary thread does the call, secondary threads are handled
> + * by calling hmi_exception_realmode() after kvmppc_hv_entry returns.
> + * r9 points to the vcpu on entry
> + */
> +hmi_realmode:
> + lbz r0, HSTATE_PTID(r13)
> + cmpwi r0, 0
> + bne guest_exit_cont
> + bl kvmppc_realmode_hmi_handler
> + ld r9, HSTATE_KVM_VCPU(r13)
> + li r12, BOOK3S_INTERRUPT_HMI
> + b guest_exit_cont
> +
> +/*
> * Check the reason we woke from nap, and take appropriate action.
> * Returns (in r3):
> * 0 if nothing needs to be done
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: not available
URL: <http://lists.ozlabs.org/pipermail/linuxppc-dev/attachments/20181005/87af981c/attachment.sig>
More information about the Linuxppc-dev
mailing list