Re: [PATCH v5 06/33] KVM: PPC: Book3S HV: Simplify real-mode interrupt handling
On Mon, Oct 08, 2018 at 04:30:52PM +1100, 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
Reviewed-by: David Gibson
> ---
> 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..fc360b5 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 r3
> + mfdsisr r4
> + std r3, VCPU_DAR(r9)
> + stw r4, 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 r3, VCPU_FAULT_DAR(r9)
> + stw r4, 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
>
[PATCH v5 06/33] KVM: PPC: Book3S HV: Simplify real-mode interrupt handling
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
---
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..fc360b5 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 r3
+ mfdsisr r4
+ std r3, VCPU_DAR(r9)
+ stw r4, 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 r3, VCPU_FAULT_DAR(r9)
+ stw r4, 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
