[PULL 20/36] kvm/ppc: IRQ disabling cleanup

Alexander Graf
2014-01-29T16:13:25Z

From: Scott Wood <scottwood@freescale.com>

Simplify the handling of lazy EE by going directly from fully-enabled
to hard-disabled. This replaces the lazy_irq_pending() check
(including its misplaced kvm_guest_exit() call).

As suggested by Tiejun Chen, move the interrupt disabling into
kvmppc_prepare_to_enter() rather than have each caller do it. Also
move the IRQ enabling on heavyweight exit into
kvmppc_prepare_to_enter().

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
arch/powerpc/include/asm/kvm_ppc.h | 6 ++++++
arch/powerpc/kvm/book3s_pr.c | 14 ++++++--------
arch/powerpc/kvm/booke.c | 12 +++++-------
arch/powerpc/kvm/powerpc.c | 26 +++++++++-----------------
4 files changed, 26 insertions(+), 32 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 629277d..fcd53f0 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -456,6 +456,12 @@ static inline void kvmppc_fix_ee_before_entry(void)
trace_hardirqs_on();

#ifdef CONFIG_PPC64
+ /*
+ * To avoid races, the caller must have gone directly from having
+ * interrupts fully-enabled to hard-disabled.
+ */
+ WARN_ON(local_paca->irq_happened != PACA_IRQ_HARD_DIS);
+
/* Only need to enable IRQs by hard enabling them after this */
local_paca->irq_happened = 0;
local_paca->soft_enabled = 1;
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index aedba68..e82fafd 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -999,14 +999,14 @@ program_interrupt:
* and if we really did time things so badly, then we just exit
* again due to a host external interrupt.
*/
- local_irq_disable();
s = kvmppc_prepare_to_enter(vcpu);
- if (s <= 0) {
- local_irq_enable();
+ if (s <= 0)
r = s;
- } else {
+ else {
+ /* interrupts now hard-disabled */
kvmppc_fix_ee_before_entry();
}
+
kvmppc_handle_lost_ext(vcpu);
}

@@ -1219,12 +1219,10 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
* really did time things so badly, then we just exit again due to
* a host external interrupt.
*/
- local_irq_disable();
ret = kvmppc_prepare_to_enter(vcpu);
- if (ret <= 0) {
- local_irq_enable();
+ if (ret <= 0)
goto out;
- }
+ /* interrupts now hard-disabled */

/* Save FPU state in thread_struct */
if (current->thread.regs->msr & MSR_FP)
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 6a8c32e..07b89c7 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -643,7 +643,7 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
local_irq_enable();
kvm_vcpu_block(vcpu);
clear_bit(KVM_REQ_UNHALT, &vcpu->requests);
- local_irq_disable();
+ hard_irq_disable();

kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS);
r = 1;
@@ -688,13 +688,12 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
return -EINVAL;
}

- local_irq_disable();
s = kvmppc_prepare_to_enter(vcpu);
if (s <= 0) {
- local_irq_enable();
ret = s;
goto out;
}
+ /* interrupts now hard-disabled */

#ifdef CONFIG_PPC_FPU
/* Save userspace FPU state in stack */
@@ -1187,12 +1186,11 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
* aren't already exiting to userspace for some other reason.
*/
if (!(r & RESUME_HOST)) {
- local_irq_disable();
s = kvmppc_prepare_to_enter(vcpu);
- if (s <= 0) {
- local_irq_enable();
+ if (s <= 0)
r = (s << 2) | RESUME_HOST | (r & RESUME_FLAG_NV);
- } else {
+ else {
+ /* interrupts now hard-disabled */
kvmppc_fix_ee_before_entry();
}
}
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 026dfaa..3cf541a 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -68,14 +68,16 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
*/
int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
{
- int r = 1;
+ int r;
+
+ WARN_ON(irqs_disabled());
+ hard_irq_disable();

- WARN_ON_ONCE(!irqs_disabled());
while (true) {
if (need_resched()) {
local_irq_enable();
cond_resched();
- local_irq_disable();
+ hard_irq_disable();
continue;
}

@@ -101,7 +103,7 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
local_irq_enable();
trace_kvm_check_requests(vcpu);
r = kvmppc_core_check_requests(vcpu);
- local_irq_disable();
+ hard_irq_disable();
if (r > 0)
continue;
break;
@@ -113,22 +115,12 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
continue;
}

-#ifdef CONFIG_PPC64
- /* lazy EE magic */
- hard_irq_disable();
- if (lazy_irq_pending()) {
- /* Got an interrupt in between, try again */
- local_irq_enable();
- local_irq_disable();
- kvm_guest_exit();
- continue;
- }
-#endif
-
kvm_guest_enter();
- break;
+ return 1;
}

+ /* return to host */
+ local_irq_enable();
return r;
}
EXPORT_SYMBOL_GPL(kvmppc_prepare_to_enter);
--
1.8.1.4