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@xxxxxxxxxxxxx>
---
v3:
- local_irq_disable -> hard_irq_disable in MSR_WE code (just for
consistency -- MSR_WE and 64-bit don't overlap).
- Check that IRQs are hard-disabled before entering the guest.
---
arch/powerpc/include/asm/kvm_ppc.h | 6 ++++++
arch/powerpc/kvm/book3s_pr.c | 12 +++---------
arch/powerpc/kvm/booke.c | 11 +++--------
arch/powerpc/kvm/powerpc.c | 23 ++++++++++-------------
4 files changed, 22 insertions(+), 30 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 6885846..e4474f8 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -404,6 +404,12 @@ 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 0b97ce4..e61e39e 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -884,14 +884,11 @@ 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
kvmppc_fix_ee_before_entry();
- }
}
trace_kvm_book3s_reenter(r, vcpu);
@@ -1121,12 +1118,9 @@ int kvmppc_vcpu_run(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;
- }
/* Save FPU state in stack */
if (current->thread.regs->msr & MSR_FP)
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 3817c67..521df2c 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -617,7 +617,7 @@ 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;
@@ -666,10 +666,8 @@ 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;
}
@@ -1154,14 +1152,11 @@ 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
kvmppc_fix_ee_before_entry();
- }
}
return r;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 4e05f8c..2f7a221 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -64,12 +64,14 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
{
int r = 1;
- WARN_ON_ONCE(!irqs_disabled());
+ WARN_ON(irqs_disabled());
+ hard_irq_disable();
+
while (true) {
if (need_resched()) {
local_irq_enable();
cond_resched();
- local_irq_disable();
+ hard_irq_disable();
continue;
}
@@ -95,7 +97,7 @@ 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;
@@ -108,21 +110,16 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
}
#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;
- }
+ WARN_ON(lazy_irq_pending());
#endif
+ /* Can't use irqs_disabled() because we want hard irq state */
+ WARN_ON(mfmsr() & MSR_EE);
kvm_guest_enter();
- break;
+ return r;
}
+ local_irq_enable();
return r;
}
#endif /* CONFIG_KVM_BOOK3S_64_HV */
--
1.7.10.4
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