On 05/07/2013 11:32 AM, Scott Wood wrote:
booke64 was not maintaing consistent lazy ee state when exiting the
One typo ;-)
s/maintaing/maintaining
guest, leading to warnings and worse.
booke32 was less affected due to the absence of lazy ee, but it was
still feeding bad information into trace_hardirqs_off/on -- we don't
want guest execution to be seen as an "IRQs off" interval. book3s_pr
also has this problem.
book3s_pr and booke both used kvmppc_lazy_ee_enable() without
hard-disabling EE first, which could lead to races when irq_happened is
cleared, or if an interrupt happens after kvmppc_lazy_ee_enable(), and
possibly other issues.
Now, on book3s_pr and booke, always hard-disable interrupts before
kvmppc_prepare_to_enter(), but leave them soft-enabled. On book3s,
this should results in the right lazy EE state when the asm code
hard-enables on an exit. On booke, we call hard_irq_disable() rather
than hard-enable immediately.
Looks we always need to call hard_irq_disable() before
kvmppc_prepare_to_enter(), so I think we can add hard_irq_disable() directly
into kvmppc_prepare_to_enater() since this can avoid forgetting to call
hard_irq_disable() when call kvmppc_prepare_to_enater() somewhere in the future.
Here I assume Ben's fix to hard_irq_disable() is before this :) So what about this?
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index d7339df..e4e2120 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -397,6 +397,13 @@ static inline void kvmppc_mmu_flush_icache(pfn_t pfn)
static inline void kvmppc_lazy_ee_enable(void)
{
#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);
+ trace_hardirqs_on();
+
/* 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 d09baf1..1ea65cd 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -884,7 +884,6 @@ 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();
@@ -1121,7 +1120,6 @@ 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();
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index dc1f590..d412749 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -666,7 +666,6 @@ 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();
@@ -832,6 +831,10 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu
*vcpu,
{
int r = RESUME_HOST;
int s;
+#ifdef CONFIG_PPC64
+ WARN_ON(local_paca->irq_happened != 0);
+#endif
+ hard_irq_disable();
/* update before a new last_exit_type is rewritten */
kvmppc_update_timing_stats(vcpu);
@@ -1143,7 +1146,6 @@ 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();
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 31084c6..147ac0e 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -64,7 +64,8 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
{
int r = 1;
- WARN_ON_ONCE(!irqs_disabled());
+ hard_irq_disable();
+
while (true) {
if (need_resched()) {
local_irq_enable();
--
1.7.9.5
Tiejun
Signed-off-by: Scott Wood <scottwood@xxxxxxxxxxxxx>
Cc: Mihai Caraman <mihai.caraman@xxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Tiejun Chen <tiejun.chen@xxxxxxxxxxxxx>
---
Only tested on booke (32 and 64 bit). Testers of book3s_pr would be
appreciated (particularly with lockdep enabled).
---
arch/powerpc/include/asm/kvm_ppc.h | 7 +++++++
arch/powerpc/kvm/book3s_pr.c | 6 ++++--
arch/powerpc/kvm/booke.c | 12 ++++++++++--
3 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index a5287fe..e55d7e5 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -399,6 +399,13 @@ static inline void kvmppc_mmu_flush_icache(pfn_t pfn)
static inline void kvmppc_lazy_ee_enable(void)
{
#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);
+ trace_hardirqs_on();
+
/* 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 d09baf1..a1e70113 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -884,7 +884,8 @@ 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();
+ hard_irq_disable();
+ trace_hardirqs_off();
s = kvmppc_prepare_to_enter(vcpu);
if (s <= 0) {
local_irq_enable();
@@ -1121,7 +1122,8 @@ 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();
+ hard_irq_disable();
+ trace_hardirqs_off();
ret = kvmppc_prepare_to_enter(vcpu);
if (ret <= 0) {
local_irq_enable();
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index ecbe908..5dc1f53 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -666,7 +666,8 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
return -EINVAL;
}
- local_irq_disable();
+ hard_irq_disable();
+ trace_hardirqs_off();
s = kvmppc_prepare_to_enter(vcpu);
if (s <= 0) {
local_irq_enable();
@@ -834,6 +835,12 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
int s;
int idx;
+#ifdef CONFIG_PPC64
+ WARN_ON(local_paca->irq_happened != 0);
+#endif
+ hard_irq_disable();
+ trace_hardirqs_off();
+
/* update before a new last_exit_type is rewritten */
kvmppc_update_timing_stats(vcpu);
@@ -1150,7 +1157,8 @@ 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();
+ hard_irq_disable();
+ trace_hardirqs_off();
s = kvmppc_prepare_to_enter(vcpu);
if (s <= 0) {
local_irq_enable();
--
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