This patch fixes the bug discussed in
https://www.mail-archive.com/[email protected]/msg109813.html
This patch uses a new field named irr_delivered to record the
delivery status of edge-triggered interrupts, and clears the
delivered interrupts in kvm_get_ioapic. So it has the same effect
of commit 0bc830b05c667218d703f2026ec866c49df974fc
("KVM: ioapic: clear IRR for edge-triggered interrupts at delivery")
while avoids the bug of Windows guests.
Signed-off-by: Wincy Van <[email protected]>
---
arch/x86/kvm/ioapic.c | 7 ++++++-
arch/x86/kvm/ioapic.h | 1 +
2 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index b1947e0..a2e9d96 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -206,6 +206,8 @@ static int ioapic_set_irq(struct kvm_ioapic *ioapic, unsigned int irq,
old_irr = ioapic->irr;
ioapic->irr |= mask;
+ if (edge)
+ ioapic->irr_delivered &= ~mask;
if ((edge && old_irr == ioapic->irr) ||
(!edge && entry.fields.remote_irr)) {
ret = 0;
@@ -349,7 +351,7 @@ static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status)
irqe.shorthand = 0;
if (irqe.trig_mode == IOAPIC_EDGE_TRIG)
- ioapic->irr &= ~(1 << irq);
+ ioapic->irr_delivered |= 1 << irq;
if (irq == RTC_GSI && line_status) {
/*
@@ -597,6 +599,7 @@ static void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
ioapic->base_address = IOAPIC_DEFAULT_BASE_ADDRESS;
ioapic->ioregsel = 0;
ioapic->irr = 0;
+ ioapic->irr_delivered = 0;
ioapic->id = 0;
memset(ioapic->irq_eoi, 0x00, IOAPIC_NUM_PINS);
rtc_irq_eoi_tracking_reset(ioapic);
@@ -654,6 +657,7 @@ int kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
spin_lock(&ioapic->lock);
memcpy(state, ioapic, sizeof(struct kvm_ioapic_state));
+ state->irr &= ~ioapic->irr_delivered;
spin_unlock(&ioapic->lock);
return 0;
}
@@ -667,6 +671,7 @@ int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
spin_lock(&ioapic->lock);
memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
ioapic->irr = 0;
+ ioapic->irr_delivered = 0;
update_handled_vectors(ioapic);
kvm_vcpu_request_scan_ioapic(kvm);
kvm_ioapic_inject_all(ioapic, state->irr);
diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
index 3c91955..a5cdfc0 100644
--- a/arch/x86/kvm/ioapic.h
+++ b/arch/x86/kvm/ioapic.h
@@ -77,6 +77,7 @@ struct kvm_ioapic {
struct rtc_status rtc_status;
struct delayed_work eoi_inject;
u32 irq_eoi[IOAPIC_NUM_PINS];
+ u32 irr_delivered;
};
#ifdef DEBUG
--
1.7.1
On 2014-12-24 04:14, Wincy Van wrote:
> This patch fixes the bug discussed in
> https://www.mail-archive.com/[email protected]/msg109813.html
>
> This patch uses a new field named irr_delivered to record the
> delivery status of edge-triggered interrupts, and clears the
> delivered interrupts in kvm_get_ioapic. So it has the same effect
> of commit 0bc830b05c667218d703f2026ec866c49df974fc
> ("KVM: ioapic: clear IRR for edge-triggered interrupts at delivery")
> while avoids the bug of Windows guests.
>
> Signed-off-by: Wincy Van <[email protected]>
> ---
> arch/x86/kvm/ioapic.c | 7 ++++++-
> arch/x86/kvm/ioapic.h | 1 +
> 2 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
> index b1947e0..a2e9d96 100644
> --- a/arch/x86/kvm/ioapic.c
> +++ b/arch/x86/kvm/ioapic.c
> @@ -206,6 +206,8 @@ static int ioapic_set_irq(struct kvm_ioapic *ioapic, unsigned int irq,
>
> old_irr = ioapic->irr;
> ioapic->irr |= mask;
> + if (edge)
> + ioapic->irr_delivered &= ~mask;
> if ((edge && old_irr == ioapic->irr) ||
> (!edge && entry.fields.remote_irr)) {
> ret = 0;
> @@ -349,7 +351,7 @@ static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status)
> irqe.shorthand = 0;
>
> if (irqe.trig_mode == IOAPIC_EDGE_TRIG)
> - ioapic->irr &= ~(1 << irq);
> + ioapic->irr_delivered |= 1 << irq;
>
> if (irq == RTC_GSI && line_status) {
> /*
> @@ -597,6 +599,7 @@ static void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
> ioapic->base_address = IOAPIC_DEFAULT_BASE_ADDRESS;
> ioapic->ioregsel = 0;
> ioapic->irr = 0;
> + ioapic->irr_delivered = 0;
> ioapic->id = 0;
> memset(ioapic->irq_eoi, 0x00, IOAPIC_NUM_PINS);
> rtc_irq_eoi_tracking_reset(ioapic);
> @@ -654,6 +657,7 @@ int kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
>
> spin_lock(&ioapic->lock);
> memcpy(state, ioapic, sizeof(struct kvm_ioapic_state));
> + state->irr &= ~ioapic->irr_delivered;
> spin_unlock(&ioapic->lock);
> return 0;
> }
> @@ -667,6 +671,7 @@ int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
> spin_lock(&ioapic->lock);
> memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
> ioapic->irr = 0;
> + ioapic->irr_delivered = 0;
> update_handled_vectors(ioapic);
> kvm_vcpu_request_scan_ioapic(kvm);
> kvm_ioapic_inject_all(ioapic, state->irr);
> diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
> index 3c91955..a5cdfc0 100644
> --- a/arch/x86/kvm/ioapic.h
> +++ b/arch/x86/kvm/ioapic.h
> @@ -77,6 +77,7 @@ struct kvm_ioapic {
> struct rtc_status rtc_status;
> struct delayed_work eoi_inject;
> u32 irq_eoi[IOAPIC_NUM_PINS];
> + u32 irr_delivered;
> };
>
> #ifdef DEBUG
>
Does this introduce a state which requires save/restore on migration? If
so, then you need to extend the existing interface - in a
backward-compatible way. If not, please leave a remark on the reason.
Jan
2014-12-24 23:29 GMT+08:00 Jan Kiszka <[email protected]>:
> On 2014-12-24 04:14, Wincy Van wrote:
>> This patch fixes the bug discussed in
>> https://www.mail-archive.com/[email protected]/msg109813.html
>>
>> This patch uses a new field named irr_delivered to record the
>> delivery status of edge-triggered interrupts, and clears the
>> delivered interrupts in kvm_get_ioapic. So it has the same effect
>> of commit 0bc830b05c667218d703f2026ec866c49df974fc
>> ("KVM: ioapic: clear IRR for edge-triggered interrupts at delivery")
>> while avoids the bug of Windows guests.
>>
>> Signed-off-by: Wincy Van <[email protected]>
>> ---
>> arch/x86/kvm/ioapic.c | 7 ++++++-
>> arch/x86/kvm/ioapic.h | 1 +
>> 2 files changed, 7 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
>> index b1947e0..a2e9d96 100644
>> --- a/arch/x86/kvm/ioapic.c
>> +++ b/arch/x86/kvm/ioapic.c
>> @@ -206,6 +206,8 @@ static int ioapic_set_irq(struct kvm_ioapic *ioapic, unsigned int irq,
>>
>> old_irr = ioapic->irr;
>> ioapic->irr |= mask;
>> + if (edge)
>> + ioapic->irr_delivered &= ~mask;
>> if ((edge && old_irr == ioapic->irr) ||
>> (!edge && entry.fields.remote_irr)) {
>> ret = 0;
>> @@ -349,7 +351,7 @@ static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status)
>> irqe.shorthand = 0;
>>
>> if (irqe.trig_mode == IOAPIC_EDGE_TRIG)
>> - ioapic->irr &= ~(1 << irq);
>> + ioapic->irr_delivered |= 1 << irq;
>>
>> if (irq == RTC_GSI && line_status) {
>> /*
>> @@ -597,6 +599,7 @@ static void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
>> ioapic->base_address = IOAPIC_DEFAULT_BASE_ADDRESS;
>> ioapic->ioregsel = 0;
>> ioapic->irr = 0;
>> + ioapic->irr_delivered = 0;
>> ioapic->id = 0;
>> memset(ioapic->irq_eoi, 0x00, IOAPIC_NUM_PINS);
>> rtc_irq_eoi_tracking_reset(ioapic);
>> @@ -654,6 +657,7 @@ int kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
>>
>> spin_lock(&ioapic->lock);
>> memcpy(state, ioapic, sizeof(struct kvm_ioapic_state));
>> + state->irr &= ~ioapic->irr_delivered;
>> spin_unlock(&ioapic->lock);
>> return 0;
>> }
>> @@ -667,6 +671,7 @@ int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
>> spin_lock(&ioapic->lock);
>> memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
>> ioapic->irr = 0;
>> + ioapic->irr_delivered = 0;
>> update_handled_vectors(ioapic);
>> kvm_vcpu_request_scan_ioapic(kvm);
>> kvm_ioapic_inject_all(ioapic, state->irr);
>> diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
>> index 3c91955..a5cdfc0 100644
>> --- a/arch/x86/kvm/ioapic.h
>> +++ b/arch/x86/kvm/ioapic.h
>> @@ -77,6 +77,7 @@ struct kvm_ioapic {
>> struct rtc_status rtc_status;
>> struct delayed_work eoi_inject;
>> u32 irq_eoi[IOAPIC_NUM_PINS];
>> + u32 irr_delivered;
>> };
>>
>> #ifdef DEBUG
>>
>
> Does this introduce a state which requires save/restore on migration? If
> so, then you need to extend the existing interface - in a
> backward-compatible way. If not, please leave a remark on the reason.
>
No, we do not need to save/restore irr_delivered.
First of all, irr_delivered affects irr only when saving ioapic's
state, it does not affect any of the ioapic's logic.
Then, let's see what will happen if we do not save/restore that field :
1. If irr_delivered is 0 before saving, it is no difference at all.
2. If a bit of irr_delivered is 1 before saving, since irr_delivered
only affects migration,
we should check that if the 2nd+ migration is OK.
There are 3 possibilities on the first destination :
(1) The edge-triggered IRQ is masked, that bit will be cleared, it
is no difference to do 2nd migration.
(2) The edge-triggered IRQ is raised and not masked, that bit will
be set again, it is no difference to do 2nd migration.
(3) The edge-triggered IRQ is lowered, and the corresponding bit
of irr is cleared,
the result of "state->irr &= ~ioapic->irr_delivered" in
kvm_get_ioapic is not affected by irr_delivered.
So it is OK to migrate with a stateless irr_delivered.
Thanks,
Wincy
> Jan
>
>