On 07/28/2010 07:37 PM, Marcelo Tosatti wrote:
On Wed, Jul 28, 2010 at 07:31:03PM +0300, Avi Kivity wrote:
On 07/28/2010 07:21 PM, Marcelo Tosatti wrote:
On Tue, Jul 27, 2010 at 04:19:35PM +0300, Avi Kivity wrote:
Instead of blindly attempting to inject an event before each guest entry,
check for a possible event first in vcpu->requests. Sites that can trigger
event injection are modified to set KVM_REQ_EVENT:
- interrupt, nmi window opening
- ppr updates
- i8259 output changes
- local apic irr changes
- rflags updates
- gif flag set
- event set on exit
This improves non-injecting entry performance, and sets the stage for
non-atomic injection.
Signed-off-by: Avi Kivity<avi@xxxxxxxxxx>
---
arch/x86/kvm/i8259.c | 1 +
arch/x86/kvm/lapic.c | 12 ++++++++++--
arch/x86/kvm/svm.c | 8 +++++++-
arch/x86/kvm/vmx.c | 6 ++++++
arch/x86/kvm/x86.c | 35 ++++++++++++++++++++++++++---------
include/linux/kvm_host.h | 1 +
6 files changed, 51 insertions(+), 12 deletions(-)
@@ -4731,17 +4737,19 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
goto out;
}
- inject_pending_event(vcpu);
+ if (kvm_check_request(KVM_REQ_EVENT, vcpu)) {
+ inject_pending_event(vcpu);
- /* enable NMI/IRQ window open exits if needed */
- if (vcpu->arch.nmi_pending)
- kvm_x86_ops->enable_nmi_window(vcpu);
- else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
- kvm_x86_ops->enable_irq_window(vcpu);
+ /* enable NMI/IRQ window open exits if needed */
+ if (vcpu->arch.nmi_pending)
+ kvm_x86_ops->enable_nmi_window(vcpu);
+ else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
+ kvm_x86_ops->enable_irq_window(vcpu);
Problem is it might not be possible to inject the event signalled by
KVM_REQ_EVENT, say an interrupt from an irqchip, if there is an event
that needs reinjection (or an exception).
That can happen event now, no? A pending exception, interrupt comes
along, injection picks up the exception but leaves the interrupt.
Now the situation can be more complicated:
- pending exception
- injection
- interrupt, sets KVM_REQ_EVENT
- notices KVM_REQ_EVENT
- drops KVM_REQ_EVENT, cancels exception (made pending again)
- goes back
- injection (injects exception again, interrupt is pending)
as far as I can tell, this is all fine.
But you cleared KVM_REQ_EVENT. Which means you're not going to inject
the pending interrupt on the next entry.
Doh. So we need to set KVM_REQ_EVENT again, after the final check for
vcpu->requests, to make sure we redo injection again.
So we can make inject_pending_event() return true if there's more in the
queue, and if it did, re-raise KVM_REQ_EVENT just before entry?
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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