From: Gleb Natapov <gleb@redhat.com>
To: Yang Zhang <yang.z.zhang@intel.com>
Cc: kvm@vger.kernel.org, mtosatti@redhat.com, xiantao.zhang@intel.com
Subject: Re: [PATCH v4 5/7] KVM: Recalculate destination vcpu map
Date: Wed, 20 Mar 2013 17:22:45 +0200 [thread overview]
Message-ID: <20130320152245.GL3889@redhat.com> (raw)
In-Reply-To: <1363779379-20212-6-git-send-email-yang.z.zhang@intel.com>
On Wed, Mar 20, 2013 at 07:36:17PM +0800, Yang Zhang wrote:
> From: Yang Zhang <yang.z.zhang@Intel.com>
>
> Update RTC interrrupt's destination vcpu map when ioapic entry of RTC
> or apic register (id, ldr, dfr) is changed.
>
> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
> ---
> virt/kvm/ioapic.c | 9 +++++++--
> 1 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
> index ddf9414..91b4c08 100644
> --- a/virt/kvm/ioapic.c
> +++ b/virt/kvm/ioapic.c
> @@ -121,6 +121,7 @@ void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu,
> {
> struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
> union kvm_ioapic_redirect_entry *e;
> + unsigned long *rtc_map = ioapic->rtc_status.vcpu_map;
> struct kvm_lapic_irq irqe;
> int index;
>
> @@ -130,15 +131,19 @@ void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu,
> if (!e->fields.mask &&
> (e->fields.trig_mode == IOAPIC_LEVEL_TRIG ||
> kvm_irq_has_notifier(ioapic->kvm, KVM_IRQCHIP_IOAPIC,
> - index))) {
> + index) || index == 8)) {
> irqe.dest_id = e->fields.dest_id;
> irqe.vector = e->fields.vector;
> irqe.dest_mode = e->fields.dest_mode;
> irqe.shorthand = 0;
>
> if (kvm_apic_match_dest(vcpu, NULL, irqe.shorthand,
> - irqe.dest_id, irqe.dest_mode))
> + irqe.dest_id, irqe.dest_mode)) {
> __set_bit(irqe.vector, eoi_exit_bitmap);
> + if (index == 8)
> + __set_bit(vcpu->vcpu_id, rtc_map);
> + } else if (index == 8)
> + __clear_bit(vcpu->vcpu_id, rtc_map);
rtc_map bitmap is accessed from different vcpus simultaneously so access
has to be atomic. We also have a race:
vcpu0 iothread
ioapic config changes
request scan ioapic
inject rtc interrupt
use old vcpu mask
scan_ioapic()
recalculate vcpu mask
So this approach (suggested by me :() will not work.
Need to think about it some more. May be your idea of building a bitmap
while injecting the interrupt is the way to go indeed: pass a pointer to
a bitmap to kvm_irq_delivery_to_apic() and build it there. Pass NULL
pointer if caller does not need to track vcpus.
--
Gleb.
next prev parent reply other threads:[~2013-03-20 15:22 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-20 11:36 [PATCH v4 0/7] Use eoi to track RTC interrupt delivery status Yang Zhang
2013-03-20 11:36 ` [PATCH v4 1/7] KVM: Call kvm_apic_match_dest() to check destination vcpu Yang Zhang
2013-03-20 12:16 ` Gleb Natapov
2013-03-20 11:36 ` [PATCH v4 2/7] KVM: Call common update function when ioapic entry changed Yang Zhang
2013-03-20 11:36 ` [PATCH v4 3/7] KVM: Add vcpu info to ioapic_update_eoi() Yang Zhang
2013-03-20 11:36 ` [PATCH v4 4/7] KVM: Introduce struct rtc_status Yang Zhang
2013-03-20 11:36 ` [PATCH v4 5/7] KVM: Recalculate destination vcpu map Yang Zhang
2013-03-20 15:22 ` Gleb Natapov [this message]
2013-03-21 3:42 ` Zhang, Yang Z
2013-03-21 5:08 ` Gleb Natapov
2013-03-21 5:30 ` Zhang, Yang Z
2013-03-21 5:34 ` Gleb Natapov
2013-03-21 5:39 ` Zhang, Yang Z
2013-03-21 6:57 ` Gleb Natapov
2013-03-21 7:01 ` Zhang, Yang Z
2013-03-21 7:02 ` Zhang, Yang Z
2013-03-21 7:04 ` Gleb Natapov
2013-03-20 11:36 ` [PATCH v4 6/7] KVM: Add reset/restore rtc_status support Yang Zhang
2013-03-20 11:36 ` [PATCH v4 7/7] KVM: Use eoi to track RTC interrupt delivery status Yang Zhang
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