From: Pavel Fedin <p.fedin@samsung.com>
To: 'Marc Zyngier' <marc.zyngier@arm.com>
Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
"'Christoffer Dall'" <christoffer.dall@linaro.org>,
"'Alex Bennée'" <alex.bennee@linaro.org>
Subject: RE: [PATCH] KVM: arm/arm64: BUG: Fix losing level-sensitive interrupts
Date: Wed, 26 Aug 2015 14:33:06 +0300 [thread overview]
Message-ID: <00d901d0dff2$fa5616d0$ef024470$@samsung.com> (raw)
In-Reply-To: <55DD9F5B.4080602@arm.com>
Hello!
> As for v4.1 not having that problem, the pl011 driver has gone though a
> lot if rework lately, and I wouldn't be surprised if it now exhibited a
> different behaviour thanks to the broken userspace behaviour.
Sorry, you misunderstood me. Or i wrote badly. I meant that _KVM_ did not have this particular
problem in kernel v4.0, because:
http://lxr.free-electrons.com/source/virt/kvm/arm/vgic.c?v=4.0#L998
you see, LR_STATE_PENDING is assigned unconditionally. Is this code correct? I believe yes. Compare
with:
http://lxr.free-electrons.com/source/virt/kvm/arm/vgic.c#L1104
Now it is possible to have neither PENDING nor ACTIVE irq. Does it even make sense? So what is
wrong with the modification as follows?
--- cut ---
if (vgic_irq_is_active(vcpu, irq)) {
vlr.state |= LR_STATE_ACTIVE;
kvm_debug("Set active, clear distributor: 0x%x\n", vlr.state);
vgic_irq_clear_active(vcpu, irq);
vgic_update_state(vcpu->kvm);
} else {
vlr.state |= LR_STATE_PENDING;
kvm_debug("Set pending: 0x%x\n", vlr.state);
}
--- cut ---
Alex, are you reading us? Can you explain, why you introduced that extra check?
> And what you're suggesting is to actually introduce a bug.
Why would that be a bug, if it was not a bug in kernel 4.0?
Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia
next prev parent reply other threads:[~2015-08-26 11:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-26 6:46 [PATCH] KVM: arm/arm64: BUG: Fix losing level-sensitive interrupts Pavel Fedin
2015-08-26 8:27 ` Marc Zyngier
2015-08-26 10:58 ` Pavel Fedin
2015-08-26 11:13 ` Marc Zyngier
2015-08-26 11:33 ` Pavel Fedin [this message]
2015-08-26 13:11 ` Pavel Fedin
2015-08-26 14:03 ` Christoffer Dall
2015-08-26 14:02 ` Christoffer Dall
2015-08-26 14:26 ` Pavel Fedin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='00d901d0dff2$fa5616d0$ef024470$@samsung.com' \
--to=p.fedin@samsung.com \
--cc=alex.bennee@linaro.org \
--cc=christoffer.dall@linaro.org \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=marc.zyngier@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox