From: Scott Wood <scottwood@freescale.com>
To: Caraman Mihai Claudiu-B02008 <B02008@freescale.com>
Cc: Wood Scott-B07421 <B07421@freescale.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>
Subject: Re: [PATCH] KVM: PPC: Book3E 64: Fix IRQs warnings and hangs
Date: Fri, 3 May 2013 17:06:48 -0500 [thread overview]
Message-ID: <1367618808.19391.11@snotra> (raw)
In-Reply-To: <300B73AA675FCE4A93EB4FC1D42459FF3E9B37@039-SN2MPN1-013.039d.mgd.msft.net> (from B02008@freescale.com on Fri May 3 15:56:47 2013)
On 05/03/2013 03:56:47 PM, Caraman Mihai Claudiu-B02008 wrote:
> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Friday, May 03, 2013 11:15 PM
> > To: Caraman Mihai Claudiu-B02008
> > Cc: Wood Scott-B07421; kvm-ppc@vger.kernel.org; kvm@vger.kernel.org;
> > linuxppc-dev@lists.ozlabs.org
> > Subject: Re: [PATCH] KVM: PPC: Book3E 64: Fix IRQs warnings and =20
> hangs
> >
> > > > > The unresponsiveness has to do with the fact that
> > > > > arch_local_irq_restore()
> > > > > does not guarantees to hard enable interrupts.
> > > >
> > > > Could you elaborate? If the saved IRQ state was "enabled", why
> > > > wouldn't arch_local_irq_restore() hard-enable IRQs? The last =20
> thing
> > > it
> > > > does is __hard_irq_enable().
> > >
> > > if (!irq_happened)
> > > return;
> >
> > OK, so the problem is that we're not setting PACA_IRQ_HARD_DIS when =20
> we
> > hard-disable interrupts?
>=20
> We enter guest with local_irq_disable() which means soft disabled,
Hmm... I don't see any obvious breakage from that, but it makes me =20
nervous. I'd be more comfortable if we just hard-disabled interrupts =20
there.
> when do we hard-disable interrupts?
Interrupts will be hard-disabled when we take an exception to exit =20
guest state.
> If we follow host exception handlers model
> they set PACA_IRQ_EE/DEC/DBELL but not PACA_IRQ_HARD_DIS. Can you =20
> give it
> a try to see how KVM behaves with PACA_IRQ_HARD_DIS? I can't do it =20
> right now.
I replaced the two calls to kvmppc_lazy_ee_enable() with calls to =20
hard_irq_disable(), and it seems to be working fine.
> > > > Where is the arch_local_irq_restore() instance you're talking =20
> about?
> > >
> > > ./arch/power/kernel/irq.c
> >
> > I meant the caller. :-P
>=20
> ./arch/powerpc/include/asm/hw_irq.h
>=20
> 55static inline unsigned long arch_local_irq_disable(void)
> 56{
> 57 unsigned long flags, zero;
> 58
> 59 asm volatile(
> 60 "li %1,0; lbz %0,%2(13); stb %1,%2(13)"
> 61 : "=3Dr" (flags), "=3D&r" (zero)
> 62 : "i" (offsetof(struct paca_struct, soft_enabled))
> 63 : "memory");
> 64
> 65 return flags;
> 66}
> 67
> 68extern void arch_local_irq_restore(unsigned long);
> 69
> 70static inline void arch_local_irq_enable(void)
> 71{
> 72 arch_local_irq_restore(1);
> 73}
Sigh. I meant the real caller, who's calling local_irq_restore().
-Scott=
next prev parent reply other threads:[~2013-05-03 22:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-03 16:11 [PATCH] KVM: PPC: Book3E 64: Fix IRQs warnings and hangs Mihai Caraman
2013-05-03 16:24 ` Alexander Graf
2013-05-03 22:03 ` Benjamin Herrenschmidt
2013-05-03 18:04 ` Scott Wood
2013-05-03 20:01 ` Caraman Mihai Claudiu-B02008
2013-05-03 20:15 ` Scott Wood
2013-05-03 20:56 ` Caraman Mihai Claudiu-B02008
2013-05-03 22:06 ` Scott Wood [this message]
2013-05-03 22:59 ` Caraman Mihai Claudiu-B02008
2013-05-03 23:30 ` Scott Wood
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=1367618808.19391.11@snotra \
--to=scottwood@freescale.com \
--cc=B02008@freescale.com \
--cc=B07421@freescale.com \
--cc=kvm-ppc@vger.kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
/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;
as well as URLs for NNTP newsgroup(s).