From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: x86: Kick VCPU outside PIC lock again Date: Wed, 24 Feb 2010 12:04:31 +0200 Message-ID: <4B84F9AF.8060804@redhat.com> References: <20100217135901.331576359@linutronix.de> <4B842A1F.50601@siemens.com> <4B84F466.2080009@siemens.com> <4B84F5D4.5020202@redhat.com> <4B84F765.5040209@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Thomas Gleixner , KVM , Gleb Natapov , RT , Linux Kernel Mailing List To: Jan Kiszka Return-path: In-Reply-To: <4B84F765.5040209@siemens.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org On 02/24/2010 11:54 AM, Jan Kiszka wrote: > Avi Kivity wrote: > >> On 02/24/2010 11:41 AM, Jan Kiszka wrote: >> >>> Thomas Gleixner wrote: >>> >>> >>>> On Tue, 23 Feb 2010, Jan Kiszka wrote: >>>> >>>> >>>> >>>>> Thomas Gleixner wrote: >>>>> >>>>> >>>>>> The i8254/i8259 locks need to be real spinlocks on preempt-rt. Convert >>>>>> them to raw_spinlock. No change for !RT kernels. >>>>>> >>>>>> >>>>> Doesn't fly for -rt anymore: pic_irq_update runs under this raw lock and >>>>> calls kvm_vcpu_kick which tries to wake_up some thread -> scheduling >>>>> while atomic. >>>>> >>>>> >>>> Hmm, a wakeup itself is fine. Is that code waking a wake queue ? >>>> >>>> >>> Yes, it's a wake queue. >>> >>> >> So what's the core issue? Is the lock_t in the wait_queue a sleeping mutex? >> > Yep. > I see. Won't we hit the same issue when we call pic functions from atomic context during the guest entry sequence? -- error compiling committee.c: too many arguments to function