From mboxrd@z Thu Jan 1 00:00:00 1970 From: pbonzini@redhat.com (Paolo Bonzini) Date: Fri, 23 Sep 2016 14:46:48 +0200 Subject: [PATCH v6] KVM: arm/arm64: Route vtimer events to user space In-Reply-To: References: <1474628854-69945-1-git-send-email-agraf@suse.de> Message-ID: <55ac71d8-7e92-aa57-9856-5fc48a7f8357@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 23/09/2016 14:36, Alexander Graf wrote: >>> >>> + if ((ret == 1) && timer_ret) { >>> + /* >>> + * We have to exit straight away to ensure that we only >>> + * ever notify user space once about a level change >>> + */ >> >> Is this really a requirement? It complicates the logic noticeably. > > The alternative would be to track the state on ioctl entry, which > Christoffer disliked :). Ok, I see. Maybe he's convinced by the ugly code. :) It's not an architectural concept, it's a KVM API concept. Tracking the state on entry just the equivalent of making this vmexit edge-triggered (both rising and falling edge). Paolo