From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH 1/8] KVM: Add MSI_ACTION flag for assigned irq Date: Sat, 27 Dec 2008 17:24:29 -0200 Message-ID: <20081227192429.GA3715@amt.cnet> References: <1230019231-16543-1-git-send-email-sheng@linux.intel.com> <1230019231-16543-2-git-send-email-sheng@linux.intel.com> <20081223173224.GA5449@amt.cnet> <200812241024.35361.sheng@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , kvm@vger.kernel.org To: Sheng Yang Return-path: Received: from mx2.redhat.com ([66.187.237.31]:41465 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753528AbYL0TYo (ORCPT ); Sat, 27 Dec 2008 14:24:44 -0500 Content-Disposition: inline In-Reply-To: <200812241024.35361.sheng@linux.intel.com> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Dec 24, 2008 at 10:24:34AM +0800, Sheng Yang wrote: > On Wednesday 24 December 2008 01:32:24 Marcelo Tosatti wrote: > > On Tue, Dec 23, 2008 at 04:00:24PM +0800, Sheng Yang wrote: > > > For MSI disable feature later. > > > > > > Notice I changed ABI here, but due to no userspace patch, I think it's > > > OK. > > > > > > Signed-off-by: Sheng Yang > > > --- > > > include/linux/kvm.h | 3 ++- > > > 1 files changed, 2 insertions(+), 1 deletions(-) > > > > > > diff --git a/include/linux/kvm.h b/include/linux/kvm.h > > > index ef7f98e..5b965f6 100644 > > > --- a/include/linux/kvm.h > > > +++ b/include/linux/kvm.h > > > @@ -544,6 +544,7 @@ struct kvm_assigned_irq { > > > > > > #define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0) > > > > > > -#define KVM_DEV_IRQ_ASSIGN_ENABLE_MSI (1 << 0) > > > +#define KVM_DEV_IRQ_ASSIGN_MSI_ACTION (1 << 0) > > > +#define KVM_DEV_IRQ_ASSIGN_ENABLE_MSI (1 << 1) > > > > This is a little confusing. KVM_DEV_IRQ_ASSIGN_MSI_ACTION is assigned > > from userspace, and in the patchset used in conjunction with msi2intx > > which is a module parameter. > > > > Is there anything that blocks control of msi2intx translate behaviour > > from userspace? > > > > Perhaps add a KVM_DEV_IRQ_UNASSIGN ioctl, and pass the desired > > guest/host irq types on the IRQ_ASSIGN ioctl, thus removing some of the > > kernel complexity. > > Marcelo, Thanks for reviewing. > > msi2intx module parameter is mostly a debug assist rather than a real option, > so we won't want this to be a real option controlled by userspace program. It seems msi2intx (as a module parameter) is not necessary. You can achieve the same from userspace by configuring KVM_DEV_IRQ_ASSIGN_ENABLE_MSI/MSI_ACTION, no? The module parameter seems a weird interface to me (even if it is a debug one). But its not a big deal, if you think it is worthwhile to keep it that way.