From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp05.au.ibm.com (e23smtp05.au.ibm.com [202.81.31.147]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 07C031A024F for ; Thu, 29 May 2014 09:38:00 +1000 (EST) Received: from /spool/local by e23smtp05.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 29 May 2014 09:37:57 +1000 Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [9.190.234.120]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 5AB022CE8040 for ; Thu, 29 May 2014 09:37:54 +1000 (EST) Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s4SNGIEQ64159794 for ; Thu, 29 May 2014 09:16:18 +1000 Received: from d23av04.au.ibm.com (localhost [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s4SNbri6023708 for ; Thu, 29 May 2014 09:37:53 +1000 Date: Thu, 29 May 2014 09:37:53 +1000 From: Gavin Shan To: Alexander Graf Subject: Re: [PATCH v7 3/3] drivers/vfio: EEH support for VFIO PCI device Message-ID: <20140528233753.GA8150@shangw> References: <1401180052-6060-1-git-send-email-gwshan@linux.vnet.ibm.com> <1401180052-6060-4-git-send-email-gwshan@linux.vnet.ibm.com> <1401214527.3289.611.camel@ul30vt.home> <5385166A.5060404@suse.de> <1401237575.3289.676.camel@ul30vt.home> <53853155.60809@suse.de> <1401238674.3289.679.camel@ul30vt.home> <5385CA86.3010700@suse.de> <1401293853.2412.36.camel@ul30vt.home> <538665DA.8090000@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <538665DA.8090000@suse.de> Cc: aik@ozlabs.ru, Gavin Shan , kvm-ppc@vger.kernel.org, Alex Williamson , qiudayu@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org Reply-To: Gavin Shan List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, May 29, 2014 at 12:40:26AM +0200, Alexander Graf wrote: >On 28.05.14 18:17, Alex Williamson wrote: >>On Wed, 2014-05-28 at 13:37 +0200, Alexander Graf wrote: >>>On 28.05.14 02:57, Alex Williamson wrote: >>>>On Wed, 2014-05-28 at 02:44 +0200, Alexander Graf wrote: >>>>>On 28.05.14 02:39, Alex Williamson wrote: >>>>>>On Wed, 2014-05-28 at 00:49 +0200, Alexander Graf wrote: >>>>>>>On 27.05.14 20:15, Alex Williamson wrote: >>>>>>>>On Tue, 2014-05-27 at 18:40 +1000, Gavin Shan wrote: >>>>>>>>>The patch adds new IOCTL commands for sPAPR VFIO container device >>>>>>>>>to support EEH functionality for PCI devices, which have been passed >>>>>>>>>through from host to somebody else via VFIO. >>>>>>>>> >>>>>>>>>Signed-off-by: Gavin Shan >>>>>>>>>--- >>>>>>>>> Documentation/vfio.txt | 92 ++++++++++++++++++++++++++++++++++++- >>>>>>>>> drivers/vfio/pci/Makefile | 1 + >>>>>>>>> drivers/vfio/pci/vfio_pci.c | 20 +++++--- >>>>>>>>> drivers/vfio/pci/vfio_pci_eeh.c | 46 +++++++++++++++++++ >>>>>>>>> drivers/vfio/pci/vfio_pci_private.h | 5 ++ >>>>>>>>> drivers/vfio/vfio_iommu_spapr_tce.c | 85 ++++++++++++++++++++++++++++++++++ >>>>>>>>> include/uapi/linux/vfio.h | 66 ++++++++++++++++++++++++++ >>>>>>>>> 7 files changed, 308 insertions(+), 7 deletions(-) >>>>>>>>> create mode 100644 drivers/vfio/pci/vfio_pci_eeh.c >>>>>>>[...] >>>>>>> >>>>>>>>>+ >>>>>>>>>+ return ret; >>>>>>>>>+} >>>>>>>>>+ >>>>>>>>> static long tce_iommu_ioctl(void *iommu_data, >>>>>>>>> unsigned int cmd, unsigned long arg) >>>>>>>>> { >>>>>>>>>@@ -283,6 +363,11 @@ static long tce_iommu_ioctl(void *iommu_data, >>>>>>>>> tce_iommu_disable(container); >>>>>>>>> mutex_unlock(&container->lock); >>>>>>>>> return 0; >>>>>>>>>+ case VFIO_EEH_PE_SET_OPTION: >>>>>>>>>+ case VFIO_EEH_PE_GET_STATE: >>>>>>>>>+ case VFIO_EEH_PE_RESET: >>>>>>>>>+ case VFIO_EEH_PE_CONFIGURE: >>>>>>>>>+ return tce_iommu_eeh_ioctl(iommu_data, cmd, arg); >>>>>>>>This is where it would have really made sense to have a single >>>>>>>>VFIO_EEH_OP ioctl with a data structure passed to indicate the sub-op. >>>>>>>>AlexG, are you really attached to splitting these out into separate >>>>>>>>ioctls? >>>>>>>I don't see the problem. We need to forward 4 ioctls to a separate piece >>>>>>>of code, so we forward 4 ioctls to a separate piece of code :). Putting >>>>>>>them into one ioctl just moves the switch() into another function. >>>>>>And uses an extra 3 ioctl numbers and gives us extra things to update if >>>>>>we ever need to add more ioctls, etc. ioctl numbers are an address >>>>>>space, how much address space do we really want to give to EEH? It's >>>>>>not a big difference, but I don't think it's completely even either. >>>>>>Thanks, >>>>>Yes, that's the point. I by far prefer to have you push back on anyone >>>>>who introduces useless ioctls rather than have a separate EEH number >>>>>space that people can just throw anything in they like ;). >>>>Well, I appreciate that, but having them as separate ioctls doesn't >>>>really prevent that either. Any one of these 4 could be set to take a >>>>sub-option to extend and contort the EEH interface. The only way to >>>>prevent that would be to avoid the argsz+flags hack that make the ioctl >>>>extendable. Thanks, >>>Sure, that's what patch review is about. I'm really more concerned about >>>whose court the number space is in - you or Gavin. If we're talking >>>about top level ioctls you will care a lot more. >>> >>>But I'm not religious about this. You're the VFIO maintainer, so it's >>>your call. I just personally cringe when I see an ioctl that gets an >>>"opcode" and a "parameter" argument where the "parameter" argument is a >>>union with one struct for each opcode. >>Well, what would it look like... >> >>struct vfio_eeh_pe_op { >> __u32 argsz; >> __u32 flags; >> __u32 op; >>}; >> >>Couldn't every single one of these be a separate "op"? Are there any >>cases where we can't use the ioctl return value? >> >>VFIO_EEH_PE_DISABLE >>VFIO_EEH_PE_ENABLE >>VFIO_EEH_PE_UNFREEZE_IO >>VFIO_EEH_PE_UNFREEZE_DMA >>VFIO_EEH_PE_GET_MODE >>VFIO_EEH_PE_RESET_DEACTIVATE >>VFIO_EEH_PE_RESET_HOT >>VFIO_EEH_PE_RESET_FUNDAMENTAL >>VFIO_EEH_PE_CONFIGURE >> >>It doesn't look that bad to me, what am I missing? Thanks, > >Yup, that looks well to me as well :) > s/VFIO_EEH_PE_GET_MODE/VFIO_EEH_PE_GET_STATE. I'll include this in next revision. Thanks, Alex. Thanks, Gavin