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30 Mar 2020 01:52:56 -0700 Received: from fmsmsx114.amr.corp.intel.com (10.18.116.8) by FMSMSX106.amr.corp.intel.com (10.18.124.204) with Microsoft SMTP Server (TLS) id 14.3.439.0; Mon, 30 Mar 2020 01:52:56 -0700 Received: from shsmsx103.ccr.corp.intel.com (10.239.4.69) by FMSMSX114.amr.corp.intel.com (10.18.116.8) with Microsoft SMTP Server (TLS) id 14.3.439.0; Mon, 30 Mar 2020 01:52:55 -0700 Received: from shsmsx104.ccr.corp.intel.com ([169.254.5.225]) by SHSMSX103.ccr.corp.intel.com ([169.254.4.146]) with mapi id 14.03.0439.000; Mon, 30 Mar 2020 16:52:52 +0800 From: "Liu, Yi L" To: "Tian, Kevin" , "alex.williamson@redhat.com" , "eric.auger@redhat.com" Subject: RE: [PATCH v1 2/8] vfio/type1: Add vfio_iommu_type1 parameter for quota tuning Thread-Topic: [PATCH v1 2/8] vfio/type1: Add vfio_iommu_type1 parameter for quota tuning Thread-Index: AQHWAEUbHl/tnnhWl0eaKvrwJMb1AqhgVzOAgACGb+A= Date: Mon, 30 Mar 2020 08:52:51 +0000 Message-ID: References: <1584880325-10561-1-git-send-email-yi.l.liu@intel.com> <1584880325-10561-3-git-send-email-yi.l.liu@intel.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-version: 11.2.0.6 dlp-reaction: no-action x-originating-ip: [10.239.127.40] MIME-Version: 1.0 Cc: "jean-philippe@linaro.org" , "Raj, Ashok" , "kvm@vger.kernel.org" , "Tian, Jun J" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "Sun, Yi Y" , "Wu, Hao" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" > From: Tian, Kevin > Sent: Monday, March 30, 2020 4:41 PM > To: Liu, Yi L ; alex.williamson@redhat.com; > Subject: RE: [PATCH v1 2/8] vfio/type1: Add vfio_iommu_type1 parameter for quota > tuning > > > From: Liu, Yi L > > Sent: Sunday, March 22, 2020 8:32 PM > > > > From: Liu Yi L > > > > This patch adds a module option to make the PASID quota tunable by > > administrator. > > > > TODO: needs to think more on how to make the tuning to be per-process. > > > > Previous discussions: > > https://patchwork.kernel.org/patch/11209429/ > > > > Cc: Kevin Tian > > CC: Jacob Pan > > Cc: Alex Williamson > > Cc: Eric Auger > > Cc: Jean-Philippe Brucker > > Signed-off-by: Liu Yi L > > --- > > drivers/vfio/vfio.c | 8 +++++++- > > drivers/vfio/vfio_iommu_type1.c | 7 ++++++- > > include/linux/vfio.h | 3 ++- > > 3 files changed, 15 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c > > index d13b483..020a792 100644 > > --- a/drivers/vfio/vfio.c > > +++ b/drivers/vfio/vfio.c > > @@ -2217,13 +2217,19 @@ struct vfio_mm *vfio_mm_get_from_task(struct > > task_struct *task) > > } > > EXPORT_SYMBOL_GPL(vfio_mm_get_from_task); > > > > -int vfio_mm_pasid_alloc(struct vfio_mm *vmm, int min, int max) > > +int vfio_mm_pasid_alloc(struct vfio_mm *vmm, int quota, int min, int max) > > { > > ioasid_t pasid; > > int ret = -ENOSPC; > > > > mutex_lock(&vmm->pasid_lock); > > > > + /* update quota as it is tunable by admin */ > > + if (vmm->pasid_quota != quota) { > > + vmm->pasid_quota = quota; > > + ioasid_adjust_set(vmm->ioasid_sid, quota); > > + } > > + > > It's a bit weird to have quota adjusted in the alloc path, since the latter might > be initiated by non-privileged users. Why not doing the simple math in vfio_ > create_mm to set the quota when the ioasid set is created? even in the future > you may allow per-process quota setting, that should come from separate > privileged path instead of thru alloc.. The reason is the kernel parameter modification has no event which can be used to adjust the quota. So I chose to adjust it in pasid_alloc path. If it's not good, how about adding one more IOCTL to let user- space trigger a quota adjustment event? Then even non-privileged user could trigger quota adjustment, the quota is actually controlled by privileged user. How about your opinion? Regards, Yi Liu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu