From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Nicolin Chen <nicolinc@nvidia.com>,
"will@kernel.org" <will@kernel.org>,
"robin.murphy@arm.com" <robin.murphy@arm.com>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"joro@8bytes.org" <joro@8bytes.org>,
"praan@google.com" <praan@google.com>,
"baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>,
"miko.lenczewski@arm.com" <miko.lenczewski@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"Williams, Dan J" <dan.j.williams@intel.com>,
"jonathan.cameron@huawei.com" <jonathan.cameron@huawei.com>,
Vikram Sethi <vsethi@nvidia.com>,
"linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>
Subject: Re: [PATCH v3 1/3] PCI: Allow ATS to be always on for CXL.cache capable devices
Date: Fri, 10 Apr 2026 09:05:08 -0300 [thread overview]
Message-ID: <20260410120508.GA2588311@nvidia.com> (raw)
In-Reply-To: <BL1PR11MB527184E183703E14F6C861118C592@BL1PR11MB5271.namprd11.prod.outlook.com>
On Fri, Apr 10, 2026 at 03:13:59AM +0000, Tian, Kevin wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Friday, April 10, 2026 6:53 AM
> >
> > On Thu, Apr 09, 2026 at 03:45:26PM -0700, Nicolin Chen wrote:
> >
> > > One question regarding VM case: if a device is ats_always_on, while
> > > VM somehow doesn't set nested_domain->enable_ats. Should the kernel
> > > at least spit a warning, given that it would surely fail the device?
> >
> > No, just let break, the resulting failure has to be contained to the
> > VM or the platform is broken..
> >
> > The HV can't turn on ATS because we it can't know what invalidations
> > to push so not much other choice.
> >
>
> Taking about in theory - host can append a devtlb invalidation cmd
> after iotlb invalidation (if vcmdq is not used)?
It can't map an ASID to a BDF without shadowing all the STE and CD
tables which we don't do for nesting.
Jason
next prev parent reply other threads:[~2026-04-10 12:05 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-06 23:41 [PATCH v3 0/3] Allow ATS to be always on for certain ATS-capable devices Nicolin Chen
2026-03-06 23:41 ` [PATCH v3 1/3] PCI: Allow ATS to be always on for CXL.cache capable devices Nicolin Chen
2026-03-08 20:49 ` Nirmoy Das
2026-03-08 20:53 ` Nirmoy Das
2026-03-09 11:48 ` Jonathan Cameron
2026-03-26 21:38 ` Bjorn Helgaas
2026-03-26 21:51 ` Jason Gunthorpe
2026-03-30 12:48 ` Jason Gunthorpe
2026-03-31 8:19 ` Tian, Kevin
2026-04-09 22:45 ` Nicolin Chen
2026-04-09 22:52 ` Jason Gunthorpe
2026-04-10 0:04 ` Nicolin Chen
2026-04-10 3:13 ` Tian, Kevin
2026-04-10 12:05 ` Jason Gunthorpe [this message]
2026-03-06 23:41 ` [PATCH v3 2/3] PCI: Allow ATS to be always on for pre-CXL devices Nicolin Chen
2026-03-08 20:50 ` Nirmoy Das
2026-03-08 20:54 ` Nirmoy Das
2026-03-09 11:50 ` Jonathan Cameron
2026-03-30 12:49 ` Jason Gunthorpe
2026-03-31 8:24 ` Tian, Kevin
2026-03-06 23:41 ` [PATCH v3 3/3] iommu/arm-smmu-v3: Allow ATS to be always on Nicolin Chen
2026-03-08 20:52 ` Nirmoy Das
2026-03-30 12:51 ` Jason Gunthorpe
2026-03-31 8:40 ` Tian, Kevin
2026-03-31 12:08 ` Jason Gunthorpe
2026-04-01 8:15 ` Tian, Kevin
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