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From: "Tian, Kevin" <kevin.tian@intel.com>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>,
	Lu Baolu <baolu.lu@linux.intel.com>
Cc: "Raj, Ashok" <ashok.raj@intel.com>,
	David Woodhouse <dwmw2@infradead.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	Jonathan Cameron <jic23@kernel.org>
Subject: RE: [PATCH v7 03/11] iommu/vt-d: Add custom allocator for IOASID
Date: Fri, 25 Oct 2019 06:40:09 +0000
Message-ID: <AADFC41AFE54684AB9EE6CBC0274A5D19D5CDC60@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <20191024214311.43d76a5c@jacob-builder>

> From: Jacob Pan [mailto:jacob.jun.pan@linux.intel.com]
> Sent: Friday, October 25, 2019 12:43 PM
> 
> Hi Baolu,
> 
> Thanks for the review. please see my comments inline.
> 
> On Fri, 25 Oct 2019 10:30:48 +0800
> Lu Baolu <baolu.lu@linux.intel.com> wrote:
> 
> > Hi Jacob,
> >
> > On 10/25/19 3:54 AM, Jacob Pan wrote:
> > > When VT-d driver runs in the guest, PASID allocation must be
> > > performed via virtual command interface. This patch registers a
> > > custom IOASID allocator which takes precedence over the default
> > > XArray based allocator. The resulting IOASID allocation will always
> > > come from the host. This ensures that PASID namespace is system-
> > > wide.
> > >
> > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> > > Signed-off-by: Liu, Yi L <yi.l.liu@intel.com>
> > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > > ---
> > >   drivers/iommu/Kconfig       |  1 +
> > >   drivers/iommu/intel-iommu.c | 67
> > > +++++++++++++++++++++++++++++++++++++++++++++
> > > include/linux/intel-iommu.h |  2 ++ 3 files changed, 70
> > > insertions(+)
> > >
> > > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> > > index fd50ddffffbf..961fe5795a90 100644
> > > --- a/drivers/iommu/Kconfig
> > > +++ b/drivers/iommu/Kconfig
> > > @@ -211,6 +211,7 @@ config INTEL_IOMMU_SVM
> > >   	bool "Support for Shared Virtual Memory with Intel IOMMU"
> > >   	depends on INTEL_IOMMU && X86
> > >   	select PCI_PASID
> > > +	select IOASID
> > >   	select MMU_NOTIFIER
> > >   	help
> > >   	  Shared Virtual Memory (SVM) provides a facility for
> > > devices diff --git a/drivers/iommu/intel-iommu.c
> > > b/drivers/iommu/intel-iommu.c index 3f974919d3bd..ced1d89ef977
> > > 100644 --- a/drivers/iommu/intel-iommu.c
> > > +++ b/drivers/iommu/intel-iommu.c
> > > @@ -1706,6 +1706,9 @@ static void free_dmar_iommu(struct
> > > intel_iommu *iommu) if (ecap_prs(iommu->ecap))
> > >   			intel_svm_finish_prq(iommu);
> > >   	}
> > > +	if (ecap_vcs(iommu->ecap) && vccap_pasid(iommu->vccap))
> > > +
> > > ioasid_unregister_allocator(&iommu->pasid_allocator);
> >
> > Since scalable mode is disabled if pasid allocator failed to register,
> > add sm_support(iommu) check here will be better.
> >
> I was thinking to be symmetric with register call, checking for the
> same conditions. Also, I like your advice below to only disable SVA
> instead of scalable mode.
> > > +
> > >   #endif
> > >   }
> > >
> > > @@ -4910,6 +4913,44 @@ static int __init
> > > probe_acpi_namespace_devices(void) return 0;
> > >   }
> > >
> > > +#ifdef CONFIG_INTEL_IOMMU_SVM
> > > +static ioasid_t intel_ioasid_alloc(ioasid_t min, ioasid_t max,
> > > void *data) +{
> > > +	struct intel_iommu *iommu = data;
> > > +	ioasid_t ioasid;
> > > +
> > > +	/*
> > > +	 * VT-d virtual command interface always uses the full 20
> > > bit
> > > +	 * PASID range. Host can partition guest PASID range based
> > > on
> > > +	 * policies but it is out of guest's control.
> > > +	 */
> > > +	if (min < PASID_MIN || max > intel_pasid_max_id)
> > > +		return INVALID_IOASID;
> > > +
> > > +	if (vcmd_alloc_pasid(iommu, &ioasid))
> > > +		return INVALID_IOASID;
> > > +
> > > +	return ioasid;
> > > +}
> > > +
> > > +static void intel_ioasid_free(ioasid_t ioasid, void *data)
> > > +{
> > > +	struct intel_iommu *iommu = data;
> > > +
> > > +	if (!iommu)
> > > +		return;
> > > +	/*
> > > +	 * Sanity check the ioasid owner is done at upper layer,
> > > e.g. VFIO
> > > +	 * We can only free the PASID when all the devices are
> > > unbond.
> > > +	 */
> > > +	if (ioasid_find(NULL, ioasid, NULL)) {
> > > +		pr_alert("Cannot free active IOASID %d\n", ioasid);
> > > +		return;
> > > +	}
> > > +	vcmd_free_pasid(iommu, ioasid);
> > > +}
> > > +#endif
> > > +
> > >   int __init intel_iommu_init(void)
> > >   {
> > >   	int ret = -ENODEV;
> > > @@ -5020,6 +5061,32 @@ int __init intel_iommu_init(void)
> > >   				       "%s", iommu->name);
> > >   		iommu_device_set_ops(&iommu->iommu,
> > > &intel_iommu_ops); iommu_device_register(&iommu->iommu);
> > > +#ifdef CONFIG_INTEL_IOMMU_SVM
> > > +		if (ecap_vcs(iommu->ecap) &&
> > > vccap_pasid(iommu->vccap)) {
> > > +			pr_info("Register custom PASID
> > > allocator\n");
> > > +			/*
> > > +			 * Register a custom ASID allocator if we
> > > are running
> > > +			 * in a guest, the purpose is to have a
> > > system wide PASID
> > > +			 * namespace among all PASID users.
> > > +			 * There can be multiple vIOMMUs in each
> > > guest but only
> > > +			 * one allocator is active. All vIOMMU
> > > allocators will
> > > +			 * eventually be calling the same host
> > > allocator.
> > > +			 */
> > > +			iommu->pasid_allocator.alloc =
> > > intel_ioasid_alloc;
> > > +			iommu->pasid_allocator.free =
> > > intel_ioasid_free;
> > > +			iommu->pasid_allocator.pdata = (void
> > > *)iommu;
> > > +			ret =
> > > ioasid_register_allocator(&iommu->pasid_allocator);
> > > +			if (ret) {
> > > +				pr_warn("Custom PASID allocator
> > > registeration failed\n");
> > > +				/*
> > > +				 * Disable scalable mode on this
> > > IOMMU if there
> > > +				 * is no custom allocator. Mixing
> > > SM capable vIOMMU
> > > +				 * and non-SM vIOMMU are not
> > > supported.
> > > +				 */
> > > +				intel_iommu_sm = 0;
> >
> > It's insufficient to disable scalable mode by only clearing
> > intel_iommu_sm. The DMA_RTADDR_SMT bit in root entry has already
> been
> > set. Probably, you need to
> >
> > for each iommu
> > 	clear DMA_RTADDR_SMT in root entry
> >
> > Alternatively, since vSVA is the only customer of this custom PASID
> > allocator, is it possible to only disable SVA here?
> >
> Yeah, I think disable SVA is better. We can still do gIOVA in SM. I
> guess we need to introduce a flag for sva_enabled.

I'm not sure whether tying above logic to SVA is the right approach.
If vcmd interface doesn't work, the whole SM mode doesn't make
sense which is based on PASID-granular protection (SVA is only one
usage atop). If the only remaining usage of SM is to map gIOVA using 
reserved PASID#0, then why not disabling SM and just fallback to 
legacy mode?

Based on that I prefer to disabling the SM mode completely (better
through an interface), and move the logic out of CONFIG_INTEL_
IOMMU_SVM


> > > +			}
> > > +		}
> > > +#endif
> > >   	}
> > >
> > >   	bus_set_iommu(&pci_bus_type, &intel_iommu_ops);
> > > diff --git a/include/linux/intel-iommu.h
> > > b/include/linux/intel-iommu.h index 1d4b8dcdc5d8..c624733cb2e6
> > > 100644 --- a/include/linux/intel-iommu.h
> > > +++ b/include/linux/intel-iommu.h
> > > @@ -19,6 +19,7 @@
> > >   #include <linux/iommu.h>
> > >   #include <linux/io-64-nonatomic-lo-hi.h>
> > >   #include <linux/dmar.h>
> > > +#include <linux/ioasid.h>
> > >
> > >   #include <asm/cacheflush.h>
> > >   #include <asm/iommu.h>
> > > @@ -546,6 +547,7 @@ struct intel_iommu {
> > >   #ifdef CONFIG_INTEL_IOMMU_SVM
> > >   	struct page_req_dsc *prq;
> > >   	unsigned char prq_name[16];    /* Name for PRQ interrupt
> > > */
> > > +	struct ioasid_allocator_ops pasid_allocator; /* Custom
> > > allocator for PASIDs */ #endif
> > >   	struct q_inval  *qi;            /* Queued invalidation
> > > info */ u32 *iommu_state; /* Store iommu states between suspend and
> > > resume.*/
> >
> > Best regards,
> > baolu
> 
> [Jacob Pan]
_______________________________________________
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  reply index

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-24 19:54 [PATCH v7 00/11] Nested Shared Virtual Address (SVA) VT-d support Jacob Pan
2019-10-24 19:54 ` [PATCH v7 01/11] iommu/vt-d: Cache virtual command capability register Jacob Pan
2019-10-25  2:53   ` Lu Baolu
2019-10-25  6:06   ` Tian, Kevin
2019-11-08 10:32   ` Auger Eric
2019-10-24 19:54 ` [PATCH v7 02/11] iommu/vt-d: Enlightened PASID allocation Jacob Pan
2019-10-25  6:19   ` Tian, Kevin
2019-10-29 17:14     ` Jacob Pan
2019-10-29 18:16       ` Tian, Kevin
2019-11-08 10:33   ` Auger Eric
2019-11-08 22:22     ` Jacob Pan
2019-10-24 19:54 ` [PATCH v7 03/11] iommu/vt-d: Add custom allocator for IOASID Jacob Pan
2019-10-25  2:30   ` Lu Baolu
2019-10-25  4:43     ` Jacob Pan
2019-10-25  6:40       ` Tian, Kevin [this message]
2019-10-25 14:39         ` Lu Baolu
2019-10-25 15:52           ` Tian, Kevin
2019-10-28 22:49             ` Jacob Pan
2019-10-29  2:22               ` Lu Baolu
2019-10-25  6:31   ` Tian, Kevin
2019-10-28 22:52     ` Jacob Pan
2019-11-08 10:40   ` Auger Eric
2019-11-08 22:26     ` Jacob Pan
2019-10-24 19:54 ` [PATCH v7 04/11] iommu/vt-d: Replace Intel specific PASID allocator with IOASID Jacob Pan
2019-10-25  5:47   ` Lu Baolu
2019-11-01 18:29     ` Jacob Pan
2019-10-25  6:41   ` Tian, Kevin
2019-10-28 22:46     ` Jacob Pan
2019-11-08 11:30   ` Auger Eric
2019-11-08 22:55     ` Jacob Pan
2019-11-12  9:54       ` Auger Eric
2019-10-24 19:54 ` [PATCH v7 05/11] iommu/vt-d: Move domain helper to header Jacob Pan
2019-10-25  5:26   ` Lu Baolu
2019-10-24 19:54 ` [PATCH v7 06/11] iommu/vt-d: Avoid duplicated code for PASID setup Jacob Pan
2019-10-25  5:32   ` Lu Baolu
2019-10-25  6:42   ` Tian, Kevin
2019-10-28 22:41     ` Jacob Pan
2019-11-12  9:54   ` Auger Eric
2019-10-24 19:55 ` [PATCH v7 07/11] iommu/vt-d: Add nested translation helper function Jacob Pan
2019-10-25  7:04   ` Tian, Kevin
2019-11-01 21:10     ` Jacob Pan
2019-10-25 15:04   ` Lu Baolu
2019-10-25 16:06     ` Jacob Pan
2019-11-08 13:55   ` Auger Eric
2019-10-24 19:55 ` [PATCH v7 08/11] iommu/vt-d: Misc macro clean up for SVM Jacob Pan
2019-10-26  1:00   ` Lu Baolu
2019-10-28 22:38     ` Jacob Pan
2019-10-24 19:55 ` [PATCH v7 09/11] iommu/vt-d: Add bind guest PASID support Jacob Pan
2019-10-25  7:19   ` Tian, Kevin
2019-10-25 17:33     ` Jacob Pan
2019-10-28  6:03       ` Tian, Kevin
2019-10-28 16:02         ` Jacob Pan
2019-10-29  7:57           ` Tian, Kevin
2019-10-29 16:11             ` Jacob Pan
2019-10-29 18:04               ` Tian, Kevin
2019-10-29  2:33         ` Lu Baolu
2019-10-26  2:01   ` Lu Baolu
2019-10-28 22:29     ` Jacob Pan
2019-10-29  2:54       ` Lu Baolu
2019-10-29  4:11         ` Jacob Pan
2019-10-29  5:04           ` Lu Baolu
2019-10-24 19:55 ` [PATCH v7 10/11] iommu/vt-d: Support flushing more translation cache types Jacob Pan
2019-10-25  7:21   ` Tian, Kevin
2019-11-01 21:30     ` Jacob Pan
2019-10-26  2:22   ` Lu Baolu
2019-11-01 21:28     ` Jacob Pan
2019-11-08 16:18   ` Auger Eric
2019-11-08 23:05     ` Jacob Pan
2019-10-24 19:55 ` [PATCH v7 11/11] iommu/vt-d: Add svm/sva invalidate function Jacob Pan
2019-10-25  7:27   ` Tian, Kevin
2019-10-26  2:40     ` Lu Baolu
2019-10-26  7:03       ` Lu Baolu
2019-10-28  6:06         ` Tian, Kevin
2019-10-28 16:10           ` Jacob Pan
2019-10-29 18:52             ` Tian, Kevin
2019-10-29 19:25               ` Jacob Pan
2019-10-28 16:13     ` Jacob Pan
2019-11-12 10:28   ` Auger Eric

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