From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
Oliver O'Halloran <oohall@gmail.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Robin Murphy <robin.murphy@arm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
"Rodel, Jorg" <jroedel@suse.de>, Joel Stanley <joel@jms.id.au>,
Alex Williamson <alex.williamson@redhat.com>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Daniel Henrique Barboza <danielhb413@gmail.com>,
Fabiano Rosas <farosas@linux.ibm.com>,
Murilo Opsfelder Araujo <muriloo@linux.ibm.com>,
Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH kernel] powerpc/iommu: Add iommu_ops to report capabilities and allow blocking domains
Date: Fri, 29 Jul 2022 12:09:09 +0000 [thread overview]
Message-ID: <YuPN5dJUPezitwn2@nvidia.com> (raw)
In-Reply-To: <BN9PR11MB52766CDF5C0A96DF0575AADE8C999@BN9PR11MB5276.namprd11.prod.outlook.com>
On Fri, Jul 29, 2022 at 04:24:36AM +0000, Tian, Kevin wrote:
> > It is a POWER specific thing with one not-so-obvious consequence of each
> > window having an independent page size (fixed at the moment or creation)
> > and (most likely) different page size, like, 4K vs. 2M.
>
> page size is anyway decided by the iommu driver. Same for other vendors.
> the caller (e.g. vfio) just tries to map as many contiguous pages as
> possible but in the end it's iommu driver to decide the actual size.
An iommu_domain with a non-uniform page_size is weird, but it could be
made to work as some device-specific thing. The only thing the core
codes care about is the minimum alignment, so you'd just have to set
it to 4k and mapping the wrong thing to the 2M area would fail.
domains with their io page size != PAGE_SIZE are already very special
things that require special handling by userspace..
Jason
next prev parent reply other threads:[~2022-07-29 12:09 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-07 13:55 [PATCH kernel] powerpc/iommu: Add iommu_ops to report capabilities and allow blocking domains Alexey Kardashevskiy
2022-07-07 15:10 ` Jason Gunthorpe
2022-07-08 4:58 ` Alexey Kardashevskiy
2022-07-08 6:34 ` Alexey Kardashevskiy
2022-07-08 7:32 ` Tian, Kevin
2022-07-08 9:45 ` Alexey Kardashevskiy
2022-07-08 10:18 ` Tian, Kevin
2022-07-29 2:21 ` Alexey Kardashevskiy
2022-07-29 2:53 ` Oliver O'Halloran
2022-07-29 3:10 ` Tian, Kevin
2022-07-29 3:50 ` Alexey Kardashevskiy
2022-07-29 4:24 ` Tian, Kevin
2022-07-29 12:09 ` Jason Gunthorpe [this message]
2022-07-08 11:55 ` Jason Gunthorpe
2022-07-08 13:10 ` Alexey Kardashevskiy
2022-07-08 13:19 ` Jason Gunthorpe
2022-07-08 13:32 ` Alexey Kardashevskiy
2022-07-08 13:59 ` Jason Gunthorpe
2022-07-09 2:58 ` Alexey Kardashevskiy
2022-07-10 6:29 ` Jason Gunthorpe
2022-07-10 12:32 ` Alexey Kardashevskiy
2022-07-11 13:24 ` Alexey Kardashevskiy
2022-07-11 18:46 ` Jason Gunthorpe
2022-07-12 2:27 ` Alexey Kardashevskiy
2022-07-12 5:44 ` Jason Gunthorpe
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