linux-kernel - Re: [RFC PATCH 11/42] iommu: Add new domain op cache_invalidate

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20231205145227.GD2787277@nvidia.com>
Date:   Tue, 5 Dec 2023 10:52:27 -0400
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Yan Zhao <yan.y.zhao@...el.com>
Cc:     iommu@...ts.linux.dev, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, alex.williamson@...hat.com,
        pbonzini@...hat.com, seanjc@...gle.com, joro@...tes.org,
        will@...nel.org, robin.murphy@....com, kevin.tian@...el.com,
        baolu.lu@...ux.intel.com, dwmw2@...radead.org, yi.l.liu@...el.com
Subject: Re: [RFC PATCH 11/42] iommu: Add new domain op cache_invalidate_kvm

On Tue, Dec 05, 2023 at 02:40:28PM +0800, Yan Zhao wrote:
> On Mon, Dec 04, 2023 at 11:09:45AM -0400, Jason Gunthorpe wrote:
> > On Sat, Dec 02, 2023 at 05:20:41PM +0800, Yan Zhao wrote:
> > > On KVM invalidates mappings that are shared to IOMMU stage 2 paging
> > > structures, IOMMU driver needs to invalidate hardware TLBs accordingly.
> > > 
> > > The new op cache_invalidate_kvm is called from IOMMUFD to invalidate
> > > hardware TLBs upon receiving invalidation notifications from KVM.
> > 
> > Why?
> > 
> > SVA hooks the invalidation directly to the mm, shouldn't KVM also hook
> > the invalidation directly from the kvm? Why do we need to call a chain
> > of function pointers? iommufd isn't adding any value in the chain
> > here.
> Do you prefer IOMMU vendor driver to register as importer to KVM directly?
> Then IOMMUFD just passes "struct kvm_tdp_fd" to IOMMU vendor driver for domain
> creation.

Yes, this is what we did for SVA

Function pointers are slow these days, so it is preferred to go
directly.

Jason