From: Sean Christopherson <seanjc@google.com>
To: Alexey Kardashevskiy <aik@amd.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Jason Gunthorpe <jgg@ziepe.ca>,
Kevin Tian <kevin.tian@intel.com>, Joerg Roedel <joro@8bytes.org>,
Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Steve Sistare <steven.sistare@oracle.com>,
Nicolin Chen <nicolinc@nvidia.com>,
iommu@lists.linux.dev, linux-coco@lists.linux.dev,
Dan Williams <dan.j.williams@intel.com>,
Santosh Shukla <santosh.shukla@amd.com>,
"Pratik R . Sampat" <prsampat@amd.com>,
Ackerley Tng <ackerleytng@google.com>,
Fuad Tabba <tabba@google.com>,
Xu Yilun <yilun.xu@linux.intel.com>,
"Aneesh Kumar K . V" <aneesh.kumar@kernel.org>
Subject: Re: [RFC PATCH kernel] iommufd: Allow mapping from KVM's guest_memfd
Date: Wed, 25 Feb 2026 05:55:22 -0800 [thread overview]
Message-ID: <aZ7-tTpobKiCFT5L@google.com> (raw)
In-Reply-To: <20260225075211.3353194-1-aik@amd.com>
On Wed, Feb 25, 2026, Alexey Kardashevskiy wrote:
> For the new guest_memfd type, no additional reference is taken as
> pinning is guaranteed by the KVM guest_memfd library.
>
> There is no KVM-GMEMFD->IOMMUFD direct notification mechanism as
> the assumption is that:
> 1) page stage change events will be handled by VMM which is going
> to call IOMMUFD to remap pages;
> 2) shrinking GMEMFD equals to VM memory unplug and VMM is going to
> handle it.
The VMM is outside of the kernel's effective TCB. Assuming the VMM will always
do the right thing is a non-starter.
next prev parent reply other threads:[~2026-02-25 13:55 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-25 7:52 [RFC PATCH kernel] iommufd: Allow mapping from KVM's guest_memfd Alexey Kardashevskiy
2026-02-25 13:55 ` Sean Christopherson [this message]
2026-02-26 6:47 ` Alexey Kardashevskiy
2026-02-26 19:27 ` Jason Gunthorpe
2026-02-27 11:03 ` Xu Yilun
2026-02-26 8:19 ` Ackerley Tng
2026-02-26 19:07 ` Jason Gunthorpe
2026-02-26 22:40 ` Sean Christopherson
2026-02-27 0:21 ` Jason Gunthorpe
2026-02-27 0:28 ` Sean Christopherson
2026-02-27 1:09 ` Jason Gunthorpe
2026-02-27 10:35 ` Xu Yilun
2026-02-27 13:18 ` Jason Gunthorpe
2026-02-28 4:14 ` Xu Yilun
2026-02-28 18:29 ` Jason Gunthorpe
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