From: Xu Yilun <yilun.xu@linux.intel.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Sean Christopherson <seanjc@google.com>,
Ackerley Tng <ackerleytng@google.com>,
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Subject: Re: [RFC PATCH v1 05/37] KVM: guest_memfd: Wire up kvm_get_memory_attributes() to per-gmem attributes
Date: Thu, 5 Feb 2026 15:04:48 +0800 [thread overview]
Message-ID: <aYRBEJSan8eoT8xw@yilunxu-OptiPlex-7050> (raw)
In-Reply-To: <20260204124715.GA2328995@ziepe.ca>
On Wed, Feb 04, 2026 at 08:47:15AM -0400, Jason Gunthorpe wrote:
> On Wed, Feb 04, 2026 at 12:43:16PM +0800, Xu Yilun wrote:
> > > Which means we need VFIO to know what they are, and hopefully it is
> > > just static based on the TDISP reports..
> >
> > I don't think VMM need to check TDISP report. The only special thing is
> > the MSI-X mixed pages which can be figured out by standard PCI
> > discovery.
>
> Either that or follow along with the guests's choices on
> shared/private.
>
> We can't let VFIO mmap a private MMIO page, so it has to know which
> pages are private at any moment, and it can't guess.
No we could only let VFIO mmap MMIO pages that need emulation (like this
MSI-X mixed page). MMIOs in such page cannot be assigned to guest so no
way to convert to private.
We don't allow VFIO mmap all asigned MMIO pages, no matter they will be
private or shared. They are assigned to guest, so host don't touch them.
Does that make sense?
>
> Jason
next prev parent reply other threads:[~2026-02-05 7:23 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-17 20:11 [RFC PATCH v1 00/37] guest_memfd: In-place conversion support Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 01/37] KVM: guest_memfd: Introduce per-gmem attributes, use to guard user mappings Ackerley Tng
2025-10-27 13:27 ` Vlastimil Babka
2025-11-12 8:58 ` Binbin Wu
2026-01-28 17:07 ` Ackerley Tng
2026-01-19 7:58 ` Yan Zhao
2026-01-28 17:50 ` Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 02/37] KVM: Rename KVM_GENERIC_MEMORY_ATTRIBUTES to KVM_VM_MEMORY_ATTRIBUTES Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 03/37] KVM: Enumerate support for PRIVATE memory iff kvm_arch_has_private_mem is defined Ackerley Tng
2025-11-13 1:42 ` Binbin Wu
2025-10-17 20:11 ` [RFC PATCH v1 04/37] KVM: Stub in ability to disable per-VM memory attribute tracking Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 05/37] KVM: guest_memfd: Wire up kvm_get_memory_attributes() to per-gmem attributes Ackerley Tng
2026-01-15 11:08 ` Alexey Kardashevskiy
2026-01-28 21:47 ` Ackerley Tng
2026-01-29 0:37 ` Jason Gunthorpe
2026-01-29 1:03 ` Sean Christopherson
2026-01-29 1:16 ` Jason Gunthorpe
2026-01-29 11:10 ` Quentin Perret
2026-01-29 13:42 ` Jason Gunthorpe
2026-01-29 14:36 ` Quentin Perret
2026-02-03 1:07 ` Alexey Kardashevskiy
2026-02-03 18:13 ` Jason Gunthorpe
2026-02-03 9:56 ` Xu Yilun
2026-02-03 18:16 ` Jason Gunthorpe
2026-02-04 4:43 ` Xu Yilun
2026-02-04 12:47 ` Jason Gunthorpe
2026-02-05 7:04 ` Xu Yilun [this message]
2025-10-17 20:11 ` [RFC PATCH v1 06/37] KVM: guest_memfd: Update kvm_gmem_populate() to use gmem attributes Ackerley Tng
2025-11-10 10:01 ` Yan Zhao
2025-11-15 0:52 ` Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 07/37] KVM: Introduce KVM_SET_MEMORY_ATTRIBUTES2 Ackerley Tng
2025-10-22 15:21 ` Steven Price
2025-10-22 16:51 ` Ackerley Tng
2025-10-22 22:45 ` Ackerley Tng
2025-10-22 23:30 ` Sean Christopherson
2025-10-23 14:01 ` Ackerley Tng
2025-10-23 15:05 ` Sean Christopherson
2025-10-24 14:36 ` Ackerley Tng
2025-10-24 15:11 ` Sean Christopherson
2025-10-24 16:41 ` Ackerley Tng
2025-10-24 17:45 ` Sean Christopherson
2025-10-27 12:48 ` Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 08/37] KVM: guest_memfd: Don't set FGP_ACCESSED when getting folios Ackerley Tng
2025-10-27 13:39 ` Vlastimil Babka
2025-10-17 20:11 ` [RFC PATCH v1 09/37] KVM: guest_memfd: Skip LRU for guest_memfd folios Ackerley Tng
2025-10-27 13:56 ` Vlastimil Babka
2026-01-27 23:46 ` Ackerley Tng
2026-01-20 2:15 ` Yan Zhao
2025-10-17 20:11 ` [RFC PATCH v1 10/37] KVM: guest_memfd: Enable INIT_SHARED on guest_memfd for x86 Coco VMs Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 11/37] KVM: guest_memfd: Add support for KVM_SET_MEMORY_ATTRIBUTES Ackerley Tng
2025-11-04 9:25 ` Yan Zhao
2025-11-04 15:29 ` Vishal Annapurve
2025-11-15 0:46 ` Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 12/37] KVM: Move KVM_VM_MEMORY_ATTRIBUTES config definition to x86 Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 13/37] KVM: Let userspace disable per-VM mem attributes, enable per-gmem attributes Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 14/37] KVM: selftests: Create gmem fd before "regular" fd when adding memslot Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 15/37] KVM: selftests: Rename guest_memfd{,_offset} to gmem_{fd,offset} Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 16/37] KVM: selftests: Add support for mmap() on guest_memfd in core library Ackerley Tng
2025-10-24 16:48 ` Ackerley Tng
2025-10-24 18:18 ` Sean Christopherson
2025-10-27 12:51 ` Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 17/37] KVM: selftests: Update framework to use KVM_SET_MEMORY_ATTRIBUTES2 Ackerley Tng
2025-10-17 20:11 ` [RFC PATCH v1 18/37] KVM: selftests: Add helpers for calling ioctls on guest_memfd Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 19/37] KVM: selftests: guest_memfd: Test basic single-page conversion flow Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 20/37] KVM: selftests: guest_memfd: Test conversion flow when INIT_SHARED Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 21/37] KVM: selftests: guest_memfd: Test indexing in guest_memfd Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 22/37] KVM: selftests: guest_memfd: Test conversion before allocation Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 23/37] KVM: selftests: guest_memfd: Convert with allocated folios in different layouts Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 24/37] KVM: selftests: guest_memfd: Test precision of conversion Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 25/37] KVM: selftests: guest_memfd: Test that truncation does not change shared/private status Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 26/37] KVM: selftests: guest_memfd: Test that shared/private status is consistent across processes Ackerley Tng
2025-10-17 23:33 ` Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 27/37] KVM: selftests: guest_memfd: Test conversion with elevated page refcount Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 28/37] KVM: selftests: Reset shared memory after hole-punching Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 29/37] KVM: selftests: Add selftests global for guest memory attributes capability Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 30/37] KVM: selftests: Provide function to look up guest_memfd details from gpa Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 31/37] KVM: selftests: Provide common function to set memory attributes Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 32/37] KVM: selftests: Check fd/flags provided to mmap() when setting up memslot Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 33/37] KVM: selftests: Make TEST_EXPECT_SIGBUS thread-safe Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 34/37] KVM: selftests: Update private_mem_conversions_test to mmap() guest_memfd Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 35/37] KVM: selftests: Add script to exercise private_mem_conversions_test Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 36/37] KVM: selftests: Update pre-fault test to work with per-guest_memfd attributes Ackerley Tng
2025-10-17 20:12 ` [RFC PATCH v1 37/37] KVM: selftests: Update private memory exits test work with per-gmem attributes Ackerley Tng
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