Re: [PATCH v8 13/46] KVM: guest_memfd: Add base support for KVM_SET_MEMORY_ATTRIBUTES2

Binbin Wu [off-list ref] writes:

On 6/19/2026 8:31 AM, Ackerley Tng via B4 Relay wrote:

quoted

From: Ackerley Tng <redacted>

Introduce base support for KVM_SET_MEMORY_ATTRIBUTES2 in guest_memfd, which
just updates attributes tracked by guest_memfd.

Validate input fields in general. Guard usage of KVM_SET_MEMORY_ATTRIBUTES2
by making sure requested attributes are supported for this instance of kvm.

A new KVM_SET_MEMORY_ATTRIBUTES2 is defined to support writes (unlike
KVM_SET_MEMORY_ATTRIBUTES) in addition to reads so it can provide error
details to userspace. This will be used in a later patch.

The two ioctls use their corresponding structs with no overlap, but
backward compatibility is baked in for future support of
KVM_SET_MEMORY_ATTRIBUTES2 and struct kvm_memory_attributes2 in the VM
ioctl.

The process of setting memory attributes is set up such that the later half
will not fail due to allocation. Any necessary checks are performed before
the point of no return.

Co-developed-by: Vishal Annapurve <redacted>
Signed-off-by: Vishal Annapurve <redacted>
Co-developed-by: Sean Christoperson <seanjc@google.com>
Signed-off-by: Sean Christoperson <seanjc@google.com>

s/Christoperson /Christopherson

Thanks!

quoted

Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Ackerley Tng <redacted>
---
 include/uapi/linux/kvm.h |  13 ++++++
 virt/kvm/Kconfig         |   1 +
 virt/kvm/guest_memfd.c   | 116 +++++++++++++++++++++++++++++++++++++++++++++++
 virt/kvm/kvm_main.c      |  12 +++++
 4 files changed, 142 insertions(+)

[...]

quoted

diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 297e4399fbd49..cfa2c78ba5fb9 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig

@@ -102,6 +102,7 @@ config KVM_MMU_LOCKLESS_AGING

 config KVM_GUEST_MEMFD
        select XARRAY_MULTI
+       select KVM_MEMORY_ATTRIBUTES

What's this?
This config is gone.

I'm surprised this compiles... I'll fix it, thanks!

quoted

        bool