From: Fuad Tabba <tabba@google.com>
To: Ackerley Tng <ackerleytng@google.com>
Cc: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-mm@kvack.org, pbonzini@redhat.com, chenhuacai@kernel.org,
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Subject: Re: [RFC PATCH v2 04/10] KVM: Add KVM capability to check if guest_memfd can be mapped by the host
Date: Mon, 5 Aug 2024 19:12:24 +0100 [thread overview]
Message-ID: <CA+EHjTwHXVxV_Y8Ckr6UkV9JE2ywcHddD3Q967QcDx6soxsR7A@mail.gmail.com> (raw)
In-Reply-To: <diqza5hqevle.fsf@ackerleytng-ctop.c.googlers.com>
Hi Ackerley,
On Mon, 5 Aug 2024 at 18:19, Ackerley Tng <ackerleytng@google.com> wrote:
>
> Fuad Tabba <tabba@google.com> writes:
>
> > Add the KVM capability KVM_CAP_GUEST_MEMFD_MAPPABLE, which is
> > true if mapping guest memory is supported by the host.
> >
> > Signed-off-by: Fuad Tabba <tabba@google.com>
> > ---
> > include/uapi/linux/kvm.h | 3 ++-
> > virt/kvm/kvm_main.c | 4 ++++
> > 2 files changed, 6 insertions(+), 1 deletion(-)
> >
> > <snip>
>
> Why do we need a cap for `KVM_CAP_GUEST_MEMFD_MAPPABLE` instead of just
> making guest_memfd mmap-able?
>
> Is this to prevent breaking userspace, because a user might be relying
> on guest_memfd being not mmap-able?
To be able to check that the ability is there, since it is a new
capability not available in Linux 6.9 not 6.10 (i.e., after
guest_memfd()) was introduced.
Cheers,
/fuad
next prev parent reply other threads:[~2024-08-05 18:13 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-01 9:01 [RFC PATCH v2 00/10] KVM: Restricted mapping of guest_memfd at the host and pKVM/arm64 support Fuad Tabba
2024-08-01 9:01 ` [RFC PATCH v2 01/10] KVM: Introduce kvm_gmem_get_pfn_locked(), which retains the folio lock Fuad Tabba
2024-08-01 9:01 ` [RFC PATCH v2 02/10] KVM: Add restricted support for mapping guestmem by the host Fuad Tabba
2024-08-05 17:14 ` Ackerley Tng
2024-08-05 18:08 ` Fuad Tabba
2024-08-01 9:01 ` [RFC PATCH v2 03/10] KVM: Implement kvm_(read|/write)_guest_page for private memory slots Fuad Tabba
2024-08-16 19:32 ` Sean Christopherson
2024-09-03 9:28 ` Fuad Tabba
2024-08-01 9:01 ` [RFC PATCH v2 04/10] KVM: Add KVM capability to check if guest_memfd can be mapped by the host Fuad Tabba
2024-08-05 17:19 ` Ackerley Tng
2024-08-05 18:12 ` Fuad Tabba [this message]
2024-08-01 9:01 ` [RFC PATCH v2 05/10] KVM: selftests: guest_memfd mmap() test when mapping is allowed Fuad Tabba
2024-08-01 9:01 ` [RFC PATCH v2 06/10] KVM: arm64: Skip VMA checks for slots without userspace address Fuad Tabba
2024-08-01 9:01 ` [RFC PATCH v2 07/10] KVM: arm64: Do not allow changes to private memory slots Fuad Tabba
2024-08-01 9:01 ` [RFC PATCH v2 08/10] KVM: arm64: Handle guest_memfd()-backed guest page faults Fuad Tabba
2024-08-01 9:01 ` [RFC PATCH v2 09/10] KVM: arm64: arm64 has private memory support when config is enabled Fuad Tabba
2024-08-15 6:27 ` Patrick Roy
2024-08-15 7:26 ` Fuad Tabba
2024-08-01 9:01 ` [RFC PATCH v2 10/10] KVM: arm64: Enable private memory kconfig for arm64 Fuad Tabba
2024-08-05 16:53 ` [RFC PATCH v2 00/10] KVM: Restricted mapping of guest_memfd at the host and pKVM/arm64 support Ackerley Tng
2024-08-05 18:13 ` Fuad Tabba
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