From: Ackerley Tng <ackerleytng@google.com>
To: Sean Christopherson <seanjc@google.com>,
David Hildenbrand <david@redhat.com>
Cc: Fuad Tabba <tabba@google.com>,
kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-mm@kvack.org, pbonzini@redhat.com, chenhuacai@kernel.org,
mpe@ellerman.id.au, anup@brainfault.org,
paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu, viro@zeniv.linux.org.uk,
brauner@kernel.org, willy@infradead.org,
akpm@linux-foundation.org, xiaoyao.li@intel.com,
yilun.xu@intel.com, chao.p.peng@linux.intel.com,
jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com,
isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz,
vannapurve@google.com, mail@maciej.szmigiero.name,
michael.roth@amd.com, wei.w.wang@intel.com,
liam.merwick@oracle.com, isaku.yamahata@gmail.com,
kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com,
steven.price@arm.com, quic_eberman@quicinc.com,
quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com,
quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com,
quic_pderrin@quicinc.com, quic_pheragu@quicinc.com,
catalin.marinas@arm.com, james.morse@arm.com,
yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org,
will@kernel.org, qperret@google.com, keirf@google.com,
roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org,
jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com,
fvdl@google.com, hughd@google.com, jthoughton@google.com,
peterx@redhat.com, pankaj.gupta@amd.com,
Yan Zhao <yan.y.zhao@intel.com>
Subject: Re: [PATCH v8 06/13] KVM: x86: Generalize private fault lookups to guest_memfd fault lookups
Date: Tue, 06 May 2025 12:27:42 -0700 [thread overview]
Message-ID: <diqzv7qdr13l.fsf@ackerleytng-ctop.c.googlers.com> (raw)
In-Reply-To: <aBlCSGB86cp3B3zn@google.com>
Sean Christopherson <seanjc@google.com> writes:
> <snip>
>
> ... we "just" need
> to update that to constrain the max order based on shared vs. private. E.g. from
> the original guest_memfd hugepage support[*] (which never landed), to take care
> of the pgoff not being properly aligned to the memslot.
>
> + /*
> + * The folio can be mapped with a hugepage if and only if the folio is
> + * fully contained by the range the memslot is bound to. Note, the
> + * caller is responsible for handling gfn alignment, this only deals
> + * with the file binding.
> + */
> + huge_index = ALIGN(index, 1ull << *max_order);
> + if (huge_index < ALIGN(slot->gmem.pgoff, 1ull << *max_order) ||
> + huge_index + (1ull << *max_order) > slot->gmem.pgoff + slot->npages)
> *max_order = 0;
>
> [*] https://lore.kernel.org/all/20231027182217.3615211-18-seanjc@google.com
>
Regarding this alignment check, did you also consider checking at
memslot binding time? Would this [1] work/be better?
[1] https://lore.kernel.org/all/diqz1pt1sfw8.fsf@ackerleytng-ctop.c.googlers.com/
next prev parent reply other threads:[~2025-05-06 19:27 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-30 16:56 [PATCH v8 00/13] KVM: Mapping guest_memfd backed memory at the host for software protected VMs Fuad Tabba
2025-04-30 16:56 ` [PATCH v8 01/13] KVM: Rename CONFIG_KVM_PRIVATE_MEM to CONFIG_KVM_GMEM Fuad Tabba
2025-05-01 17:38 ` Ira Weiny
2025-04-30 16:56 ` [PATCH v8 02/13] KVM: Rename CONFIG_KVM_GENERIC_PRIVATE_MEM to CONFIG_KVM_GENERIC_GMEM_POPULATE Fuad Tabba
2025-05-01 18:10 ` Ira Weiny
2025-05-02 6:44 ` David Hildenbrand
2025-05-02 14:24 ` Ira Weiny
2025-04-30 16:56 ` [PATCH v8 03/13] KVM: Rename kvm_arch_has_private_mem() to kvm_arch_supports_gmem() Fuad Tabba
2025-05-01 18:18 ` Ira Weiny
2025-04-30 16:56 ` [PATCH v8 04/13] KVM: x86: Rename kvm->arch.has_private_mem to kvm->arch.supports_gmem Fuad Tabba
2025-05-01 18:19 ` Ira Weiny
2025-04-30 16:56 ` [PATCH v8 05/13] KVM: Rename kvm_slot_can_be_private() to kvm_slot_has_gmem() Fuad Tabba
2025-05-01 21:37 ` Ira Weiny
2025-04-30 16:56 ` [PATCH v8 06/13] KVM: x86: Generalize private fault lookups to guest_memfd fault lookups Fuad Tabba
2025-04-30 18:58 ` Ackerley Tng
2025-05-01 9:53 ` Fuad Tabba
2025-05-02 15:04 ` David Hildenbrand
2025-05-02 16:21 ` Sean Christopherson
2025-05-02 22:00 ` Ackerley Tng
2025-05-05 8:01 ` David Hildenbrand
2025-05-05 22:57 ` Sean Christopherson
2025-05-06 5:17 ` Vishal Annapurve
2025-05-06 5:28 ` Vishal Annapurve
2025-05-06 13:58 ` Sean Christopherson
2025-05-06 14:15 ` David Hildenbrand
2025-05-06 20:46 ` Ackerley Tng
2025-05-08 14:12 ` Sean Christopherson
2025-05-08 14:46 ` David Hildenbrand
2025-05-09 21:04 ` James Houghton
2025-05-09 22:29 ` David Hildenbrand
2025-05-09 22:38 ` James Houghton
2025-05-06 19:27 ` Ackerley Tng [this message]
2025-05-05 23:09 ` Ackerley Tng
2025-05-05 23:17 ` Sean Christopherson
2025-05-01 21:38 ` Ira Weiny
2025-04-30 16:56 ` [PATCH v8 07/13] KVM: Fix comments that refer to slots_lock Fuad Tabba
2025-04-30 21:30 ` David Hildenbrand
2025-05-01 21:43 ` Ira Weiny
2025-05-02 12:07 ` Fuad Tabba
2025-04-30 16:56 ` [PATCH v8 08/13] KVM: guest_memfd: Allow host to map guest_memfd() pages Fuad Tabba
2025-04-30 21:33 ` David Hildenbrand
2025-05-01 8:07 ` Fuad Tabba
2025-05-02 15:11 ` David Hildenbrand
2025-05-02 22:06 ` Ackerley Tng
2025-05-02 22:29 ` Ackerley Tng
2025-05-06 8:47 ` Yan Zhao
2025-05-05 21:06 ` Ira Weiny
2025-05-06 12:15 ` Fuad Tabba
2025-05-09 20:54 ` James Houghton
2025-05-11 8:03 ` David Hildenbrand
2025-05-12 7:08 ` Fuad Tabba
2025-05-12 19:29 ` James Houghton
2025-05-12 7:46 ` Roy, Patrick
2025-04-30 16:56 ` [PATCH v8 09/13] KVM: arm64: Refactor user_mem_abort() calculation of force_pte Fuad Tabba
2025-04-30 21:35 ` David Hildenbrand
2025-04-30 16:56 ` [PATCH v8 10/13] KVM: arm64: Handle guest_memfd()-backed guest page faults Fuad Tabba
2025-05-09 20:15 ` James Houghton
2025-05-12 7:07 ` Fuad Tabba
2025-04-30 16:56 ` [PATCH v8 11/13] KVM: arm64: Enable mapping guest_memfd in arm64 Fuad Tabba
2025-05-09 21:08 ` James Houghton
2025-05-12 6:55 ` Fuad Tabba
2025-04-30 16:56 ` [PATCH v8 12/13] KVM: x86: KVM_X86_SW_PROTECTED_VM to support guest_memfd shared memory Fuad Tabba
2025-04-30 16:56 ` [PATCH v8 13/13] KVM: guest_memfd: selftests: guest_memfd mmap() test when mapping is allowed Fuad Tabba
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