From: David Hildenbrand <david@redhat.com>
To: Fuad Tabba <tabba@google.com>,
kvm@vger.kernel.org, kvmarm@lists.linux.dev
Cc: pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au,
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Subject: Re: [RFC PATCH v1 04/26] KVM: Don't allow private attribute to be set if mapped by host
Date: Thu, 18 Apr 2024 12:54:57 +0200 [thread overview]
Message-ID: <b706671a-0a11-40a3-882a-89be26f24505@redhat.com> (raw)
In-Reply-To: <20240222161047.402609-5-tabba@google.com>
On 22.02.24 17:10, Fuad Tabba wrote:
> Guest private memory should never be mapped by the host.
> Therefore, do not allow setting the private attribute to guest
> memory if that memory is mapped by the host.
>
> Signed-off-by: Fuad Tabba <tabba@google.com>
> ---
> include/linux/kvm_host.h | 7 ++++++
> virt/kvm/kvm_main.c | 51 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 58 insertions(+)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index fad296baa84e..f52d5503ddef 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -2408,11 +2408,18 @@ static inline bool kvm_gmem_is_mappable(struct kvm *kvm, gfn_t gfn)
> return !(kvm_get_memory_attributes(kvm, gfn) &
> KVM_MEMORY_ATTRIBUTE_NOT_MAPPABLE);
> }
> +
> +bool kvm_is_gmem_mapped(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);
> #else
> static inline bool kvm_gmem_is_mappable(struct kvm *kvm, gfn_t gfn)
> {
> return false;
> }
> +
> +static inline bool kvm_is_gmem_mapped(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
> +{
> + return false;
> +}
> #endif /* CONFIG_KVM_GENERIC_PRIVATE_MEM_MAPPABLE */
>
> #endif
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index fba4dc6e4107..9f6ff314bda3 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2516,6 +2516,48 @@ static __always_inline void kvm_handle_gfn_range(struct kvm *kvm,
> KVM_MMU_UNLOCK(kvm);
> }
>
> +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM_MAPPABLE
> +bool kvm_is_gmem_mapped(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
> +{
> + struct kvm_memslot_iter iter;
> +
> + kvm_for_each_memslot_in_gfn_range(&iter, kvm_memslots(kvm), gfn_start, gfn_end) {
> + struct kvm_memory_slot *memslot = iter.slot;
> + gfn_t start, end, i;
> +
> + start = max(gfn_start, memslot->base_gfn);
> + end = min(gfn_end, memslot->base_gfn + memslot->npages);
> + if (WARN_ON_ONCE(start >= end))
> + continue;
> +
> + for (i = start; i < end; i++) {
> + struct page *page;
> + bool is_mapped;
> + kvm_pfn_t pfn;
> + int ret;
> +
> + /*
> + * Check the page_mapcount with the page lock held to
> + * avoid racing with kvm_gmem_fault().
> + */
> + ret = kvm_gmem_get_pfn_locked(kvm, memslot, i, &pfn, NULL);
> + if (WARN_ON_ONCE(ret))
> + continue;
> +
> + page = pfn_to_page(pfn);
> + is_mapped = page_mapcount(page);
> + unlock_page(page);
> + put_page(page);
Stumbling over this, please avoid using page_mapcount(). page_mapped()
-- or better folio_mapped() -- is what you should be using here (iow,
convert it to work on folios).
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2024-04-18 10:55 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-22 16:10 [RFC PATCH v1 00/26] KVM: Restricted mapping of guest_memfd at the host and pKVM/arm64 support Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 01/26] KVM: Split KVM memory attributes into user and kernel attributes Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 02/26] KVM: Introduce kvm_gmem_get_pfn_locked(), which retains the folio lock Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 03/26] KVM: Add restricted support for mapping guestmem by the host Fuad Tabba
2024-02-22 16:28 ` David Hildenbrand
2024-02-26 8:58 ` Fuad Tabba
2024-02-26 9:57 ` David Hildenbrand
2024-02-26 17:30 ` Fuad Tabba
2024-02-27 7:40 ` David Hildenbrand
2024-02-22 16:10 ` [RFC PATCH v1 04/26] KVM: Don't allow private attribute to be set if mapped by host Fuad Tabba
2024-04-17 23:27 ` Sean Christopherson
2024-04-18 10:54 ` David Hildenbrand [this message]
2024-02-22 16:10 ` [RFC PATCH v1 05/26] KVM: Don't allow private attribute to be removed for unmappable memory Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 06/26] KVM: Implement kvm_(read|/write)_guest_page for private memory slots Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 07/26] KVM: arm64: Turn llist of pinned pages into an rb-tree Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 08/26] KVM: arm64: Implement MEM_RELINQUISH SMCCC hypercall Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 09/26] KVM: arm64: Strictly check page type in MEM_RELINQUISH hypercall Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 10/26] KVM: arm64: Avoid unnecessary unmap walk " Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 11/26] KVM: arm64: Add initial support for KVM_CAP_EXIT_HYPERCALL Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 12/26] KVM: arm64: Allow userspace to receive SHARE and UNSHARE notifications Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 13/26] KVM: arm64: Create hypercall return handler Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 14/26] KVM: arm64: Refactor code around handling return from host to guest Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 15/26] KVM: arm64: Rename kvm_pinned_page to kvm_guest_page Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 16/26] KVM: arm64: Add a field to indicate whether the guest page was pinned Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 17/26] KVM: arm64: Do not allow changes to private memory slots Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 18/26] KVM: arm64: Skip VMA checks for slots without userspace address Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 19/26] KVM: arm64: Handle guest_memfd()-backed guest page faults Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 20/26] KVM: arm64: Track sharing of memory from protected guest to host Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 21/26] KVM: arm64: Mark a protected VM's memory as unmappable at initialization Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 22/26] KVM: arm64: Handle unshare on way back to guest entry rather than exit Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 23/26] KVM: arm64: Check that host unmaps memory unshared by guest Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 24/26] KVM: arm64: Add handlers for kvm_arch_*_set_memory_attributes() Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 25/26] KVM: arm64: Enable private memory support when pKVM is enabled Fuad Tabba
2024-02-22 16:10 ` [RFC PATCH v1 26/26] KVM: arm64: Enable private memory kconfig for arm64 Fuad Tabba
2024-02-22 23:43 ` [RFC PATCH v1 00/26] KVM: Restricted mapping of guest_memfd at the host and pKVM/arm64 support Elliot Berman
2024-02-23 0:35 ` folio_mmapped Matthew Wilcox
2024-02-26 9:28 ` folio_mmapped David Hildenbrand
2024-02-26 21:14 ` folio_mmapped Elliot Berman
2024-02-27 14:59 ` folio_mmapped David Hildenbrand
2024-02-28 10:48 ` folio_mmapped Quentin Perret
2024-02-28 11:11 ` folio_mmapped David Hildenbrand
2024-02-28 12:44 ` folio_mmapped Quentin Perret
2024-02-28 13:00 ` folio_mmapped David Hildenbrand
2024-02-28 13:34 ` folio_mmapped Quentin Perret
2024-02-28 18:43 ` folio_mmapped Elliot Berman
2024-02-28 18:51 ` Quentin Perret
2024-02-29 10:04 ` folio_mmapped David Hildenbrand
2024-02-29 19:01 ` folio_mmapped Fuad Tabba
2024-03-01 0:40 ` folio_mmapped Elliot Berman
2024-03-01 11:16 ` folio_mmapped David Hildenbrand
2024-03-04 12:53 ` folio_mmapped Quentin Perret
2024-03-04 20:22 ` folio_mmapped David Hildenbrand
2024-03-01 11:06 ` folio_mmapped David Hildenbrand
2024-03-04 12:36 ` folio_mmapped Quentin Perret
2024-03-04 19:04 ` folio_mmapped Sean Christopherson
2024-03-04 20:17 ` folio_mmapped David Hildenbrand
2024-03-04 21:43 ` folio_mmapped Elliot Berman
2024-03-04 21:58 ` folio_mmapped David Hildenbrand
2024-03-19 9:47 ` folio_mmapped Quentin Perret
2024-03-19 9:54 ` folio_mmapped David Hildenbrand
2024-03-18 17:06 ` folio_mmapped Vishal Annapurve
2024-03-18 22:02 ` folio_mmapped David Hildenbrand
2024-03-18 23:07 ` folio_mmapped Vishal Annapurve
2024-03-19 0:10 ` folio_mmapped Sean Christopherson
2024-03-19 10:26 ` folio_mmapped David Hildenbrand
2024-03-19 13:19 ` folio_mmapped David Hildenbrand
2024-03-19 14:31 ` folio_mmapped Will Deacon
2024-03-19 23:54 ` folio_mmapped Elliot Berman
2024-03-22 16:36 ` Will Deacon
2024-03-22 18:46 ` Elliot Berman
2024-03-27 19:31 ` Will Deacon
2024-03-22 17:52 ` folio_mmapped David Hildenbrand
2024-03-22 21:21 ` folio_mmapped David Hildenbrand
2024-03-26 22:04 ` folio_mmapped Elliot Berman
2024-03-27 17:50 ` folio_mmapped David Hildenbrand
2024-03-27 19:34 ` folio_mmapped Will Deacon
2024-03-28 9:06 ` folio_mmapped David Hildenbrand
2024-03-28 10:10 ` folio_mmapped Quentin Perret
2024-03-28 10:32 ` folio_mmapped David Hildenbrand
2024-03-28 10:58 ` folio_mmapped Quentin Perret
2024-03-28 11:41 ` folio_mmapped David Hildenbrand
2024-03-29 18:38 ` folio_mmapped Vishal Annapurve
2024-04-04 0:15 ` folio_mmapped Sean Christopherson
2024-03-19 15:04 ` folio_mmapped Sean Christopherson
2024-03-22 17:16 ` folio_mmapped David Hildenbrand
2024-02-26 9:03 ` [RFC PATCH v1 00/26] KVM: Restricted mapping of guest_memfd at the host and pKVM/arm64 support Fuad Tabba
2024-02-23 12:00 ` Alexandru Elisei
2024-02-26 9:05 ` Fuad Tabba
2024-02-26 9:47 ` David Hildenbrand
2024-02-27 9:37 ` Fuad Tabba
2024-02-27 14:41 ` David Hildenbrand
2024-02-27 14:49 ` David Hildenbrand
2024-02-28 9:57 ` Fuad Tabba
2024-02-28 10:12 ` David Hildenbrand
2024-02-28 14:01 ` Quentin Perret
2024-02-29 9:51 ` David Hildenbrand
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