From: Quentin Perret <qperret@google.com>
To: Will Deacon <will@kernel.org>
Cc: kvmarm@lists.linux.dev, "Sean Christopherson" <seanjc@google.com>,
"Vincent Donnefort" <vdonnefort@google.com>,
"Alexandru Elisei" <alexandru.elisei@arm.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>,
"James Morse" <james.morse@arm.com>,
"Chao Peng" <chao.p.peng@linux.intel.com>,
"Suzuki K Poulose" <suzuki.poulose@arm.com>,
"Mark Rutland" <mark.rutland@arm.com>,
"Fuad Tabba" <tabba@google.com>,
"Oliver Upton" <oliver.upton@linux.dev>,
"Marc Zyngier" <maz@kernel.org>,
kernel-team@android.com, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 20/25] KVM: arm64: Return guest memory from EL2 via dedicated teardown memcache
Date: Thu, 27 Oct 2022 13:13:38 +0000 [thread overview]
Message-ID: <Y1qEAokfFPcLaWiq@google.com> (raw)
In-Reply-To: <20221020133827.5541-21-will@kernel.org>
On Thursday 20 Oct 2022 at 14:38:22 (+0100), Will Deacon wrote:
> +static void
> +teardown_donated_memory(struct kvm_hyp_memcache *mc, void *addr, size_t size)
> +{
> + size = PAGE_ALIGN(size);
> + memset(addr, 0, size);
> +
> + for (void *start = addr; start < addr + size; start += PAGE_SIZE)
> + push_hyp_memcache(mc, start, hyp_virt_to_phys);
> +
> + unmap_donated_memory_noclear(addr, size);
> +}
> +
> int __pkvm_teardown_vm(pkvm_handle_t handle)
> {
> + struct kvm_hyp_memcache *mc;
> struct pkvm_hyp_vm *hyp_vm;
> unsigned int idx;
> size_t vm_size;
> @@ -552,7 +565,8 @@ int __pkvm_teardown_vm(pkvm_handle_t handle)
> hyp_spin_unlock(&vm_table_lock);
>
> /* Reclaim guest pages (including page-table pages) */
> - reclaim_guest_pages(hyp_vm);
> + mc = &hyp_vm->host_kvm->arch.pkvm.teardown_mc;
> + reclaim_guest_pages(hyp_vm, mc);
> unpin_host_vcpus(hyp_vm->vcpus, hyp_vm->nr_vcpus);
>
> /* Push the metadata pages to the teardown memcache */
> @@ -561,11 +575,11 @@ int __pkvm_teardown_vm(pkvm_handle_t handle)
> for (idx = 0; idx < hyp_vm->nr_vcpus; ++idx) {
> struct pkvm_hyp_vcpu *hyp_vcpu = hyp_vm->vcpus[idx];
>
> - unmap_donated_memory(hyp_vcpu, sizeof(*hyp_vcpu));
> + teardown_donated_memory(mc, hyp_vcpu, sizeof(*hyp_vcpu));
> }
>
> vm_size = pkvm_get_hyp_vm_size(hyp_vm->kvm.created_vcpus);
> - unmap_donated_memory(hyp_vm, vm_size);
> + teardown_donated_memory(mc, hyp_vm, vm_size);
We should move the unpinning of the host's kvm struct down here as 'mc'
here is part of it. Otherwise nothing prevents the host from unsharing
the pages and donating them, etc. Probably hard to exploit but still
worth fixing IMO.
Thanks,
Quentin
> return 0;
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next prev parent reply other threads:[~2022-10-27 13:30 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-20 13:38 [PATCH v5 00/25] KVM: arm64: Introduce pKVM hyp VM and vCPU state at EL2 Will Deacon
2022-10-20 13:38 ` [PATCH v5 01/25] KVM: arm64: Move hyp refcount manipulation helpers to common header file Will Deacon
2022-10-20 13:38 ` [PATCH v5 02/25] KVM: arm64: Allow attaching of non-coalescable pages to a hyp pool Will Deacon
2022-10-28 0:17 ` Oliver Upton
2022-10-28 8:09 ` Oliver Upton
2022-10-28 9:29 ` Quentin Perret
2022-10-28 9:28 ` Quentin Perret
2022-10-20 13:38 ` [PATCH v5 03/25] KVM: arm64: Back the hypervisor 'struct hyp_page' array for all memory Will Deacon
2022-10-20 13:38 ` [PATCH v5 04/25] KVM: arm64: Fix-up hyp stage-1 refcounts for all pages mapped at EL2 Will Deacon
2022-10-28 0:31 ` Oliver Upton
2022-10-20 13:38 ` [PATCH v5 05/25] KVM: arm64: Unify identifiers used to distinguish host and hypervisor Will Deacon
2022-10-28 0:32 ` Oliver Upton
2022-10-20 13:38 ` [PATCH v5 06/25] KVM: arm64: Implement do_donate() helper for donating memory Will Deacon
2022-10-28 7:52 ` Oliver Upton
2022-10-28 10:01 ` Quentin Perret
2022-10-20 13:38 ` [PATCH v5 07/25] KVM: arm64: Prevent the donation of no-map pages Will Deacon
2022-10-20 13:38 ` [PATCH v5 08/25] KVM: arm64: Add helpers to pin memory shared with the hypervisor at EL2 Will Deacon
2022-10-20 13:38 ` [PATCH v5 09/25] KVM: arm64: Include asm/kvm_mmu.h in nvhe/mem_protect.h Will Deacon
2022-10-20 13:38 ` [PATCH v5 10/25] KVM: arm64: Add hyp_spinlock_t static initializer Will Deacon
2022-10-20 13:38 ` [PATCH v5 11/25] KVM: arm64: Rename 'host_kvm' to 'host_mmu' Will Deacon
2022-10-20 13:38 ` [PATCH v5 12/25] KVM: arm64: Add infrastructure to create and track pKVM instances at EL2 Will Deacon
2022-10-20 13:38 ` [PATCH v5 13/25] KVM: arm64: Instantiate pKVM hypervisor VM and vCPU structures from EL1 Will Deacon
2022-10-20 13:38 ` [PATCH v5 14/25] KVM: arm64: Add per-cpu fixmap infrastructure at EL2 Will Deacon
2022-10-20 13:38 ` [PATCH v5 15/25] KVM: arm64: Initialise hypervisor copies of host symbols unconditionally Will Deacon
2022-10-20 13:38 ` [PATCH v5 16/25] KVM: arm64: Provide I-cache invalidation by virtual address at EL2 Will Deacon
2022-10-20 13:38 ` [PATCH v5 17/25] KVM: arm64: Add generic hyp_memcache helpers Will Deacon
2022-10-20 13:38 ` [PATCH v5 18/25] KVM: arm64: Consolidate stage-2 initialisation into a single function Will Deacon
2022-10-20 13:38 ` [PATCH v5 19/25] KVM: arm64: Instantiate guest stage-2 page-tables at EL2 Will Deacon
2022-10-20 13:38 ` [PATCH v5 20/25] KVM: arm64: Return guest memory from EL2 via dedicated teardown memcache Will Deacon
2022-10-27 13:13 ` Quentin Perret [this message]
2022-10-20 13:38 ` [PATCH v5 21/25] KVM: arm64: Unmap 'kvm_arm_hyp_percpu_base' from the host Will Deacon
2022-10-20 13:38 ` [PATCH v5 22/25] KVM: arm64: Maintain a copy of 'kvm_arm_vmid_bits' at EL2 Will Deacon
2022-10-20 13:38 ` [PATCH v5 23/25] KVM: arm64: Explicitly map 'kvm_vgic_global_state' " Will Deacon
2022-10-20 13:38 ` [PATCH v5 24/25] KVM: arm64: Don't unnecessarily map host kernel sections " Will Deacon
2022-10-20 13:38 ` [RFC PATCH v5 25/25] KVM: arm64: Use the pKVM hyp vCPU structure in handle___kvm_vcpu_run() Will Deacon
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