From: Will Deacon <will@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, qperret@google.com,
dbrazdil@google.com, Srivatsa Vaddagiri <vatsa@codeaurora.org>,
Shanker R Donthineni <sdonthineni@nvidia.com>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
kernel-team@android.com
Subject: Re: [PATCH 04/16] KVM: arm64: Add MMIO checking infrastructure
Date: Fri, 30 Jul 2021 13:26:59 +0100 [thread overview]
Message-ID: <20210730122658.GG23589@willie-the-truck> (raw)
In-Reply-To: <8735ryep6d.wl-maz@kernel.org>
On Wed, Jul 28, 2021 at 10:57:30AM +0100, Marc Zyngier wrote:
> On Tue, 27 Jul 2021 19:11:08 +0100,
> Will Deacon <will@kernel.org> wrote:
> > On Thu, Jul 15, 2021 at 05:31:47PM +0100, Marc Zyngier wrote:
> > > +bool kvm_install_ioguard_page(struct kvm_vcpu *vcpu, gpa_t ipa)
> > > +{
> > > + struct kvm_mmu_memory_cache *memcache;
> > > + struct kvm_memory_slot *memslot;
> > > + int ret, idx;
> > > +
> > > + if (!test_bit(KVM_ARCH_FLAG_MMIO_GUARD, &vcpu->kvm->arch.flags))
> > > + return false;
> > > +
> > > + /* Must be page-aligned */
> > > + if (ipa & ~PAGE_MASK)
> > > + return false;
> > > +
> > > + /*
> > > + * The page cannot be in a memslot. At some point, this will
> > > + * have to deal with device mappings though.
> > > + */
> > > + idx = srcu_read_lock(&vcpu->kvm->srcu);
> > > + memslot = gfn_to_memslot(vcpu->kvm, ipa >> PAGE_SHIFT);
> > > + srcu_read_unlock(&vcpu->kvm->srcu, idx);
> >
> > What does this memslot check achieve? A new memslot could be added after
> > you've checked, no?
>
> If you start allowing S2 annotations to coexist with potential memory
> mappings, you're in for trouble. The faulting logic will happily
> overwrite the annotation, and that's probably not what you want.
I don't disagree, but the check above appears to be racy.
> As for new (or moving) memslots, I guess they should be checked
> against existing annotations.
Something like that, but the devil is in the details as it will need to
synchronize with this check somehow.
Will
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next prev parent reply other threads:[~2021-07-30 12:29 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-15 16:31 [PATCH 00/16] KVM: arm64: MMIO guard PV services Marc Zyngier
2021-07-15 16:31 ` [PATCH 01/16] KVM: arm64: Generalise VM features into a set of flags Marc Zyngier
2021-07-27 18:10 ` Will Deacon
2021-07-28 9:41 ` Marc Zyngier
2021-07-28 14:51 ` Steven Price
2021-07-15 16:31 ` [PATCH 02/16] KVM: arm64: Don't issue CMOs when the physical address is invalid Marc Zyngier
2021-07-19 17:18 ` Quentin Perret
2021-07-20 8:04 ` Marc Zyngier
2021-07-27 18:10 ` Will Deacon
2021-07-28 9:45 ` Marc Zyngier
2021-07-15 16:31 ` [PATCH 03/16] KVM: arm64: Turn kvm_pgtable_stage2_set_owner into kvm_pgtable_stage2_annotate Marc Zyngier
2021-07-20 10:09 ` Quentin Perret
2021-07-20 10:21 ` Marc Zyngier
2021-07-20 10:38 ` Quentin Perret
2021-07-20 11:20 ` Marc Zyngier
2021-07-20 11:36 ` Quentin Perret
2021-07-20 13:13 ` Marc Zyngier
2021-07-15 16:31 ` [PATCH 04/16] KVM: arm64: Add MMIO checking infrastructure Marc Zyngier
2021-07-20 11:13 ` Quentin Perret
2021-07-20 13:15 ` Marc Zyngier
2021-07-20 15:49 ` Quentin Perret
2021-07-22 18:04 ` Marc Zyngier
2021-07-23 10:16 ` Quentin Perret
2021-07-27 18:11 ` Will Deacon
2021-07-28 9:57 ` Marc Zyngier
2021-07-30 12:26 ` Will Deacon [this message]
2021-07-30 13:04 ` Marc Zyngier
2021-07-30 12:58 ` Quentin Perret
2021-07-15 16:31 ` [PATCH 05/16] KVM: arm64: Plumb MMIO checking into the fault handling Marc Zyngier
2021-07-27 18:11 ` Will Deacon
2021-07-28 10:21 ` Marc Zyngier
2021-07-30 12:38 ` Will Deacon
2021-07-15 16:31 ` [PATCH 06/16] KVM: arm64: Force a full unmap on vpcu reinit Marc Zyngier
2021-07-27 18:11 ` Will Deacon
2021-07-28 10:38 ` Marc Zyngier
2021-07-30 12:50 ` Will Deacon
2021-07-15 16:31 ` [PATCH 07/16] KVM: arm64: Wire MMIO guard hypercalls Marc Zyngier
2021-07-27 18:11 ` Will Deacon
2021-07-28 10:47 ` Marc Zyngier
2021-07-30 13:11 ` Will Deacon
2021-08-01 11:20 ` Marc Zyngier
2021-07-15 16:31 ` [PATCH 08/16] KVM: arm64: Add tracepoint for failed MMIO guard check Marc Zyngier
2021-07-15 16:31 ` [PATCH 09/16] KVM: arm64: Advertise a capability for MMIO guard Marc Zyngier
2021-07-15 16:31 ` [PATCH 10/16] KVM: arm64: Add some documentation for the MMIO guard feature Marc Zyngier
2021-07-21 21:17 ` Andrew Jones
2021-07-23 13:30 ` Marc Zyngier
2021-07-23 13:38 ` Andrew Jones
2021-07-23 13:52 ` Marc Zyngier
2021-07-15 16:31 ` [PATCH 11/16] firmware/smccc: Call arch-specific hook on discovering KVM services Marc Zyngier
2021-07-15 16:31 ` [PATCH 12/16] mm/ioremap: Add arch-specific callbacks on ioremap/iounmap calls Marc Zyngier
2021-07-27 18:12 ` Will Deacon
2021-07-28 11:01 ` Marc Zyngier
2021-07-30 14:07 ` Will Deacon
2021-07-15 16:31 ` [PATCH 13/16] arm64: Implement ioremap/iounmap hooks calling into KVM's MMIO guard Marc Zyngier
2021-07-15 16:31 ` [PATCH 14/16] arm64: Enroll into KVM's MMIO guard if required Marc Zyngier
2021-07-15 16:31 ` [PATCH 15/16] arm64: Add a helper to retrieve the PTE of a fixmap Marc Zyngier
2021-07-20 11:16 ` Quentin Perret
2021-07-15 16:31 ` [PATCH 16/16] arm64: Register earlycon fixmap with the MMIO guard Marc Zyngier
2021-07-21 21:42 ` [PATCH 00/16] KVM: arm64: MMIO guard PV services Andrew Jones
2021-07-22 10:00 ` Marc Zyngier
2021-07-22 13:25 ` Andrew Jones
2021-07-22 15:30 ` Marc Zyngier
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