From: Andrew Jones <drjones@redhat.com>
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, will@kernel.org,
qperret@google.com, dbrazdil@google.com,
Steven Price <steven.price@arm.com>,
Fuad Tabba <tabba@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 v2 00/16] KVM: arm64: MMIO guard PV services
Date: Thu, 7 Oct 2021 17:52:48 +0200 [thread overview]
Message-ID: <20211007155248.ejwclkwnnsaunmc6@gator> (raw)
In-Reply-To: <20211004174849.2831548-1-maz@kernel.org>
On Mon, Oct 04, 2021 at 06:48:33PM +0100, Marc Zyngier wrote:
> This is the second version of this series initially posted at [1] that
> aims at letting a guest express what it considers as MMIO, and only
> let this through to userspace. Together with the guest memory made
> (mostly) inaccessible to the host kernel and userspace, this allows an
> implementation of a hardened IO subsystem.
>
> A lot has been fixed/revamped/improved since the initial posting,
> although I am still not pleased with the ioremap plugging on the guest
> side. I'll take any idea to get rid of it!
>
Pros/cons of the hooks
Pros:
1) VM only needs to have a kernel that supports the feature (and a
kernel command line that enables it)
2) All the ioremapped MMIO ranges are permitted immediately, rather than
deferring until some other event (which would probably be too late in
many cases)
Cons:
1) Having to have hooks, which is never pretty
2) Adding the hypcalls to each ioremap, which adds some overhead
3) Having to reference count all the mappings, which adds even more overhead
4) Not giving the owner of the VM control over what MMIO is permitted
(Well, maybe the VM owner just needs to blacklist drivers for anything
that it doesn't want.)
I don't think any of the Con's are too bad and probably Pro-2 more or less
makes the hooks a necessity.
Thanks,
drew
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prev parent reply other threads:[~2021-10-07 15:55 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-04 17:48 [PATCH v2 00/16] KVM: arm64: MMIO guard PV services Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 01/16] KVM: arm64: Generalise VM features into a set of flags Marc Zyngier
2021-10-06 10:24 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 02/16] KVM: arm64: Check for PTE valitity when checking for executable/cacheable Marc Zyngier
2021-10-06 10:41 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 03/16] KVM: arm64: Turn kvm_pgtable_stage2_set_owner into kvm_pgtable_stage2_annotate Marc Zyngier
2021-10-06 11:02 ` Andrew Jones
2021-10-06 11:22 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 04/16] KVM: arm64: Add MMIO checking infrastructure Marc Zyngier
2021-10-06 11:37 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 05/16] KVM: arm64: Plumb MMIO checking into the fault handling Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 06/16] KVM: arm64: Force a full unmap on vpcu reinit Marc Zyngier
2021-10-07 13:49 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 07/16] KVM: arm64: Wire MMIO guard hypercalls Marc Zyngier
2021-10-07 13:53 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 08/16] KVM: arm64: Add tracepoint for failed MMIO guard check Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 09/16] KVM: arm64: Advertise a capability for MMIO guard Marc Zyngier
2021-10-07 14:22 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 10/16] KVM: arm64: Add some documentation for the MMIO guard feature Marc Zyngier
2021-10-07 14:38 ` Andrew Jones
2021-10-07 14:42 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 11/16] firmware/smccc: Call arch-specific hook on discovering KVM services Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 12/16] mm/vmalloc: Add arch-specific callbacks to track io{remap, unmap} physical pages Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 13/16] arm64: Implement ioremap/iounmap hooks calling into KVM's MMIO guard Marc Zyngier
2021-10-07 15:36 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 14/16] arm64: Enroll into KVM's MMIO guard if required Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 15/16] arm64: Add a helper to retrieve the PTE of a fixmap Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 16/16] arm64: Register earlycon fixmap with the MMIO guard Marc Zyngier
2021-10-07 15:52 ` Andrew Jones [this message]
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