From: Marc Zyngier <maz@kernel.org>
To: "Lameter, Christopher" <cl@os.amperecomputing.com>
Cc: "Russell King (Oracle)" <linux@armlinux.org.uk>,
Ard Biesheuvel <ardb@kernel.org>,
Quentin Perret <qperret@google.com>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Jonathan Corbet <corbet@lwn.net>, Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH RFC 00/17] arm64 kernel text replication
Date: Tue, 27 Jun 2023 09:02:09 +0100 [thread overview]
Message-ID: <86fs6dbaf2.wl-maz@kernel.org> (raw)
In-Reply-To: <7ddd3c78-5392-9f8d-8f9-d898795c89@os.amperecomputing.com>
On Tue, 27 Jun 2023 00:42:53 +0100,
"Lameter, Christopher" <cl@os.amperecomputing.com> wrote:
>
> On Fri, 23 Jun 2023, Marc Zyngier wrote:
>
> >> That sounds great, but my initial question would be whether, with such a
> >> setup, one could then run VMs under such a kernel without hardware that
> >> supports nested virtualisation? I suspect the answer would be no.
> >
> > The answer is yes. All you need to do is to switch between the host
> > and guest stage-2s in the hypervisor, which is what KVM running in
> > protected mode does.
>
> Well I think his point was that there are machines running without a
> hypervisor and kernel replication needs to work on that. We certainly
> benefit a lot from kernel replication and our customers may elect to
> run ARM64 kernels without hypervisors on bare metal.
These are not incompatible goals.
The hypervisor is a function that the user may want to enable or not.
Irrespective of that, the HW that underpins the virtualisation
functionality is available and allows you to solve this particular
problem in a different way. This doesn't preclude from running
bare-metal at all.
There is even precedent in using stage-2 to work around critical bugs
(the Socionext PCIe fiasco springs to mind).
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2023-06-27 8:03 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-30 14:04 [PATCH RFC 00/17] arm64 kernel text replication Russell King (Oracle)
2023-05-30 14:04 ` [PATCH RFC 01/17] arm64: consolidate rox page protection logic Russell King (Oracle)
2023-05-30 14:04 ` [PATCH RFC 02/17] arm64: place kernel in its own L0 page table entry Russell King (Oracle)
[not found] ` <ZIb+Lg9F9b4ay90p@FVFF77S0Q05N>
2023-06-12 15:04 ` Russell King (Oracle)
2023-05-30 14:04 ` [PATCH RFC 03/17] arm64: provide cpu_replace_ttbr1_phys() Russell King (Oracle)
2023-05-30 14:04 ` [PATCH RFC 04/17] arm64: make clean_dcache_range_nopatch() visible Russell King (Oracle)
2023-05-30 14:04 ` [PATCH RFC 05/17] arm64: text replication: add init function Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 06/17] arm64: text replication: add sanity checks Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 07/17] arm64: text replication: copy initial kernel text Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 08/17] arm64: text replication: add node text patching Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 09/17] arm64: text replication: add node 0 page table definitions Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 10/17] arm64: text replication: add swapper page directory helpers Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 11/17] arm64: text replication: create per-node kernel page tables Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 12/17] arm64: text replication: boot secondary CPUs with appropriate TTBR1 Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 13/17] arm64: text replication: update cnp support Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 14/17] arm64: text replication: setup page tables for copied kernel Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 15/17] arm64: text replication: include most of read-only data as well Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 16/17] arm64: text replication: early kernel option to enable replication Russell King (Oracle)
2023-05-30 14:05 ` [PATCH RFC 17/17] arm64: text replication: add Kconfig Russell King (Oracle)
2023-06-05 9:05 ` [PATCH RFC 00/17] arm64 kernel text replication Russell King (Oracle)
2023-06-05 13:46 ` Mark Rutland
2023-06-23 15:24 ` Ard Biesheuvel
2023-06-23 15:34 ` Russell King (Oracle)
2023-06-23 15:54 ` Marc Zyngier
2023-06-26 23:42 ` Lameter, Christopher
2023-06-27 8:02 ` Marc Zyngier [this message]
2023-06-23 16:37 ` Marc Zyngier
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