From: Marc Zyngier <maz@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
Will Deacon <will@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
Shuah Khan <skhan@linuxfoundation.org>, kvm <kvm@vger.kernel.org>,
Linux Doc Mailing List <linux-doc@vger.kernel.org>,
"Kernel Mailing List, Linux" <linux-kernel@vger.kernel.org>,
Sean Christopherson <seanjc@google.com>,
Jim Mattson <jmattson@google.com>,
Oliver Upton <oupton@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Raghavendra Rao Ananta <rananta@google.com>,
Eric Auger <eric.auger@redhat.com>, Kees Cook <kees@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Nathan Chancellor <nathan@kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
kvmarm@lists.linux.dev,
linux-kselftest <linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH] Documentation: KVM: Document guest-visible compatibility expectations
Date: Tue, 19 May 2026 13:56:26 +0100 [thread overview]
Message-ID: <86pl2rwoat.wl-maz@kernel.org> (raw)
In-Reply-To: <86qzn7wp3y.wl-maz@kernel.org>
On Tue, 19 May 2026 13:38:57 +0100,
Marc Zyngier <maz@kernel.org> wrote:
>
> As I said before, I'd be OK with something that would restore IIDR to
> REV1. But not something that actively breaks the GIC emulation by
> reintroducing a bug. That's, by construction, dead code that will only
> bitrot, because there is no SW that can make use of this nonsense.
I will also add that if we make it a policy to preserve buggy
behaviours that the guest cannot be relying on, then I question
whether we should be fixing anything at all.
For example, 6.19 fixed a totally buggy behaviour where a guest
couldn't not have more than (on most HW) 4 interrupts in flight at any
given time. This was obviously totally bogus, and this was fixed
unconditionally, as legitimate guests could experience gold-platted
lock-ups.
Should we revert to the previous behaviour? In the affirmative, I will
simply stop fixing things, and someone else can have fun retrofitting
buggy crap.
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2026-05-19 12:56 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-11 8:57 [PATCH] Documentation: KVM: Document guest-visible compatibility expectations David Woodhouse
2026-05-11 15:14 ` Paolo Bonzini
2026-05-11 16:38 ` David Woodhouse
2026-05-11 16:56 ` Paolo Bonzini
2026-05-11 17:53 ` David Woodhouse
2026-05-13 8:42 ` Marc Zyngier
2026-05-13 9:24 ` David Woodhouse
2026-05-13 12:43 ` Paolo Bonzini
2026-05-13 13:03 ` Eric Auger
2026-05-13 13:57 ` David Woodhouse
2026-05-13 16:24 ` Paolo Bonzini
2026-05-13 18:26 ` David Woodhouse
2026-05-19 10:41 ` David Woodhouse
2026-05-19 11:11 ` Will Deacon
2026-05-19 11:44 ` David Woodhouse
2026-05-19 12:13 ` Paolo Bonzini
2026-05-19 12:38 ` Marc Zyngier
2026-05-19 12:56 ` Marc Zyngier [this message]
2026-05-19 13:24 ` David Woodhouse
2026-05-19 12:59 ` David Woodhouse
2026-05-19 13:53 ` Paolo Bonzini
2026-05-19 14:13 ` David Woodhouse
2026-05-19 21:10 ` Oliver Upton
2026-05-19 21:58 ` David Woodhouse
2026-05-19 22:57 ` Oliver Upton
2026-05-19 23:33 ` David Woodhouse
2026-05-20 17:47 ` Oliver Upton
2026-05-20 18:29 ` David Woodhouse
2026-05-19 12:42 ` David Woodhouse
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