From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Richard Henderson <richard.henderson@linaro.org>,
qemu-arm@nongnu.org, alex.bennee@linaro.org,
qemu-devel@nongnu.org
Subject: Re: [PATCH v3 00/17] target/arm: Implement LVA, LPA, LPA2 features
Date: Tue, 1 Mar 2022 16:28:26 +0000 [thread overview]
Message-ID: <Yh5Jqg8oDDfPZ2c9@redhat.com> (raw)
In-Reply-To: <CAFEAcA_+70hkNaRhbT=ZT457x+cgD-qSad5QoJY8VAEds5UKeA@mail.gmail.com>
On Tue, Mar 01, 2022 at 04:16:25PM +0000, Peter Maydell wrote:
> On Tue, 1 Mar 2022 at 16:08, Peter Maydell <peter.maydell@linaro.org> wrote:
> >
> > On Wed, 23 Feb 2022 at 22:31, Richard Henderson
> > <richard.henderson@linaro.org> wrote:
> > >
> > > Changes for v3:
> > > * Update emulation.rst.
> > > * Split out separate update to ID_AA64MMFR0.
> > > * Hack for avocado.
> > >
> > > If the avocado hack isn't acceptable, perhaps just drop the
> > > last two patches for now?
> >
> > I think that given that there are Linux kernels out there
> > that won't boot if LPA2 is enabled, we should probably have
> > a -cpu command line option to disable it. Otherwise we might
> > get a bunch of "why did my kernel stop booting" bug reports.
>
> ...and should using a versioned machine type also default
> -cpu max to not enabling that? Not sure what x86 or other
> precedent is there.
I don't recall us coming across an important scenario where a guest
would fail to boot when we /enable/ a given CPU feature on x86,
requiring us to hide it from -cpu max/host.
Assuming the QEMU/KVM implementation of a CPU feature is correct
per the relevant spec, then artificially hiding it by default from
-cpu max feels questionable, as that penalizes non-buggy guest OS.
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
WARNING: multiple messages have this Message-ID (diff)
From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: alex.bennee@linaro.org, qemu-arm@nongnu.org,
Richard Henderson <richard.henderson@linaro.org>,
qemu-devel@nongnu.org
Subject: Re: [PATCH v3 00/17] target/arm: Implement LVA, LPA, LPA2 features
Date: Tue, 1 Mar 2022 16:28:26 +0000 [thread overview]
Message-ID: <Yh5Jqg8oDDfPZ2c9@redhat.com> (raw)
In-Reply-To: <CAFEAcA_+70hkNaRhbT=ZT457x+cgD-qSad5QoJY8VAEds5UKeA@mail.gmail.com>
On Tue, Mar 01, 2022 at 04:16:25PM +0000, Peter Maydell wrote:
> On Tue, 1 Mar 2022 at 16:08, Peter Maydell <peter.maydell@linaro.org> wrote:
> >
> > On Wed, 23 Feb 2022 at 22:31, Richard Henderson
> > <richard.henderson@linaro.org> wrote:
> > >
> > > Changes for v3:
> > > * Update emulation.rst.
> > > * Split out separate update to ID_AA64MMFR0.
> > > * Hack for avocado.
> > >
> > > If the avocado hack isn't acceptable, perhaps just drop the
> > > last two patches for now?
> >
> > I think that given that there are Linux kernels out there
> > that won't boot if LPA2 is enabled, we should probably have
> > a -cpu command line option to disable it. Otherwise we might
> > get a bunch of "why did my kernel stop booting" bug reports.
>
> ...and should using a versioned machine type also default
> -cpu max to not enabling that? Not sure what x86 or other
> precedent is there.
I don't recall us coming across an important scenario where a guest
would fail to boot when we /enable/ a given CPU feature on x86,
requiring us to hide it from -cpu max/host.
Assuming the QEMU/KVM implementation of a CPU feature is correct
per the relevant spec, then artificially hiding it by default from
-cpu max feels questionable, as that penalizes non-buggy guest OS.
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
next prev parent reply other threads:[~2022-03-01 16:28 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-23 22:31 [PATCH v3 00/17] target/arm: Implement LVA, LPA, LPA2 features Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 01/17] hw/registerfields: Add FIELD_SEX<N> and FIELD_SDP<N> Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 02/17] target/arm: Set TCR_EL1.TSZ for user-only Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 03/17] target/arm: Fault on invalid TCR_ELx.TxSZ Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 04/17] target/arm: Move arm_pamax out of line Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 05/17] target/arm: Pass outputsize down to check_s2_mmu_setup Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 06/17] target/arm: Use MAKE_64BIT_MASK to compute indexmask Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 07/17] target/arm: Honor TCR_ELx.{I}PS Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 08/17] target/arm: Prepare DBGBVR and DBGWVR for FEAT_LVA Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 09/17] target/arm: Implement FEAT_LVA Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 10/17] target/arm: Implement FEAT_LPA Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 11/17] target/arm: Extend arm_fi_to_lfsc to level -1 Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 12/17] target/arm: Introduce tlbi_aa64_get_range Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 13/17] target/arm: Fix TLBIRange.base for 16k and 64k pages Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 14/17] target/arm: Validate tlbi TG matches translation granule in use Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 15/17] target/arm: Advertise all page sizes for -cpu max Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 16/17] tests/avocado: Limit test_virt_tcg_gicv[23] to cortex-a72 Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-02-23 22:31 ` [PATCH v3 17/17] target/arm: Implement FEAT_LPA2 Richard Henderson
2022-02-23 22:31 ` Richard Henderson
2022-03-01 16:08 ` [PATCH v3 00/17] target/arm: Implement LVA, LPA, LPA2 features Peter Maydell
2022-03-01 16:08 ` Peter Maydell
2022-03-01 16:16 ` Peter Maydell
2022-03-01 16:16 ` Peter Maydell
2022-03-01 16:28 ` Daniel P. Berrangé [this message]
2022-03-01 16:28 ` Daniel P. Berrangé
2022-03-01 16:30 ` Peter Maydell
2022-03-01 16:30 ` Peter Maydell
2022-03-01 16:47 ` Daniel P. Berrangé
2022-03-01 16:47 ` Daniel P. Berrangé
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