From: Will Deacon <will.deacon@arm.com>
To: Andre Przywara <andre.przywara@arm.com>
Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Subject: Re: [PATCH kvmtool 6/6] arm: Auto-detect guest GIC type
Date: Wed, 30 Jan 2019 18:20:46 +0000 [thread overview]
Message-ID: <20190130182046.GI18558@fuggles.cambridge.arm.com> (raw)
In-Reply-To: <20190125180801.209910-7-andre.przywara@arm.com>
On Fri, Jan 25, 2019 at 06:08:01PM +0000, Andre Przywara wrote:
> At the moment kvmtool always tries to instantiate a virtual GICv2 for
> the guest, and fails with some scary error message if that doesn't work.
> The user has then to manually specify "--irqchip=gicv3", which is not
> really obvious.
> With the advent of more GICv3-only machines, let's try to be more
> clever and implement some auto-detection of the GIC type needed:
> - We try GICv3 first. On GICv3-only hosts this will be the only working
> option, so we don't loose anything. On GICv2-backwards compatible GICv3
> machines GICv3 is probably the better choice these days.
Could you elaborate on "probably the better choice" please?
> - If that fails, we try GICv2.
> - If that fails, we ran out out options and bail out.
>
> We deduce the choice between "ITS vs. pure GICv3" and "GICv2m vs. GICv2" by
> the presence of PCI devices, they would be the only MSI users anyway.
This feels really flakey. Why don't we just try, in order:
v3 + ITS
v3
v2m
v2
regardless of the VM configuration?
Will
next prev parent reply other threads:[~2019-01-30 18:20 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-25 18:07 [PATCH kvmtool 0/6] Various convenience fixes Andre Przywara
2019-01-25 18:07 ` [PATCH kvmtool 1/6] arm: turn pr_info() into pr_debug() messages Andre Przywara
2019-01-25 18:07 ` [PATCH kvmtool 2/6] arm: fdt: add stdout-path to /chosen node Andre Przywara
2019-01-30 18:20 ` Will Deacon
2019-01-31 14:57 ` Andre Przywara
2019-02-01 6:26 ` Will Deacon
2019-02-01 11:03 ` Andre Przywara
2019-01-25 18:07 ` [PATCH kvmtool 3/6] Makefile: support -s switch Andre Przywara
2019-01-30 18:20 ` Will Deacon
2019-01-31 13:48 ` Andre Przywara
2019-01-25 18:07 ` [PATCH kvmtool 4/6] Makefile: Remove echoing of kvmtools version file Andre Przywara
2019-01-30 18:20 ` Will Deacon
2019-01-31 18:36 ` Andre Przywara
2019-01-25 18:08 ` [PATCH kvmtool 5/6] arm: pmu: Improve PMU error reporting Andre Przywara
2019-01-25 18:08 ` [PATCH kvmtool 6/6] arm: Auto-detect guest GIC type Andre Przywara
2019-01-30 18:20 ` Will Deacon [this message]
2019-01-31 18:46 ` Andre Przywara
2019-01-30 18:20 ` [PATCH kvmtool 0/6] Various convenience fixes Will Deacon
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