From: Marc Zyngier <maz@kernel.org>
To: Andrew Jones <drjones@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org, kernel-team@android.com,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: arm64: Fix reporting of endianess when the access originates at EL0
Date: Tue, 12 Oct 2021 15:20:20 +0100 [thread overview]
Message-ID: <87ee8qpbob.wl-maz@kernel.org> (raw)
In-Reply-To: <20211012120040.4tfkzlm7uju2n3sa@gator>
On Tue, 12 Oct 2021 13:00:40 +0100,
Andrew Jones <drjones@redhat.com> wrote:
>
> On Tue, Oct 12, 2021 at 12:23:12PM +0100, Marc Zyngier wrote:
> > We currently check SCTLR_EL1.EE when computing the address of
> > a faulting guest access. However, the fault could have occured at
> > EL0, in which case the right bit to check would be SCTLR_EL1.E0E.
> >
> > This is pretty unlikely to cause any issue in practice: You'd have
> > to have a guest with a LE EL1 and a BE EL0 (or the other way around),
> > and have mapped a device into the EL0 page tables.
>
> I wonder if that's something a usermode network driver might want?
I don't know what it wants, but I don't want it the first place! Think
of what a kernel would need to do to run its userspace in a different
endianness... Userspace device access is just an additional headache.
Whoever does this needs urgent medical attention!
> Reviewed-by: Andrew Jones <drjones@redhat.com>
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Andrew Jones <drjones@redhat.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org, kernel-team@android.com
Subject: Re: [PATCH] KVM: arm64: Fix reporting of endianess when the access originates at EL0
Date: Tue, 12 Oct 2021 15:20:20 +0100 [thread overview]
Message-ID: <87ee8qpbob.wl-maz@kernel.org> (raw)
In-Reply-To: <20211012120040.4tfkzlm7uju2n3sa@gator>
On Tue, 12 Oct 2021 13:00:40 +0100,
Andrew Jones <drjones@redhat.com> wrote:
>
> On Tue, Oct 12, 2021 at 12:23:12PM +0100, Marc Zyngier wrote:
> > We currently check SCTLR_EL1.EE when computing the address of
> > a faulting guest access. However, the fault could have occured at
> > EL0, in which case the right bit to check would be SCTLR_EL1.E0E.
> >
> > This is pretty unlikely to cause any issue in practice: You'd have
> > to have a guest with a LE EL1 and a BE EL0 (or the other way around),
> > and have mapped a device into the EL0 page tables.
>
> I wonder if that's something a usermode network driver might want?
I don't know what it wants, but I don't want it the first place! Think
of what a kernel would need to do to run its userspace in a different
endianness... Userspace device access is just an additional headache.
Whoever does this needs urgent medical attention!
> Reviewed-by: Andrew Jones <drjones@redhat.com>
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Andrew Jones <drjones@redhat.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org, kernel-team@android.com
Subject: Re: [PATCH] KVM: arm64: Fix reporting of endianess when the access originates at EL0
Date: Tue, 12 Oct 2021 15:20:20 +0100 [thread overview]
Message-ID: <87ee8qpbob.wl-maz@kernel.org> (raw)
In-Reply-To: <20211012120040.4tfkzlm7uju2n3sa@gator>
On Tue, 12 Oct 2021 13:00:40 +0100,
Andrew Jones <drjones@redhat.com> wrote:
>
> On Tue, Oct 12, 2021 at 12:23:12PM +0100, Marc Zyngier wrote:
> > We currently check SCTLR_EL1.EE when computing the address of
> > a faulting guest access. However, the fault could have occured at
> > EL0, in which case the right bit to check would be SCTLR_EL1.E0E.
> >
> > This is pretty unlikely to cause any issue in practice: You'd have
> > to have a guest with a LE EL1 and a BE EL0 (or the other way around),
> > and have mapped a device into the EL0 page tables.
>
> I wonder if that's something a usermode network driver might want?
I don't know what it wants, but I don't want it the first place! Think
of what a kernel would need to do to run its userspace in a different
endianness... Userspace device access is just an additional headache.
Whoever does this needs urgent medical attention!
> Reviewed-by: Andrew Jones <drjones@redhat.com>
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2021-10-12 14:20 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-12 11:23 [PATCH] KVM: arm64: Fix reporting of endianess when the access originates at EL0 Marc Zyngier
2021-10-12 11:23 ` Marc Zyngier
2021-10-12 11:23 ` Marc Zyngier
2021-10-12 12:00 ` Andrew Jones
2021-10-12 12:00 ` Andrew Jones
2021-10-12 12:00 ` Andrew Jones
2021-10-12 14:20 ` Marc Zyngier [this message]
2021-10-12 14:20 ` Marc Zyngier
2021-10-12 14:20 ` Marc Zyngier
2021-10-17 10:20 ` Marc Zyngier
2021-10-17 10:20 ` Marc Zyngier
2021-10-17 10:20 ` Marc Zyngier
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