From: Paolo Bonzini <pbonzini@redhat.com>
To: Dave Hansen <dave.hansen@intel.com>,
Sean Christopherson <seanjc@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: Finish removing MPX from arch/x86?
Date: Wed, 5 Oct 2022 14:04:09 +0200 [thread overview]
Message-ID: <d074cb45-72d3-a4a4-30f9-cfb664bb010a@redhat.com> (raw)
In-Reply-To: <547a1203-0339-7ad2-9505-eab027046298@intel.com>
On 10/4/22 19:34, Dave Hansen wrote:
> We zapped the userspace MPX ABIs and most of its supporting code in here:
>
> 45fc24e89b7c ("x86/mpx: remove MPX from arch/x86")
>
> But, the XSAVE enabling and KVM code were left in place. This let folks
> at least keep running guests with MPX.
>
> It's been a couple of years and I don't think I've had a single person
> opine about the loss of MPX. Intel also followed through and there's no
> MPX to be found on newer CPUs like my "Tiger Lake" 11th Gen Intel(R)
> Core(TM) i7-1165G7.
>
> Is it time to zap MPX from arch/x86/kvm/?
I agree that the likelihood of anybody complaining about MPX is low but
Jim is right that the timeline for removing it is unfortunately quite long.
Removing MPX from XFEATURE_MASK_USER_SUPPORTED is possible, though we
need to add a new XFEATURE_MASK_GUEST_SUPPORTED that includes MPX. I'll
take a look.
Also, it's worth noting that MPX lives in the sigcontext ABI because it
uses the non-compacted format. Because of that it is not possible to
remove the structs from include/asm/fpu/types.h, for example.
Paolo
prev parent reply other threads:[~2022-10-05 12:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-04 17:34 Finish removing MPX from arch/x86? Dave Hansen
2022-10-04 18:21 ` Jim Mattson
2022-10-04 21:07 ` Dave Hansen
2022-10-04 21:42 ` Jim Mattson
2022-10-05 12:04 ` Paolo Bonzini [this message]
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