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From: Kim Phillips <kim.phillips@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	linux-coco@lists.linux.dev, kvm@vger.kernel.org,
	Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	Nikunj A Dadhania <nikunj@amd.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Michael Roth <michael.roth@amd.com>,
	Naveen Rao <naveen.rao@amd.com>,
	David Kaplan <david.kaplan@amd.com>,
	Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Nathan Fontenot <nathan.fontenot@amd.com>
Subject: Re: [PATCH v5 1/8] x86/bugs: Allow forcing Automatic IBRS with SNP active using spectre_v2=eibrs
Date: Fri, 25 Sep 2026 21:14:52 -0500	[thread overview]
Message-ID: <4cf2033d-0819-4b71-ba42-d9c3201f3856@amd.com> (raw)
In-Reply-To: <20260925164748.GAaraltFwtJs59WAsj@fat_crate.local>

On 9/25/26 11:47 AM, Borislav Petkov wrote:
> On Thu, Sep 24, 2026 at 01:45:52PM -0500, Kim Phillips wrote:
>> For a guest-dominated host that trade plausibly goes the other way, and only
>> the admin knows their deployment.
> 
> Just holding down the current arguments here *without* AI:
> 
> We have had an internal discussion in the past about this already. It can
> potentially cause performance disadvantages in certain scenarios.
> 
> If this is ever going to go anywhere, I would like to see:
> 
> - a proper use case which people are *actually* asking for
> 
> - have it properly documented in Documentation/admin-guide/hw-vuln/ along with
>    the potential impact so that people can make an *informed* decision whether
>    they really want it
This patch can be dropped for now then.

Please continue your review on patch 2/8.

Thanks,

Kim

  reply	other threads:[~2026-09-26  2:15 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-26 22:35 [PATCH v5 0/8] Add SEV-SNP BTB Isolation and IBPB-on-Entry guest features Kim Phillips
2026-08-26 22:35 ` [PATCH v5 1/8] x86/bugs: Allow forcing Automatic IBRS with SNP active using spectre_v2=eibrs Kim Phillips
2026-08-27  4:32   ` Pawan Gupta
2026-09-03  4:03   ` Borislav Petkov
2026-09-18 23:00     ` Kim Phillips
2026-09-24  1:45       ` Borislav Petkov
2026-09-24 18:45         ` Kim Phillips
2026-09-25 16:47           ` Borislav Petkov
2026-09-26  2:14             ` Kim Phillips [this message]
2026-08-26 22:35 ` [PATCH v5 2/8] x86/bugs: Allow spectre_v2=ibrs on x86 vendors other than Intel Kim Phillips
2026-08-27  4:33   ` Pawan Gupta
2026-09-09 21:01   ` Borislav Petkov
2026-09-18 23:01     ` Kim Phillips
2026-08-26 22:35 ` [PATCH v5 3/8] KVM: SVM: Define SVM_SEV_FEAT_* flags using BIT_ULL() Kim Phillips
2026-08-26 22:35 ` [PATCH v5 4/8] KVM: selftests: sev_init2: Use BIT_ULL for VMSA feature bit definition Kim Phillips
2026-08-26 22:35 ` [PATCH v5 5/8] KVM: SEV: Disallow setting SNP-only features for non-SNP guests via a single mask Kim Phillips
2026-08-26 22:35 ` [PATCH v5 6/8] KVM: SEV: Advertise SVM_SEV_FEAT_SNP_ACTIVE Kim Phillips
2026-08-26 22:35 ` [PATCH v5 7/8] KVM: SEV: Add support for IBPB-on-Entry Kim Phillips
2026-08-26 22:35 ` [PATCH v5 8/8] KVM: SEV: Add support for SNP BTB Isolation Kim Phillips

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