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Date:   Sun, 13 Aug 2023 12:36:57 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org, David.Kaplan@amd.com,
        Andrew.Cooper3@citrix.com, jpoimboe@kernel.org,
        gregkh@linuxfoundation.org
Subject: Re: [RFC][PATCH 07/17] x86/cpu/kvm: Provide UNTRAIN_RET_VM
Message-ID: <20230813103657.GCZNiySRVa8TcT7SAW@fat_crate.local>
References: <20230809071218.000335006@infradead.org>
 <20230809072200.922634286@infradead.org>
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On Wed, Aug 09, 2023 at 09:12:25AM +0200, Peter Zijlstra wrote:
> With the difference being that UNTRAIN_RET_VM uses
> X86_FEATURE_IBPB_ON_VMEXIT instead of X86_FEATURE_ENTRY_IBPB.
> 
> This cures VMEXIT doing potentially unret+IBPB or double IBPB.

Can't - I have a separate flag for that and I set it only when !IBPB:

        case SRSO_CMD_IBPB_ON_VMEXIT:
                if (IS_ENABLED(CONFIG_CPU_SRSO)) {
                        if (!boot_cpu_has(X86_FEATURE_ENTRY_IBPB) && has_microcode) {
                                setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT);


But I like the separate macro.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette