From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B84BC3859DD for ; Fri, 13 Mar 2026 22:17:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773440231; cv=none; b=bQO9b4U3vqiOWRsR6f6wf3LUvmuwWytFyQpKr6mg9SB8n5g8Sj7wMIm+/dcaJ28qlerv7BxAJETCmb92NHxpoBp/myoxCi3w1iWNfHyWU3r/Tqq4hyOkfwT2xfCjEQO0ZLhl7teTly1YJK26OVVeEm2WoWU2vzU4TazyfyUtBF4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773440231; c=relaxed/simple; bh=IPH5Ej3PDUUNxCzPQNelFX1QxXieJceC0jZ3nnZPpTQ=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=VrvdxG4m12vW/L+dDtwl9XqvSmWnROA4GKPp2wrXMkmbpbKGUf8rNv4GL4HQn4aSS58yeMHSt17rc2gAnSq2SwaI5TuvULiulQtvdhJY0LRGOsewbIdCFKy3mBB15HFVUq0os20lQGbVKVS2Der0bQ9+xfRe5/qzFbg6MhS8Llg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=QXi9ehdz; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="QXi9ehdz" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2aad5fec175so118579135ad.2 for ; Fri, 13 Mar 2026 15:17:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1773440229; x=1774045029; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=sT6d3N37fL+kvB+pZajEl2dnTkN9RP3PeWa3L8uub+Y=; b=QXi9ehdzNQB40Opn+QXxQCEhfXtZQfR0nn3e3cRtg+s5/FlA09vfa0gNHIns0l2gqL JpMcbORz3SjR3KscBqCuxNagVwwmNKo1ODGLsEnuOPrXE8TG8/huYUocyfLckwo6yvpW bxBI3H8ul7Pg8vmccsk2hCZdlu4FxZnWb1pxyKcSd+jQrY7BD9XFqS4fGSwPVoMSuEUS PNKgDc1kIJT+YQ+S4SJZRKPChOz48I7o57Z8CO0wfLqQbXL9A9H+eis/9Lqs7lNCU1p5 0CTo+z1F7j1QsEuu5cwOU9AHsTQM71EMWAvYMjJjindpe79h/5oMcdNikGevjMV6wyw8 mjaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773440229; x=1774045029; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=sT6d3N37fL+kvB+pZajEl2dnTkN9RP3PeWa3L8uub+Y=; b=ILu50W98mkVEa+ZFK+DreMpzA4OmR+DftukuncqPqzK651OTTu9WuUUORLEACrUIQQ 9nCp24Hdm53jNJkfadeqg0kBLqTHwj8HlKBOFT8+5YWcqlzplnBujbnrRTbgxZ0s5get CdLVP9noMB095twouLe5cH0RHkhbYZyxagu4+rntzo5dw9RaHNEK5XZgf4e9k9h52P+F IN4fzmrtTkot42mzVfke9vHuDgB1DwXpMYUE6uGHWaCbHfjx06vwgI0SZFxfutfKdRzM GQwxQloTatpZrvPeFavN8rEt2fcG7faBgmQp1vhwWEDxOKYGQXWbbS5OetsE9m7n/thz 9HXQ== X-Forwarded-Encrypted: i=1; AJvYcCWt31Jt8YWpYNFPig1gPZt8XQfu/nkyzc2J55kdKcv6+TwW4nbVzAl3jwO9L7In/NkQAYq0gjMs2COJ0as=@vger.kernel.org X-Gm-Message-State: AOJu0YzBANLLssJNAK1azpiVbAfFd8CX2uRD79BS+OehFNTexPAgajNA RCgNzCWDejBa8f0nePRkRmQTkKspOoAP5y88f+zpXWB+NDIupXXQyFYZbLdJ4AUC/H9oBfltrnm uh7TPDA== X-Received: from plbkh16.prod.google.com ([2002:a17:903:650:b0:2ae:4e8d:56b4]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:17c7:b0:2ae:47c9:68b9 with SMTP id d9443c01a7336-2aecac4dedamr45715115ad.49.1773440228916; Fri, 13 Mar 2026 15:17:08 -0700 (PDT) Date: Fri, 13 Mar 2026 15:17:07 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260310220414.2569208-1-seanjc@google.com> Message-ID: Subject: Re: [PATCH] KVM: SVM: Add a helper to get LBR field pointer to dedup MSR accesses From: Sean Christopherson To: Yosry Ahmed Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Fri, Mar 13, 2026, Yosry Ahmed wrote: > > Hrm, I was assuming the compiler would be smart to understand the other cases > > are unreachable. What clang version, and are you doing anything special with > > your config? > > Debian clang version 18.1.8 (20+build1) > > Nothing special with my config AFAICT. Lame. Given that it's Friday and I'm about to become a pumpkin, and it doesn't really matter if it's compile-timer assert or not, I'm going to sqaush it to this: static u64 *svm_vmcb_lbr(struct vcpu_svm *svm, u32 msr) { switch (msr) { case MSR_IA32_LASTBRANCHFROMIP: return &svm->vmcb->save.br_from; case MSR_IA32_LASTBRANCHTOIP: return &svm->vmcb->save.br_to; case MSR_IA32_LASTINTFROMIP: return &svm->vmcb->save.last_excp_from; case MSR_IA32_LASTINTTOIP: return &svm->vmcb->save.last_excp_to; default: break; } KVM_BUG_ON(1, svm->vcpu.kvm); return &svm->vmcb->save.br_from; } Can you double check that kvm-x86/nested builds for you? In the process of rebuilding kvm-x86/next...