From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) (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 C39623546C9 for ; Thu, 18 Jun 2026 09:01:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781773297; cv=none; b=J5YJp+70+rKWaWsBejJ6gXuTdNUB2aAb7q6l7ELffB9Jz2zZ+dyHSasHYhTHodDmDmhwOHkbMoSV2zRmMZiR1TKqR1/6ltPDCeb0kQXGam0J+bbefSxHVV4E1RRTQwE7YaWBS9kddB6V3hovdODrjmtyF0Eb+25lvEZ4UPthXQc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781773297; c=relaxed/simple; bh=44l2bWmHh9oqwDlLgfnpVWipXB6VIDnQV2gMJ2iiF10=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=grDZSpc2lzgin+XbN/Gu6kilXhGcocH5VTzkVza+G1OQ8in/WDRtxWJh84Ru2agp3/5IRcQXhoqCFobqInEaX5aVKuR0d2enhPvJ6XjTBgL3q4dm+cwGXwqZTtdDIBXhDqz/QxIOkJBLyxDpu17RYRptXUuwdqnw+YNrmoBpHjw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--tabba.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=OaOG/Aby; arc=none smtp.client-ip=209.85.128.74 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--tabba.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="OaOG/Aby" Received: by mail-wm1-f74.google.com with SMTP id 5b1f17b1804b1-490b8adf8b8so6118655e9.0 for ; Thu, 18 Jun 2026 02:01:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1781773294; x=1782378094; 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=vSbfsSuF8XQoOBhzJ79rNhpPjL/Yakp0GnQrnvhxx5s=; b=OaOG/Aby5kikOyZ/U/v4Di95QGmfqV29f3ScstobWOdJ/EKLy5i4J3qU5S7EirF7MG UnJ3qyi0E9sQ1WzCykGubvt3ToiF/lLk+ho9ZI211VhYbQ+sHNBrYRvOANGHtnP/0CVi q0iW/FbshsUQEbqZk2GsDomlTyMzDgYbIDm/kocw15bceFQ8VxzhHZO/sAkvcvsfGW2A HNOegmo6yzuYxVruQGs3/a9rGYI2z9ntQVPzse7d7sW33tKCIaMATUjKeX9gCXsvwQWS z4HLeo0T6ZP0IVYdzxup5I89UqAY9DoDrdCOPjvOQv6NTBWYAKaA6pgjbdYQfVfVZJFx OlPg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781773294; x=1782378094; 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=vSbfsSuF8XQoOBhzJ79rNhpPjL/Yakp0GnQrnvhxx5s=; b=pnMjO37MoDembZmzcXMCIgi41mDoFJIHsXnSlXOTXa3jOaqM+XehcO8LssZylE0Led OCVHfsXaZiZaATYzq+JL13tUBVlSc6nrys7Tguz7bv7BsEJiQJQmH872nWicMNrGGd76 aAFd8pUGF5ZSh9ShKCv2Ladmg/coCpNs58WlcNoo0rPZJVxAz7n+nKNsluS+l57QzG36 vmK3iEL3Uq9Md1gqmvHv76p8AaKrNLPSz5yWVWujv7IPeiVul+uudk+/C7LS8s5aFm2P cq3wUrA7YYWH9wjlS8lMS9Ox1sHTcQ3y33zBMnt9mHPFhkD52S7bbS/VrMh/lOlmbhPA 6+7Q== X-Forwarded-Encrypted: i=1; AFNElJ+TvMUME4Wii1Hp2H6T9yzuAccKHkB2CW5JGDOa+2ipoOevMVSK4V1WpzntkpT9UTBpm8Si1mX4RWFuSv0=@vger.kernel.org X-Gm-Message-State: AOJu0YyPkwpHVSz0xZfE/EVgeiS2MSE0Sm7s37AJJip6wRWPdLGaJvwW nQDCmL7GvOXK2AXRZ8Ai87KH2y/QHdcABUuaHcdxi4E0wqjo9O4cHp1gacw2P7aSHC8zKEWNsFg z4w== X-Received: from wmim8.prod.google.com ([2002:a7b:cb88:0:b0:492:2b56:8534]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600d:6447:10b0:490:c2a3:23cf with SMTP id 5b1f17b1804b1-492333dfdbcmr103923175e9.34.1781773294140; Thu, 18 Jun 2026 02:01:34 -0700 (PDT) Date: Thu, 18 Jun 2026 10:01:28 +0100 In-Reply-To: <20260618090128.3913688-1-tabba@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260618090128.3913688-1-tabba@google.com> X-Mailer: git-send-email 2.54.0.1189.g8c84645362-goog Message-ID: <20260618090128.3913688-4-tabba@google.com> Subject: [PATCH 3/3] KVM: arm64: Drop redundant READ_ONCE() in pkvm_hyp_vm_is_created() From: Fuad Tabba To: Marc Zyngier , Oliver Upton , Catalin Marinas , Will Deacon Cc: Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Vincent Donnefort , Keir Fraser , Hyunwoo Kim , Fuad Tabba , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" is_created is written under config_lock. Every concurrent reader is serialised against that write: pkvm_create_hyp_vm() under config_lock, and the memslot path (kvm_arch_prepare_memory_region) via slots_lock, which the creation writer also holds. The teardown-path accesses have no concurrent writer. The read is therefore serialised, and the READ_ONCE() is unnecessary. Signed-off-by: Fuad Tabba --- arch/arm64/kvm/pkvm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c index 67b90a58fbea..008766273912 100644 --- a/arch/arm64/kvm/pkvm.c +++ b/arch/arm64/kvm/pkvm.c @@ -185,7 +185,11 @@ static int __pkvm_create_hyp_vm(struct kvm *kvm) bool pkvm_hyp_vm_is_created(struct kvm *kvm) { - return READ_ONCE(kvm->arch.pkvm.is_created); + /* + * Serialised by config_lock/slots_lock, or by VM lifecycle at + * teardown, so a plain read suffices. + */ + return kvm->arch.pkvm.is_created; } int pkvm_create_hyp_vm(struct kvm *kvm) -- 2.54.0.1189.g8c84645362-goog