From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0AA0CCD98F2 for ; Thu, 18 Jun 2026 09:01:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:Cc:To:From: Subject:Message-ID:References:Mime-Version:In-Reply-To:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vSbfsSuF8XQoOBhzJ79rNhpPjL/Yakp0GnQrnvhxx5s=; b=JDtEpwToPr4eM1frDld+lHlpeN vBwxAjQiuWzOSuEH0tJzVloZi8Z6TrfykmzD/csdgvKwfCIhfh/0ywBRd1pfaGkLLa/7H1XG85bW/ AXqoxZ4JYQFB3fCxY9a1EycztY46IX8Ux16LNvV/vHHCVnswWgf959uLsYBySwjA8EY8sV/pEUrHv pIo+g90VAuDQVPYLQPtufY6tywfkXKARHQ7PdSw9Fka3MwXXoig4cFDytihvGL75jwFdhuAx7xYgz 3mANxxZUS6SlEX7n89hqI3Ujl65AQFtMeLD1lEqoF4RibXh8Z7oiPOmHzUJn8N4dCxzFBQ/ozQUUE +U4zQ8Mw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wa8d1-00000000tE4-0l8a; Thu, 18 Jun 2026 09:01:39 +0000 Received: from mail-wm1-x349.google.com ([2a00:1450:4864:20::349]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wa8cy-00000000tC3-1pVD for linux-arm-kernel@lists.infradead.org; Thu, 18 Jun 2026 09:01:37 +0000 Received: by mail-wm1-x349.google.com with SMTP id 5b1f17b1804b1-490e547f3cfso5997505e9.3 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=lists.infradead.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=e4b77n8a8i36DFZD1JD8IfiVDeL+6gqpWbp8+LA089md3brY5yttE1y+ytMLXgb7ud c33JAHvUULBYagsFner+z8xBI1XZ82YV27uffzX04nBwNjHVXnHQ85vOcugcjlIFur3S ZgvIZbh95wN+DTMyUpAe6Q1KE80aLhHAV0HJSU4tCXoFo9WMaz6eI39S0x5K3gscZJTO wKUeT6NbikIW8kyHnWQtRb4jEu2BpaVGZJ4Y5XpckK5+giugYvF1Mdb2EGowaYObwnmU YmqqsuOG1CXgYf8cUBqhYL7Zxw21v8WwmBPWlDtmCX5wldJo/oasf1BoNzmdD1l8WDkO 6BEA== 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=e7JVmR7J2pqoQY4/649B0eH1d7+7b8USch/dZVR2KvmTWIchVItiyPJxBAMjkh/J8G 4nQZOxKB9APYo/GGpRd9+k6AgsXvClE+2Ld7eMUgpytHLYBOhfD9SxIVILQq8qYhIo6V PP59UADdhWAkoCxv40occV6Cph1+cHFr8PM9v407GHjb/+6YaIG65RaVqqXgjnpc19wb GggCGNzqOdJAQUSJ8L22RiAcPi2UUjofIFRTKwm9f5mqQsCh1DFNXE/GK6MEWi31F4RD loi4TTnvZDuBd+fnroM4/S4T+EXZ9Lm7GIFfSRdmu+1amIKUh1lrdCa+wfHJkTBWOk0n ob6w== X-Forwarded-Encrypted: i=1; AFNElJ9cxS3EI/XrN7jPKAmb3ZjwBtGvYFfQHESSE21Qr37lyGPX5u8xtHglWmSPGKNMIm9pp7kzaoHb4VRSF2Tb+HYr@lists.infradead.org X-Gm-Message-State: AOJu0YxxVQaf4vecJ4GRYheU2ldqhQ+PIhvf4YYpzmnIvhnjoGNvpo7H Q2gkXVeDQcYDYcFlYC6jztA/bkeiMmu3/bQiCdQessI/a41U2enT7TVUXi94gv1dBi/Re6uT7bZ Hvw== 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> 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" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260618_020136_557946_48239D78 X-CRM114-Status: GOOD ( 11.77 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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