From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7EEE2606A321 for ; Mon, 26 Oct 2026 18:12:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=1fmCmW3n; dkim=pass (1024-bit key, unprotected) header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=HaGbgBhG 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-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc: To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; 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Mon, 26 Oct 2026 11:12:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1793038341; bh=wWJzTR3+Htr+1KB+CeXE1r7KMO3Eq6qQO8tranbjgEk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HaGbgBhGvHNrCSoZMQZwE2Rf+O7xkvPrz8EmYBL5er1/HwqECfBXYRDWtWQR5/akt H29jkInDU8TVzJ/EY6x/NrfrEC5SJpx/2ZTHZlIRabLVwtJe6gjhw1nE4dvJijMwCw 1BY5t2eXAWy1WXZLn4ljoJUkMWmP5t/p13GzHy9Y= From: Leonardo Bras To: Tian Zheng Cc: Leonardo Bras , maz@kernel.org, oupton@kernel.org, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, pbonzini@redhat.com, yuzenghui@huawei.com, wangzhou1@hisilicon.com, yangjinqian1@huawei.com, caijian11@h-partners.com, liuyonglong@huawei.com, tangchengchang@huawei.com, yezhenyu2@huawei.com, yubihong@huawei.com, linuxarm@huawei.com, joey.gouly@arm.com, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, seiden@linux.ibm.com, suzuki.poulose@arm.com, fuad.tabba@linux.dev, mark.rutland@arm.com, seanjc@google.com, rdunlap@infradead.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, skhan@linuxfoundation.org Subject: Re: [PATCH v5 06/15] KVM: arm64: Add support for FEAT_HDBSS Date: Mon, 26 Oct 2026 18:12:15 +0000 Message-ID: X-Mailer: git-send-email 2.56.0 In-Reply-To: <20260929103655.85107-7-zhengtian10@huawei.com> References: <20260929103655.85107-1-zhengtian10@huawei.com> <20260929103655.85107-7-zhengtian10@huawei.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261026_111222_049860_0ABC0967 X-CRM114-Status: GOOD ( 14.35 ) X-Spam-Score: -4.4 (----) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-14.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Sep 29, 2026 at 06:36:46PM +0800, Tian Zheng wrote: > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 32102c3912fa..12fa37328dd2 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -2158,6 +2158,11 @@ static bool hvhe_possible(const struct arm64_cpu_capabilities *entry, > return arm64_test_sw_feature_override(ARM64_SW_FEATURE_OVERRIDE_HVHE); > } > > +static bool has_vhe_hdbss(const struct arm64_cpu_capabilities *entry, int scope) > +{ > + return is_kernel_in_hyp_mode() && has_cpuid_feature(entry, scope); > +} > + IIUC you run this on every cpu in the system, to make sure it's matching the feature. Is there any chance the kernel is in EL2 only on some of the cpus here? If not, maybe we can run it on system_supports_hdbss() instead, which would be easier for the user to understand it only runs in EL2, on top of not needing the above. Other than that, seems ok to me. Thanks! Leo