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 EC105C197A0 for ; Thu, 16 Nov 2023 13:09:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:References :In-Reply-To:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Uq7FhliLFTfe1tpkt4UlX7/COzuj0tcVUGwd3ceOuCA=; b=kZ98QtcObINbn9 ouTxu8gttSeZQ975LkW+khHe5ANEFPtCr0BGuLa8TGOGPMXhHpjkVKplMoQ7d68qYqqtjacSSIJF5 lI1BIjuDll9KxLa9s97OP5HHEMAofEgX1YOPR/Uyws18cP5FYmfreKG6SUG9FurqtbmZwQIiVfHn4 G3lB3jkK818TMUHRUu3KHZuzzShF3CBYgTvFyssm7JcuKouQhneQbulE2JdhE+veQY6kQbrw4jw5M p3qg7ga+0qPpP9OvT3KvSxjEOTwQY49Fw9W5S4NvSeUj1TgCiib6dDWe/2Ybewpyhdn/u4MuLGNOW TDTHk6Q/t3rE2Ux+Ealw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1r3c7M-003YCO-1T; Thu, 16 Nov 2023 13:09:12 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1r3c7J-003YBi-2O for linux-arm-kernel@lists.infradead.org; Thu, 16 Nov 2023 13:09:10 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700140147; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=MonhjC3WXqcY3h7WdCFO745+80UlcrRmMeuYZtAtOeE=; b=I3KUmWXBd8oWu6lI0d4wk0pssSTDH+jPIA5LzYTCWUgaDFZS01QUkcTwG4d/q/dSNd6yMA uPvWxvXsZRPDXrOoR/TlQ1MKjAH3ZUYuKVYgdEV8LnbtC75xfK6bM1McdwqBrcP1JUmhIi mhKCZpyg/HpRrRLpX/9s/m4kNi+xaZQ= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-139-Xo8IBKGHMtuhjaOTJw4t7w-1; Thu, 16 Nov 2023 08:09:01 -0500 X-MC-Unique: Xo8IBKGHMtuhjaOTJw4t7w-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D054F3C11A0C; Thu, 16 Nov 2023 13:09:00 +0000 (UTC) Received: from localhost (unknown [10.39.193.127]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2758640C6EB9; Thu, 16 Nov 2023 13:08:59 +0000 (UTC) From: Cornelia Huck To: Jianyong Wu , maz@kernel.org, james.morse@arm.com, will@kernel.org Cc: rmk@armlinux.org.uk, salil.mehta@huawei.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, justin.he@arm.com, jianyong.wu@arm.com Subject: Re: [PATCH] arm64/kvm: Introduce feature extension for SMCCC filter In-Reply-To: <20231116114152.912344-1-jianyong.wu@arm.com> Organization: "Red Hat GmbH, Sitz: Werner-von-Siemens-Ring 12, D-85630 Grasbrunn, Handelsregister: Amtsgericht =?utf-8?Q?M=C3=BCnchen=2C?= HRB 153243, =?utf-8?Q?Gesch=C3=A4ftsf=C3=BChrer=3A?= Ryan Barnhart, Charles Cachera, Michael O'Neill, Amy Ross" References: <20231116114152.912344-1-jianyong.wu@arm.com> User-Agent: Notmuch/0.37 (https://notmuchmail.org) Date: Thu, 16 Nov 2023 14:08:58 +0100 Message-ID: <877cmhq1zp.fsf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231116_050909_872956_CFB86DA5 X-CRM114-Status: GOOD ( 12.72 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Nov 16 2023, Jianyong Wu wrote: > 821d935c87b introduces support for userspace SMCCC filtering, but lack > of a way to tell userspace if we have this feature. Add a corresponding > feature extension can resolve this issue. > > For example, the incoming feature Vcpu Hotplug needs the SMCCC filter. > As there is no way to check this feature, VMM will run into error when > it calls this feature on an old kernel. It's bad for backward compatible. Can't you simply query via KVM_HAS_DEVICE_ATTR whether the SMCCC filtering controls exist? > > Signed-off-by: Jianyong Wu > --- > Documentation/virt/kvm/api.rst | 3 ++- > arch/arm64/kvm/arm.c | 1 + > include/uapi/linux/kvm.h | 1 + > 3 files changed, 4 insertions(+), 1 deletion(-) > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel