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 8B499C54FB9 for ; Thu, 16 Nov 2023 14:06:55 +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:In-Reply-To:References: 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-Owner; bh=c7A2KotABH7lGGmJygAJOGBvtQ/yJ1/4eTBJ5cLl1Yw=; b=gGCkl9luXS/mEI 1eZVa2gKOAM2b3oyrjRIbEq/0Yp96/6oV+LdjpZ2xwJqAUd3LcdSlIEhXdatDOgoGjUNvJesnKQG3 qPdyjvU5h0cGbNh+4ysEFZu3ciOzC8SWWK2Em4UE1xhBRPh6SCv3aX9d3c+F1/8dMyS8SLViTw5M6 qfu0gBAIusW3WT5iIsfz6VZGJe+LtfUpjxC24vDU7KP/s6+SJUGZkI3JH790A8KSerfBUn9Qj8w6I IB38LGjlcYSuK6zlvkFt2YYQxhnQwS6D7ysHfhUoW1OzjumiCFq+cjOEUks5u2l0NRIgtNBGwJGyg /ad2f9ZPLnh41+pUOPuQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1r3d0i-003eZa-0i; Thu, 16 Nov 2023 14:06:24 +0000 Received: from frasgout.his.huawei.com ([185.176.79.56]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1r3d0f-003eYX-2j for linux-arm-kernel@lists.infradead.org; Thu, 16 Nov 2023 14:06:23 +0000 Received: from lhrpeml500003.china.huawei.com (unknown [172.18.147.200]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4SWMC54dvMz6GDCc; Thu, 16 Nov 2023 22:01:21 +0800 (CST) Received: from lhrpeml500001.china.huawei.com (7.191.163.213) by lhrpeml500003.china.huawei.com (7.191.162.67) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Thu, 16 Nov 2023 14:06:03 +0000 Received: from lhrpeml500001.china.huawei.com ([7.191.163.213]) by lhrpeml500001.china.huawei.com ([7.191.163.213]) with mapi id 15.01.2507.031; Thu, 16 Nov 2023 14:06:03 +0000 From: Salil Mehta To: Cornelia Huck , Jianyong Wu , "maz@kernel.org" , "james.morse@arm.com" , "will@kernel.org" CC: "rmk@armlinux.org.uk" , "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 Thread-Topic: [PATCH] arm64/kvm: Introduce feature extension for SMCCC filter Thread-Index: AQHaGIJSPxqmEiVqkkOrXIqhoEeoZ7B86xkAgAAOImA= Date: Thu, 16 Nov 2023 14:06:03 +0000 Message-ID: <2ea495b04a7d484aa570059298e20862@huawei.com> References: <20231116114152.912344-1-jianyong.wu@arm.com> <877cmhq1zp.fsf@redhat.com> In-Reply-To: <877cmhq1zp.fsf@redhat.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.48.150.188] MIME-Version: 1.0 X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231116_060622_055860_C788A95E X-CRM114-Status: GOOD ( 16.52 ) 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 > From: Cornelia Huck > Sent: Thursday, November 16, 2023 1:09 PM > To: Jianyong Wu ; maz@kernel.org; james.morse@arm.com; > will@kernel.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? Agreed. In fact, this is what I had earlier intended to do but deferred this change. As of now, RFC V2 of vCPU Hotplug series does not have this check yet while installing the SMCCC filters in KVM Host. Thanks > > 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