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 X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20543C10F0C for ; Thu, 4 Apr 2019 15:07:33 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id E30CD2064A for ; Thu, 4 Apr 2019 15:07:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="usNzq3lm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E30CD2064A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=kiJXksyfUAmH69oo4pUx9NJY+3UHAVdnciTL5YGOljI=; b=usNzq3lmFSI3BA Mgu+8QDFsIoJ5o8TzDZOX9C9748t3lhXHkaRdXFckoMkP9wU67wnCwoIVxrxJZtZkW1ImaTPfmrrO t0UXpClVBmmeekf2ob+BCMu54IrgEeGL+ZCIDQwl/uz0sMyhxfkO83QffBe4/5FpCAabbeCCAJ3QQ 22TOsWRdUv9BvN5bcLGWeDn7X6EDleXGXgr08KvGRCycyIXyt7k8xewFe3EbX/v+QWvbma5MLvgc7 KFF3BV20Rk/0mNYJvLn/nhti10yETC0HxM9YSrOFMBPLyFSjNwT1Tk8jx5oS/dWyjqH/w/nbUHOhV EVNTgNSq+6ODwA4yeARw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hC3xe-0002ij-FG; Thu, 04 Apr 2019 15:07:26 +0000 Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hC3xT-0002i2-Em for linux-arm-kernel@lists.infradead.org; Thu, 04 Apr 2019 15:07:21 +0000 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B2EE39F75C; Thu, 4 Apr 2019 15:07:14 +0000 (UTC) Received: from kamzik.brq.redhat.com (unknown [10.43.2.160]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5C7E185733; Thu, 4 Apr 2019 15:07:12 +0000 (UTC) Date: Thu, 4 Apr 2019 17:07:09 +0200 From: Andrew Jones To: Dave Martin Subject: Re: [PATCH v7 22/27] KVM: arm/arm64: Add KVM_ARM_VCPU_FINALIZE ioctl Message-ID: <20190404150709.ihxlndxc6mvuwomp@kamzik.brq.redhat.com> References: <1553864452-15080-1-git-send-email-Dave.Martin@arm.com> <1553864452-15080-23-git-send-email-Dave.Martin@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1553864452-15080-23-git-send-email-Dave.Martin@arm.com> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 04 Apr 2019 15:07:14 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190404_080715_607261_9067CF6E X-CRM114-Status: GOOD ( 35.16 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Okamoto Takayuki , Christoffer Dall , Ard Biesheuvel , Marc Zyngier , Catalin Marinas , Will Deacon , Zhang Lei , Julien Grall , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Mar 29, 2019 at 01:00:47PM +0000, Dave Martin wrote: > Some aspects of vcpu configuration may be too complex to be > completed inside KVM_ARM_VCPU_INIT. Thus, there may be a > requirement for userspace to do some additional configuration > before various other ioctls will work in a consistent way. > > In particular this will be the case for SVE, where userspace will > need to negotiate the set of vector lengths to be made available to > the guest before the vcpu becomes fully usable. > > In order to provide an explicit way for userspace to confirm that > it has finished setting up a particular vcpu feature, this patch > adds a new ioctl KVM_ARM_VCPU_FINALIZE. > > When userspace has opted into a feature that requires finalization, > typically by means of a feature flag passed to KVM_ARM_VCPU_INIT, a > matching call to KVM_ARM_VCPU_FINALIZE is now required before > KVM_RUN or KVM_GET_REG_LIST is allowed. Individual features may > impose additional restrictions where appropriate. > > No existing vcpu features are affected by this, so current > userspace implementations will continue to work exactly as before, > with no need to issue KVM_ARM_VCPU_FINALIZE. > > As implemented in this patch, KVM_ARM_VCPU_FINALIZE is currently a > placeholder: no finalizable features exist yet, so ioctl is not > required and will always yield EINVAL. Subsequent patches will add > the finalization logic to make use of this ioctl for SVE. > > No functional change for existing userspace. > > Signed-off-by: Dave Martin > Reviewed-by: Julien Thierry > Tested-by: zhang.lei > > --- > > Changes since v5: > > * Commit message, including subject line, rewritten. > > This patch is a rework of "KVM: arm/arm64: Add hook to finalize the > vcpu configuration". The old subject line and commit message no > longer accurately described what the patch does. However, the code > is an evolution of the previous patch rather than a wholesale > rewrite. > > * Added an explicit KVM_ARM_VCPU_FINALIZE ioctl, rather than just > providing internal hooks in the kernel to finalize the vcpu > configuration implicitly. This allows userspace to confirm exactly > when it has finished configuring the vcpu and is ready to use it. > > This results in simpler (and hopefully more maintainable) ioctl > ordering rules. > --- > arch/arm/include/asm/kvm_host.h | 4 ++++ > arch/arm64/include/asm/kvm_host.h | 4 ++++ > include/uapi/linux/kvm.h | 3 +++ > virt/kvm/arm/arm.c | 18 ++++++++++++++++++ > 4 files changed, 29 insertions(+) > > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > index a49ee01..e80cfc1 100644 > --- a/arch/arm/include/asm/kvm_host.h > +++ b/arch/arm/include/asm/kvm_host.h > @@ -19,6 +19,7 @@ > #ifndef __ARM_KVM_HOST_H__ > #define __ARM_KVM_HOST_H__ > > +#include > #include > #include > #include > @@ -411,4 +412,7 @@ static inline int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type) > return 0; > } > > +#define kvm_arm_vcpu_finalize(vcpu, what) (-EINVAL) > +#define kvm_arm_vcpu_is_finalized(vcpu) true > + We usually use inline functions for the stubs. > #endif /* __ARM_KVM_HOST_H__ */ > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 3e89509..98658f7 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -23,6 +23,7 @@ > #define __ARM64_KVM_HOST_H__ > > #include > +#include > #include > #include > #include > @@ -625,4 +626,7 @@ void kvm_arch_free_vm(struct kvm *kvm); > > int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type); > > +#define kvm_arm_vcpu_finalize(vcpu, what) (-EINVAL) > +#define kvm_arm_vcpu_is_finalized(vcpu) true Same as above. > + > #endif /* __ARM64_KVM_HOST_H__ */ > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index dc77a5a..c3b8e7a 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -1441,6 +1441,9 @@ struct kvm_enc_region { > /* Available with KVM_CAP_HYPERV_CPUID */ > #define KVM_GET_SUPPORTED_HV_CPUID _IOWR(KVMIO, 0xc1, struct kvm_cpuid2) > > +/* Available with KVM_CAP_ARM_SVE */ > +#define KVM_ARM_VCPU_FINALIZE _IOW(KVMIO, 0xc2, int) > + > /* Secure Encrypted Virtualization command */ > enum sev_cmd_id { > /* Guest initialization commands */ > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c > index c69e137..9edbf0f 100644 > --- a/virt/kvm/arm/arm.c > +++ b/virt/kvm/arm/arm.c > @@ -545,6 +545,9 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu) > if (likely(vcpu->arch.has_run_once)) > return 0; > > + if (!kvm_arm_vcpu_is_finalized(vcpu)) > + return -EPERM; > + > vcpu->arch.has_run_once = true; > > if (likely(irqchip_in_kernel(kvm))) { > @@ -1116,6 +1119,10 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > if (unlikely(!kvm_vcpu_initialized(vcpu))) > break; > > + r = -EPERM; > + if (!kvm_arm_vcpu_is_finalized(vcpu)) > + break; > + What's the rationale for using EPERM? The finalized concept is very similar to the initialized one. So why not also use ENOEXEC for it too? > r = -EFAULT; > if (copy_from_user(®_list, user_list, sizeof(reg_list))) > break; > @@ -1169,6 +1176,17 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > > return kvm_arm_vcpu_set_events(vcpu, &events); > } > + case KVM_ARM_VCPU_FINALIZE: { > + int what; > + > + if (!kvm_vcpu_initialized(vcpu)) > + return -ENOEXEC; > + > + if (get_user(what, (const int __user *)argp)) > + return -EFAULT; > + > + return kvm_arm_vcpu_finalize(vcpu, what); Almost all the cases use the 'r = ...; break;' type of pattern, leaving it to the 'return r' at the end of the function. I guess that's in case at some point more stuff is added after the switch. The only cases that don't do that are the most recent ones KVM_GET/SET_VCPU_EVENTS, which should probably be changed to fit the pattern too, rather than this new ioctl following there pattern. > + } > default: > r = -EINVAL; > } > -- > 2.1.4 > Thanks, drew _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel