From patchwork Thu Feb 15 15:29:15 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 773176 Received: from mail.xenproject.org (mail.xenproject.org [104.130.215.37]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 822B8131E32; Thu, 15 Feb 2024 15:44:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=104.130.215.37 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708011872; cv=none; b=u3tau9wW1xXZF/ic6t0Z2NqTe+seSHubrVhy+QsC6EBxxhnWmM21cQ48Tf7Gde068ISvNdv1BqK32PP5bENKcy8S/ZpYaY+igy647U+ZXa9TBvQzC4FCC8SltQt/TPRO/ai9c7ZxwjaI3rFZOYm4A61U58ZMJP3qd0k5OMJE41Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708011872; c=relaxed/simple; bh=tf6LMRayvs8aoSZxiqZEwaZ7V5TgcIo9fVJuyWSO+FU=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=MIbkIkbfq95LFtAdnYBXvTYW5WXkvUI8pwJCZxe9tw9Hqj+ruhCEzlj1fO1wU8tQzkYNKaSxV/lTzsaWJsrgjFPtPcE8qhoJq/JIo+dyZG8J1OOAMEFPhPa9jsLDTDgWkvGtq9WimbL5LCb3gw4Z6FKiK6Be9tjzIBpBjbbBNnM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org; spf=pass smtp.mailfrom=xen.org; dkim=pass (1024-bit key) header.d=xen.org header.i=@xen.org header.b=wOERm6ZT; arc=none smtp.client-ip=104.130.215.37 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xen.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=xen.org header.i=@xen.org header.b="wOERm6ZT" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:MIME-Version:References: In-Reply-To:Message-Id:Date:Subject:To:From; bh=I+0HAEEY7B8ebrh7W7mzXaPfOq28o4tU8rT0p+AqpXE=; b=wOERm6ZTM/pzHUgQEadMvJJAX3 PDRpCWSkDxShRD5XRBxbf1et0sPLU3iAt1IbskBDHW/J8BU/g8YpTS1anHfvaF0bKlU1WFfLcbMFz JDd+Zzm2ACaDvFpGoWLTWLSyL0gFq+2eJ/LcA/mJQz/1+DJF0P7MkfJcWIWbsgx6sf18=; Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1raduL-0001WM-SP; Thu, 15 Feb 2024 15:44:17 +0000 Received: from 54-240-197-226.amazon.com ([54.240.197.226] helo=REM-PW02S00X.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1radhd-00089r-Po; Thu, 15 Feb 2024 15:31:10 +0000 From: Paul Durrant To: Paolo Bonzini , Jonathan Corbet , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , David Hildenbrand , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , David Woodhouse , Paul Durrant , Shuah Khan , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v13 20/21] KVM: x86/xen: allow vcpu_info content to be 'safely' copied Date: Thu, 15 Feb 2024 15:29:15 +0000 Message-Id: <20240215152916.1158-21-paul@xen.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240215152916.1158-1-paul@xen.org> References: <20240215152916.1158-1-paul@xen.org> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Paul Durrant If the guest sets an explicit vcpu_info GPA then, for any of the first 32 vCPUs, the content of the default vcpu_info in the shared_info page must be copied into the new location. Because this copy may race with event delivery (which updates the 'evtchn_pending_sel' field in vcpu_info) there needs to be a way to defer that until the copy is complete. Happily there is already a shadow of 'evtchn_pending_sel' in kvm_vcpu_xen that is used in atomic context if the vcpu_info PFN cache has been invalidated so that the update of vcpu_info can be deferred until the cache can be refreshed (on vCPU thread's the way back into guest context). Also use this shadow if the vcpu_info cache has been *deactivated*, so that the VMM can safely copy the vcpu_info content and then re-activate the cache with the new GPA. To do this, stop considering an inactive vcpu_info cache as a hard error in kvm_xen_set_evtchn_fast(). Signed-off-by: Paul Durrant Reviewed-by: David Woodhouse --- Cc: David Woodhouse Cc: Sean Christopherson Cc: Paolo Bonzini Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: x86@kernel.org v13: - Patch title change. v8: - Update commit comment. v6: - New in this version. --- arch/x86/kvm/xen.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 8650141b266e..11ab62ca011d 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -1802,9 +1802,6 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm) WRITE_ONCE(xe->vcpu_idx, vcpu->vcpu_idx); } - if (!vcpu->arch.xen.vcpu_info_cache.active) - return -EINVAL; - if (xe->port >= max_evtchn_port(kvm)) return -EINVAL;