From patchwork Wed Feb 3 15:01:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Woodhouse X-Patchwork-Id: 12064557 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 909BCC433E6 for ; Wed, 3 Feb 2021 15:05:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A35D64F84 for ; Wed, 3 Feb 2021 15:05:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233996AbhBCPFe (ORCPT ); Wed, 3 Feb 2021 10:05:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233603AbhBCPDT (ORCPT ); Wed, 3 Feb 2021 10:03:19 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62DE4C06121C for ; Wed, 3 Feb 2021 07:01:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=RjNpm5dDXU16bpww+ucYeEgqh6ygR6CUUaklkn/NfwQ=; b=d9L7NuWzEJtQaRLSQ+HtaeU8kG 5B8NgUwGTPEdInGinS4Hnb8pCODAsnpzh/a9ZSy0mkMMFniwT5QXuA890uKRxhP98FI3HclwB4bWG He8yN/g0G9mLe8DlIoHkyq7MnV4SMrPZVe7ByFHEk1l5lA4QgcDwguzx6R9qnmJOSKVyDDhxALv2g Z4xkcSVJBvXJFHOerv+4CCY5qbjCjLBsJy8TSdUnYq/frbumHA1pP28qovGhWlF0iCFbzNg3thAne 2/qMTWqQfmZOMW6J8AoTX75p/j4cbt8IktU/O6vJO/U0uvRYwIDvRsGmAnB2U8WBWpSVgP/p6bH+a +FR7lH8w==; Received: from i7.infradead.org ([2001:8b0:10b:1:21e:67ff:fecb:7a92]) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1l7Jef-00H3zO-V0; Wed, 03 Feb 2021 15:01:20 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1l7Jef-003rf3-Hv; Wed, 03 Feb 2021 15:01:17 +0000 From: David Woodhouse To: kvm@vger.kernel.org Cc: Paolo Bonzini , Ankur Arora , Joao Martins , Boris Ostrovsky , Sean Christopherson , graf@amazon.com, iaslan@amazon.de, pdurrant@amazon.com, aagch@amazon.com, fandree@amazon.com, hch@infradead.org Subject: [PATCH v6 19/19] KVM: Add documentation for Xen hypercall and shared_info updates Date: Wed, 3 Feb 2021 15:01:14 +0000 Message-Id: <20210203150114.920335-20-dwmw2@infradead.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210203150114.920335-1-dwmw2@infradead.org> References: <20210203150114.920335-1-dwmw2@infradead.org> MIME-Version: 1.0 Sender: David Woodhouse X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: David Woodhouse Signed-off-by: David Woodhouse --- Documentation/virt/kvm/api.rst | 170 ++++++++++++++++++++++++++++++++- 1 file changed, 165 insertions(+), 5 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 99ceb978c8b0..9c454c5b785c 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -960,6 +960,13 @@ memory. __u8 pad2[30]; }; +If the KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL flag is returned from the +KVM_CAP_XEN_HVM check, it may be set in the flags field of this ioctl. +This requests KVM to generate the contents of the hypercall page +automatically, and also to intercept hypercalls with KVM_EXIT_XEN. +In this case, all of the blob size and address fields must be zero. + +No other flags are currently valid in the struct kvm_xen_hvm_config. 4.29 KVM_GET_CLOCK ------------------ @@ -4831,6 +4838,101 @@ into user space. If a vCPU is in running state while this ioctl is invoked, the vCPU may experience inconsistent filtering behavior on MSR accesses. +4.127 KVM_XEN_HVM_SET_ATTR +-------------------------- + +:Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO +:Architectures: x86 +:Type: vm ioctl +:Parameters: struct kvm_xen_hvm_attr +:Returns: 0 on success, < 0 on error + +:: + + struct kvm_xen_hvm_attr { + __u16 type; + __u16 pad[3]; + union { + __u8 long_mode; + __u8 vector; + struct { + __u64 gfn; + } shared_info; + __u64 pad[4]; + } u; + }; + +type values: + +KVM_XEN_ATTR_TYPE_LONG_MODE + Sets the ABI mode of the VM to 32-bit or 64-bit (long mode). This + determines the layout of the shared info pages exposed to the VM. + +KVM_XEN_ATTR_TYPE_SHARED_INFO + Sets the guest physical frame number at which the Xen "shared info" + page resides. Note that although Xen places vcpu_info for the first + 32 vCPUs in the shared_info page, KVM does not automatically do so + and instead requires that KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO be used + explicitly even when the vcpu_info for a given vCPU resides at the + "default" location in the shared_info page. This is because KVM is + not aware of the Xen CPU id which is used as the index into the + vcpu_info[] array, so cannot know the correct default location. + +KVM_XEN_ATTR_TYPE_UPCALL_VECTOR + Sets the exception vector used to deliver Xen event channel upcalls. + +4.128 KVM_XEN_HVM_GET_ATTR +-------------------------- + +:Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO +:Architectures: x86 +:Type: vm ioctl +:Parameters: struct kvm_xen_hvm_attr +:Returns: 0 on success, < 0 on error + +Allows Xen VM attributes to be read. For the structure and types, +see KVM_XEN_HVM_SET_ATTR above. + +4.129 KVM_XEN_VCPU_SET_ATTR +--------------------------- + +:Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO +:Architectures: x86 +:Type: vcpu ioctl +:Parameters: struct kvm_xen_vcpu_attr +:Returns: 0 on success, < 0 on error + +:: + + struct kvm_xen_vcpu_attr { + __u16 type; + __u16 pad[3]; + union { + __u64 gpa; + __u64 pad[4]; + } u; + }; + +type values: + +KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO + Sets the guest physical address of the vcpu_info for a given vCPU. + +KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO + Sets the guest physical address of an additional pvclock structure + for a given vCPU. This is typically used for guest vsyscall support. + +4.130 KVM_XEN_VCPU_GET_ATTR +-------------------------- + +:Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO +:Architectures: x86 +:Type: vcpu ioctl +:Parameters: struct kvm_xen_vcpu_attr +:Returns: 0 on success, < 0 on error + +Allows Xen vCPU attributes to be read. For the structure and types, +see KVM_XEN_VCPU_SET_ATTR above. 5. The kvm_run structure ======================== @@ -4996,13 +5098,18 @@ to the byte array. .. note:: - For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_PAPR, + For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_PAPR, KVM_EXIT_XEN, KVM_EXIT_EPR, KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR the corresponding operations are complete (and guest state is consistent) only after userspace has re-entered the kernel with KVM_RUN. The kernel side will first finish - incomplete operations and then check for pending signals. Userspace - can re-enter the guest with an unmasked signal pending to complete - pending operations. + incomplete operations and then check for pending signals. + + The pending state of the operation is not preserved in state which is + visible to userspace, thus userspace should ensure that the operation is + completed before performing a live migration. Userspace can re-enter the + guest with an unmasked signal pending or with the immediate_exit field set + to complete pending operations without allowing any further instructions + to be executed. :: @@ -5327,6 +5434,34 @@ wants to write. Once finished processing the event, user space must continue vCPU execution. If the MSR write was unsuccessful, user space also sets the "error" field to "1". +:: + + + struct kvm_xen_exit { + #define KVM_EXIT_XEN_HCALL 1 + __u32 type; + union { + struct { + __u32 longmode; + __u32 cpl; + __u64 input; + __u64 result; + __u64 params[6]; + } hcall; + } u; + }; + /* KVM_EXIT_XEN */ + struct kvm_hyperv_exit xen; + +Indicates that the VCPU exits into userspace to process some tasks +related to Xen emulation. + +Valid values for 'type' are: + + - KVM_EXIT_XEN_HCALL -- synchronously notify user-space about Xen hypercall. + Userspace is expected to place the hypercall result into the appropriate + field before invoking KVM_RUN again. + :: /* Fix the size of the union. */ @@ -6415,7 +6550,6 @@ guest according to the bits in the KVM_CPUID_FEATURES CPUID leaf (0x40000001). Otherwise, a guest may use the paravirtual features regardless of what has actually been exposed through the CPUID leaf. - 8.29 KVM_CAP_DIRTY_LOG_RING --------------------------- @@ -6502,3 +6636,29 @@ KVM_GET_DIRTY_LOG and KVM_CLEAR_DIRTY_LOG. After enabling KVM_CAP_DIRTY_LOG_RING with an acceptable dirty ring size, the virtual machine will switch to ring-buffer dirty page tracking and further KVM_GET_DIRTY_LOG or KVM_CLEAR_DIRTY_LOG ioctls will fail. + +8.30 KVM_CAP_XEN_HVM +-------------------- + +:Architectures: x86 + +This capability indicates the features that Xen supports for hosting Xen +PVHVM guests. Valid flags are:: + + #define KVM_XEN_HVM_CONFIG_HYPERCALL_MSR (1 << 0) + #define KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL (1 << 1) + #define KVM_XEN_HVM_CONFIG_SHARED_INFO (1 << 2) + +The KVM_XEN_HVM_CONFIG_HYPERCALL_MSR flag indicates that the KVM_XEN_HVM_CONFIG +ioctl is available, for the guest to set its hypercall page. + +If KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL is also set, the same flag may also be +provided in the flags to KVM_XEN_HVM_CONFIG, without providing hypercall page +contents, to request that KVM generate hypercall page content automatically +and also enable interception of guest hypercalls with KVM_EXIT_XEN. + +The KVM_XEN_HVM_CONFIG_SHARED_INFO flag indicates the availability of the +KVM_XEN_HVM_SET_ATTR, KVM_XEN_HVM_GET_ATTR, KVM_XEN_VCPU_SET_ATTR and +KVM_XEN_VCPU_GET_ATTR ioctls, as well as the delivery of exception vectors +for event channel upcalls when the evtchn_upcall_pending field of a vcpu's +vcpu_info is set.