From patchwork Tue Jul 24 08:53:59 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Raghavendra K T X-Patchwork-Id: 1230571 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id D9BA8DF25A for ; Tue, 24 Jul 2012 08:57:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752162Ab2GXI4y (ORCPT ); Tue, 24 Jul 2012 04:56:54 -0400 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:56528 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751947Ab2GXI4x (ORCPT ); Tue, 24 Jul 2012 04:56:53 -0400 Received: from /spool/local by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Peter Anvin" , Raghavendra K T , Marcelo Tosatti , Gleb Natapov , Ingo Molnar , Avi Kivity , Jan Kiszka Date: Tue, 24 Jul 2012 14:23:59 +0530 Message-Id: <20120724085359.11344.91022.sendpatchset@codeblue.in.ibm.com> Subject: [PATCH] Documentation/kvm : Add documentation on Hypercalls x-cbid: 12072408-3568-0000-0000-00000230B2D4 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Raghavendra K T Thanks Alex for KVM_HC_FEATURES inputs and Jan for VAPIC_POLL_IRQ, and Peter (HPA) for suggesting hypercall ABI addition. Signed-off-by: Raghavendra K T --- Please have a closer look at Hypercall ABI newly added Changes since last post: - Added hypercall ABI (Peter) - made KVM_HC_VAPIC_POLL_IRQ active explicitly (Randy) TODO: We need to add history details of each hypercall as suggested by HPA, which I could not trace easily. Hope it is easy for hypercall authors Documentation/virtual/hypercalls.txt | 71 ++++++++++++++++++++++++++++++++++ 1 files changed, 71 insertions(+), 0 deletions(-) create mode 100644 Documentation/virtual/hypercalls.txt -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/Documentation/virtual/hypercalls.txt b/Documentation/virtual/hypercalls.txt new file mode 100644 index 0000000..caffc08 --- /dev/null +++ b/Documentation/virtual/hypercalls.txt @@ -0,0 +1,71 @@ +Hypercall ABI: +============= +A brief look at calling conventions of X86, S390 and PPC +X86: + KVM Hypercalls have a three-byte sequence of either the vmrun or the vmmrun + instruction. The hypervisor can replace it with instructions that are + guaranteed to be supported. + + Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively. + The hypercall number should be placed in rax and the return value will be + placed in rax. No other registers will be clobbered unless explicitly stated + by the particular hypercall. + +S390: + R2-R7 are used for parameters 1-6. In addition, R1 is used for hypercall + number. The return value is written to R2. + + S390 uses diagnose instruction as hypercall (0x500) along with hypercall + number in R1. + + PoewerPC: + It uses R3-R10 and hypercall number in R11. R4-R11 are used as output registers. + Return value is placed in R3. + + KVM hypercalls uses 4 byte opcode, that are patched with 'hypercall-instructions' + property inside the device tree's /hypervisor node. + For more information refer to Documentation/virtual/kvm/ppc-pv.txt + +KVM Hypercalls Documentation +=========================== +The template for each hypercall is: +1. Hypercall name, value. +2. Architecture(s) +3. Status (deprecated, obsolete, active) +4. Purpose + +1. KVM_HC_VAPIC_POLL_IRQ +------------------------ +Value: 1 +Architecture: x86 +Status: active +Purpose: Trigger guest exit so that the host can check for pending +interrupts on reentry. + +2. KVM_HC_MMU_OP +------------------------ +Value: 2 +Architecture: x86 +Status: deprecated. +Purpose: Support MMU operations such as writing to PTE, +flushing TLB, release PT. + +3. KVM_HC_FEATURES +------------------------ +Value: 3 +Architecture: PPC +Status: active +Purpose: Expose hypercall availability to the guest. On x86 platforms, cpuid +used to enumerate which hypercalls are available. On PPC, either device tree +based lookup ( which is also what EPAPR dictates) OR KVM specific enumeration +mechanism (which is this hypercall) can be used. + +4. KVM_HC_PPC_MAP_MAGIC_PAGE +------------------------ +Value: 4 +Architecture: PPC +Status: active +Purpose: To enable communication between the hypervisor and guest there is a +shared page that contains parts of supervisor visible register state. +The guest can map this shared page to access its supervisor register through +memory using this hypercall.