Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754780Ab2HAKvm (ORCPT ); Wed, 1 Aug 2012 06:51:42 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:36936 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754366Ab2HAKvj (ORCPT ); Wed, 1 Aug 2012 06:51:39 -0400 Message-ID: <5019099D.9050608@linux.vnet.ibm.com> Date: Wed, 01 Aug 2012 16:19:01 +0530 From: Raghavendra K T Organization: IBM User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 MIME-Version: 1.0 To: Marcelo Tosatti CC: Rob Landley , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Alexander Graf , Randy Dunlap , KVM , "H. Peter Anvin" , Gleb Natapov , Ingo Molnar , Avi Kivity , Jan Kiszka Subject: Re: [PATCH] Documentation/kvm : Add documentation on Hypercalls References: <20120724085359.11344.91022.sendpatchset@codeblue.in.ibm.com> <20120801030736.GA31711@amt.cnet> In-Reply-To: <20120801030736.GA31711@amt.cnet> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit x-cbid: 12080110-9264-0000-0000-000002099958 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3025 Lines: 74 On 08/01/2012 08:37 AM, Marcelo Tosatti wrote: > On Tue, Jul 24, 2012 at 02:23:59PM +0530, Raghavendra K T wrote: >> 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 >> >> 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. > > vmcall. How is this: KVM Hypercalls have a three-byte sequence of vmcall instruction. But The hypervisor can replace it with the instructions that are guaranteed to be supported. (Related question: Is it not that vmcall instruction is patched by 0f 01 09 vmmcall instruction sequence for amd?. So I think we need to change documentation I referred from arch/x86/include/asm/kvm_para.h. It should be vmcall / vmmcall instead of vmrun and vmmrun) > >> + >> + 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. > > It depends on the hypercall. It happens that current hypercalls use > the four registers, but its not an ABI (hyper-v hypercalls uses r8, for example). > Okay, agree. I did not know about hyper-v. Above one is for X86 and KVM (and not X86 / hyper-v). So I should remove ABI and probably say, KVM x86 Hypercall ================== 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/