From mboxrd@z Thu Jan 1 00:00:00 1970 From: Don Slutz Subject: Re: [PATCH v8 4/7] xen: Add vmware_port support Date: Tue, 10 Feb 2015 14:30:49 -0500 Message-ID: <54DA5C69.1060409@terremark.com> References: <1412285417-19180-1-git-send-email-dslutz@verizon.com> <1412285417-19180-5-git-send-email-dslutz@verizon.com> <542DCA92.1030701@terremark.com> <542DD44F.6030101@terremark.com> <54B8F1740200007800055B42@mail.emea.novell.com> <54BFE768.3090309@terremark.com> <54C0C39F0200007800057F73@mail.emea.novell.com> <54C6643B.1@terremark.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <54C6643B.1@terremark.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Don Slutz , Jan Beulich Cc: Jun Nakajima , Tim Deegan , Kevin Tian , Keir Fraser , Ian Campbell , Stefano Stabellini , George Dunlap , Andrew Cooper , Ian Jackson , xen-devel@lists.xen.org, Eddie Dong , Suravee Suthikulpanit , Boris Ostrovsky List-Id: xen-devel@lists.xenproject.org On 01/26/15 10:58, Don Slutz wrote: > On 01/22/15 03:32, Jan Beulich wrote: >>>>> On 21.01.15 at 18:52, wrote: >>> On 01/16/15 05:09, Jan Beulich wrote: >>>>>>> On 03.10.14 at 00:40, wrote: >>>>> This is a new domain_create() flag, DOMCRF_vmware_port. It is >>>>> passed to domctl as XEN_DOMCTL_CDF_vmware_port. >>>> Can you explain why a HVM param isn't suitable here? >>>> >>> The issue is that you need this flag during construct_vmcb() and >>> construct_vmcs(). While Intel has vmx_update_exception_bitmap() >>> AMD does not. So when HVM param's are setup and/or changed there >>> currently is no way to adjust AMD's exception bitmap. >>> >>> So this is the simpler way. >> But the less desirable one from a design/consistency perspective. >> Unless other maintainers disagree, I'd like to see this changed. > > Ok, but will wait some time to see if "Unless other maintainers disagree" > While coding this is up I have hit issues that I need input on: As a HVM_PARAM_ item, I would assume I should be following what HVM_PARAM_VIRIDIAN does. It has this comment: case HVM_PARAM_VIRIDIAN: /* This should only ever be set once by the tools and read by the guest. */ Which is almost true. However the code allows you to change from 0 to non-zero any time in the life of the DomU. I am assuming that this is why xc_domain_save() and xc_domain_restore() save and restore this HVM_PARAM_ item. With the enable of vmware_port the same way, I feel it would be a bug to allow the enable after "create" to not also adjust QEMU. Currently there is no way for the hypervisor to tell QEMU to enable vmware_port handling. So to avoid adding this code to xen and QEMU, it looks to me that adding code to make this a true write only 1 time would be needed so that you cannot use the hyper call to change later. So, should I extend this change to cover other HVM_PARAM_? Is all this additional code (xc_domain_save(), xc_domain_restore(), write only 1 time) still better then a domain_create() flag? -Don Slutz