Xen-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Joao Martins <joao.m.martins@oracle.com>
To: Juergen Gross <jgross@suse.com>
Cc: sstabellini@kernel.org, konrad.wilk@oracle.com,
	linux-kernel@vger.kernel.org,
	Ankur Arora <ankur.a.arora@oracle.com>,
	pbonzini@redhat.com, xen-devel@lists.xenproject.org,
	boris.ostrovsky@oracle.com
Subject: Re: [Xen-devel] [RFC PATCH 00/16] xenhost support
Date: Fri, 7 Jun 2019 16:22:56 +0100
Message-ID: <ede6db03-121c-9ec6-f8eb-dbcc605977b4@oracle.com> (raw)
In-Reply-To: <5649cfd1-24df-2196-2888-b00fc3ace7ad@suse.com>

On 6/7/19 3:51 PM, Juergen Gross wrote:
> On 09.05.19 19:25, Ankur Arora wrote:
>> Hi all,
>>
>> This is an RFC for xenhost support, outlined here by Juergen here:
>> https://lkml.org/lkml/2019/4/8/67.
> 
> First: thanks for all the effort you've put into this series!
> 
>> The high level idea is to provide an abstraction of the Xen
>> communication interface, as a xenhost_t.
>>
>> xenhost_t expose ops for communication between the guest and Xen
>> (hypercall, cpuid, shared_info/vcpu_info, evtchn, grant-table and on top
>> of those, xenbus, ballooning), and these can differ based on the kind
>> of underlying Xen: regular, local, and nested.
> 
> I'm not sure we need to abstract away hypercalls and cpuid. I believe in
> case of nested Xen all contacts to the L0 hypervisor should be done via
> the L1 hypervisor. So we might need to issue some kind of passthrough
> hypercall when e.g. granting a page to L0 dom0, but this should be
> handled via the grant abstraction (events should be similar).
> 
Just to be clear: By "kind of passthrough hypercall" you mean (e.g. for every
access/modify of grant table frames) you would proxy hypercall to L0 Xen via L1 Xen?

> So IMO we should drop patches 2-5.
> 
>> (Since this abstraction is largely about guest -- xenhost communication,
>> no ops are needed for timer, clock, sched, memory (MMU, P2M), VCPU mgmt.
>> etc.)
>>
>> Xenhost use-cases:
>>
>> Regular-Xen: the standard Xen interface presented to a guest,
>> specifically for comunication between Lx-guest and Lx-Xen.
>>
>> Local-Xen: a Xen like interface which runs in the same address space as
>> the guest (dom0). This, can act as the default xenhost.
>>
>> The major ways it differs from a regular Xen interface is in presenting
>> a different hypercall interface (call instead of a syscall/vmcall), and
>> in an inability to do grant-mappings: since local-Xen exists in the same
>> address space as Xen, there's no way for it to cheaply change the
>> physical page that a GFN maps to (assuming no P2M tables.)
>>
>> Nested-Xen: this channel is to Xen, one level removed: from L1-guest to
>> L0-Xen. The use case is that we want L0-dom0-backends to talk to
>> L1-dom0-frontend drivers which can then present PV devices which can
>> in-turn be used by the L1-dom0-backend drivers as raw underlying devices.
>> The interfaces themselves, broadly remain similar.
>>
>> Note: L0-Xen, L1-Xen represent Xen running at that nesting level
>> and L0-guest, L1-guest represent guests that are children of Xen
>> at that nesting level. Lx, represents any level.
>>
>> Patches 1-7,
>>    "x86/xen: add xenhost_t interface"
>>    "x86/xen: cpuid support in xenhost_t"
>>    "x86/xen: make hypercall_page generic"
>>    "x86/xen: hypercall support for xenhost_t"
>>    "x86/xen: add feature support in xenhost_t"
>>    "x86/xen: add shared_info support to xenhost_t"
>>    "x86/xen: make vcpu_info part of xenhost_t"
>> abstract out interfaces that setup hypercalls/cpuid/shared_info/vcpu_info etc.
>>
>> Patch 8, "x86/xen: irq/upcall handling with multiple xenhosts"
>> sets up the upcall and pv_irq ops based on vcpu_info.
>>
>> Patch 9, "xen/evtchn: support evtchn in xenhost_t" adds xenhost based
>> evtchn support for evtchn_2l.
>>
>> Patches 10 and 16, "xen/balloon: support ballooning in xenhost_t" and
>> "xen/grant-table: host_addr fixup in mapping on xenhost_r0"
>> implement support from GNTTABOP_map_grant_ref for xenhosts of type
>> xenhost_r0 (xenhost local.)
>>
>> Patch 12, "xen/xenbus: support xenbus frontend/backend with xenhost_t"
>> makes xenbus so that both its frontend and backend can be bootstrapped
>> separately via separate xenhosts.
>>
>> Remaining patches, 11, 13, 14, 15:
>>    "xen/grant-table: make grant-table xenhost aware"
>>    "drivers/xen: gnttab, evtchn, xenbus API changes"
>>    "xen/blk: gnttab, evtchn, xenbus API changes"
>>    "xen/net: gnttab, evtchn, xenbus API changes"
>> are mostly mechanical changes for APIs that now take xenhost_t *
>> as parameter.
>>
>> The code itself is RFC quality, and is mostly meant to get feedback before
>> proceeding further. Also note that the FIFO logic and some Xen drivers
>> (input, pciback, scsi etc) are mostly unchanged, so will not build.
>>
>>
>> Please take a look.
> 
> 
> Juergen
> 

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  reply index

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-09 17:25 Ankur Arora
2019-05-09 17:25 ` [Xen-devel] [RFC PATCH 01/16] x86/xen: add xenhost_t interface Ankur Arora
2019-06-07 15:04   ` Juergen Gross
2019-06-11  7:16     ` Ankur Arora
2019-06-14 11:52       ` Juergen Gross
2019-05-09 17:25 ` Ankur Arora
2019-05-09 17:25 ` [RFC PATCH 02/16] x86/xen: cpuid support in xenhost_t Ankur Arora
2019-05-09 17:25   ` [Xen-devel] " Ankur Arora
2019-06-12 21:09   ` Andrew Cooper
2019-05-09 17:25 ` [Xen-devel] [RFC PATCH 03/16] x86/xen: make hypercall_page generic Ankur Arora
2019-05-09 17:25 ` Ankur Arora
2019-05-09 17:25 ` [RFC PATCH 04/16] x86/xen: hypercall support for xenhost_t Ankur Arora
2019-05-09 17:25 ` [Xen-devel] " Ankur Arora
2019-06-12 21:15   ` Andrew Cooper
2019-06-14  7:20     ` Ankur Arora
2019-06-14  7:35       ` Juergen Gross
2019-06-14  8:00         ` Andrew Cooper
2019-05-09 17:25 ` [RFC PATCH 05/16] x86/xen: add feature support in xenhost_t Ankur Arora
2019-05-09 17:25 ` [Xen-devel] " Ankur Arora
2019-05-09 17:25 ` [Xen-devel] [RFC PATCH 06/16] x86/xen: add shared_info support to xenhost_t Ankur Arora
2019-06-07 15:08   ` Juergen Gross
2019-06-08  5:01     ` Ankur Arora
2019-05-09 17:25 ` Ankur Arora
2019-05-09 17:25 ` [RFC PATCH 07/16] x86/xen: make vcpu_info part of xenhost_t Ankur Arora
2019-05-09 17:25   ` [Xen-devel] " Ankur Arora
2019-06-14 11:53   ` Juergen Gross
2019-06-17  6:28     ` Ankur Arora
2019-05-09 17:25 ` [RFC PATCH 08/16] x86/xen: irq/upcall handling with multiple xenhosts Ankur Arora
2019-05-09 17:25 ` [Xen-devel] " Ankur Arora
2019-06-14 12:01   ` Juergen Gross
2019-05-09 17:25 ` [RFC PATCH 09/16] xen/evtchn: support evtchn in xenhost_t Ankur Arora
2019-05-09 17:25 ` [Xen-devel] " Ankur Arora
2019-06-14 12:04   ` Juergen Gross
2019-06-17  6:09     ` Ankur Arora
2019-05-09 17:25 ` [RFC PATCH 10/16] xen/balloon: support ballooning " Ankur Arora
2019-05-09 17:25 ` [Xen-devel] " Ankur Arora
2019-06-17  9:28   ` Juergen Gross
2019-06-19  2:24     ` Ankur Arora
2019-05-09 17:25 ` [RFC PATCH 11/16] xen/grant-table: make grant-table xenhost aware Ankur Arora
2019-05-09 17:25   ` [Xen-devel] " Ankur Arora
2019-06-17  9:36   ` Juergen Gross
2019-06-19  2:25     ` Ankur Arora
2019-05-09 17:25 ` [RFC PATCH 12/16] xen/xenbus: support xenbus frontend/backend with xenhost_t Ankur Arora
2019-05-09 17:25 ` [Xen-devel] " Ankur Arora
2019-06-17  9:50   ` Juergen Gross
2019-06-19  2:38     ` Ankur Arora
2019-05-09 17:25 ` [Xen-devel] [RFC PATCH 13/16] drivers/xen: gnttab, evtchn, xenbus API changes Ankur Arora
2019-06-17 10:07   ` Juergen Gross
2019-06-19  2:55     ` Ankur Arora
2019-05-09 17:25 ` Ankur Arora
2019-05-09 17:25 ` [Xen-devel] [RFC PATCH 14/16] xen/blk: " Ankur Arora
2019-06-17 10:14   ` Juergen Gross
2019-06-19  2:59     ` Ankur Arora
2019-05-09 17:25 ` Ankur Arora
2019-05-09 17:25 ` [RFC PATCH 15/16] xen/net: " Ankur Arora
2019-05-09 17:25 ` [Xen-devel] " Ankur Arora
2019-06-17 10:14   ` Juergen Gross
2019-05-09 17:25 ` [Xen-devel] [RFC PATCH 16/16] xen/grant-table: host_addr fixup in mapping on xenhost_r0 Ankur Arora
2019-06-17 10:55   ` Juergen Gross
2019-06-19  3:02     ` Ankur Arora
2019-05-09 17:25 ` Ankur Arora
2019-06-07 14:51 ` [Xen-devel] [RFC PATCH 00/16] xenhost support Juergen Gross
2019-06-07 15:22   ` Joao Martins [this message]
2019-06-07 16:21     ` Juergen Gross
2019-06-08  5:50       ` Ankur Arora
2019-06-08  5:33   ` Ankur Arora

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=ede6db03-121c-9ec6-f8eb-dbcc605977b4@oracle.com \
    --to=joao.m.martins@oracle.com \
    --cc=ankur.a.arora@oracle.com \
    --cc=boris.ostrovsky@oracle.com \
    --cc=jgross@suse.com \
    --cc=konrad.wilk@oracle.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=sstabellini@kernel.org \
    --cc=xen-devel@lists.xenproject.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Xen-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/xen-devel/0 xen-devel/git/0.git
	git clone --mirror https://lore.kernel.org/xen-devel/1 xen-devel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 xen-devel xen-devel/ https://lore.kernel.org/xen-devel \
		xen-devel@lists.xenproject.org xen-devel@lists.xen.org xen-devel@archiver.kernel.org
	public-inbox-index xen-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.xenproject.lists.xen-devel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox