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Message-ID: <8afe2703-cabd-3d60-ccf0-084666bfcaaa@oracle.com>
Date: Tue, 18 Jun 2019 19:38:51 -0700
From: Ankur Arora <ankur.a.arora@...cle.com>
To: Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
xen-devel@...ts.xenproject.org
Cc: pbonzini@...hat.com, boris.ostrovsky@...cle.com,
konrad.wilk@...cle.com, sstabellini@...nel.org,
joao.m.martins@...cle.com
Subject: Re: [RFC PATCH 12/16] xen/xenbus: support xenbus frontend/backend
with xenhost_t
On 6/17/19 2:50 AM, Juergen Gross wrote:
> On 09.05.19 19:25, Ankur Arora wrote:
>> As part of xenbus init, both frontend, backend interfaces need to talk
>> on the correct xenbus. This might be a local xenstore (backend) or might
>> be a XS_PV/XS_HVM interface (frontend) which needs to talk over xenbus
>> with the remote xenstored. We bootstrap all of these with evtchn/gfn
>> parameters from (*setup_xs)().
>>
>> Given this we can do appropriate device discovery (in case of frontend)
>> and device connectivity for the backend.
>> Once done, we stash the xenhost_t * in xen_bus_type, xenbus_device or
>> xenbus_watch and then the frontend and backend devices implicitly use
>> the correct interface.
>>
>> The rest of patch is just changing the interfaces where needed.
>>
>> Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
>> ---
>> drivers/block/xen-blkback/blkback.c | 10 +-
>> drivers/net/xen-netfront.c | 14 +-
>> drivers/pci/xen-pcifront.c | 4 +-
>> drivers/xen/cpu_hotplug.c | 4 +-
>> drivers/xen/manage.c | 28 +--
>> drivers/xen/xen-balloon.c | 8 +-
>> drivers/xen/xenbus/xenbus.h | 45 ++--
>> drivers/xen/xenbus/xenbus_client.c | 32 +--
>> drivers/xen/xenbus/xenbus_comms.c | 121 +++++-----
>> drivers/xen/xenbus/xenbus_dev_backend.c | 30 ++-
>> drivers/xen/xenbus/xenbus_dev_frontend.c | 22 +-
>> drivers/xen/xenbus/xenbus_probe.c | 246 +++++++++++++--------
>> drivers/xen/xenbus/xenbus_probe_backend.c | 19 +-
>> drivers/xen/xenbus/xenbus_probe_frontend.c | 65 +++---
>> drivers/xen/xenbus/xenbus_xs.c | 188 +++++++++-------
>> include/xen/xen-ops.h | 3 +
>> include/xen/xenbus.h | 54 +++--
>> include/xen/xenhost.h | 20 ++
>> 18 files changed, 536 insertions(+), 377 deletions(-)
>>
>> diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c
>> b/drivers/xen/xenbus/xenbus_dev_frontend.c
>> index c3e201025ef0..d6e0c397c6a0 100644
>> --- a/drivers/xen/xenbus/xenbus_dev_frontend.c
>> +++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
>> @@ -58,10 +58,14 @@
>> #include <xen/xenbus.h>
>> #include <xen/xen.h>
>> +#include <xen/interface/xen.h>
>> +#include <xen/xenhost.h>
>> #include <asm/xen/hypervisor.h>
>> #include "xenbus.h"
>> +static xenhost_t *xh;
>> +
>> /*
>> * An element of a list of outstanding transactions, for which we're
>> * still waiting a reply.
>> @@ -312,13 +316,13 @@ static void xenbus_file_free(struct kref *kref)
>> */
>> list_for_each_entry_safe(trans, tmp, &u->transactions, list) {
>> - xenbus_transaction_end(trans->handle, 1);
>> + xenbus_transaction_end(xh, trans->handle, 1);
>> list_del(&trans->list);
>> kfree(trans);
>> }
>> list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) {
>> - unregister_xenbus_watch(&watch->watch);
>> + unregister_xenbus_watch(xh, &watch->watch);
>> list_del(&watch->list);
>> free_watch_adapter(watch);
>> }
>> @@ -450,7 +454,7 @@ static int xenbus_write_transaction(unsigned
>> msg_type,
>> (!strcmp(msg->body, "T") || !strcmp(msg->body, "F"))))
>> return xenbus_command_reply(u, XS_ERROR, "EINVAL");
>> - rc = xenbus_dev_request_and_reply(&msg->hdr, u);
>> + rc = xenbus_dev_request_and_reply(xh, &msg->hdr, u);
>> if (rc && trans) {
>> list_del(&trans->list);
>> kfree(trans);
>> @@ -489,7 +493,7 @@ static int xenbus_write_watch(unsigned msg_type,
>> struct xenbus_file_priv *u)
>> watch->watch.callback = watch_fired;
>> watch->dev_data = u;
>> - err = register_xenbus_watch(&watch->watch);
>> + err = register_xenbus_watch(xh, &watch->watch);
>> if (err) {
>> free_watch_adapter(watch);
>> rc = err;
>> @@ -500,7 +504,7 @@ static int xenbus_write_watch(unsigned msg_type,
>> struct xenbus_file_priv *u)
>> list_for_each_entry(watch, &u->watches, list) {
>> if (!strcmp(watch->token, token) &&
>> !strcmp(watch->watch.node, path)) {
>> - unregister_xenbus_watch(&watch->watch);
>> + unregister_xenbus_watch(xh, &watch->watch);
>> list_del(&watch->list);
>> free_watch_adapter(watch);
>> break;
>> @@ -618,8 +622,9 @@ static ssize_t xenbus_file_write(struct file *filp,
>> static int xenbus_file_open(struct inode *inode, struct file *filp)
>> {
>> struct xenbus_file_priv *u;
>> + struct xenstore_private *xs = xs_priv(xh);
>> - if (xen_store_evtchn == 0)
>> + if (xs->store_evtchn == 0)
>> return -ENOENT;
>> nonseekable_open(inode, filp);
>> @@ -687,6 +692,11 @@ static int __init xenbus_init(void)
>> if (!xen_domain())
>> return -ENODEV;
>> + if (xen_driver_domain() && xen_nested())
>> + xh = xh_remote;
>> + else
>> + xh = xh_default;
>
> This precludes any mixed use of L0 and L1 frontends. With this move you
> make it impossible to e.g. use a driver domain for networking in L1 with
> a L1-local PV disk, or pygrub in L1 dom0.
Ah, yes. I hadn't thought about that case.
Let me see how I can rework this interface.
Ankur
>
>
> Juergen
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