From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Wei Liu <wei.liu2@citrix.com>,
ross.lagerwall@citrix.com, andrew.cooper3@citrix.com,
Ian Jackson <ian.jackson@eu.citrix.com>,
mpohlack@amazon.de, sasha.levin@oracle.com,
xen-devel@lists.xenproject.org,
Daniel De Graaf <dgdegra@tycho.nsa.gov>
Subject: Re: [PATCH v9 04/27] xen/xsplice: Hypervisor implementation of XEN_XSPLICE_op
Date: Tue, 26 Apr 2016 13:50:03 -0400 [thread overview]
Message-ID: <20160426174954.GA6301@localhost.localdomain> (raw)
In-Reply-To: <571F5D3602000078000E5BE0@prv-mh.provo.novell.com>
On Tue, Apr 26, 2016 at 04:21:10AM -0600, Jan Beulich wrote:
> >>> On 25.04.16 at 17:34, <konrad.wilk@oracle.com> wrote:
> > The implementation does not actually do any patching.
> >
> > It just adds the framework for doing the hypercalls,
> > keeping track of ELF payloads, and the basic operations:
> > - query which payloads exist,
> > - query for specific payloads,
> > - check*1, apply*1, replace*1, and unload payloads.
> >
> > *1: Which of course in this patch are nops.
> >
> > The functionality is disabled on ARM until all arch
> > components are implemented.
> >
> > Also by default it is disabled until the implementation
> > is in place.
> >
> > We also use recursive spinlocks to so that the find_payload
> > function does not need to have a 'lock' and 'non-lock' variant.
> >
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
> > Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
> > Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
>
> I'm hesitant to say that, but with all of this:
>
> > v9:
> > s/find_name/get_name/, drop locks when allocating data.
> > Drop conditional expression on copyback
> > Move the allocation on upload outside the spinlock.
> > Add (TECH PREVIEW) to the Kconfig help
> > Return -EINVAL if the CHECK or UNLOAD action is to be performed and the payload
> > state is not in expected state.
> > Print 'c' not 'u' when invoking the keyhandler.
>
> ... I'm not sure the earlier R-b can still be considered valid. Andrew?
I don't know what the criteria is for dropping an Reviewed-by.
I am happy to drop it if you would like - but it may be that Andrew
is OK with the way he had his review?
Or is this more of your view as maintainer - that is the patch
changed considerably (and what is that? percentage of the patch?
small amount of the patch? Trivial changes? Dropping code?)?
>
> > +static int get_name(const xen_xsplice_name_t *name, char *n)
> > +{
> > + if ( !name->size || name->size > XEN_XSPLICE_NAME_SIZE )
> > + return -EINVAL;
> > +
> > + if ( name->pad[0] || name->pad[1] || name->pad[2] )
> > + return -EINVAL;
> > +
> > + if ( !guest_handle_okay(name->name, name->size) )
> > + return -EINVAL;
> > +
> > + if ( __copy_from_guest(n, name->name, name->size) )
> > + return -EFAULT;
>
> Quoting part of my v8.1 reply:
> "Is there a particular reason why you open code copy_from_guest() here?"
You mean why I use guest_handle_okay and __copy_from_guest instead of
say copy_from_guest?
I think it is an artificat of earlier changes - in which the find_name
would only check 'name-size' and then in another function we would
just do '__copy_from_guest'. But that is not needed anymore - so let
me change it to 'copy_from_guest'
I thought at some point you asked for that as the check was done for
it once and there was no point
>
> > +static int xsplice_upload(xen_sysctl_xsplice_upload_t *upload)
> > +{
> > + struct payload *data, *found;
> > + char n[XEN_XSPLICE_NAME_SIZE];
> > + int rc;
> > +
> > + rc = verify_payload(upload, n);
> > + if ( rc )
> > + return rc;
> > +
> > + data = xzalloc(struct payload);
> > +
> > + spin_lock(&payload_lock);
> > +
> > + found = find_payload(n);
> > + if ( IS_ERR(found) )
> > + {
> > + rc = PTR_ERR(found);
> > + goto out;
> > + }
> > + else if ( found )
> > + {
> > + rc = -EEXIST;
> > + goto out;
> > + }
> > +
> > + if ( !data )
> > + {
> > + rc = -ENOMEM;
> > + goto out;
> > + }
> > +
> > + rc = 0;
>
> rc is already zero by the time we get here.
>
> I also wonder whether the code wouldn't be easier to read if you
> used just a sequence of if()/else if() here, without any goto-s.
But I do need to free(data) and unlock the spinlock - so having
a common code to pass through makes sense.
Unless you mean have an condition on if ( !rc ), and do the normal path?
Like so:
rc = verify_payload(upload, n);
if ( rc )
return rc;
data = xzalloc(struct payload);
spin_lock(&payload_lock);
found = find_payload(n);
if ( IS_ERR(found) )
rc = PTR_ERR(found);
else if ( found )
rc = -EEXIST;
if ( !rc && !data )
rc = -ENOMEM;
if ( !rc )
{
memcpy(data->name, n, strlen(n));
data->state = XSPLICE_STATE_CHECKED;
INIT_LIST_HEAD(&data->list);
list_add_tail(&data->list, &payload_list);
payload_cnt++;
payload_version++;
}
spin_unlock(&payload_lock);
if ( rc )
xfree(data);
return rc;
That looks fine here, but in the subsequent patch I have to also
check for
if ( __copy_from_guest(raw_data, upload->payload, upload->size) )
and
rc = load_payload_data(data, raw_data, upload->size);
and goto statement help a lot there.
I would rather have it the way it is now if you are OK with that?
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next prev parent reply other threads:[~2016-04-26 17:50 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-25 15:34 [PATCH 9] xSplice v1 design and implementation Konrad Rzeszutek Wilk
2016-04-25 15:34 ` [PATCH v9 01/27] Revert "libxc/libxl/python/xenstat/ocaml: Use new XEN_VERSION hypercall" Konrad Rzeszutek Wilk
2016-04-25 15:48 ` Jan Beulich
2016-04-25 15:53 ` Wei Liu
2016-04-25 15:34 ` [PATCH v9 02/27] Revert "HYPERCALL_version_op. New hypercall mirroring XENVER_ but sane." Konrad Rzeszutek Wilk
2016-04-25 15:34 ` [PATCH v9 03/27] xsplice: Design document Konrad Rzeszutek Wilk
2016-04-25 15:34 ` [PATCH v9 04/27] xen/xsplice: Hypervisor implementation of XEN_XSPLICE_op Konrad Rzeszutek Wilk
2016-04-26 7:48 ` Ross Lagerwall
2016-04-26 7:52 ` Ross Lagerwall
2016-04-26 10:21 ` Jan Beulich
2016-04-26 17:50 ` Konrad Rzeszutek Wilk [this message]
2016-04-27 6:51 ` Jan Beulich
2016-04-27 13:47 ` Konrad Rzeszutek Wilk
2016-04-27 14:11 ` Jan Beulich
2016-04-25 15:34 ` [PATCH v9 05/27] libxc: Implementation of XEN_XSPLICE_op in libxc Konrad Rzeszutek Wilk
2016-04-26 7:51 ` Ross Lagerwall
2016-04-25 15:34 ` [PATCH v9 06/27] xen-xsplice: Tool to manipulate xsplice payloads Konrad Rzeszutek Wilk
2016-04-26 7:49 ` Ross Lagerwall
2016-04-25 15:34 ` [PATCH v9 07/27] arm/x86: Use struct virtual_region to do bug, symbol, and (x86) exception tables lookup Konrad Rzeszutek Wilk
2016-04-26 10:31 ` Jan Beulich
2016-04-25 15:34 ` [PATCH v9 08/27] arm/x86/vmap: Add v[z|m]alloc_xen and vm_init_type Konrad Rzeszutek Wilk
2016-04-26 10:47 ` Jan Beulich
2016-04-27 2:38 ` Konrad Rzeszutek Wilk
2016-04-27 7:12 ` Jan Beulich
2016-04-27 13:46 ` Konrad Rzeszutek Wilk
2016-04-27 14:15 ` Jan Beulich
2016-04-25 15:34 ` [PATCH v9 09/27] x86/mm: Introduce modify_xen_mappings() Konrad Rzeszutek Wilk
2016-04-25 15:34 ` [PATCH v9 10/27] xsplice: Add helper elf routines Konrad Rzeszutek Wilk
2016-04-26 10:05 ` Ross Lagerwall
2016-04-26 11:52 ` Jan Beulich
2016-04-26 12:37 ` Jan Beulich
2016-04-27 1:59 ` Konrad Rzeszutek Wilk
2016-04-27 7:27 ` Jan Beulich
2016-04-27 14:00 ` Konrad Rzeszutek Wilk
2016-04-27 4:06 ` Konrad Rzeszutek Wilk
2016-04-27 7:52 ` Jan Beulich
2016-04-27 18:45 ` Konrad Rzeszutek Wilk
2016-04-25 15:34 ` [PATCH v9 11/27] xsplice: Implement payload loading Konrad Rzeszutek Wilk
2016-04-26 10:48 ` Ross Lagerwall
2016-04-26 13:39 ` Jan Beulich
2016-04-27 1:47 ` Konrad Rzeszutek Wilk
2016-04-27 7:57 ` Jan Beulich
2016-04-27 3:28 ` Konrad Rzeszutek Wilk
2016-04-27 8:28 ` Jan Beulich
2016-04-27 15:48 ` Konrad Rzeszutek Wilk
2016-04-27 16:06 ` Jan Beulich
2016-04-27 16:14 ` Jan Beulich
2016-04-27 18:40 ` Konrad Rzeszutek Wilk
2016-04-25 15:34 ` [PATCH v9 12/27] xsplice: Implement support for applying/reverting/replacing patches Konrad Rzeszutek Wilk
2016-04-26 15:21 ` Jan Beulich
2016-04-27 3:39 ` Konrad Rzeszutek Wilk
2016-04-27 8:36 ` Jan Beulich
2016-05-11 9:51 ` Martin Pohlack
2016-05-11 13:56 ` Konrad Rzeszutek Wilk
2016-04-25 15:35 ` [PATCH v9 13/27] x86/xen_hello_world.xsplice: Test payload for patching 'xen_extra_version' Konrad Rzeszutek Wilk
2016-04-26 15:31 ` Jan Beulich
2016-04-25 15:35 ` [PATCH v9 14/27] xsplice, symbols: Implement symbol name resolution on address Konrad Rzeszutek Wilk
2016-04-26 15:48 ` Jan Beulich
2016-04-25 15:35 ` [PATCH v9 15/27] xsplice, symbols: Implement fast symbol names -> virtual addresses lookup Konrad Rzeszutek Wilk
2016-04-26 15:53 ` Jan Beulich
2016-04-25 15:35 ` [PATCH v9 16/27] x86, xsplice: Print payload's symbol name and payload name in backtraces Konrad Rzeszutek Wilk
2016-04-26 11:06 ` Ross Lagerwall
2016-04-26 12:41 ` Jan Beulich
2016-04-26 12:48 ` Ross Lagerwall
2016-04-26 13:41 ` Jan Beulich
2016-04-27 3:31 ` Konrad Rzeszutek Wilk
2016-04-27 8:37 ` Jan Beulich
2016-04-25 15:35 ` [PATCH v9 17/27] xsplice: Add support for bug frames Konrad Rzeszutek Wilk
2016-04-26 11:05 ` Ross Lagerwall
2016-04-26 13:08 ` Ross Lagerwall
2016-04-26 15:58 ` Jan Beulich
2016-04-25 15:35 ` [PATCH v9 18/27] xsplice: Add support for exception tables Konrad Rzeszutek Wilk
2016-04-26 16:01 ` Jan Beulich
2016-04-25 15:35 ` [PATCH v9 19/27] xsplice: Add support for alternatives Konrad Rzeszutek Wilk
2016-04-27 8:58 ` Jan Beulich
2016-04-25 15:35 ` [PATCH v9 20/27] build_id: Provide ld-embedded build-ids Konrad Rzeszutek Wilk
2016-04-25 15:35 ` [PATCH v9 21/27] xsplice: Print build_id in keyhandler and on bootup Konrad Rzeszutek Wilk
2016-04-25 15:35 ` [PATCH v9 22/27] XENVER_build_id/libxc: Provide ld-embedded build-id Konrad Rzeszutek Wilk
2016-04-25 15:35 ` [PATCH v9 23/27] libxl: info: Display build_id of the hypervisor Konrad Rzeszutek Wilk
2016-04-25 15:35 ` [PATCH v9 24/27] xsplice: Stacking build-id dependency checking Konrad Rzeszutek Wilk
2016-04-27 9:27 ` Jan Beulich
2016-04-27 16:36 ` Konrad Rzeszutek Wilk
2016-04-28 9:47 ` Jan Beulich
2016-04-25 15:35 ` [PATCH v9 25/27] xsplice/xen_replace_world: Test-case for XSPLICE_ACTION_REPLACE Konrad Rzeszutek Wilk
2016-04-25 15:35 ` [PATCH v9 26/27] xsplice: Prevent duplicate payloads from being loaded Konrad Rzeszutek Wilk
2016-04-27 9:31 ` Jan Beulich
2016-04-25 15:35 ` [PATCH v9 27/27] MAINTAINERS/xsplice: Add myself and Ross as the maintainers Konrad Rzeszutek Wilk
2016-04-25 15:41 ` [PATCH 9] xSplice v1 design and implementation Jan Beulich
2016-04-25 15:47 ` Konrad Rzeszutek Wilk
2016-04-25 15:54 ` Jan Beulich
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