From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: Tamas K Lengyel <tamas@tklengyel.com>,
Tamas K Lengyel <tamas.lengyel@intel.com>, Wei Liu <wl@xen.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>,
George Dunlap <george.dunlap@citrix.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Xen-devel <xen-devel@lists.xenproject.org>,
Julien Grall <julien@xen.org>
Subject: Re: [Xen-devel] [PATCH v12 1/3] xen/mem_sharing: VM forking
Date: Thu, 26 Mar 2020 09:42:50 +0100 [thread overview]
Message-ID: <20200326084250.GH28601@Air-de-Roger> (raw)
In-Reply-To: <a3ff04a8-a3ec-9726-373a-56dcdc9927ac@suse.com>
On Thu, Mar 26, 2020 at 08:02:22AM +0100, Jan Beulich wrote:
> On 25.03.2020 17:54, Roger Pau Monné wrote:
> > On Wed, Mar 25, 2020 at 04:42:07PM +0000, Julien Grall wrote:
> >> On 25/03/2020 16:34, Tamas K Lengyel wrote:
> >>>>> --- a/xen/common/domain.c
> >>>>> +++ b/xen/common/domain.c
> >>>>> @@ -1270,6 +1270,9 @@ int map_vcpu_info(struct vcpu *v, unsigned long gfn, unsigned offset)
> >>>>>
> >>>>> v->vcpu_info = new_info;
> >>>>> v->vcpu_info_mfn = page_to_mfn(page);
> >>>>> +#ifdef CONFIG_MEM_SHARING
> >>>>> + v->vcpu_info_offset = offset;
> >>>>
> >>>> There's no need to introduce this field, you can just use v->vcpu_info
> >>>> & ~PAGE_MASK AFAICT.
> >>>
> >>> Just doing what you suggest above results in:
> >>>
> >>> mem_sharing.c:1603:55: error: invalid operands to binary & (have
> >>> ‘vcpu_info_t * const’ {aka ‘union <anonymous> * const’} and ‘long
> >>> int’)
> >>> d_vcpu->vcpu_info & ~PAGE_MASK);
> >>>
> >>> I can of course cast the vcpu_info pointer to (long int), it's just a
> >>> bit ugly. Thoughts?
> >>
> >> FWIW, I will also need the offset for liveupdate. I have used (unsigned
> >> long)v->vcpu_info & ~PAGE_MASK so far but this is not really pretty.
> >
> > I think using:
> >
> > (vaddr_t)v->vcpu_info & ~PAGE_MASK
> >
> > is acceptable, but that would require adding a vaddr_t typedef to x86.
>
> I don't think vaddr_t is necessary given that all over the place we
> assume conversions between pointers and unsigned long to be fine.
Right, using unsigned long is indeed fine, but I also agree with Tamas
that it's slightly ugly and hence wanted to provide a 'cleaner'
suggestion.
Roger.
next prev parent reply other threads:[~2020-03-26 8:43 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-23 17:04 [Xen-devel] [PATCH v12 0/3] VM forking Tamas K Lengyel
2020-03-23 17:04 ` [Xen-devel] [PATCH v12 1/3] xen/mem_sharing: " Tamas K Lengyel
2020-03-25 15:47 ` Roger Pau Monné
2020-03-25 16:04 ` Tamas K Lengyel
2020-03-25 16:16 ` Tamas K Lengyel
2020-03-25 16:34 ` Tamas K Lengyel
2020-03-25 16:42 ` Julien Grall
2020-03-25 16:47 ` Tamas K Lengyel
2020-03-25 16:51 ` Julien Grall
2020-03-25 17:00 ` Tamas K Lengyel
2020-03-25 17:16 ` Roger Pau Monné
2020-03-25 17:47 ` Tamas K Lengyel
2020-03-25 16:54 ` Roger Pau Monné
2020-03-26 7:02 ` Jan Beulich
2020-03-26 8:42 ` Roger Pau Monné [this message]
2020-03-26 7:07 ` Jan Beulich
2020-03-26 9:10 ` Roger Pau Monné
2020-03-26 17:01 ` Tamas K Lengyel
2020-03-26 12:33 ` Jan Beulich
2020-03-26 14:52 ` Tamas K Lengyel
2020-03-23 17:04 ` [Xen-devel] [PATCH v12 2/3] x86/mem_sharing: reset a fork Tamas K Lengyel
2020-03-25 15:52 ` Roger Pau Monné
2020-03-25 15:54 ` Tamas K Lengyel
2020-03-26 10:16 ` Jan Beulich
2020-03-26 14:48 ` Tamas K Lengyel
2020-03-26 14:52 ` Jan Beulich
2020-03-26 14:53 ` Tamas K Lengyel
2020-03-26 23:40 ` Tamas K Lengyel
2020-03-23 17:04 ` [Xen-devel] [PATCH v12 3/3] xen/tools: VM forking toolstack side Tamas K Lengyel
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