From: Anchal Agarwal <anchalag@amazon.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: eduval@amazon.com, len.brown@intel.com, peterz@infradead.org,
benh@kernel.crashing.org, x86@kernel.org, linux-mm@kvack.org,
pavel@ucw.cz, hpa@zytor.com, sstabellini@kernel.org,
kamatam@amazon.com, mingo@redhat.com,
xen-devel@lists.xenproject.org, sblbir@amazon.com,
axboe@kernel.dk, konrad.wilk@oracle.com, bp@alien8.de,
tglx@linutronix.de, jgross@suse.com, netdev@vger.kernel.org,
linux-pm@vger.kernel.org, rjw@rjwysocki.net,
linux-kernel@vger.kernel.org, vkuznets@redhat.com,
davem@davemloft.net, dwmw@amazon.co.uk, roger.pau@citrix.com
Subject: Re: [PATCH 03/12] x86/xen: Introduce new function to map HYPERVISOR_shared_info on Resume
Date: Mon, 8 Jun 2020 16:52:35 +0000 [thread overview]
Message-ID: <20200608165235.GA1330@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> (raw)
In-Reply-To: <9644a5f1-e1f8-5fe1-3135-cc6b4baf893b@oracle.com>
On Fri, Jun 05, 2020 at 05:39:54PM -0400, Boris Ostrovsky wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
>
>
>
> On 6/4/20 7:03 PM, Anchal Agarwal wrote:
> > On Sat, May 30, 2020 at 07:02:01PM -0400, Boris Ostrovsky wrote:
> >> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
> >>
> >>
> >>
> >> On 5/19/20 7:25 PM, Anchal Agarwal wrote:
> >>> Introduce a small function which re-uses shared page's PA allocated
> >>> during guest initialization time in reserve_shared_info() and not
> >>> allocate new page during resume flow.
> >>> It also does the mapping of shared_info_page by calling
> >>> xen_hvm_init_shared_info() to use the function.
> >>>
> >>> Signed-off-by: Anchal Agarwal <anchalag@amazon.com>
> >>> ---
> >>> arch/x86/xen/enlighten_hvm.c | 7 +++++++
> >>> arch/x86/xen/xen-ops.h | 1 +
> >>> 2 files changed, 8 insertions(+)
> >>>
> >>> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
> >>> index e138f7de52d2..75b1ec7a0fcd 100644
> >>> --- a/arch/x86/xen/enlighten_hvm.c
> >>> +++ b/arch/x86/xen/enlighten_hvm.c
> >>> @@ -27,6 +27,13 @@
> >>>
> >>> static unsigned long shared_info_pfn;
> >>>
> >>> +void xen_hvm_map_shared_info(void)
> >>> +{
> >>> + xen_hvm_init_shared_info();
> >>> + if (shared_info_pfn)
> >>> + HYPERVISOR_shared_info = __va(PFN_PHYS(shared_info_pfn));
> >>> +}
> >>> +
> >>
> >> AFAICT it is only called once so I don't see a need for new routine.
> >>
> >>
> > HYPERVISOR_shared_info can only be mapped in this scope without refactoring
> > much of the code.
>
>
> Refactoring what? All am suggesting is
>
shared_info_pfn does not seem to be in scope here, it's scope is limited
to enlighten_hvm.c. That's the reason I introduced a new function there.
> --- a/arch/x86/xen/suspend.c
> +++ b/arch/x86/xen/suspend.c
> @@ -124,7 +124,9 @@ static void xen_syscore_resume(void)
> return;
>
> /* No need to setup vcpu_info as it's already moved off */
> - xen_hvm_map_shared_info();
> + xen_hvm_init_shared_info();
> + if (shared_info_pfn)
> + HYPERVISOR_shared_info = __va(PFN_PHYS(shared_info_pfn));
>
> pvclock_resume();
>
> >> And is it possible for shared_info_pfn to be NULL in resume path (which
> >> is where this is called)?
> >>
> >>
> > I don't think it should be, still a sanity check but I don't think its needed there
> > because hibernation will fail in any case if thats the case.
>
>
> If shared_info_pfn is NULL you'd have problems long before hibernation
> started. We set it in xen_hvm_guest_init() and never touch again.
>
>
> In fact, I'd argue that it should be __ro_after_init.
>
>
I agree, and I should have mentioned that I will remove that check and its not
necessary as this gets mapped way early in the boot process.
> > However, HYPERVISOR_shared_info does needs to be re-mapped on resume as its been
> > marked to dummy address on suspend. Its also safe in case va changes.
> > Does the answer your question?
>
>
> I wasn't arguing whether HYPERVISOR_shared_info needs to be set, I was
> only saying that shared_info_pfn doesn't need to be tested.
>
Got it. :)
>
> -boris
>
Thanks,
Anchal
>
next prev parent reply other threads:[~2020-06-08 16:53 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 23:24 [PATCH 00/12] Fix PM hibernation in Xen guests Anchal Agarwal
2020-05-19 23:24 ` [PATCH 01/12] xen/manage: keep track of the on-going suspend mode Anchal Agarwal
2020-05-30 22:26 ` Boris Ostrovsky
2020-06-01 21:00 ` Agarwal, Anchal
2020-06-01 22:39 ` Boris Ostrovsky
2020-05-19 23:25 ` [PATCH 02/12] xenbus: add freeze/thaw/restore callbacks support Anchal Agarwal
2020-05-30 22:56 ` Boris Ostrovsky
2020-06-01 23:36 ` Agarwal, Anchal
2020-05-19 23:25 ` [PATCH 03/12] x86/xen: Introduce new function to map HYPERVISOR_shared_info on Resume Anchal Agarwal
2020-05-30 23:02 ` Boris Ostrovsky
2020-06-04 23:03 ` Anchal Agarwal
2020-06-05 21:39 ` Boris Ostrovsky
2020-06-08 16:52 ` Anchal Agarwal [this message]
2020-06-08 18:49 ` Boris Ostrovsky
2020-05-19 23:26 ` [PATCH 04/12] x86/xen: add system core suspend and resume callbacks Anchal Agarwal
2020-05-30 23:10 ` Boris Ostrovsky
2020-06-03 22:40 ` Agarwal, Anchal
2020-06-05 21:24 ` Boris Ostrovsky
2020-06-08 17:09 ` Anchal Agarwal
2020-05-19 23:26 ` [PATCH 05/12] genirq: Shutdown irq chips in suspend/resume during hibernation Anchal Agarwal
2020-05-19 23:29 ` Singh, Balbir
2020-05-19 23:36 ` Agarwal, Anchal
2020-05-19 23:34 ` Anchal Agarwal
2020-05-30 23:17 ` Boris Ostrovsky
2020-06-01 20:46 ` Agarwal, Anchal
2020-05-19 23:27 ` [PATCH 06/12] xen-blkfront: add callbacks for PM suspend and hibernation Anchal Agarwal
2020-05-20 5:00 ` kbuild test robot
2020-05-20 5:07 ` kbuild test robot
2020-05-21 23:48 ` Anchal Agarwal
2020-05-22 1:43 ` Singh, Balbir
2020-05-23 12:32 ` kbuild test robot
2020-05-28 12:30 ` Roger Pau Monné
2020-05-19 23:28 ` [PATCH 07/12] xen-netfront: " Anchal Agarwal
2020-05-19 23:28 ` [PATCH 08/12] xen/time: introduce xen_{save,restore}_steal_clock Anchal Agarwal
2020-05-30 23:32 ` Boris Ostrovsky
2020-05-19 23:28 ` [PATCH 09/12] x86/xen: save and restore steal clock Anchal Agarwal
2020-05-30 23:44 ` Boris Ostrovsky
2020-06-04 18:33 ` Anchal Agarwal
2020-05-19 23:29 ` [PATCH 10/12] xen: Introduce wrapper for save/restore sched clock offset Anchal Agarwal
2020-05-19 23:29 ` [PATCH 11/12] xen: Update sched clock offset to avoid system instability in hibernation Anchal Agarwal
2020-05-19 23:29 ` [PATCH 12/12] PM / hibernate: update the resume offset on SNAPSHOT_SET_SWAP_AREA Anchal Agarwal
2020-05-28 17:59 ` [PATCH 00/12] Fix PM hibernation in Xen guests Agarwal, Anchal
Reply instructions:
You may reply publicly 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=20200608165235.GA1330@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com \
--to=anchalag@amazon.com \
--cc=axboe@kernel.dk \
--cc=benh@kernel.crashing.org \
--cc=boris.ostrovsky@oracle.com \
--cc=bp@alien8.de \
--cc=davem@davemloft.net \
--cc=dwmw@amazon.co.uk \
--cc=eduval@amazon.com \
--cc=hpa@zytor.com \
--cc=jgross@suse.com \
--cc=kamatam@amazon.com \
--cc=konrad.wilk@oracle.com \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-pm@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=pavel@ucw.cz \
--cc=peterz@infradead.org \
--cc=rjw@rjwysocki.net \
--cc=roger.pau@citrix.com \
--cc=sblbir@amazon.com \
--cc=sstabellini@kernel.org \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--cc=x86@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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).