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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Anchal Agarwal <anchalag@amazon.com>
Cc: "tglx@linutronix.de" <tglx@linutronix.de>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"bp@alien8.de" <bp@alien8.de>, "hpa@zytor.com" <hpa@zytor.com>,
	"jgross@suse.com" <jgross@suse.com>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"sstabellini@kernel.org" <sstabellini@kernel.org>,
	"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
	"roger.pau@citrix.com" <roger.pau@citrix.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"rjw@rjwysocki.net" <rjw@rjwysocki.net>,
	"len.brown@intel.com" <len.brown@intel.com>,
	"pavel@ucw.cz" <pavel@ucw.cz>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"vkuznets@redhat.com" <vkuznets@redhat.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"dwmw@amazon.co.uk" <dwmw@amazon.co.uk>
Subject: Re: [PATCH v3 01/11] xen/manage: keep track of the on-going suspend mode
Date: Thu, 3 Jun 2021 21:49:04 -0400	[thread overview]
Message-ID: <07fca94f-86e1-3a0a-0078-0c0d6aa52363@oracle.com> (raw)
In-Reply-To: <20210603232742.GB14368@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com>


On 6/3/21 7:27 PM, Anchal Agarwal wrote:
> On Thu, Jun 03, 2021 at 04:11:46PM -0400, Boris Ostrovsky wrote:
>
>> But if KASLR is on then this comparison not failing should cause xen_vcpu pointer in the loaded image to become bogus because xen_vcpu is now registered for a different xen_vcpu_info address during boot.
>>
> The reason for that I think is once you jump into the image that information is
> getting lost. But there is  some residue somewhere that's causing the resume to
> fail. I haven't been able to pinpoint the exact field value that may be causing
> that issue.


xen_vcpu now points to address which is not where the hypervisor thinks vcpu_info should be.


> Correct me if I am wrong here, but even if hypothetically I put a hack to tell the kernel
> somehow re-register vcpu it won't pass because there is no hypercall to
> unregister it in first place? 


Right. You will be shown the door in map_vcpu_info():

       if ( !mfn_eq(v->vcpu_info_mfn, INVALID_MFN) )
           return -EINVAL;


> Can the resumed kernel use the new values in that
> case [Now this is me just throwing wild guesses!!]


I don't think so --- hypervisor is now pointing to a random location in your image.


-boris





  reply	other threads:[~2021-06-04  1:50 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-21 22:22 [PATCH v3 00/11] Fix PM hibernation in Xen guests Anchal Agarwal
2020-08-21 22:25 ` [PATCH v3 01/11] xen/manage: keep track of the on-going suspend mode Anchal Agarwal
2020-09-13 15:43   ` boris.ostrovsky
2020-09-14 21:47     ` Anchal Agarwal
2020-09-15  0:24       ` boris.ostrovsky
2020-09-15 18:00         ` Anchal Agarwal
2020-09-15 19:58           ` boris.ostrovsky
2020-09-21 21:54             ` Anchal Agarwal
2020-09-22 16:18               ` boris.ostrovsky
2020-09-22 23:17                 ` Anchal Agarwal
2020-09-25 19:04                   ` Anchal Agarwal
2020-09-25 20:02                     ` boris.ostrovsky
2020-09-25 22:28                       ` Anchal Agarwal
2020-09-28 18:49                         ` boris.ostrovsky
2020-09-30 21:29                           ` Anchal Agarwal
2020-10-01 12:43                             ` boris.ostrovsky
2021-05-21  5:26                               ` Anchal Agarwal
2021-05-25 22:23                                 ` Boris Ostrovsky
2021-05-26  4:40                                   ` Anchal Agarwal
2021-05-26 18:29                                     ` Boris Ostrovsky
2021-05-28 21:50                                       ` Anchal Agarwal
2021-06-01 14:18                                         ` Boris Ostrovsky
2021-06-02 19:37                                           ` Anchal Agarwal
2021-06-03 20:11                                             ` Boris Ostrovsky
2021-06-03 23:27                                               ` Anchal Agarwal
2021-06-04  1:49                                                 ` Boris Ostrovsky [this message]
2020-09-13 17:07   ` boris.ostrovsky
2020-08-21 22:26 ` [PATCH v3 02/11] xenbus: add freeze/thaw/restore callbacks support Anchal Agarwal
2020-09-13 16:11   ` boris.ostrovsky
2020-09-15 19:56     ` Anchal Agarwal
2020-08-21 22:26 ` [PATCH v3 03/11] x86/xen: Introduce new function to map HYPERVISOR_shared_info on Resume Anchal Agarwal
2020-08-21 22:27 ` [PATCH v3 04/11] x86/xen: add system core suspend and resume callbacks Anchal Agarwal
2020-09-13 17:25   ` boris.ostrovsky
2020-08-21 22:28 ` [PATCH v3 06/11] xen-blkfront: add callbacks for PM suspend and hibernation Anchal Agarwal
2020-08-21 22:29 ` [PATCH v3 07/11] xen-netfront: " Anchal Agarwal
2020-08-21 22:29 ` [PATCH v3 08/11] x86/xen: save and restore steal clock during PM hibernation Anchal Agarwal
2020-08-21 22:30 ` [PATCH v3 09/11] xen: Introduce wrapper for save/restore sched clock offset Anchal Agarwal
2020-08-21 22:30 ` [PATCH v3 10/11] xen: Update sched clock offset to avoid system instability in hibernation Anchal Agarwal
2020-09-13 17:52   ` boris.ostrovsky
2020-08-21 22:31 ` [PATCH v3 11/11] PM / hibernate: update the resume offset on SNAPSHOT_SET_SWAP_AREA Anchal Agarwal
     [not found] ` <d9bcd552c946ac56f3f17cc0c1be57247d4a3004.1598042152.git.anchalag@amazon.com>
2020-08-22  0:36   ` [PATCH v3 05/11] genirq: Shutdown irq chips in suspend/resume during hibernation Thomas Gleixner
2020-08-24 17:25     ` Anchal Agarwal
2020-08-25 13:20     ` Christoph Hellwig
2020-08-25 15:25       ` Thomas Gleixner
2020-08-28 18:26 ` [PATCH v3 00/11] Fix PM hibernation in Xen guests Anchal Agarwal
2020-08-28 18:29   ` Rafael J. Wysocki
2020-08-28 18:39     ` Anchal Agarwal
2020-09-11 20:44       ` Anchal Agarwal
2020-09-11 15:19 ` boris.ostrovsky

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