* [PATCH v3] mm/page_alloc: make bootscrub happen in idle-loop
@ 2018-11-07 11:11 Sergey Dyasli
2018-11-07 12:17 ` Wei Liu
0 siblings, 1 reply; 4+ messages in thread
From: Sergey Dyasli @ 2018-11-07 11:11 UTC (permalink / raw)
To: xen-devel
Cc: Sergey Dyasli, Wei Liu, George Dunlap, Andrew Cooper,
Julien Grall, Jan Beulich, Boris Ostrovsky
Scrubbing RAM during boot may take a long time on machines with lots
of RAM. Add 'idle' option to bootscrub which marks all pages dirty
initially so they will eventually be scrubbed in idle-loop on every
online CPU.
It's guaranteed that the allocator will return scrubbed pages by doing
eager scrubbing during allocation (unless MEMF_no_scrub was provided).
Use the new 'idle' option as the default one.
Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
v2 --> v3:
- Removed "= 0" from enum bootscrub_mode
- Removed num_online_nodes() from printk()
- Added Reviewed-by
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
CC: George Dunlap <George.Dunlap@eu.citrix.com>
CC: Jan Beulich <jbeulich@suse.com>
CC: Julien Grall <julien.grall@arm.com>
CC: Wei Liu <wei.liu2@citrix.com>
---
docs/misc/xen-command-line.markdown | 9 ++++-
xen/common/page_alloc.c | 61 +++++++++++++++++++++++++++--
2 files changed, 64 insertions(+), 6 deletions(-)
diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
index 2c7046eb86..9028bcde2e 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -227,14 +227,19 @@ that byte `0x12345678` is bad, you would place `badpage=0x12345` on
Xen's command line.
### bootscrub
-> `= <boolean>`
+> `= idle | <boolean>`
-> Default: `true`
+> Default: `idle`
Scrub free RAM during boot. This is a safety feature to prevent
accidentally leaking sensitive VM data into other VMs if Xen crashes
and reboots.
+In `idle` mode, RAM is scrubbed in background on all CPUs during idle-loop
+with a guarantee that memory allocations always provide scrubbed pages.
+This option reduces boot time on machines with a large amount of RAM while
+still providing security benefits.
+
### bootscrub\_chunk
> `= <size>`
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 16e1b0c357..f587d2e81b 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -161,8 +161,42 @@ string_param("badpage", opt_badpage);
/*
* no-bootscrub -> Free pages are not zeroed during boot.
*/
-static bool_t opt_bootscrub __initdata = 1;
-boolean_param("bootscrub", opt_bootscrub);
+enum bootscrub_mode {
+ BOOTSCRUB_OFF,
+ BOOTSCRUB_ON,
+ BOOTSCRUB_IDLE,
+};
+static enum bootscrub_mode __initdata opt_bootscrub = BOOTSCRUB_IDLE;
+static int __init parse_bootscrub_param(const char *s)
+{
+ /* Interpret 'bootscrub' alone in its positive boolean form */
+ if ( *s == '\0' )
+ {
+ opt_bootscrub = BOOTSCRUB_ON;
+ return 0;
+ }
+
+ switch ( parse_bool(s, NULL) )
+ {
+ case 0:
+ opt_bootscrub = BOOTSCRUB_OFF;
+ break;
+
+ case 1:
+ opt_bootscrub = BOOTSCRUB_ON;
+ break;
+
+ default:
+ if ( !strcmp(s, "idle") )
+ opt_bootscrub = BOOTSCRUB_IDLE;
+ else
+ return -EINVAL;
+ break;
+ }
+
+ return 0;
+}
+custom_param("bootscrub", parse_bootscrub_param);
/*
* bootscrub_chunk -> Amount of bytes to scrub lockstep on non-SMT CPUs
@@ -1726,6 +1760,7 @@ static void init_heap_pages(
struct page_info *pg, unsigned long nr_pages)
{
unsigned long i;
+ bool idle_scrub = false;
/*
* Some pages may not go through the boot allocator (e.g reserved
@@ -1737,6 +1772,9 @@ static void init_heap_pages(
first_valid_mfn = mfn_min(page_to_mfn(pg), first_valid_mfn);
spin_unlock(&heap_lock);
+ if ( system_state < SYS_STATE_active && opt_bootscrub == BOOTSCRUB_IDLE )
+ idle_scrub = true;
+
for ( i = 0; i < nr_pages; i++ )
{
unsigned int nid = phys_to_nid(page_to_maddr(pg+i));
@@ -1763,7 +1801,7 @@ static void init_heap_pages(
nr_pages -= n;
}
- free_heap_pages(pg + i, 0, scrub_debug);
+ free_heap_pages(pg + i, 0, scrub_debug || idle_scrub);
}
}
@@ -2039,8 +2077,23 @@ void __init heap_init_late(void)
*/
setup_low_mem_virq();
- if ( opt_bootscrub )
+ switch ( opt_bootscrub )
+ {
+ default:
+ ASSERT_UNREACHABLE();
+ /* Fall through */
+
+ case BOOTSCRUB_IDLE:
+ printk("Scrubbing Free RAM in background\n");
+ break;
+
+ case BOOTSCRUB_ON:
scrub_heap_pages();
+ break;
+
+ case BOOTSCRUB_OFF:
+ break;
+ }
}
--
2.17.1
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v3] mm/page_alloc: make bootscrub happen in idle-loop
2018-11-07 11:11 [PATCH v3] mm/page_alloc: make bootscrub happen in idle-loop Sergey Dyasli
@ 2018-11-07 12:17 ` Wei Liu
2018-11-07 16:36 ` Sergey Dyasli
0 siblings, 1 reply; 4+ messages in thread
From: Wei Liu @ 2018-11-07 12:17 UTC (permalink / raw)
To: Sergey Dyasli
Cc: Wei Liu, George Dunlap, Andrew Cooper, xen-devel, Julien Grall,
Jan Beulich, Boris Ostrovsky
On Wed, Nov 07, 2018 at 11:11:49AM +0000, Sergey Dyasli wrote:
> Scrubbing RAM during boot may take a long time on machines with lots
> of RAM. Add 'idle' option to bootscrub which marks all pages dirty
> initially so they will eventually be scrubbed in idle-loop on every
> online CPU.
>
> It's guaranteed that the allocator will return scrubbed pages by doing
> eager scrubbing during allocation (unless MEMF_no_scrub was provided).
>
> Use the new 'idle' option as the default one.
>
> Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
> ---
> v2 --> v3:
> - Removed "= 0" from enum bootscrub_mode
> - Removed num_online_nodes() from printk()
> - Added Reviewed-by
I think your patch (v2?) is already committed.
Wei.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3] mm/page_alloc: make bootscrub happen in idle-loop
2018-11-07 12:17 ` Wei Liu
@ 2018-11-07 16:36 ` Sergey Dyasli
2018-11-07 16:42 ` Wei Liu
0 siblings, 1 reply; 4+ messages in thread
From: Sergey Dyasli @ 2018-11-07 16:36 UTC (permalink / raw)
To: Wei Liu, xen-devel, Jan Beulich
Cc: George Dunlap, Andrew Cooper, Boris Ostrovsky, Julien Grall,
sergey.dyasli@citrix.com >> Sergey Dyasli
On 07/11/2018 12:17, Wei Liu wrote:
> On Wed, Nov 07, 2018 at 11:11:49AM +0000, Sergey Dyasli wrote:
>> Scrubbing RAM during boot may take a long time on machines with lots
>> of RAM. Add 'idle' option to bootscrub which marks all pages dirty
>> initially so they will eventually be scrubbed in idle-loop on every
>> online CPU.
>>
>> It's guaranteed that the allocator will return scrubbed pages by doing
>> eager scrubbing during allocation (unless MEMF_no_scrub was provided).
>>
>> Use the new 'idle' option as the default one.
>>
>> Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
>> Reviewed-by: Jan Beulich <jbeulich@suse.com>
>> ---
>> v2 --> v3:
>> - Removed "= 0" from enum bootscrub_mode
>> - Removed num_online_nodes() from printk()
>> - Added Reviewed-by
>
> I think your patch (v2?) is already committed.
Hmm, you are right: CommitDate: Wed Nov 7 09:34:17 2018 +0100
Sorry, I wasn't expecting that.
Though printk() in the committed version has a typo:
printk("Scrubbing free RAM on in background\n");
^^
--
Thanks,
Sergey
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3] mm/page_alloc: make bootscrub happen in idle-loop
2018-11-07 16:36 ` Sergey Dyasli
@ 2018-11-07 16:42 ` Wei Liu
0 siblings, 0 replies; 4+ messages in thread
From: Wei Liu @ 2018-11-07 16:42 UTC (permalink / raw)
To: Sergey Dyasli
Cc: Wei Liu, George Dunlap, Andrew Cooper, xen-devel, Julien Grall,
Jan Beulich, Boris Ostrovsky
On Wed, Nov 07, 2018 at 04:36:08PM +0000, Sergey Dyasli wrote:
> On 07/11/2018 12:17, Wei Liu wrote:
> > On Wed, Nov 07, 2018 at 11:11:49AM +0000, Sergey Dyasli wrote:
> >> Scrubbing RAM during boot may take a long time on machines with lots
> >> of RAM. Add 'idle' option to bootscrub which marks all pages dirty
> >> initially so they will eventually be scrubbed in idle-loop on every
> >> online CPU.
> >>
> >> It's guaranteed that the allocator will return scrubbed pages by doing
> >> eager scrubbing during allocation (unless MEMF_no_scrub was provided).
> >>
> >> Use the new 'idle' option as the default one.
> >>
> >> Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
> >> Reviewed-by: Jan Beulich <jbeulich@suse.com>
> >> ---
> >> v2 --> v3:
> >> - Removed "= 0" from enum bootscrub_mode
> >> - Removed num_online_nodes() from printk()
> >> - Added Reviewed-by
> >
> > I think your patch (v2?) is already committed.
>
> Hmm, you are right: CommitDate: Wed Nov 7 09:34:17 2018 +0100
> Sorry, I wasn't expecting that.
>
> Though printk() in the committed version has a typo:
>
> printk("Scrubbing free RAM on in background\n");
> ^^
Feel free to send a followup patch to fix that.
Wei.
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2018-11-07 11:11 [PATCH v3] mm/page_alloc: make bootscrub happen in idle-loop Sergey Dyasli
2018-11-07 12:17 ` Wei Liu
2018-11-07 16:36 ` Sergey Dyasli
2018-11-07 16:42 ` Wei Liu
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