Re: [Xen-devel] [PATCH for-4.12 4/8] x86/shadow: alloc enough pages so initialization doesn't fail

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.02.19 at 16:53, <roger.pau@xxxxxxxxxx> wrote:
> On Tue, Feb 05, 2019 at 08:15:27AM -0700, Jan Beulich wrote:
>> >>> On 05.02.19 at 14:52, <roger.pau@xxxxxxxxxx> wrote:
>> > I don't think the amount of guest memory matters here, the following
>> > example with 8G of RAM and 8 vCPUs fails in the same way:
>> > 
>> > # cat test.c
>> > test.c       test.c.gcov  test.cfg     test.core
>> > root@:~ # cat test.cfg
>> > name = "test"
>> > type = "hvm"
>> > 
>> > memory = 8192
>> > vcpus = 8
>> > hap = 0
>> > # xl create test.cfg
>> > Parsing config from test.cfg
>> > libxl: error: libxl_create.c:578:libxl__domain_make: domain creation fail: 
>> > Cannot allocate memory
>> > libxl: error: libxl_create.c:975:initiate_domain_create: cannot make 
>> > domain: 
>> > -3
>> > 
>> > And I think that's a perfectly suitable guest config.
>> 
>> Indeed. And it doesn't seem to work for me anymore either. Must be
>> a regression, as I'm pretty sure it did still work not all that long ago.
>> Not even "shadow_memory=256" helps.
> 
> No, because shadow_init is called from domain_create, and it's
> impossible to increase the shadow memory pool before the domain is
> actually created.

Okay, I misunderstood the problem initially. Aiui this is a
regression from the early setting of ->max_vcpus, as that now
causes shadow_min_acceptable_pages() to block far more pages
than it did before from use for p2m allocs during domain creation.
I think I see an alternative way of fixing this for the moment
(without adding re-size logic yet when d->tot_pages grows), but
this will have to wait until tomorrow.

Jan



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