linux-kernel - Re: [PATCH 2/6] KVM: selftests: Stash the host page size in a global in the guest

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <diqzikh01lgd.fsf@google.com>
Date: Tue, 30 Sep 2025 06:52:18 +0000
From: Ackerley Tng <ackerleytng@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Christian Borntraeger <borntraeger@...ux.ibm.com>, 
	Janosch Frank <frankja@...ux.ibm.com>, Claudio Imbrenda <imbrenda@...ux.ibm.com>, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, David Hildenbrand <david@...hat.com>, 
	Fuad Tabba <tabba@...gle.com>
Subject: Re: [PATCH 2/6] KVM: selftests: Stash the host page size in a global
 in the guest_memfd test

Sean Christopherson <seanjc@...gle.com> writes:

> On Mon, Sep 29, 2025, Ackerley Tng wrote:
>> Sean Christopherson <seanjc@...gle.com> writes:
>> 
>> > Use a global variable to track the host page size in the guest_memfd test
>> > so that the information doesn't need to be constantly passed around.  The
>> > state is purely a reflection of the underlying system, i.e. can't be set
>> > by the test and is constant for a given invocation of the test, and thus
>> > explicitly passing the host page size to individual testcases adds no
>> > value, e.g. doesn't allow testing different combinations.
>> >
>> 
>> I was going to pass in page_size to each of these test cases to test
>> HugeTLB support, that's how page_size crept into the parameters of these
>> functions.
>> 
>> Could we do a getpagesize() within the gmem_test() macro that you
>> introduced instead?
>
> We could, and I actually had it that way to start.  But I found that burying the
> effective setting of page_size made it harder to see that it's a runtime constant,
> versus something that can be configured by the test.

I guess I could also just update the global static variable page_size
for HugeTLB tests since we won't be running tests with different page
sizes in parallel. Maybe that's better, actually.