linux-kernel - Re: [PATCH v5 2/4] KVM: X86: Add paravirt remote TLB flush

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: <CANRm+CwLcz7hQMPjxfWuTnrZCXApjQfHurAzCphMvmVyB+rMEA@mail.gmail.com>
Date:   Thu, 16 Nov 2017 16:51:39 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kvm <kvm@...r.kernel.org>, Paolo Bonzini <pbonzini@...hat.com>,
        "Radim Kr??m????" <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH v5 2/4] KVM: X86: Add paravirt remote TLB flush

2017-11-16 16:38 GMT+08:00 Peter Zijlstra <peterz@...radead.org>:
> On Thu, Nov 16, 2017 at 01:30:57PM +0800, Wanpeng Li wrote:
>> -static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask);
>> +static DEFINE_PER_CPU(cpumask_t, __pv_tlb_mask);
>
> NR_CPUS=512 is a fairly common distro setting, that means cpumask_t is
> 64 bytes. So for my 144 CPU system, that is 9216 bytes I'll never see
> again.
>
> Not nice :/

Refer to "DECLARE_PER_CPU_SHARED_ALIGNED(cpumask_t, cpu_sibling_map)"
in arch/ia64/include/asm/smp.h, it also defines variable directly,
however, some other archs are not. kvmclock_init() is also called very
early during boot, it utilizes memblock to alloc some memory.

Regards,
Wanpeng Li