From: Roman Kagan <rkagan@virtuozzo.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Nadav Amit" <nadav.amit@gmail.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"Stephen Hemminger" <sthemmin@microsoft.com>,
"Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>
Subject: Re: [PATCH v2 1/4] x86/hyper-v: move synic/stimer control structures definitions to hyperv-tlfs.h
Date: Thu, 29 Nov 2018 07:52:12 +0000 [thread overview]
Message-ID: <20181129075208.GA9010@rkaganb.sw.ru> (raw)
In-Reply-To: <alpine.DEB.2.21.1811281404230.1532@nanos.tec.linutronix.de>
On Wed, Nov 28, 2018 at 02:07:42PM +0100, Thomas Gleixner wrote:
> On Wed, 28 Nov 2018, Vitaly Kuznetsov wrote:
>
> > Nadav Amit <nadav.amit@gmail.com> writes:
> >
> > >
> > > On a different note: how come all of the hyper-v structs are not marked
> > > with the “packed" attribute?
> >
> > "packed" should not be needed with proper padding; I vaguely remember
> > someone (from x86@?) arguing _against_ "packed".
>
> Packed needs to be used, when describing fixed format data structures in
> hardware or other ABIs, so the compiler cannot put alignment holes into
> them.
>
> Using packed for generic data structures might result in suboptimal layouts
> and prevents layout randomization.
Sorry for my illiteracy, I didn't watch this field closely so I had to
google about layout randomization. Is my understanding correct that one
can't rely any more on the compiler to naturally align the struct
members with minimal padding? My life will never be the same...
Roman.
next prev parent reply other threads:[~2018-11-29 7:53 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 15:47 [PATCH v2 0/4] x86/kvm/hyper-v: Implement Direct Mode for synthetic timers Vitaly Kuznetsov
2018-11-26 15:47 ` [PATCH v2 1/4] x86/hyper-v: move synic/stimer control structures definitions to hyperv-tlfs.h Vitaly Kuznetsov
2018-11-26 17:00 ` Michael Kelley
2018-11-26 20:04 ` Roman Kagan
2018-11-27 13:10 ` Vitaly Kuznetsov
2018-11-27 15:52 ` Michael Kelley
2018-11-27 16:32 ` Vitaly Kuznetsov
2018-11-27 18:48 ` Roman Kagan
2018-11-28 1:49 ` Nadav Amit
2018-11-28 10:37 ` Vitaly Kuznetsov
2018-11-28 13:07 ` Thomas Gleixner
2018-11-28 17:55 ` Nadav Amit
2018-11-29 11:36 ` Vitaly Kuznetsov
2018-11-29 19:22 ` Thomas Gleixner
2018-11-29 7:52 ` Roman Kagan [this message]
2018-11-28 8:40 ` Paolo Bonzini
2018-11-26 15:47 ` [PATCH v2 2/4] x86/kvm/hyper-v: use stimer config definition from hyperv-tlfs.h Vitaly Kuznetsov
2018-11-26 15:47 ` [PATCH v2 3/4] x86/kvm/hyper-v: direct mode for synthetic timers Vitaly Kuznetsov
2018-11-26 16:44 ` Paolo Bonzini
2018-11-26 17:14 ` Vitaly Kuznetsov
2018-11-27 8:37 ` Roman Kagan
2018-11-27 13:54 ` Paolo Bonzini
2018-11-27 19:05 ` Roman Kagan
2018-11-28 8:43 ` Paolo Bonzini
2018-11-27 8:21 ` Roman Kagan
2018-12-03 17:12 ` Roman Kagan
2018-12-04 12:36 ` Vitaly Kuznetsov
2018-12-10 12:06 ` Roman Kagan
2018-12-10 12:54 ` Vitaly Kuznetsov
2018-12-10 13:21 ` Roman Kagan
2018-12-10 14:53 ` Vitaly Kuznetsov
2018-11-26 15:47 ` [PATCH v2 4/4] x86/kvm/hyper-v: avoid open-coding stimer_mark_pending() in kvm_hv_notify_acked_sint() Vitaly Kuznetsov
2018-11-26 16:45 ` Paolo Bonzini
2018-11-27 8:49 ` Roman Kagan
2018-11-26 16:45 ` [PATCH v2 0/4] x86/kvm/hyper-v: Implement Direct Mode for synthetic timers Paolo Bonzini
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