From: Borislav Petkov <bp@alien8.de>
To: Baoquan He <bhe@redhat.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 4/4] x86/mm/KASLR: Adjust the padding size for the direct mapping.
Date: Fri, 13 Dec 2019 17:38:18 +0100 [thread overview]
Message-ID: <20191213163818.GB25899@zn.tnic> (raw)
In-Reply-To: <20191213145448.GH28917@MiWiFi-R3L-srv>
On Fri, Dec 13, 2019 at 10:54:48PM +0800, Baoquan He wrote:
> On 12/13/19 at 03:15pm, Borislav Petkov wrote:
> > On Fri, Dec 13, 2019 at 09:28:50PM +0800, Baoquan He wrote:
> > > In Documentation/x86/x86_64/mm.rst, the physical memory regions mapping
> > > with page_offset is called as the direct mapping of physical memory.
> >
> > The fact that it happens to compute the *first* region's size, which
> > *happens* to be the direct mapping of all physical memory is immaterial
> > here.
> >
> > It is actually causing more confusion in an already complex piece of
> > code. You can call this function just as well
> >
> > calc_region_size()
> >
> > which won't confuse readers. Because all you care about here is the
> > region's size - not which region it is.
>
> Won't calc_region_size be too generic? We also have vmalloc and vmemmap,
> and here we are specifically calculating the direct mapping of physical
> memory.
It sounds like you didn't read what I wrote above so read it again pls.
> If not knowing the max address to cover all the possible hotplugged
> memory, later memory hotplug will fail.
You don't have to state the obvious - I can see that in the code.
So let me ask you differently: can the parsing of the SRAT table happen
shortly before kernel_randomize_memory() *without* adding all that gunk
to the compressed stage, and without adding the boot_params member and
done only for memory hot_add machines?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2019-12-13 20:39 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-15 14:49 [PATCH v5 0/4] Adjust the padding size for KASLR Masayoshi Mizuma
2019-11-15 14:49 ` [PATCH v5 1/4] x86/boot: Wrap up the SRAT traversing code into subtable_parse() Masayoshi Mizuma
2019-12-12 20:18 ` Borislav Petkov
2019-11-15 14:49 ` [PATCH v5 2/4] x86/boot: Add max_addr field in struct boot_params Masayoshi Mizuma
2019-11-15 14:49 ` [PATCH v5 3/4] x86/boot: Get the max address from SRAT Masayoshi Mizuma
2019-11-15 14:49 ` [PATCH v5 4/4] x86/mm/KASLR: Adjust the padding size for the direct mapping Masayoshi Mizuma
2019-11-17 0:42 ` Baoquan He
2019-12-12 20:19 ` Borislav Petkov
2019-12-13 13:28 ` Baoquan He
2019-12-13 14:15 ` Borislav Petkov
2019-12-13 14:54 ` Baoquan He
2019-12-13 16:38 ` Borislav Petkov [this message]
2019-12-13 23:29 ` Baoquan He
2019-12-14 7:13 ` Borislav Petkov
2019-12-14 10:07 ` Baoquan He
2019-12-14 3:33 ` Baoquan He
2019-12-14 7:15 ` Borislav Petkov
2019-12-12 20:17 ` [PATCH v5 0/4] Adjust the padding size for KASLR Borislav Petkov
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