From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Ard Biesheuvel <ardb+git@google.com>, linux-kernel@vger.kernel.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
Jason Andryuk <jason.andryuk@amd.com>,
Juergen Gross <jgross@suse.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
x86@kernel.org, xen-devel@lists.xenproject.org
Subject: Re: [PATCH 2/5] x86/pvh: Use correct size value in GDT descriptor
Date: Thu, 26 Sep 2024 15:29:02 +0100 [thread overview]
Message-ID: <58eb8a15-4369-40c6-90fe-71999cffcb63@citrix.com> (raw)
In-Reply-To: <20240926104113.80146-9-ardb+git@google.com>
On 26/09/2024 11:41 am, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> The size field in a GDT descriptor is offset by 1, so subtract 1 from
> the calculated range.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
I realise this is probably nitpicking, but the GDT descriptor has a
limit field, which is (intentionally) not a size field.
This is why there's a difference of 1 between them.
Working in terms of limits rather than sizes avoids needing a 16th bit
on the segment limit circuitry, which mattered for the 286.
~Andrew
next prev parent reply other threads:[~2024-09-26 14:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-26 10:41 [PATCH 0/5] x86/xen: Drop absolute references from startup code Ard Biesheuvel
2024-09-26 10:41 ` [PATCH 1/5] x86/pvh: Call C code via the kernel virtual mapping Ard Biesheuvel
2024-09-26 10:55 ` Ard Biesheuvel
2024-09-26 20:29 ` Jason Andryuk
2024-09-26 10:41 ` [PATCH 2/5] x86/pvh: Use correct size value in GDT descriptor Ard Biesheuvel
2024-09-26 14:29 ` Andrew Cooper [this message]
2024-09-26 20:32 ` Jason Andryuk
2024-09-26 10:41 ` [PATCH 3/5] x86/pvh: Omit needless clearing of phys_base Ard Biesheuvel
2024-09-26 20:35 ` Jason Andryuk
2024-09-26 10:41 ` [PATCH 4/5] x86/xen: Avoid relocatable quantities in Xen ELF notes Ard Biesheuvel
2024-09-27 1:46 ` Jason Andryuk
2024-09-27 5:49 ` Ard Biesheuvel
2024-09-27 7:21 ` Ard Biesheuvel
2024-09-26 10:41 ` [PATCH 5/5] x86/pvh: Avoid absolute symbol references in .head.text Ard Biesheuvel
2024-09-27 22:12 ` Jason Andryuk
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