linux-kernel - Re: [PATCH v3] x86/sev: Fix making shared pages private during kdump

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Message-ID: <18d4f1d7-0b40-06eb-f328-fbe198a2832d@amd.com>
Date: Fri, 2 May 2025 14:40:28 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: "Kalra, Ashish" <ashish.kalra@....com>, tglx@...utronix.de,
 mingo@...hat.com, dave.hansen@...ux.intel.com, x86@...nel.org, bp@...en8.de,
 hpa@...or.com
Cc: michael.roth@....com, nikunj@....com, seanjc@...gle.com, ardb@...nel.org,
 stable@...r.kernel.org, linux-kernel@...r.kernel.org,
 kexec@...ts.infradead.org, linux-coco@...ts.linux.dev
Subject: Re: [PATCH v3] x86/sev: Fix making shared pages private during kdump

On 5/2/25 14:32, Kalra, Ashish wrote:
> Hello Tom,
> 
> On 5/1/2025 8:56 AM, Tom Lendacky wrote:
>> On 4/30/25 18:17, Ashish Kalra wrote:
>>> From: Ashish Kalra <ashish.kalra@....com>

> 
> I agree, i really don't need the check as i can simply apply the mask as
> the mask is based on page level/size.
> 
> mask = page_level_mask(level);
> ghcb = (struct ghcb *)((unsigned long)ghcb & mask);

There's also a lot of casting back and forth with the ghcb variable. It
might be better to define it as an unsigned long and reduce all that.

Thanks,
Tom

>