linux-kernel - Re: [PATCH -v2] x86/sev: Make the #VC exception stacks part of the default stacks storage

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Message-ID: <eb92de7a-e0d2-cf2e-f05b-599d27a58012@amd.com>
Date:   Tue, 5 Oct 2021 11:28:01 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Borislav Petkov <bp@...en8.de>, Joerg Roedel <jroedel@...e.de>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH -v2] x86/sev: Make the #VC exception stacks part of the
 default stacks storage

On 10/4/21 4:41 PM, Borislav Petkov wrote:
> Yap,
> 
> here's v2, now tested. It seems we do need that optional_stack_size
> second arg to ESTACKS_MEMBERS(), thx Tom.
> 
> ---
> From: Borislav Petkov <bp@...e.de>

Tested-by: Tom Lendacky <thomas.lendacky@....com>

> 
> The size of the exception stacks was increased by the commit in Fixes,
> resulting in stack sizes greater than a page in size. The #VC exception
> handling was only mapping the first (bottom) page, resulting in an
> SEV-ES guest failing to boot.
> 
> Make the #VC exception stacks part of the default exception stacks
> storage and allocate them with a CONFIG_AMD_MEM_ENCRYPT=y .config. Map
> them only when a SEV-ES guest has been detected.
> 
> Rip out the custom VC stacks mapping and storage code.
> 
>   [ bp: Steal and adapt Tom's commit message. ]
> 
> Fixes: 7fae4c24a2b8 ("x86: Increase exception stack sizes")
> Signed-off-by: Borislav Petkov <bp@...e.de>