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Subject: Re: [PATCH] x86/sev: Fully map the #VC exception stacks
From:   Tom Lendacky <thomas.lendacky@amd.com>
To:     linux-kernel@vger.kernel.org, x86@kernel.org
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Joerg Roedel <jroedel@suse.de>,
        Brijesh Singh <brijesh.singh@amd.com>
References: <113eca80a14cd280540c38488fd31ac0fa7bf36c.1633063250.git.thomas.lendacky@amd.com>
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Date:   Thu, 30 Sep 2021 23:49:11 -0500
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On 9/30/21 11:40 PM, Tom Lendacky wrote:
> The size of the exception stacks was recently increased, 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.
> 
> Update setup_vc_stacks() to map all the pages of both the IST stack area
> and the fallback stack area.
> 
> Fixes: 7fae4c24a2b8 ("x86: Increase exception stack sizes")

Arguably the Fixes: tag may not be completely accurate, since it was an 
issue within setup_vc_stacks(). But, this is more for if someone was to 
pull the patch identified by the Fixes: tag, then they would definitely 
need this patch to run SEV-ES.

Thanks,
Tom

> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
>   arch/x86/kernel/sev.c | 24 ++++++++++++++++--------
>   1 file changed, 16 insertions(+), 8 deletions(-)