linux-kernel - Re: [PATCH V2] x86/sev-es: Fix SEV-ES #VC handler for string port IO

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Message-ID: <1c7f7df6-11f0-e290-cb26-6d8c01b45e2c@amd.com>
Date:   Mon, 11 Jan 2021 12:29:08 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     "Hyunwook (Wooky) Baek" <baekhw@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>
Cc:     Joerg Roedel <jroedel@...e.de>,
        David Rientjes <rientjes@...gle.com>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH V2] x86/sev-es: Fix SEV-ES #VC handler for string port IO

On 1/10/21 1:11 AM, Hyunwook (Wooky) Baek wrote:
> Don't assume dest/source buffers are userspace addresses when manually
> copying data for string I/O or MOVS MMIO, as {get,put}_user() will fail
> if handed a kernel address and ultimately lead to a kernel panic.
> 
> Signed-off-by: Hyunwook (Wooky) Baek <baekhw@...gle.com>
> Acked-by: David Rientjes <rientjes@...gle.com>
> ---
> 
> This patch is tested by invoking INSB/OUTSB instructions in kernel space in a
> SEV-ES-enabled VM. Without the patch, the kernel crashed with the following
> message:
>    "SEV-ES: Unsupported exception in #VC instruction emulation - can't continue"
> With the patch, the instructions successfully read/wrote the string from/to
> the I/O port.

Shouldn't this have a Fixes: tag?

Thanks,
Tom

> 
>   arch/x86/kernel/sev-es.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
>