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

From: David Rientjes
Date: Mon Jan 11 2021 - 13:56:35 EST


On Mon, 11 Jan 2021, Tom Lendacky 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@xxxxxxxxxx>
> > Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
> > ---
> >
> > 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?
>

Makes sense, I think this should likely be:

Fixes: f980f9c31a92 ("x86/sev-es: Compile early handler code into kernel image")