Re: [PATCH 38/62] x86/sev-es: Handle instruction fetches from user-space

On Tue, Feb 11, 2020 at 5:53 AM Joerg Roedel [off-list ref] wrote:

From: Joerg Roedel <redacted>

When a #VC exception is triggered by user-space the instruction
decoder needs to read the instruction bytes from user addresses.
Enhance es_fetch_insn_byte() to safely fetch kernel and user
instruction bytes.

I realize that this is a somewhat arbitrary point in the series to
complain about this, but: the kernel already has infrastructure to
decode and fix up an instruction-based exception.  See
fixup_umip_exception().  Please refactor code so that you can share
the same infrastructure rather than creating an entirely new thing.

FWIW, the fixup_umip_exception() code seems to have much more robust
segment handling than yours :)

--Andy