linux-kernel - [PATCH 0/8] KVM: SEV-ES: fixes for string I/O emulation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 13 Oct 2021 12:56:08 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     fwilhelm@...gle.com, seanjc@...gle.com, oupton@...gle.com
Subject: [PATCH 0/8] KVM: SEV-ES: fixes for string I/O emulation

This series, namely patches 1 and 8, fix two bugs in string I/O
emulation for SEV-ES:

- first, the length is completely off for "rep ins" and "rep outs"
  operation of size > 1.  After setup_vmgexit_scratch, svm->ghcb_sa_len
  is in bytes, but kvm_sev_es_string_io expects the number of PIO
  operations.

- second, the size of the GHCB buffer can exceed the size of
  vcpu->arch.pio_data.  If that happens, we need to go over the GHCB
  buffer in multiple passes.

The second bug was reported by Felix Wilhelm.  The first was found by
me by code inspection; on one hand it seems *too* egregious so I'll be
gladly proven wrong on this, on the other hand... I know I'm bad at code
review, but not _that_ bad.

Patches 2 to 7 are a bunch of cleanups to emulator_pio_in and
emulator_pio_in_out, so that the final SEV code is a little easier
to reason on.  Just a little, no big promises.

Tested by booting a SEV-ES guest and with "regular" kvm-unit-tests.
For SEV-ES I also bounded the limit to 12 bytes, and checked in the
resulting trace that both the read and write paths were hit when
booting a guest.

Paolo

Paolo Bonzini (8):
  KVM: SEV-ES: fix length of string I/O
  KVM: SEV-ES: rename guest_ins_data to sev_pio_data
  KVM: x86: leave vcpu->arch.pio.count alone in emulator_pio_in_out
  KVM: SEV-ES: clean up kvm_sev_es_ins/outs
  KVM: x86: split the two parts of emulator_pio_in
  KVM: x86: remove unnecessary arguments from complete_emulator_pio_in
  KVM: SEV-ES: keep INS functions together
  KVM: SEV-ES: go over the sev_pio_data buffer in multiple passes if
    needed

 arch/x86/include/asm/kvm_host.h |   3 +-
 arch/x86/kvm/svm/sev.c          |   2 +-
 arch/x86/kvm/x86.c              | 136 +++++++++++++++++++++-----------
 3 files changed, 95 insertions(+), 46 deletions(-)

-- 
2.27.0