linux-kernel - [PATCH v6 0/2] x86/jailhouse: improve probing of platform UARTs

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Date:   Thu, 10 Oct 2019 12:21:00 +0200
From:   Ralf Ramsauer <ralf.ramsauer@...-regensburg.de>
To:     Jan Kiszka <jan.kiszka@...mens.com>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        jailhouse-dev@...glegroups.com, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ralf Ramsauer <ralf.ramsauer@...-regensburg.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>
Subject: [PATCH v6 0/2] x86/jailhouse: improve probing of platform UARTs

Hi,

probing of platform UARTs is a problem for x86 Jailhouse non-root
cells: Linux doesn't know which UARTs belong to the cell and will probe
for all platform UARTs. This crashes the guest if access isn't
permitted. Current workarounds (tuning via 8250.nr_uarts) are hacky and
limited.

Jailhouse now comes with flags inside setup_data that indicate
availability of UARTs, so simply use it.

  Ralf

since v5:
  - Link: https://lore.kernel.org/r/20191007123819.161432-1-ralf.ramsauer@oth-regensburg.de
          alt: https://www.mail-archive.com/jailhouse-dev@googlegroups.com/msg07568.html
  - Address Borislav's comments:
    - Improve commit messages
    - 1/2: Use min_t instead of min
    - 2/2: Add __init attribute to jailhouse_serial_workaround 
    - 2/2: Remove __initdata from setup_data, as it it is used by
      jailhouse_serial_fixup(), which can not become __init. It is
      passed over to serial8250_set_isa_configurator and can be used
      after bootup.

since v4:
  - Link: https://lore.kernel.org/r/20190909151030.152012-1-ralf.ramsauer@oth-regensburg.de
          alt: https://www.mail-archive.com/jailhouse-dev@googlegroups.com/msg07483.html
  - rebase and test on latest master and resolve conflicts
  - Add linux-kernel ML

since v3:
  - Link: https://lore.kernel.org/r/20190819183408.988013-1-ralf.ramsauer@oth-regensburg.de
          alt: https://www.mail-archive.com/jailhouse-dev@googlegroups.com/msg07365.html
  - Address Thomas' comments (and it really looks nicer)
  - Address Jan's comment on patch 1 and add his Reviewed-by tag

since v2:
  - Link: https://lore.kernel.org/r/20190812110650.631305-1-ralf.ramsauer@oth-regensburg.de
          alt: https://www.mail-archive.com/jailhouse-dev@googlegroups.com/msg07334.html
  - avoid imbalances of early_memremap and early_memunmap

since v1:
  - Link: https://lore.kernel.org/r/20190802123333.4008-1-ralf.ramsauer@oth-regensburg.de
  -       alt: https://www.mail-archive.com/jailhouse-dev@googlegroups.com/msg07283.html
  - setup data version check wasn't really prepared for extensions of
    the structure. Add a patch that improves the checks.

Ralf Ramsauer (2):
  x86/jailhouse: improve setup data version comparison
  x86/jailhouse: Only enable platform UARTs if available

 arch/x86/include/uapi/asm/bootparam.h |  25 +++--
 arch/x86/kernel/jailhouse.c           | 136 ++++++++++++++++++++------
 2 files changed, 120 insertions(+), 41 deletions(-)

-- 
2.23.0