Message-Id: <1422635379-12476-1-git-send-email-pure.logic@nexus-software.ie>
Date:	Fri, 30 Jan 2015 16:29:37 +0000
From:	Bryan O'Donoghue <pure.logic@...us-software.ie>
To:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, dvhart@...radead.org, andy.shevchenko@...il.com,
	boon.leong.ong@...el.com, linux-kernel@...r.kernel.org
Cc:	Bryan O'Donoghue <pure.logic@...us-software.ie>
Subject: [PATCH v8 0/2] x86: Add IMR support to Quark/Galileo

This patchset adds support for Isolated Memory Regions to the kernel.

Quark SoC X1000 contains a set of registers called Isolated Memory Regions.
IMRs provide fine grained memory access control to various system agents
within the SoC such as CPU SMM/non-SMM mode, PCIe virtual channels, CPU
snoop cycles, eSRAM flush cycles and the RMU. In simple terms, IMRs provide
a mechanism to protect memory regions from unwarranted access by system
agents that should not have access to that memory.

IMRs support a lock bit. Once a lock bit is set for an individual IMR it is
not possible to tear down that IMR without performing a cold boot of the
system. IMRs support reporting of violations. The SoC system can be
configured to reboot immediately when an IMR violation has taken place.
Immediate reboot of the system on IMR violation is recommended and is
currently how Quark BIOS configures the system.

An example of IMRs in use is given with Arduino compatiable Galileo boards
which ship with an IMR around the ACPI runtime services memory. If a DMA
read/write cycle were to occur to this region of memory this would trigger
the IMR violation mechansim.

As part of the IMR init code all unlocked IMRs are removed to ensure the
EFI memory map and IMR memory map are consistent. This is necessary since at
various stages during the boot of Quark systems firmware and second stage
bootloader will place unlocked IMRs around various assets in memory, with
the expectation that subsequent phases of boot will tear-down unlocked/stale
IMRs before proceeding. The kernel needs to tear-down unlocked IMRs placed
around the boot params structure and compressed kernel in memory. Without
doing so DMA addresses given out by the kernel to DMA capable hardware runs
the risk of triggering an IMR fault when DMA happens to those addresses.
As a result any unlocked IMR must be torn down by the kernel early in the
boot process to sanitize the memory map. 

As an additional protection to the run-time kernel from unwarranted memory
transactions an IMR is placed around the kernel's .text and .rodata
sections. 

Changes since v7:
 - Reviewed-by/Tested-by/Suggested-by
   Updated to reflect all reviews/testing/suggestions to date
   Andy Shevchenko, Darren Hart, Ingo Molnar, Thomas Gleixner, Ong Boon Leong
 - newline dropped after mutex_unlock @ debugfs_state_show
   Andy Shevchenko
 - PTR_ERR used to trap debugfs hook error
   Andy Shevchenko
 - imr_check_param
   pr_warn -> pr_err
   Andy Shevchenko
 - imr_add_range
   !imr_is_enabled returns -ENOTSUPP
   Andy Shevchenko
 - imr_add_range
   Address overlap ret = -EINVAL assigned once
   Andy Shevchenko
 - imr_add_range
   Return -ENOMEM not -ENODEV for no available IMR
   Andy Shevchenko
 - imr_remove_range - comment typo addressed
   Andy Shevchenko
 - IMR selftest result print
   Converted to pr_info in both cases
   Andy Shevchenko
 - imr_check_params
   Needless -ENOMEM removed
   Andy Shevchenko/Bryan O'Donoghue
 - imr_remove_range
   Checking of address range done for non-index case only
   Andy Shevchenko/Bryan O'Donoghue
Changes since v6:
 - done label renamed failed
   Ingo Molnar
 - imr_write failure trapped
   On imr_write fail an attempt will be made to backout the IMR change
   Ingo Molnar
 - WARN_ONCE
   Used for IMR use before init == true
   Ingo Molnar
 - imr_check_range -> imr_check_params
   Check for zero size added to imr_check_params
   Ingo Molnar
 - imr_fixup_size -> imr_raw_size
   raw_size used in add/remove range functions after imr_raw_size() call
   Ingo Molnar
 - Comment "Allocate IMR" -> "Enable IMR at specified range"
   Ingo Molnar
 - found == false -> !found
   Ingo Molnar
 - EXPORT_SYMBOL -> EXPORT_SYMBOL_GPL
   Ingo Molnar
 - MTRR-like external index dropped from imr_del_range
   Ingo Molnar
 - imr_clear
   Used as internal helper function to enable tear-down of unlocked IMRs
   Ingo Molnar
 - Self test updated to reflect subtract of index from external API
   Bryan O'Donoghue
 - Newline added to Kconfig.debug
   Ong, Boon Leong

Changes since v5:
 - Full stops
   Added to all comments - including one-liners.
   Andy Shevchenko
 - %zu and %zx
   Used to print size_t variables
   Andy Shevchenko
 - imr_selftest
   Split into seperate module
   Andy Shevchenko

Changes since v4:
 - Quark added as a platform in a separate patch to IMRs
   Andy Shevchenko
 - imr_read
   Add extra reg++ to end of read for consistency
   Andy Shevchenko
 - ret
   Declarations of return variable moved to end of each declaration block
   Andy Shevchenko
 - Parameters passed to debugfs hooks
   Andy Shevchenko
 - struct imr_dev *idev = &imr_dev;
   Used globally for entry point functions
   Andy Shevchenko/Bryan O'Donoghue
 - struct imr_dev * passed to static functions
   Andy Shevchenko/Bryan O'Donoghue
 - Comment in imr_fixup_memmap
   Paried down and made more readable
   Andy Shevchenko
 - imr_fixup_memmap/imr_selftest
   phys_addr_t used for base
   Andy Shevchenko
 - phys_addr_t/size_t
   Supplemented globally in place of unsigned long where appropriate
   Bryan O'Donoghue
 - print routines to take %pa globally
   In place of pr_info("0x%08lx\n", (unsigned long)some_phs_addr_t_variable);
   Andy Shevchenko
 - debugfs hook moved to after init = true
   Andy Shevchenko

Changes since v3:
 - Remove reference to imr.o in arch/x86/kernel/Makefile
   Bryan O'Donoghue

Changes since v2:
 - Move IMR code to arch/x86/platform/intel-quark/imr.c
   Thomas Gleixner/Darren Hart
 - #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
    Andy Shevchenko
 - ret = iosf_mbi_read()
    Style made consistent in imr_write
    Andy Shevchenko
 - reg++/IMR_NUM_REGS
    Offset used for lock bit in imr_write
    Andy Shevchenko
 - debugfs s->private pointer used
    Andy Shevchenko
 - debugfs
    Conditional compilation defines removed
    Andy Shevchenko
 - debugfs
    Failure to hook debugfs treated as non-fatal
    Andy Shevchenko
 - phys_addr_t
    Updated API to use phys_addr_t in place of unsigned long for base param
    Andy Shevchenko
 - printk
    "KiB" instead of "k"
    Andy Shevchenko
 - imr_enabled
    -> static inline imr_is_enabled
    Ong, Boon Leong/Andy Shevchenko
 - imr_write
    trap final ret from iosf_mbi_write for lock bit in imr_write - bugfix
    Ong, Boon Leong
 - imr_fixup_size
    -> static inline imr_fixup_size
    Ong, Boon Leong
 - imr_address_overlap
    -> imr_address_overlap
    Ong, Boon Leong
 - imr_add_range
    End address in imr_add_range calculated after imr_fixup_size()
    Ong, Boon Leong
 - imr_del_range
    Pass i in place of reg in imr_del_range() - bugfix
    Ong, Boon Leong
 - Add test case
    imr_del_range(-1, addr, size)
    Ong, Boon Leong/Andy Shevchenko
 - Added text "aligned to 1 KiB" removed reference to "4 k"
    Ong, Boon Leong
 - imr_is_enabled
    Definition of enabled updated to be negation of disabled
    Bryan O'Donoghue
 - imr_add_range
    Add check for adding an IMR in the disabled state
    Bryan O'Donoghue
 - Add test case IMR @ invalid address, @0 with rmask/wmask=CPU, @ 0 size 0x800
    Bryan O'Donoghue
 - Add WARN() to failed IMR test in print routine
    Bryan O'Donoghue
 - Update license to Dual BSD/GPL
    Reflect licensing in Intel reference code
    Bryan O'Donoghue

Changes since v1:
 - Galileo platform code
    Removed completely. Policy to tear-down unlocked IMRs and setup IMR
    around kernel .text and .rodata as part of IMR init code.
    Darren Hart/Ong, Boon Leong
 - imr_add/imr_del
    Renamed to imr_add_range and imr_del_range respectively.
    Andy Shevchenko
 - x86_match_cpu
    Used in place of DMI strings specific to Galileo.
    Andy Shevchenko/Ong, Boon Leong
 - Expanded git log definitions of IMRs
    Addition of more descriptive text to deliniate between different IMR
    types.
    Ong, Boon Leong
 - struct imr
    Renamed to struct imr_regs
    Andy Shevchenko/Darren Hart
 - imr_read/imr_write
    Flow reworked flow of register indexing
    Andy Shevchenko
 - debugfs hooks changed
    Andy Shevchenko
 - imr_enabled
    Definition of an enabled IMR updated to include read/write mask values
    present in IMR. Address @ zero and read/write mask in conjunction will
    be the definition of a disabled IMR on X1000 to be consistent with
    firmware both old and current which also defines a disabled IMR this
    way.
    Darren Hart/Ong, Boon Leong
 - Overlapping
    Comment added to code to explain the design decision not to allow IMR
    overlaps.
    Darren Hart/Ong, Boon Leong
 - CONFIG_DEBUG_IMR_SELFTEST
    Automated IMR self test moved from removed Galileo platform code and
    added to IMR init code. Option exists in the kernel hacking section.
    Darren Hart
 - IMR self test
    Expanded to over more scenarios
    Bryan O'Donoghue
 - Remove reference to IMR_ENABLE bit
    Undocumented bit with respect to Quark X1000
    Ong, Boon Leong
 - Expanded kernel IMR to encompass .text and .rodata
    IMR protecting both .text and .rodata as in the same way as .text and
    .rodata are marked read-only in the relevant page-table entries.
    Bryan O'Donoghue
 - Overlap bounds checking
    Moved range checking of overlap into a function
    Andy Shevchenko

Bryan O'Donoghue (2):
  x86: Add Isolated Memory Regions for Quark X1000
  x86, quark: Add Intel Quark platform support

 arch/x86/Kconfig                             |  16 +
 arch/x86/Kconfig.debug                       |  13 +
 arch/x86/include/asm/imr.h                   |  60 +++
 arch/x86/platform/Makefile                   |   1 +
 arch/x86/platform/intel-quark/Makefile       |   2 +
 arch/x86/platform/intel-quark/imr.c          | 668 +++++++++++++++++++++++++++
 arch/x86/platform/intel-quark/imr_selftest.c | 129 ++++++
 drivers/platform/x86/Kconfig                 |  25 +
 8 files changed, 914 insertions(+)
 create mode 100644 arch/x86/include/asm/imr.h
 create mode 100644 arch/x86/platform/intel-quark/Makefile
 create mode 100644 arch/x86/platform/intel-quark/imr.c
 create mode 100644 arch/x86/platform/intel-quark/imr_selftest.c

-- 
1.9.1

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