[PATCH v6 0/2] x86: Add IMR support to Quark/Galileo

[PATCH v6 0/2] x86: Add IMR support to Quark/Galileo

[Bryan O'Donoghue]

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 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                       |  12 +
 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          | 616 +++++++++++++++++++++++++++
 arch/x86/platform/intel-quark/imr_selftest.c | 135 ++++++
 drivers/platform/x86/Kconfig                 |  25 ++
 8 files changed, 867 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

[PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

Intel's Quark X1000 SoC contains a set of registers called Isolated Memory
Regions. IMRs are accessed over the IOSF mailbox interface. IMRs are areas
carved out of memory that define read/write access rights to the various
system agents within the Quark system. For a given agent in the system it is
possible to specify if that agent may read or write an area of memory
defined by an IMR with a granularity of 1 KiB.

Quark_SecureBootPRM_330234_001.pdf section 4.5 details the concept of IMRs
quark-x1000-datasheet.pdf section 12.7.4 details the implementation of IMRs
in silicon.

eSRAM flush, CPU Snoop write-only, CPU SMM Mode, CPU non-SMM mode, RMU and
PCIe Virtual Channels (VC0 and VC1) can have individual read/write access
masks applied to them for a given memory region in Quark X1000. This
enables IMRs to treat each memory transaction type listed above on an
individual basis and to filter appropriately based on the IMR access mask
for the memory region. Quark supports eight IMRs.

Since all of the DMA capable SoC components in the X1000 are mapped to VC0
it is possible to define sections of memory as invalid for DMA write
operations originating from Ethernet, USB, SD and any other DMA capable
south-cluster component on VC0. Similarly it is possible to mark kernel
memory as non-SMM mode read/write only or to mark BIOS runtime memory as SMM
mode accessible only depending on the particular memory footprint on a given
system.

On an IMR violation Quark SoC X1000 systems are configured to reset the
system, so ensuring that the IMR memory map is consistent with the EFI
provided memory map is critical to ensure no IMR violations reset the
system.

The API for accessing IMRs is based on MTRR code but doesn't provide a /proc
or /sys interface to manipulate IMRs. Defining the size and extent of IMRs
is exclusively the domain of in-kernel code.

Quark firmware sets up a series of locked IMRs around pieces of memory that
firmware owns such as ACPI runtime data. During boot a series of unlocked
IMRs are placed around items in memory to guarantee no DMA modification of
those items can take place. Grub also places an unlocked IMR around the
kernel boot params data structure and compressed kernel image. It is
necessary for the kernel to tear down all unlocked IMRs in order to ensure
that the kernel's view of memory passed via the EFI memory map is consistent
with the IMR memory map. Without tearing down all unlocked IMRs on boot
transitory IMRs such as those used to protect the compressed kernel image
will cause IMR violations and system reboots.

The IMR init code tears down all unlocked IMRs and sets a protective IMR
around the kernel .text and .rodata as one contiguous block. This sanitizes
the IMR memory map with respect to the EFI memory map and protects the
read-only portions of the kernel from unwarranted DMA access.

Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
---
 arch/x86/Kconfig.debug                       |  12 +
 arch/x86/include/asm/imr.h                   |  60 +++
 arch/x86/platform/intel-quark/Makefile       |   2 +
 arch/x86/platform/intel-quark/imr.c          | 616 +++++++++++++++++++++++++++
 arch/x86/platform/intel-quark/imr_selftest.c | 135 ++++++
 drivers/platform/x86/Kconfig                 |  25 ++
 6 files changed, 850 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

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 61bd2ad..fcf5701 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -313,6 +313,18 @@ config DEBUG_NMI_SELFTEST
 
 	  If unsure, say N.
 
+config DEBUG_IMR_SELFTEST
+	bool "Isolated Memory Region self test"
+	default n
+	depends on INTEL_IMR
+	---help---
+	  This option enables automated sanity testing of the IMR code.
+	  Some simple tests are run to verify IMR bounds checking, alignment
+	  and overlapping. This option is really only useful if you are
+	  debugging an IMR memory map or are modifying the IMR code and want to
+	  test your changes.
+
+	  If unsure say N here.
 config X86_DEBUG_STATIC_CPU_HAS
 	bool "Debug alternatives"
 	depends on DEBUG_KERNEL
diff --git a/arch/x86/include/asm/imr.h b/arch/x86/include/asm/imr.h
new file mode 100644
index 0000000..0542dc2
--- /dev/null
+++ b/arch/x86/include/asm/imr.h
@@ -0,0 +1,60 @@
+/*
+ * imr.h: Isolated Memory Region API
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ * Copyright(c) 2015 Bryan O'Donoghue <pure.logic@nexus-software.ie>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+#ifndef _IMR_H
+#define _IMR_H
+
+#include <linux/types.h>
+
+/*
+ * IMR agent access mask bits
+ * See section 12.7.4.7 from quark-x1000-datasheet.pdf for register
+ * definitions.
+ */
+#define IMR_ESRAM_FLUSH		BIT(31)
+#define IMR_CPU_SNOOP		BIT(30)		/* Applicable only to write */
+#define IMR_RMU			BIT(29)
+#define IMR_VC1_SAI_ID3		BIT(15)
+#define IMR_VC1_SAI_ID2		BIT(14)
+#define IMR_VC1_SAI_ID1		BIT(13)
+#define IMR_VC1_SAI_ID0		BIT(12)
+#define IMR_VC0_SAI_ID3		BIT(11)
+#define IMR_VC0_SAI_ID2		BIT(10)
+#define IMR_VC0_SAI_ID1		BIT(9)
+#define IMR_VC0_SAI_ID0		BIT(8)
+#define IMR_CPU_0		BIT(1)		/* SMM mode */
+#define IMR_CPU			BIT(0)		/* Non SMM mode */
+#define IMR_ACCESS_NONE		0
+
+/*
+ * Read/Write access-all bits here include some reserved bits
+ * These are the values firmware uses and are accepted by hardware.
+ * The kernel defines read/write access-all in the same way as firmware
+ * in order to have a consistent and crisp definition across firmware,
+ * bootloader and kernel.
+ */
+#define IMR_READ_ACCESS_ALL	0xBFFFFFFF
+#define IMR_WRITE_ACCESS_ALL	0xFFFFFFFF
+
+/* Number of IMRs provided by Quark X1000 SoC */
+#define QUARK_X1000_IMR_MAX	0x08
+#define QUARK_X1000_IMR_REGBASE 0x40
+
+/* IMR alignment bits - only bits 31:10 are checked for IMR validity */
+#define IMR_ALIGN		0x400
+#define IMR_MASK		(IMR_ALIGN - 1)
+
+int imr_add_range(phys_addr_t base, size_t size,
+		  unsigned int rmask, unsigned int wmask, bool lock);
+
+int imr_remove_range(int reg, phys_addr_t base, size_t size);
+
+#endif /* _IMR_H */
diff --git a/arch/x86/platform/intel-quark/Makefile b/arch/x86/platform/intel-quark/Makefile
new file mode 100644
index 0000000..9cc57ed
--- /dev/null
+++ b/arch/x86/platform/intel-quark/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_INTEL_IMR) += imr.o
+obj-$(CONFIG_DEBUG_IMR_SELFTEST) += imr_selftest.o
diff --git a/arch/x86/platform/intel-quark/imr.c b/arch/x86/platform/intel-quark/imr.c
new file mode 100644
index 0000000..6157a3b
--- /dev/null
+++ b/arch/x86/platform/intel-quark/imr.c
@@ -0,0 +1,616 @@
+/**
+ * imr.c
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ * Copyright(c) 2015 Bryan O'Donoghue <pure.logic@nexus-software.ie>
+ *
+ * IMR registers define an isolated region of memory that can
+ * be masked to prohibit certain system agents from accessing memory.
+ * When a device behind a masked port performs an access - snooped or
+ * not, an IMR may optionally prevent that transaction from changing
+ * the state of memory or from getting correct data in response to the
+ * operation.
+ *
+ * Write data will be dropped and reads will return 0xFFFFFFFF, the
+ * system will reset and system BIOS will print out an error message to
+ * inform the user that an IMR has been violated.
+ *
+ * This code is based on the Linux MTRR code and reference code from
+ * Intel's Quark BSP EFI, Linux and grub code.
+ *
+ * See quark-x1000-datasheet.pdf for register definitions.
+ * http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/quark-x1000-datasheet.pdf
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <asm-generic/sections.h>
+#include <asm/cpu_device_id.h>
+#include <asm/imr.h>
+#include <asm/iosf_mbi.h>
+#include <linux/debugfs.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+struct imr_device {
+	struct dentry	*file;
+	bool		init;
+	struct mutex	lock;
+	int		max_imr;
+	int		reg_base;
+};
+
+static struct imr_device imr_dev;
+
+/*
+ * IMR read/write mask control registers.
+ * See quark-x1000-datasheet.pdf sections 12.7.4.5 and 12.7.4.6 for
+ * bit definitions.
+ *
+ * addr_hi
+ * 31		Lock bit
+ * 30:24	Reserved
+ * 23:2		1 KiB aligned lo address
+ * 1:0		Reserved
+ *
+ * addr_hi
+ * 31:24	Reserved
+ * 23:2		1 KiB aligned hi address
+ * 1:0		Reserved
+ */
+#define IMR_LOCK	BIT(31)
+
+struct imr_regs {
+	u32 addr_lo;
+	u32 addr_hi;
+	u32 rmask;
+	u32 wmask;
+};
+
+#define IMR_NUM_REGS	(sizeof(struct imr_regs)/sizeof(u32))
+#define IMR_SHIFT	8
+#define imr_to_phys(x)	((x) << IMR_SHIFT)
+#define phys_to_imr(x)	((x) >> IMR_SHIFT)
+
+/**
+ * imr_is_enabled - true if an IMR is enabled false otherwise.
+ *
+ * Determines if an IMR is enabled based on address range and read/write
+ * mask. An IMR set with an address range set to zero and a read/write
+ * access mask set to all is considered to be disabled. An IMR in any
+ * other state - for example set to zero but without read/write access
+ * all is considered to be enabled. This definition of disabled is how
+ * firmware switches off an IMR and is maintained in kernel for
+ * consistency.
+ *
+ * @imr:	pointer to IMR descriptor.
+ * @return:	true if IMR enabled false if disabled.
+ */
+static inline int imr_is_enabled(struct imr_regs *imr)
+{
+	return !(imr->rmask == IMR_READ_ACCESS_ALL &&
+		 imr->wmask == IMR_WRITE_ACCESS_ALL &&
+		 imr_to_phys(imr->addr_lo) == 0 &&
+		 imr_to_phys(imr->addr_hi) == 0);
+}
+
+/**
+ * imr_read - read an IMR at a given index.
+ *
+ * Requires caller to hold imr mutex.
+ *
+ * @idev:	pointer to imr_device structure.
+ * @imr_id:	IMR entry to read.
+ * @imr:	IMR structure representing address and access masks.
+ * @return:	0 on success or error code passed from mbi_iosf on failure.
+ */
+static int imr_read(struct imr_device *idev, u32 imr_id, struct imr_regs *imr)
+{
+	u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base;
+	int ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				reg++, &imr->addr_lo);
+	if (ret)
+		return ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				reg++, &imr->addr_hi);
+	if (ret)
+		return ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				reg++, &imr->rmask);
+	if (ret)
+		return ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				reg++, &imr->wmask);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+/**
+ * imr_write - write an IMR at a given index.
+ *
+ * Requires caller to hold imr mutex.
+ * Note lock bits need to be written independently of address bits.
+ *
+ * @idev:	pointer to imr_device structure.
+ * @imr_id:	IMR entry to write.
+ * @imr:	IMR structure representing address and access masks.
+ * @lock:	indicates if the IMR lock bit should be applied.
+ * @return:	0 on success or error code passed from mbi_iosf on failure.
+ */
+static int imr_write(struct imr_device *idev, u32 imr_id,
+		     struct imr_regs *imr, bool lock)
+{
+	unsigned long flags;
+	u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base;
+	int ret;
+
+	local_irq_save(flags);
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE, reg++,
+				imr->addr_lo);
+	if (ret)
+		goto done;
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+				reg++, imr->addr_hi);
+	if (ret)
+		goto done;
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+				reg++, imr->rmask);
+	if (ret)
+		goto done;
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+				reg++, imr->wmask);
+	if (ret)
+		goto done;
+
+	/* Lock bit must be set separately to addr_lo address bits. */
+	if (lock) {
+		imr->addr_lo |= IMR_LOCK;
+		ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+					reg - IMR_NUM_REGS, imr->addr_lo);
+		if (ret)
+			goto done;
+	}
+
+	local_irq_restore(flags);
+	return 0;
+done:
+	/*
+	 * If writing to the IOSF failed then we're in an unknown state,
+	 * likely a very bad state. An IMR in an invalid state will almost
+	 * certainly lead to a memory access violation.
+	 */
+	local_irq_restore(flags);
+	WARN(ret, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n",
+	     imr_to_phys(imr->addr_lo), imr_to_phys(imr->addr_hi) + IMR_MASK);
+
+	return ret;
+}
+
+/**
+ * imr_dbgfs_state_show - print state of IMR registers.
+ *
+ * @s:		pointer to seq_file for output.
+ * @unused:	unused parameter.
+ * @return:	0 on success or error code passed from mbi_iosf on failure.
+ */
+static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
+{
+	phys_addr_t base;
+	phys_addr_t end;
+	int i;
+	struct imr_device *idev = s->private;
+	struct imr_regs imr;
+	size_t size;
+	int ret = -ENODEV;
+
+	mutex_lock(&idev->lock);
+
+	for (i = 0; i < idev->max_imr; i++) {
+
+		ret = imr_read(idev, i, &imr);
+		if (ret)
+			break;
+
+		/*
+		 * Remember to add IMR_ALIGN bytes to size to indicate the
+		 * inherent IMR_ALIGN size bytes contained in the masked away
+		 * lower ten bits.
+		 */
+		if (imr_is_enabled(&imr)) {
+			base = imr_to_phys(imr.addr_lo);
+			end = imr_to_phys(imr.addr_hi) + IMR_MASK;
+		} else {
+			base = 0;
+			end = 0;
+		}
+		size = end - base;
+		seq_printf(s, "imr%02i: base=%pa, end=%pa, size=0x%08zx "
+			   "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i,
+			   &base, &end, size, imr.rmask, imr.wmask,
+			   imr_is_enabled(&imr) ? "enabled " : "disabled",
+			   imr.addr_lo & IMR_LOCK ? "locked" : "unlocked");
+	}
+
+	mutex_unlock(&idev->lock);
+
+	return ret;
+}
+
+/**
+ * imr_state_open - debugfs open callback.
+ *
+ * @inode:	pointer to struct inode.
+ * @file:	pointer to struct file.
+ * @return:	result of single open.
+ */
+static int imr_state_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, imr_dbgfs_state_show, inode->i_private);
+}
+
+static const struct file_operations imr_state_ops = {
+	.open		= imr_state_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+/**
+ * imr_debugfs_register - register debugfs hooks.
+ *
+ * @idev:	pointer to imr_device structure.
+ * @return:	0 on success - errno on failure.
+ */
+static int imr_debugfs_register(struct imr_device *idev)
+{
+	idev->file = debugfs_create_file("imr_state", S_IFREG | S_IRUGO, NULL,
+					 idev, &imr_state_ops);
+	if (!idev->file)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * imr_debugfs_unregister - unregister debugfs hooks.
+ *
+ * @idev:	pointer to imr_device structure.
+ * @return:
+ */
+static void imr_debugfs_unregister(struct imr_device *idev)
+{
+	debugfs_remove(idev->file);
+}
+
+/**
+ * imr_check_range - checks passed address range for an IMR is aligned.
+ *
+ * @base:	base address of intended IMR.
+ * @size:	size of intended IMR.
+ * @return:	zero on valid range -EINVAL on unaligned base/size.
+ */
+static int imr_check_range(phys_addr_t base, size_t size)
+{
+	if ((base & IMR_MASK) || (size & IMR_MASK)) {
+		pr_warn("base %pa size 0x%08zx must align to 1KiB\n",
+			&base, size);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/**
+ * imr_fixup_size - account for the IMR_ALIGN bytes that addr_hi appends.
+ *
+ * IMR addr_hi has a built in offset of plus IMR_ALIGN (0x400) bytes from the
+ * value in the register. We need to subtract IMR_ALIGN bytes from input sizes
+ * as a result.
+ *
+ * @size:	input size bytes.
+ * @return:	reduced size.
+ */
+static inline size_t imr_fixup_size(size_t size)
+{
+	return size - IMR_ALIGN;
+}
+
+/**
+ * imr_address_overlap - detects an address overlap.
+ *
+ * @addr:	address to check against an existing IMR.
+ * @imr:	imr being checked.
+ * @return:	true for overlap false for no overlap.
+ */
+static inline int imr_address_overlap(phys_addr_t addr, struct imr_regs *imr)
+{
+	return addr >= imr_to_phys(imr->addr_lo) && addr <= imr_to_phys(imr->addr_hi);
+}
+
+/**
+ * imr_add_range - add an Isolated Memory Region.
+ *
+ * @base:	physical base address of region aligned to 1KiB.
+ * @size:	physical size of region in bytes must be aligned to 1KiB.
+ * @read_mask:	read access mask.
+ * @write_mask:	write access mask.
+ * @lock:	indicates whether or not to permanently lock this region.
+ * @return:	index of the IMR allocated or negative value indicating error.
+ */
+int imr_add_range(phys_addr_t base, size_t size,
+		  unsigned int rmask, unsigned int wmask, bool lock)
+{
+	phys_addr_t end;
+	unsigned int i;
+	struct imr_device *idev = &imr_dev;
+	struct imr_regs imr;
+	int reg;
+	int ret;
+
+	if (idev->init == false)
+		return -ENODEV;
+
+	ret = imr_check_range(base, size);
+	if (ret)
+		return ret;
+
+	if (size == 0)
+		return -EINVAL;
+
+	/* Tweak the size value. */
+	size = imr_fixup_size(size);
+	end = base + size;
+
+	/*
+	 * Check for reserved IMR value common to firmware, kernel and grub
+	 * indicating a disabled IMR.
+	 */
+	imr.addr_lo = phys_to_imr(base);
+	imr.addr_hi = phys_to_imr(end);
+	imr.rmask = rmask;
+	imr.wmask = wmask;
+	if (!imr_is_enabled(&imr))
+		return -EINVAL;
+
+	mutex_lock(&idev->lock);
+
+	/*
+	 * Find a free IMR while checking for an existing overlapping range.
+	 * Note there's no restriction in silicon to prevent IMR overlaps.
+	 * For the sake of simplicity and ease in defining/debugging an IMR
+	 * memory map we exclude IMR overlaps.
+	 */
+	reg = -1;
+	for (i = 0; i < idev->max_imr; i++) {
+		ret = imr_read(idev, i, &imr);
+		if (ret)
+			goto done;
+
+		/* Find overlap @ base or end of requested range. */
+		if (imr_is_enabled(&imr)) {
+			if (imr_address_overlap(base, &imr)) {
+				ret = -EINVAL;
+				goto done;
+			}
+			if (imr_address_overlap(end, &imr)) {
+				ret = -EINVAL;
+				goto done;
+			}
+		} else {
+			reg = i;
+		}
+	}
+
+	/* Error out if we have no free IMR entries. */
+	if (reg == -1) {
+		ret = -ENODEV;
+		goto done;
+	}
+
+	pr_debug("IMR %d phys %pa-%pa rmask 0x%08x wmask 0x%08x\n",
+		reg, &base, &end, rmask, wmask);
+
+	/* Allocate IMR. */
+	imr.addr_lo = phys_to_imr(base);
+	imr.addr_hi = phys_to_imr(end);
+	imr.rmask = rmask;
+	imr.wmask = wmask;
+
+	ret = imr_write(idev, reg, &imr, lock);
+
+done:
+	mutex_unlock(&idev->lock);
+	return ret == 0 ? reg : ret;
+}
+EXPORT_SYMBOL(imr_add_range);
+
+/**
+ * imr_remove_range - delete an Isolated Memory Region.
+ *
+ * This function allows you to delete an IMR by its index specified by reg or
+ * by address range specified by base and size respectively. If you specify an
+ * index on its own the base and size parameters are ignored.
+ * imr_remove_range(0, size, base); delete IMR at index 0 base/size ignored.
+ * imr_remove_range(-1, base, size); delete IMR from base to base+size.
+ *
+ * @reg:	imr index to remove.
+ * @base:	physical base address of region aligned to 1 KiB.
+ * @size:	physical size of region in bytes aligned to 1 KiB.
+ * @return:	-EINVAL on invalid range or out or range id
+ *		-ENODEV if reg is valid but no IMR exists or is locked
+ *		0 on success.
+ */
+int imr_remove_range(int reg, phys_addr_t base, size_t size)
+{
+	phys_addr_t end;
+	bool found = false;
+	unsigned int i;
+	struct imr_device *idev = &imr_dev;
+	struct imr_regs imr;
+	int ret = 0;
+
+	if (idev->init == false)
+		return -ENODEV;
+
+	if (imr_check_range(base, size))
+		return -EINVAL;
+
+	if (reg >= idev->max_imr)
+		return -EINVAL;
+
+	/* Tweak the size value. */
+	size = imr_fixup_size(size);
+	end = base + size;
+
+	mutex_lock(&idev->lock);
+
+	if (reg >= 0) {
+		/* If a specific IMR is given try to use it. */
+		ret = imr_read(idev, reg, &imr);
+		if (ret)
+			goto done;
+
+		if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
+			ret = -ENODEV;
+			goto done;
+		}
+		found = true;
+	} else {
+		/* Search for match based on address range. */
+		for (i = 0; i < idev->max_imr; i++) {
+			ret = imr_read(idev, i, &imr);
+			if (ret)
+				goto done;
+
+			if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK)
+				continue;
+
+			if ((imr_to_phys(imr.addr_lo) == base) &&
+			    (imr_to_phys(imr.addr_hi) == end)) {
+				found = true;
+				reg = i;
+				break;
+			}
+		}
+	}
+
+	if (found == false) {
+		ret = -ENODEV;
+		goto done;
+	}
+
+	/* Tear down the IMR. */
+	imr.addr_lo = 0;
+	imr.addr_hi = 0;
+	imr.rmask = IMR_READ_ACCESS_ALL;
+	imr.wmask = IMR_WRITE_ACCESS_ALL;
+
+	ret = imr_write(idev, reg, &imr, false);
+
+done:
+	mutex_unlock(&idev->lock);
+	return ret;
+}
+EXPORT_SYMBOL(imr_remove_range);
+
+/**
+ * imr_fixup_memmap - Tear down IMRs used during bootup.
+ *
+ * BIOS and Grub both setup IMRs around compressed kernel, initrd memory
+ * that need to be removed before the kernel hands out one of the IMR
+ * encased addresses to a downstream DMA agent such as the SD or Ethernet.
+ * IMRs on Galileo are setup to immediately reset the system on violation.
+ * As a result if you're running a root filesystem from SD - you'll need
+ * the boot-time IMRs torn down or you'll find seemingly random resets when
+ * using your filesystem.
+ *
+ * @idev:	pointer to imr_device structure.
+ * @return:
+ */
+static void __init imr_fixup_memmap(struct imr_device *idev)
+{
+	phys_addr_t base = virt_to_phys(&_text);
+	size_t size = virt_to_phys(&__end_rodata) - base;
+	int i;
+	int ret;
+
+	/* Tear down all existing unlocked IMRs. */
+	for (i = 0; i < idev->max_imr; i++)
+		imr_remove_range(i, 0, 0);
+
+	/*
+	 * Setup a locked IMR around the physical extent of the kernel
+	 * from the beginning of the .text secton to the end of the
+	 * .rodata section as one physically contiguous block.
+	 */
+	ret = imr_add_range(base, size, IMR_CPU, IMR_CPU, true);
+	if (ret < 0)
+		pr_err("unable to setup IMR for kernel: (%p - %p)\n",
+			&_text, &__end_rodata);
+	else
+		pr_info("protecting kernel .text - .rodata: %zu KiB (%p - %p)\n",
+			size / 1024, &_text, &__end_rodata);
+
+}
+
+static const struct x86_cpu_id imr_ids[] __initconst = {
+	{ X86_VENDOR_INTEL, 5, 9 },	/* Intel Quark SoC X1000. */
+	{}
+};
+MODULE_DEVICE_TABLE(x86cpu, imr_ids);
+
+/**
+ * imr_init - entry point for IMR driver.
+ *
+ * return: -ENODEV for no IMR support 0 if good to go.
+ */
+static int __init imr_init(void)
+{
+	struct imr_device *idev = &imr_dev;
+	int ret;
+
+	if (!x86_match_cpu(imr_ids) || !iosf_mbi_available())
+		return -ENODEV;
+
+	idev->max_imr = QUARK_X1000_IMR_MAX;
+	idev->reg_base = QUARK_X1000_IMR_REGBASE;
+	idev->init = true;
+
+	mutex_init(&idev->lock);
+	ret = imr_debugfs_register(idev);
+	if (ret != 0)
+		pr_warn("debugfs register failed!\n");
+	imr_fixup_memmap(idev);
+	return 0;
+}
+
+/**
+ * imr_exit - exit point for IMR code.
+ *
+ * Deregisters debugfs, leave IMR state as-is.
+ *
+ * return:
+ */
+static void __exit imr_exit(void)
+{
+	imr_debugfs_unregister(&imr_dev);
+}
+
+module_init(imr_init);
+module_exit(imr_exit);
+
+MODULE_AUTHOR("Bryan O'Donoghue <pure.logic@nexus-software.ie>");
+MODULE_DESCRIPTION("Intel Isolated Memory Region driver");
+MODULE_LICENSE("Dual BSD/GPL");
diff --git a/arch/x86/platform/intel-quark/imr_selftest.c b/arch/x86/platform/intel-quark/imr_selftest.c
new file mode 100644
index 0000000..ddecd6e
--- /dev/null
+++ b/arch/x86/platform/intel-quark/imr_selftest.c
@@ -0,0 +1,135 @@
+/**
+ * imr_selftest.c
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ * Copyright(c) 2015 Bryan O'Donoghue <pure.logic@nexus-software.ie>
+ *
+ * IMR self test. The purpose of this module is to run a set of tests on the
+ * IMR API to validate it's sanity. We check for overlapping, reserved
+ * addresses and setup/teardown sanity.
+ *
+ */
+
+#include <asm-generic/sections.h>
+#include <asm/imr.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#define SELFTEST KBUILD_MODNAME ": self_test "
+/**
+ * imr_self_test_result - Print result string for self test.
+ *
+ * @res:	result code - true if test passed false otherwise.
+ * @fmt:	format string.
+ * ...		variadic argument list.
+ */
+static void __init imr_self_test_result(int res, const char *fmt, ...)
+{
+	va_list vlist;
+
+	va_start(vlist, fmt);
+	if (res)
+		printk(KERN_INFO SELFTEST "pass ");
+	else
+		printk(KERN_ERR SELFTEST "fail ");
+	vprintk(fmt, vlist);
+	va_end(vlist);
+	WARN(res == 0, "test failed");
+}
+#undef SELFTEST
+
+/**
+ * imr_self_test
+ *
+ * Verify IMR self_test with some simple tests to verify overlap,
+ * zero sized allocations and 1 KiB sized areas.
+ *
+ */
+static void __init imr_self_test(void)
+{
+	phys_addr_t base  = virt_to_phys(&_text);
+	size_t size = virt_to_phys(&__end_rodata) - base;
+	const char *fmt_over = "overlapped IMR @ (0x%08lx - 0x%08lx)\n";
+	int idx;
+
+	/* Test zero zero. */
+	idx = imr_add_range(0, 0, 0, 0, false);
+	imr_self_test_result(idx < 0, "zero sized IMR\n");
+
+	/* Test exact overlap. */
+	idx = imr_add_range(base, size, IMR_CPU, IMR_CPU, false);
+	imr_self_test_result(idx < 0, fmt_over, __va(base), __va(base + size));
+
+	/* Test overlap with base inside of existing. */
+	base += size - IMR_ALIGN;
+	idx = imr_add_range(base, size, IMR_CPU, IMR_CPU, false);
+	imr_self_test_result(idx < 0, fmt_over, __va(base), __va(base + size));
+
+	/* Test overlap with end inside of existing. */
+	base -= size + IMR_ALIGN * 2;
+	idx = imr_add_range(base, size, IMR_CPU, IMR_CPU, false);
+	imr_self_test_result(idx < 0, fmt_over, __va(base), __va(base + size));
+
+	/* Test that a 1 KiB IMR @ zero with read/write all will bomb out. */
+	idx = imr_add_range(0, IMR_ALIGN, IMR_READ_ACCESS_ALL,
+			    IMR_WRITE_ACCESS_ALL, false);
+	imr_self_test_result(idx < 0, "1KiB IMR @ 0x00000000 - access-all\n");
+
+	/* Test that a 1 KiB IMR @ zero with CPU only will work. */
+	idx = imr_add_range(0, IMR_ALIGN, IMR_CPU, IMR_CPU, false);
+	imr_self_test_result(idx >= 0, "1KiB IMR @ 0x00000000 - cpu access\n");
+	if (idx >= 0) {
+		/* For an index removal address doesn't matter. */
+		idx = imr_remove_range(idx, 0, 0);
+		imr_self_test_result(idx == 0, "index-teardown - cpu access\n");
+	}
+
+	/* Test 2 KiB works - remove based on index. */
+	size = IMR_ALIGN * 2;
+	idx = imr_add_range(0, size, IMR_READ_ACCESS_ALL,
+			    IMR_WRITE_ACCESS_ALL, false);
+	imr_self_test_result(idx >= 0, "2KiB IMR @ 0x00000000\n");
+	if (idx >= 0) {
+		/* For an index removal address doesn't matter. */
+		idx = imr_remove_range(idx, 0, 0);
+		imr_self_test_result(idx == 0, "index-teardown 2KiB\n");
+	}
+
+	/* Test 1 KiB - remove based on address range. */
+	idx = imr_add_range(0, size, IMR_READ_ACCESS_ALL,
+			    IMR_WRITE_ACCESS_ALL, false);
+	imr_self_test_result(idx >= 0, "2KiB IMR @ 0x00000000\n");
+	if (idx >= 0) {
+		idx = imr_remove_range(-1, 0, size);
+		imr_self_test_result(idx == 0, "addr-teardown 2KiB\n");
+	}
+}
+
+/**
+ * imr_self_test_init - entry point for IMR driver.
+ *
+ * return: -ENODEV for no IMR support 0 if good to go.
+ */
+static int __init imr_self_test_init(void)
+{
+	imr_self_test();
+	return 0;
+}
+
+/**
+ * imr_self_test_exit - exit point for IMR code.
+ *
+ * return:
+ */
+static void __exit imr_self_test_exit(void)
+{
+}
+
+module_init(imr_self_test_init);
+module_exit(imr_self_test_exit);
+
+MODULE_AUTHOR("Bryan O'Donoghue <pure.logic@nexus-software.ie>");
+MODULE_DESCRIPTION("Intel Isolated Memory Region self-test driver");
+MODULE_LICENSE("Dual BSD/GPL");
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 638e7970..9752761 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -735,6 +735,31 @@ config INTEL_IPS
 	  functionality.  If in doubt, say Y here; it will only load on
 	  supported platforms.
 
+config INTEL_IMR
+	bool "Intel Isolated Memory Region support"
+	default n
+	depends on X86_INTEL_QUARK && IOSF_MBI
+	---help---
+	  This option provides a means to manipulate Isolated Memory Regions.
+	  IMRs are a set of registers that define read and write access masks
+	  to prohibit certain system agents from accessing memory with 1 KiB
+	  granularity.
+
+	  IMRs make it possible to control read/write access to an address
+	  by hardware agents inside the SoC. Read and write masks can be
+	  defined for:
+		- eSRAM flush
+		- Dirty CPU snoop (write only)
+		- RMU access
+		- PCI Virtual Channel 0/Virtual Channel 1
+		- SMM mode
+		- Non SMM mode
+
+	  Quark contains a set of eight IMR registers and makes use of those
+	  registers during its bootup process.
+
+	  If you are running on a Galileo/Quark say Y here.
+
 config IBM_RTL
 	tristate "Device driver to enable PRTL support"
 	depends on X86 && PCI
-- 
1.9.1

[PATCH 2/2] x86, quark: Add Intel Quark platform support

[Bryan O'Donoghue]

Add Intel Quark platform support. Quark needs to pull down all unlocked IMRs
to ensure agreement with the EFI memory map post boot.

This patch adds an entry in Kconfig for Quark as a platform and makes IMR
support mandatory if selected.

Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 arch/x86/Kconfig           | 16 ++++++++++++++++
 arch/x86/platform/Makefile |  1 +
 2 files changed, 17 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0dc9d01..36d50cd 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -485,6 +485,22 @@ config X86_INTEL_MID
 	  Intel MID platforms are based on an Intel processor and chipset which
 	  consume less power than most of the x86 derivatives.
 
+config X86_INTEL_QUARK
+	bool "Intel Quark platform support"
+	depends on X86_32
+	depends on X86_EXTENDED_PLATFORM
+	depends on X86_PLATFORM_DEVICES
+	depends on X86_TSC
+	depends on PCI
+	depends on PCI_GOANY
+	depends on X86_IO_APIC
+	select IOSF_MBI
+	select INTEL_IMR
+	---help---
+	  Select to include support for Quark X1000 SoC.
+	  Say Y here if you have a Quark based system such as the Arduino
+	  compatible Intel Galileo.
+
 config X86_INTEL_LPSS
 	bool "Intel Low Power Subsystem Support"
 	depends on ACPI
diff --git a/arch/x86/platform/Makefile b/arch/x86/platform/Makefile
index 85afde1..a62e0be 100644
--- a/arch/x86/platform/Makefile
+++ b/arch/x86/platform/Makefile
@@ -5,6 +5,7 @@ obj-y	+= geode/
 obj-y	+= goldfish/
 obj-y	+= iris/
 obj-y	+= intel-mid/
+obj-y	+= intel-quark/
 obj-y	+= olpc/
 obj-y	+= scx200/
 obj-y	+= sfi/
-- 
1.9.1

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Darren Hart]

On Wed, Jan 28, 2015 at 06:36:25PM +0000, Bryan O'Donoghue wrote:
> Intel's Quark X1000 SoC contains a set of registers called Isolated Memory
> Regions. IMRs are accessed over the IOSF mailbox interface. IMRs are areas
> carved out of memory that define read/write access rights to the various
> system agents within the Quark system. For a given agent in the system it is
> possible to specify if that agent may read or write an area of memory
> defined by an IMR with a granularity of 1 KiB.
> 
> Quark_SecureBootPRM_330234_001.pdf section 4.5 details the concept of IMRs
> quark-x1000-datasheet.pdf section 12.7.4 details the implementation of IMRs
> in silicon.
> 
> eSRAM flush, CPU Snoop write-only, CPU SMM Mode, CPU non-SMM mode, RMU and
> PCIe Virtual Channels (VC0 and VC1) can have individual read/write access
> masks applied to them for a given memory region in Quark X1000. This
> enables IMRs to treat each memory transaction type listed above on an
> individual basis and to filter appropriately based on the IMR access mask
> for the memory region. Quark supports eight IMRs.
> 
> Since all of the DMA capable SoC components in the X1000 are mapped to VC0
> it is possible to define sections of memory as invalid for DMA write
> operations originating from Ethernet, USB, SD and any other DMA capable
> south-cluster component on VC0. Similarly it is possible to mark kernel
> memory as non-SMM mode read/write only or to mark BIOS runtime memory as SMM
> mode accessible only depending on the particular memory footprint on a given
> system.
> 
> On an IMR violation Quark SoC X1000 systems are configured to reset the
> system, so ensuring that the IMR memory map is consistent with the EFI
> provided memory map is critical to ensure no IMR violations reset the
> system.
> 
> The API for accessing IMRs is based on MTRR code but doesn't provide a /proc
> or /sys interface to manipulate IMRs. Defining the size and extent of IMRs
> is exclusively the domain of in-kernel code.
> 
> Quark firmware sets up a series of locked IMRs around pieces of memory that
> firmware owns such as ACPI runtime data. During boot a series of unlocked
> IMRs are placed around items in memory to guarantee no DMA modification of
> those items can take place. Grub also places an unlocked IMR around the
> kernel boot params data structure and compressed kernel image. It is
> necessary for the kernel to tear down all unlocked IMRs in order to ensure
> that the kernel's view of memory passed via the EFI memory map is consistent
> with the IMR memory map. Without tearing down all unlocked IMRs on boot
> transitory IMRs such as those used to protect the compressed kernel image
> will cause IMR violations and system reboots.
> 
> The IMR init code tears down all unlocked IMRs and sets a protective IMR
> around the kernel .text and .rodata as one contiguous block. This sanitizes
> the IMR memory map with respect to the EFI memory map and protects the
> read-only portions of the kernel from unwarranted DMA access.
> 
> Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>

Most of my concerns were addressed by V3 or so, but I've followed along and
concur with the subsequent improvements.

Reviewed-by: Darren Hart <dvhart@linux.intel.com>

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ingo Molnar]

* Bryan O'Donoghue <pure.logic@nexus-software.ie> wrote:

> Intel's Quark X1000 SoC contains a set of registers called 
> Isolated Memory Regions. IMRs are accessed over the IOSF 
> mailbox interface. IMRs are areas carved out of memory that 
> define read/write access rights to the various system agents 
> within the Quark system. For a given agent in the system it is 
> possible to specify if that agent may read or write an area of 
> memory defined by an IMR with a granularity of 1 KiB.

A couple of minor details:

> +	if (ret)
> +		goto done;
> +
> +	/* Lock bit must be set separately to addr_lo address bits. */
> +	if (lock) {
> +		imr->addr_lo |= IMR_LOCK;
> +		ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
> +					reg - IMR_NUM_REGS, imr->addr_lo);
> +		if (ret)
> +			goto done;
> +	}
> +
> +	local_irq_restore(flags);
> +	return 0;
> +done:
> +	/*
> +	 * If writing to the IOSF failed then we're in an unknown state,
> +	 * likely a very bad state. An IMR in an invalid state will almost
> +	 * certainly lead to a memory access violation.
> +	 */
> +	local_irq_restore(flags);
> +	WARN(ret, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n",
> +	     imr_to_phys(imr->addr_lo), imr_to_phys(imr->addr_hi) + IMR_MASK);
> +
> +	return ret;
> +}

looks like the 'done' label really wants to be 'error' or 
'failed'?

Also, if this message ever triggers in practice, if the IMR is in 
a likely bad state, we might as well attempt to turn it off, so 
that we have a chance to get the log out and all that?

> +
> +/**
> + * imr_dbgfs_state_show - print state of IMR registers.
> + *
> + * @s:		pointer to seq_file for output.
> + * @unused:	unused parameter.
> + * @return:	0 on success or error code passed from mbi_iosf on failure.
> + */
> +static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
> +{
> +	phys_addr_t base;
> +	phys_addr_t end;
> +	int i;
> +	struct imr_device *idev = s->private;
> +	struct imr_regs imr;
> +	size_t size;
> +	int ret = -ENODEV;
> +
> +	mutex_lock(&idev->lock);
> +
> +	for (i = 0; i < idev->max_imr; i++) {
>
> +int imr_add_range(phys_addr_t base, size_t size,
> +		  unsigned int rmask, unsigned int wmask, bool lock)
> +{
> +	phys_addr_t end;
> +	unsigned int i;
> +	struct imr_device *idev = &imr_dev;
> +	struct imr_regs imr;
> +	int reg;
> +	int ret;
> +
> +	if (idev->init == false)
> +		return -ENODEV;

You might want to add a WARN_ONCE() here? Someone tried to add an 
IMR but has done it too early. Return values get ignored so 
often, kernel messages not so much.

(Just like imr_check_range() does emit warnings.)

> +	ret = imr_check_range(base, size);
> +	if (ret)
> +		return ret;
> +
> +	if (size == 0)
> +		return -EINVAL;

Looks like the zero-size check could be added to 
imr_check_range(), and be renamed to imr_check_params() or so?

> +	/* Tweak the size value. */
> +	size = imr_fixup_size(size);

So why not add a 'raw_size' (or so) variable and use that, to not 
confuse user provided size with the offset-corrected size?

Then imr_fixup_size() could be renamed to imr_raw_size() as well, 
making it slightly easier on the eyes as well.

> +	end = base + size;
> +
> +	/*
> +	 * Check for reserved IMR value common to firmware, kernel and grub
> +	 * indicating a disabled IMR.
> +	 */
> +	imr.addr_lo = phys_to_imr(base);
> +	imr.addr_hi = phys_to_imr(end);
> +	imr.rmask = rmask;
> +	imr.wmask = wmask;
> +	if (!imr_is_enabled(&imr))
> +		return -EINVAL;
> +
> +	mutex_lock(&idev->lock);
> +
> +	/*
> +	 * Find a free IMR while checking for an existing overlapping range.
> +	 * Note there's no restriction in silicon to prevent IMR overlaps.
> +	 * For the sake of simplicity and ease in defining/debugging an IMR
> +	 * memory map we exclude IMR overlaps.
> +	 */
> +	reg = -1;
> +	for (i = 0; i < idev->max_imr; i++) {
> +		ret = imr_read(idev, i, &imr);
> +		if (ret)
> +			goto done;
> +
> +		/* Find overlap @ base or end of requested range. */
> +		if (imr_is_enabled(&imr)) {
> +			if (imr_address_overlap(base, &imr)) {
> +				ret = -EINVAL;
> +				goto done;
> +			}
> +			if (imr_address_overlap(end, &imr)) {
> +				ret = -EINVAL;
> +				goto done;
> +			}
> +		} else {
> +			reg = i;
> +		}
> +	}
> +
> +	/* Error out if we have no free IMR entries. */
> +	if (reg == -1) {
> +		ret = -ENODEV;
> +		goto done;
> +	}
> +
> +	pr_debug("IMR %d phys %pa-%pa rmask 0x%08x wmask 0x%08x\n",
> +		reg, &base, &end, rmask, wmask);
> +
> +	/* Allocate IMR. */

Technically we don't 'allocate' the IMR here, we write to an 
existing, currently disabled IMR, right?

> +	imr.addr_lo = phys_to_imr(base);
> +	imr.addr_hi = phys_to_imr(end);
> +	imr.rmask = rmask;
> +	imr.wmask = wmask;
> +
> +	ret = imr_write(idev, reg, &imr, lock);
> +
> +done:

So 'done:' should really be named 'fail:'.

> +	mutex_unlock(&idev->lock);
> +	return ret == 0 ? reg : ret;

So we have a variable named 'ret', but it turns out to not be the 
return value after all?

Why not just 'ret'? It's not like users of this API are supposed 
to know about the internals of the IMR code: in which register it 
was stored and such. (See my comments below about the removal 
API.)

If this is simply an MTRR leftover then good riddance!

> +}
> +EXPORT_SYMBOL(imr_add_range);

That should really be EXPORT_SYMBOL_GPL().

> +/**
> + * imr_remove_range - delete an Isolated Memory Region.
> + *
> + * This function allows you to delete an IMR by its index specified by reg or
> + * by address range specified by base and size respectively. If you specify an
> + * index on its own the base and size parameters are ignored.
> + * imr_remove_range(0, size, base); delete IMR at index 0 base/size ignored.
> + * imr_remove_range(-1, base, size); delete IMR from base to base+size.
> + *
> + * @reg:	imr index to remove.
> + * @base:	physical base address of region aligned to 1 KiB.
> + * @size:	physical size of region in bytes aligned to 1 KiB.
> + * @return:	-EINVAL on invalid range or out or range id
> + *		-ENODEV if reg is valid but no IMR exists or is locked
> + *		0 on success.
> + */
> +int imr_remove_range(int reg, phys_addr_t base, size_t size)

I think this API should lose the MTRR-ism as well: instead of 
allowing this weird deletion by index and by address as well, 
just split it in two variants, and only allow external users to 
delete by address.

That will simplify things and will allow future enhancements as 
well: like transparent merging and even reshuffling of IMRs, 
should the need arise.

> +{
> +	phys_addr_t end;
> +	bool found = false;
> +	unsigned int i;
> +	struct imr_device *idev = &imr_dev;
> +	struct imr_regs imr;
> +	int ret = 0;
> +
> +	if (idev->init == false)
> +		return -ENODEV;
> +
> +	if (imr_check_range(base, size))
> +		return -EINVAL;
> +
> +	if (reg >= idev->max_imr)
> +		return -EINVAL;
> +
> +	/* Tweak the size value. */
> +	size = imr_fixup_size(size);
> +	end = base + size;
> +
> +	mutex_lock(&idev->lock);
> +
> +	if (reg >= 0) {
> +		/* If a specific IMR is given try to use it. */
> +		ret = imr_read(idev, reg, &imr);
> +		if (ret)
> +			goto done;
> +
> +		if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
> +			ret = -ENODEV;
> +			goto done;
> +		}
> +		found = true;

By my simplification suggestions above this branch would go away 
from the external API.

> +	} else {
> +		/* Search for match based on address range. */
> +		for (i = 0; i < idev->max_imr; i++) {
> +			ret = imr_read(idev, i, &imr);
> +			if (ret)
> +				goto done;
> +
> +			if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK)
> +				continue;
> +
> +			if ((imr_to_phys(imr.addr_lo) == base) &&
> +			    (imr_to_phys(imr.addr_hi) == end)) {
> +				found = true;
> +				reg = i;
> +				break;
> +			}
> +		}
> +	}
> +
> +	if (found == false) {

So writing this as:

	if (!found) {

is a lot more readable, right?

> +		ret = -ENODEV;
> +		goto done;
> +	}
> +
> +	/* Tear down the IMR. */
> +	imr.addr_lo = 0;
> +	imr.addr_hi = 0;
> +	imr.rmask = IMR_READ_ACCESS_ALL;
> +	imr.wmask = IMR_WRITE_ACCESS_ALL;
> +
> +	ret = imr_write(idev, reg, &imr, false);

So 'ret' here gets mixed with other potential failure modes.

If imr_write() fails here then that's a highly anomalous internal 
failure - so it might be better to add a WARN_ON(ret) or so.

> +
> +done:

s/done/failed/, or so.

> +	mutex_unlock(&idev->lock);
> +	return ret;
> +}
> +EXPORT_SYMBOL(imr_remove_range);

Please make all new kernel internal symbol exports _GPL.

> +
> +/**
> + * imr_fixup_memmap - Tear down IMRs used during bootup.
> + *
> + * BIOS and Grub both setup IMRs around compressed kernel, initrd memory
> + * that need to be removed before the kernel hands out one of the IMR
> + * encased addresses to a downstream DMA agent such as the SD or Ethernet.
> + * IMRs on Galileo are setup to immediately reset the system on violation.
> + * As a result if you're running a root filesystem from SD - you'll need
> + * the boot-time IMRs torn down or you'll find seemingly random resets when
> + * using your filesystem.
> + *
> + * @idev:	pointer to imr_device structure.
> + * @return:
> + */
> +static void __init imr_fixup_memmap(struct imr_device *idev)
> +{
> +	phys_addr_t base = virt_to_phys(&_text);
> +	size_t size = virt_to_phys(&__end_rodata) - base;
> +	int i;
> +	int ret;
> +
> +	/* Tear down all existing unlocked IMRs. */
> +	for (i = 0; i < idev->max_imr; i++)
> +		imr_remove_range(i, 0, 0);

This would use a simpler variant of imr_remove_range() which is 
basically just an imr_write(). It might even be written as an 
imr_clear() helper.

> +
> +	/*
> +	 * Setup a locked IMR around the physical extent of the kernel
> +	 * from the beginning of the .text secton to the end of the
> +	 * .rodata section as one physically contiguous block.
> +	 */
> +	ret = imr_add_range(base, size, IMR_CPU, IMR_CPU, true);
> +	if (ret < 0)
> +		pr_err("unable to setup IMR for kernel: (%p - %p)\n",
> +			&_text, &__end_rodata);
> +	else
> +		pr_info("protecting kernel .text - .rodata: %zu KiB (%p - %p)\n",
> +			size / 1024, &_text, &__end_rodata);

Curly braces around multi-line statements and all that.

> --- /dev/null
> +++ b/arch/x86/platform/intel-quark/imr_selftest.c
> @@ -0,0 +1,135 @@
> +/**
> + * imr_selftest.c
> + *
> + * Copyright(c) 2013 Intel Corporation.
> + * Copyright(c) 2015 Bryan O'Donoghue <pure.logic@nexus-software.ie>
> + *
> + * IMR self test. The purpose of this module is to run a set of tests on the
> + * IMR API to validate it's sanity. We check for overlapping, reserved
> + * addresses and setup/teardown sanity.
> + *
> + */

Looks like we could shrink the kernel source code by 3 bytes 
there!

In any case, I don't see any major problems with this code, so if 
it's fixed it could go into v3.20.

Thanks,

	Ingo

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

Bryan, a minor fix on the config below... 

>diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index
>61bd2ad..fcf5701 100644
>--- a/arch/x86/Kconfig.debug
>+++ b/arch/x86/Kconfig.debug
>@@ -313,6 +313,18 @@ config DEBUG_NMI_SELFTEST
>
> 	  If unsure, say N.
>
>+config DEBUG_IMR_SELFTEST
>+	bool "Isolated Memory Region self test"
>+	default n
>+	depends on INTEL_IMR
>+	---help---
>+	  This option enables automated sanity testing of the IMR code.
>+	  Some simple tests are run to verify IMR bounds checking, alignment
>+	  and overlapping. This option is really only useful if you are
>+	  debugging an IMR memory map or are modifying the IMR code and
>want to
>+	  test your changes.
>+
>+	  If unsure say N here.
Miss a newline here. 

> config X86_DEBUG_STATIC_CPU_HAS
> 	bool "Debug alternatives"
> 	depends on DEBUG_KERNEL

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Andy Shevchenko]

On Thu, Jan 29, 2015 at 9:44 AM, Ingo Molnar <mingo@kernel.org> wrote:
> * Bryan O'Donoghue <pure.logic@nexus-software.ie> wrote:

[]

> In any case, I don't see any major problems with this code, so if
> it's fixed it could go into v3.20.

Brian, it would be really nice to have it in 3.20 since we have
several drivers already in upstream or be ready for 3.20.
It would be then first upstream kernel with minimal Quark support.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 29/01/15 10:08, Andy Shevchenko wrote:
> On Thu, Jan 29, 2015 at 9:44 AM, Ingo Molnar <mingo@kernel.org> wrote:
>> * Bryan O'Donoghue <pure.logic@nexus-software.ie> wrote:
>
> []
>
>> In any case, I don't see any major problems with this code, so if
>> it's fixed it could go into v3.20.
>
> Brian, it would be really nice to have it in 3.20 since we have
> several drivers already in upstream or be ready for 3.20.
> It would be then first upstream kernel with minimal Quark support.

NP lads - I'll get a patch out today

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 29/01/15 07:44, Ingo Molnar wrote:

Hi Ingo.

I'll transmit those changes in with the following exception

>> +	ret = imr_write(idev, reg, &imr, false);
>
> So 'ret' here gets mixed with other potential failure modes.
>
> If imr_write() fails here then that's a highly anomalous internal
> failure - so it might be better to add a WARN_ON(ret) or so.
>

imr_write() already does a WARN - so no need to do it again.

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

Bryan,

Once you have the next revision ready, I would like to test it on my end across both Galileo Gen v1 & v2. 

Cheers,
BL  

>-----Original Message-----
>From: Bryan O'Donoghue [mailto:pure.logic@nexus-software.ie]
>Sent: Thursday, January 29, 2015 6:12 PM
>To: Andy Shevchenko; Ingo Molnar
>Cc: Thomas Gleixner; Ingo Molnar; H. Peter Anvin; x86@kernel.org;
>dvhart@infradead.org; Ong, Boon Leong; linux-kernel@vger.kernel.org
>Subject: Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000
>
>On 29/01/15 10:08, Andy Shevchenko wrote:
>> On Thu, Jan 29, 2015 at 9:44 AM, Ingo Molnar <mingo@kernel.org> wrote:
>>> * Bryan O'Donoghue <pure.logic@nexus-software.ie> wrote:
>>
>> []
>>
>>> In any case, I don't see any major problems with this code, so if
>>> it's fixed it could go into v3.20.
>>
>> Brian, it would be really nice to have it in 3.20 since we have
>> several drivers already in upstream or be ready for 3.20.
>> It would be then first upstream kernel with minimal Quark support.
>
>NP lads - I'll get a patch out today

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

Hi Bryan,

These two patches requires another patch "x86: Re-enable IO-APIC for non-SMP X86_32" 
to be included to make sure we have the right build for Quark.

I tested v6 on Galileo Gen v2 just now. I am happy with it.
Many thanks.

Below are the logs:

root@quark:/proc# dmesg | grep imr
[    3.727884] imr: protecting kernel .text - .rodata: 9240 KiB (c1000000 - c1906000)
[    3.736421] imr_selftest: self_test pass zero sized IMR
[    3.742413] imr_selftest: self_test pass overlapped IMR @ (0xc1000000 - 0xc1906000)
[    3.751164] imr_selftest: self_test pass overlapped IMR @ (0xc1905c00 - 0xc220bc00)
[    3.759916] imr_selftest: self_test pass overlapped IMR @ (0xc0fff400 - 0xc1905400)
[    3.768566] imr_selftest: self_test pass 1KiB IMR @ 0x00000000 - access-all
[    3.776542] imr_selftest: self_test pass 1KiB IMR @ 0x00000000 - cpu access
[    3.784442] imr_selftest: self_test pass index-teardown - cpu access
[    3.791690] imr_selftest: self_test pass 2KiB IMR @ 0x00000000
[    3.798396] imr_selftest: self_test pass index-teardown 2KiB
[    3.804957] imr_selftest: self_test pass 2KiB IMR @ 0x00000000
[    3.811616] imr_selftest: self_test pass addr-teardown 2KiB
root@quark:/proc# cat /sys/kernel/debug/imr_state
imr00: base=0x00000000, end=0x00000000, size=0x00000000 rmask=0xbfffffff, wmask=0xffffffff, disabled, unlocked
imr01: base=0x00000000, end=0x00000000, size=0x00000000 rmask=0xbfffffff, wmask=0xffffffff, disabled, unlocked
imr02: base=0x00000000, end=0x00000000, size=0x00000000 rmask=0xbfffffff, wmask=0xffffffff, disabled, unlocked
imr03: base=0x00000000, end=0x00000000, size=0x00000000 rmask=0xbfffffff, wmask=0xffffffff, disabled, unlocked
imr04: base=0x00000000, end=0x00000000, size=0x00000000 rmask=0xbfffffff, wmask=0xffffffff, disabled, unlocked
imr05: base=0x00000000, end=0x00000000, size=0x00000000 rmask=0xbfffffff, wmask=0xffffffff, disabled, unlocked
imr06: base=0x00000000, end=0x00000000, size=0x00000000 rmask=0xbfffffff, wmask=0xffffffff, disabled, unlocked
imr07: base=0x01000000, end=0x01905fff, size=0x00905fff rmask=0x00000001, wmask=0x00000001, enabled , locked

 

>-----Original Message-----
>From: Ong, Boon Leong
>Sent: Thursday, January 29, 2015 9:47 PM
>To: 'Bryan O'Donoghue'
>Cc: Thomas Gleixner; Ingo Molnar; H. Peter Anvin; x86@kernel.org;
>dvhart@infradead.org; linux-kernel@vger.kernel.org; Andy Shevchenko; Ingo
>Molnar
>Subject: RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000
>
>Bryan,
>
>Once you have the next revision ready, I would like to test it on my end across
>both Galileo Gen v1 & v2.
>
>Cheers,
>BL
>
>>-----Original Message-----
>>From: Bryan O'Donoghue [mailto:pure.logic@nexus-software.ie]
>>Sent: Thursday, January 29, 2015 6:12 PM
>>To: Andy Shevchenko; Ingo Molnar
>>Cc: Thomas Gleixner; Ingo Molnar; H. Peter Anvin; x86@kernel.org;
>>dvhart@infradead.org; Ong, Boon Leong; linux-kernel@vger.kernel.org
>>Subject: Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark
>>X1000
>>
>>On 29/01/15 10:08, Andy Shevchenko wrote:
>>> On Thu, Jan 29, 2015 at 9:44 AM, Ingo Molnar <mingo@kernel.org> wrote:
>>>> * Bryan O'Donoghue <pure.logic@nexus-software.ie> wrote:
>>>
>>> []
>>>
>>>> In any case, I don't see any major problems with this code, so if
>>>> it's fixed it could go into v3.20.
>>>
>>> Brian, it would be really nice to have it in 3.20 since we have
>>> several drivers already in upstream or be ready for 3.20.
>>> It would be then first upstream kernel with minimal Quark support.
>>
>>NP lads - I'll get a patch out today

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 29/01/15 13:47, Ong, Boon Leong wrote:
> Bryan,
>
> Once you have the next revision ready, I would like to test it on my end across both Galileo Gen v1 & v2.
>
> Cheers,
> BL

Andy/BL - thanks for taking the time to test.

I may end up dropping the imr_del_range() tests based on index as a 
result of changing the external interface as suggested by Ingo.

If you guys have a clear preference to keep those tests shout now and 
I'll re-merge the imr_selftest code into the main chunk of IMR code.

--
BOD

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>-----Original Message-----
>From: Bryan O'Donoghue [mailto:pure.logic@nexus-software.ie]
>Sent: Thursday, January 29, 2015 11:22 PM
>To: Ong, Boon Leong
>Cc: Thomas Gleixner; Ingo Molnar; H. Peter Anvin; x86@kernel.org;
>dvhart@infradead.org; linux-kernel@vger.kernel.org; Andy Shevchenko; Ingo
>Molnar
>Subject: Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000
>
>On 29/01/15 13:47, Ong, Boon Leong wrote:
>> Bryan,
>>
>> Once you have the next revision ready, I would like to test it on my end across
>both Galileo Gen v1 & v2.
>>
>> Cheers,
>> BL
>
>Andy/BL - thanks for taking the time to test.
>
>I may end up dropping the imr_del_range() tests based on index as a result of
>changing the external interface as suggested by Ingo.
It would be nice to have two variants (1) index based & (2) address based. 

>
>If you guys have a clear preference to keep those tests shout now and I'll re-
>merge the imr_selftest code into the main chunk of IMR code.
Ok, once you have that ready, I will re-run the test on my end. 

>
>--
>BOD

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 29/01/15 15:32, Ong, Boon Leong wrote:
>
>
>> -----Original Message-----
>> From: Bryan O'Donoghue [mailto:pure.logic@nexus-software.ie]
>> Sent: Thursday, January 29, 2015 11:22 PM
>> To: Ong, Boon Leong
>> Cc: Thomas Gleixner; Ingo Molnar; H. Peter Anvin; x86@kernel.org;
>> dvhart@infradead.org; linux-kernel@vger.kernel.org; Andy Shevchenko; Ingo
>> Molnar
>> Subject: Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000
>>
>> On 29/01/15 13:47, Ong, Boon Leong wrote:
>>> Bryan,
>>>
>>> Once you have the next revision ready, I would like to test it on my end across
>> both Galileo Gen v1 & v2.
>>>
>>> Cheers,
>>> BL
>>
>> Andy/BL - thanks for taking the time to test.
>>
>> I may end up dropping the imr_del_range() tests based on index as a result of
>> changing the external interface as suggested by Ingo.
> It would be nice to have two variants (1) index based & (2) address based.

Understood. The direction from Ingo was to have address based external 
interface imr_del_range() and support an index based internal 
imr_clear() - internally.

So - in order to get test coverage - I'll move the self-test code back 
into the main IMR code

Not as pretty that way - but better coverage :)

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 29/01/15 15:40, Bryan O'Donoghue wrote:
>> It would be nice to have two variants (1) index based & (2) address
>> based.
>
> Understood. The direction from Ingo was to have address based external
> interface imr_del_range() and support an index based internal
> imr_clear() - internally.
>
> So - in order to get test coverage - I'll move the self-test code back
> into the main IMR code
>
> Not as pretty that way - but better coverage :)

Talking to myself in public...

Second (third) thought - there's no advantage to moving the test code 
back in - since imr_add_range() won't return the index anymore...

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>On 29/01/15 15:40, Bryan O'Donoghue wrote:
>>> It would be nice to have two variants (1) index based & (2) address
>>> based.
>>
>> Understood. The direction from Ingo was to have address based external
>> interface imr_del_range() and support an index based internal
>> imr_clear() - internally.
>>
>> So - in order to get test coverage - I'll move the self-test code back
>> into the main IMR code
It will be nice to have the separation of test code. However, that also means
the index-based variant needs to be external function. 
Ingo, what is your preference? 

>>
>> Not as pretty that way - but better coverage :)
>
>Talking to myself in public...
>
>Second (third) thought - there's no advantage to moving the test code back in -
>since imr_add_range() won't return the index anymore...

It does. See below from v6:

+	ret = imr_write(idev, reg, &imr, lock);
			          ^^ =========== IMR ID
+
+done:
+	mutex_unlock(&idev->lock);
+	return ret == 0 ? reg : ret;
			 ^^  ============ IMR ID
+}
+EXPORT_SYMBOL(imr_add_range);

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Darren Hart]

On Thu, Jan 08, 2015 at 03:11:35PM +0000, Bryan O'Donoghue wrote:
> 
> >Suggest to split the imr_del() into 2 functions:-
> >(1) by address + size
> >(2) by IMR index
> >At current implementation, it does not support (2) only because it fails at
> >imr_check_range().
> 
> Hi Boon Leong.
> 
> I'll have a think about that :)
> 
> Just on imr_del() though, it does support removal by way of index.
> 
> +static void __init intel_galileo_imr_init(void)
> +{
> +	unsigned long base  = virt_to_phys(&_text);
> +	unsigned long size = virt_to_phys(&_sinittext) - base - IMR_ALIGN;
> +	int i, ret;
> +
> +	/* Tear down all existing unlocked IMRs */
> +	for (i = 0; i <= QUARK_X1000_IMR_NUM; i++)
> +		imr_del(i, 0, 0);
> 
> That's what the platform code has to do for every unlocked IMR, to make sure
> there are no stale IMRs left that could conflict with the EFI memory map !

I'm OK with a single function so long as by index works without having to
specify the address. Please update the kernel doc to describe this usage though.

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Darren Hart]

On Thu, Jan 08, 2015 at 03:11:35PM +0000, Bryan O'Donoghue wrote:
> 
> >Suggest to split the imr_del() into 2 functions:-
> >(1) by address + size
> >(2) by IMR index
> >At current implementation, it does not support (2) only because it fails at
> >imr_check_range().
> 
> Hi Boon Leong.
> 
> I'll have a think about that :)
> 
> Just on imr_del() though, it does support removal by way of index.
> 
> +static void __init intel_galileo_imr_init(void)
> +{
> +	unsigned long base  = virt_to_phys(&_text);
> +	unsigned long size = virt_to_phys(&_sinittext) - base - IMR_ALIGN;
> +	int i, ret;
> +
> +	/* Tear down all existing unlocked IMRs */
> +	for (i = 0; i <= QUARK_X1000_IMR_NUM; i++)
> +		imr_del(i, 0, 0);
> 
> That's what the platform code has to do for every unlocked IMR, to make sure
> there are no stale IMRs left that could conflict with the EFI memory map !

I'm OK with a single function so long as by index works without having to
specify the address. Please update the kernel doc to describe this usage though.

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

> Suggest to split the imr_del() into 2 functions:-
> (1) by address + size
> (2) by IMR index
> At current implementation, it does not support (2) only because it fails at
> imr_check_range().

Hi Boon Leong.

I'll have a think about that :)

Just on imr_del() though, it does support removal by way of index.

+static void __init intel_galileo_imr_init(void)
+{
+	unsigned long base  = virt_to_phys(&_text);
+	unsigned long size = virt_to_phys(&_sinittext) - base - IMR_ALIGN;
+	int i, ret;
+
+	/* Tear down all existing unlocked IMRs */
+	for (i = 0; i <= QUARK_X1000_IMR_NUM; i++)
+		imr_del(i, 0, 0);

That's what the platform code has to do for every unlocked IMR, to make 
sure there are no stale IMRs left that could conflict with the EFI 
memory map !

--
BOD

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

> Suggest to split the imr_del() into 2 functions:-
> (1) by address + size
> (2) by IMR index
> At current implementation, it does not support (2) only because it fails at
> imr_check_range().

Hi Boon Leong.

I'll have a think about that :)

Just on imr_del() though, it does support removal by way of index.

+static void __init intel_galileo_imr_init(void)
+{
+	unsigned long base  = virt_to_phys(&_text);
+	unsigned long size = virt_to_phys(&_sinittext) - base - IMR_ALIGN;
+	int i, ret;
+
+	/* Tear down all existing unlocked IMRs */
+	for (i = 0; i <= QUARK_X1000_IMR_NUM; i++)
+		imr_del(i, 0, 0);

That's what the platform code has to do for every unlocked IMR, to make 
sure there are no stale IMRs left that could conflict with the EFI 
memory map !

--
BOD

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>On 07/01/15 23:45, Ong, Boon Leong wrote:
>>> Since BIOS and grub code both use 0x00000000 as the 'off' address I
>>> think it makes sense for the kernel to continue to use that address.
>>
>> Just add on top of what Daren mentioned in another mail, based on the
>> Quark document, the base address can start from zero. Say lo=0, hi=0,
>> and WM & RM may be changed from default value, 1st 1KiB will be marked as
>IMR. It seems to me that there is no good way to test if an IMR is 'occupied'
>and/or 'enabled'
>> since enable-bit is not available. But, what is benefit of testing
>> against lo=0 & hi=0? The logic to calculate size will work under
>> lo=0 & hi=0 anway.
>
>Hi Boon Leong.
>
>I think it does make sense to add a check for rmask and wmask in the 'access all'
>state when determining if an IMR is enabled on X1000 or not

Ya, checking against rmask & wmask whether they have been changed from default stage
would help here. Thanks 

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>On 07/01/15 23:45, Ong, Boon Leong wrote:
>>> Since BIOS and grub code both use 0x00000000 as the 'off' address I
>>> think it makes sense for the kernel to continue to use that address.
>>
>> Just add on top of what Daren mentioned in another mail, based on the
>> Quark document, the base address can start from zero. Say lo=0, hi=0,
>> and WM & RM may be changed from default value, 1st 1KiB will be marked as
>IMR. It seems to me that there is no good way to test if an IMR is 'occupied'
>and/or 'enabled'
>> since enable-bit is not available. But, what is benefit of testing
>> against lo=0 & hi=0? The logic to calculate size will work under
>> lo=0 & hi=0 anway.
>
>Hi Boon Leong.
>
>I think it does make sense to add a check for rmask and wmask in the 'access all'
>state when determining if an IMR is enabled on X1000 or not

Ya, checking against rmask & wmask whether they have been changed from default stage
would help here. Thanks 

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>>> +/**
>>> + * imr_del_range - Delete an Isolated Memory Region
>>> + * @reg: IMR index to remove
>>> + * @base: Physical base address of region aligned to 4k
>>> + * @size: Physical size of region in bytes
>>> + * @return:	-EINVAL on invalid range or out or range id
>>> + *		-ENODEV if reg is valid but no IMR exists or is locked
>>> + *		0 on success
>>> + */
>>> +int imr_del(int reg, unsigned long base, unsigned long size);
>>
>> How about just offer imr delete based index-only as returned by imr_add()?
>> We just need to check if that IMR is locked. If locked, then bail out.
>> Else, we will zero-out IMR register for that index to remove it.
>
>Hmm.
>
>The MTRR API this is based on allows you to specific an address range and I think
>that makes sense for an IMR API too because - say you want to tear down the
>IMR around the kernel .text area - but you don't know which IMR it is.
>
>You'd just do
>
>unsigned long base  = virt_to_phys(&_text); unsigned long size =
>virt_to_phys(&_sinittext) - base - IMR_ALIGN;
>
>imr_del(-1, base, size);
>
>Rather than having to know which specific index to kill. Also later silicon may
>have more - or less IMR indices - so deleting based on an address range is a
>valuable feature I think.

imr_add() returns IMR index, so I would expect that I can use the index directly
if I need to remove it. 

Suggest to split the imr_del() into 2 functions:- 
(1) by address + size 
(2) by IMR index
At current implementation, it does not support (2) only because it fails at 
imr_check_range().

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>>> +/**
>>> + * imr_del_range - Delete an Isolated Memory Region
>>> + * @reg: IMR index to remove
>>> + * @base: Physical base address of region aligned to 4k
>>> + * @size: Physical size of region in bytes
>>> + * @return:	-EINVAL on invalid range or out or range id
>>> + *		-ENODEV if reg is valid but no IMR exists or is locked
>>> + *		0 on success
>>> + */
>>> +int imr_del(int reg, unsigned long base, unsigned long size);
>>
>> How about just offer imr delete based index-only as returned by imr_add()?
>> We just need to check if that IMR is locked. If locked, then bail out.
>> Else, we will zero-out IMR register for that index to remove it.
>
>Hmm.
>
>The MTRR API this is based on allows you to specific an address range and I think
>that makes sense for an IMR API too because - say you want to tear down the
>IMR around the kernel .text area - but you don't know which IMR it is.
>
>You'd just do
>
>unsigned long base  = virt_to_phys(&_text); unsigned long size =
>virt_to_phys(&_sinittext) - base - IMR_ALIGN;
>
>imr_del(-1, base, size);
>
>Rather than having to know which specific index to kill. Also later silicon may
>have more - or less IMR indices - so deleting based on an address range is a
>valuable feature I think.

imr_add() returns IMR index, so I would expect that I can use the index directly
if I need to remove it. 

Suggest to split the imr_del() into 2 functions:- 
(1) by address + size 
(2) by IMR index
At current implementation, it does not support (2) only because it fails at 
imr_check_range().

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 08/01/15 00:04, Ong, Boon Leong wrote:

Hi Boon Leong - skipping the simple stuff.

>> +/**
>> + * imr_del_range - Delete an Isolated Memory Region
>> + * @reg: IMR index to remove
>> + * @base: Physical base address of region aligned to 4k
>> + * @size: Physical size of region in bytes
>> + * @return:	-EINVAL on invalid range or out or range id
>> + *		-ENODEV if reg is valid but no IMR exists or is locked
>> + *		0 on success
>> + */
>> +int imr_del(int reg, unsigned long base, unsigned long size);
>
> How about just offer imr delete based index-only as returned by imr_add()?
> We just need to check if that IMR is locked. If locked, then bail out.
> Else, we will zero-out IMR register for that index to remove it.

Hmm.

The MTRR API this is based on allows you to specific an address range 
and I think that makes sense for an IMR API too because - say you want 
to tear down the IMR around the kernel .text area - but you don't know 
which IMR it is.

You'd just do

unsigned long base  = virt_to_phys(&_text);
unsigned long size = virt_to_phys(&_sinittext) - base - IMR_ALIGN;

imr_del(-1, base, size);

Rather than having to know which specific index to kill. Also later 
silicon may have more - or less IMR indices - so deleting based on an 
address range is a valuable feature I think.

> if (!x86_match_cpu(soc_imr_ids) || !iosf_mbi_available()) {
> 	pr_info("IMR init failed due to IOSF_MBI not available or SoC is not Quark.\n");
> 	return -ENODEV;
> } else {
> 	imr_dev.num = QUARK_X1000_IMR_NUM;
> 	imr_dev.reg_base = QUARK_X1000_IMR_REGBASE;
> }

That works for me.

--
BOD

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 08/01/15 00:04, Ong, Boon Leong wrote:

Hi Boon Leong - skipping the simple stuff.

>> +/**
>> + * imr_del_range - Delete an Isolated Memory Region
>> + * @reg: IMR index to remove
>> + * @base: Physical base address of region aligned to 4k
>> + * @size: Physical size of region in bytes
>> + * @return:	-EINVAL on invalid range or out or range id
>> + *		-ENODEV if reg is valid but no IMR exists or is locked
>> + *		0 on success
>> + */
>> +int imr_del(int reg, unsigned long base, unsigned long size);
>
> How about just offer imr delete based index-only as returned by imr_add()?
> We just need to check if that IMR is locked. If locked, then bail out.
> Else, we will zero-out IMR register for that index to remove it.

Hmm.

The MTRR API this is based on allows you to specific an address range 
and I think that makes sense for an IMR API too because - say you want 
to tear down the IMR around the kernel .text area - but you don't know 
which IMR it is.

You'd just do

unsigned long base  = virt_to_phys(&_text);
unsigned long size = virt_to_phys(&_sinittext) - base - IMR_ALIGN;

imr_del(-1, base, size);

Rather than having to know which specific index to kill. Also later 
silicon may have more - or less IMR indices - so deleting based on an 
address range is a valuable feature I think.

> if (!x86_match_cpu(soc_imr_ids) || !iosf_mbi_available()) {
> 	pr_info("IMR init failed due to IOSF_MBI not available or SoC is not Quark.\n");
> 	return -ENODEV;
> } else {
> 	imr_dev.num = QUARK_X1000_IMR_NUM;
> 	imr_dev.reg_base = QUARK_X1000_IMR_REGBASE;
> }

That works for me.

--
BOD

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 07/01/15 23:45, Ong, Boon Leong wrote:
>> Since BIOS and grub code both use 0x00000000 as the 'off' address I think it
>> makes sense for the kernel to continue to use that address.
>
> Just add on top of what Daren mentioned in another mail, based on the Quark document,
> the base address can start from zero. Say lo=0, hi=0, and WM & RM may be changed from default value,
> 1st 1KiB will be marked as IMR. It seems to me that there is no good way to test if an IMR is 'occupied' and/or 'enabled'
> since enable-bit is not available. But, what is benefit of testing against lo=0 & hi=0? The logic to calculate size will work under
> lo=0 & hi=0 anway.

Hi Boon Leong.

I think it does make sense to add a check for rmask and wmask in the 
'access all' state when determining if an IMR is enabled on X1000 or not.

>> My own view is that it's not really desirable and easier to debug IMRs
>> generally on a platform if overlaps aren't allowed.
> I do agree on the benefit listed above. Perhaps, you can add explanation here
> to mention the design decision.

Will do.

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 07/01/15 23:45, Ong, Boon Leong wrote:
>> Since BIOS and grub code both use 0x00000000 as the 'off' address I think it
>> makes sense for the kernel to continue to use that address.
>
> Just add on top of what Daren mentioned in another mail, based on the Quark document,
> the base address can start from zero. Say lo=0, hi=0, and WM & RM may be changed from default value,
> 1st 1KiB will be marked as IMR. It seems to me that there is no good way to test if an IMR is 'occupied' and/or 'enabled'
> since enable-bit is not available. But, what is benefit of testing against lo=0 & hi=0? The logic to calculate size will work under
> lo=0 & hi=0 anway.

Hi Boon Leong.

I think it does make sense to add a check for rmask and wmask in the 
'access all' state when determining if an IMR is enabled on X1000 or not.

>> My own view is that it's not really desirable and easier to debug IMRs
>> generally on a platform if overlaps aren't allowed.
> I do agree on the benefit listed above. Perhaps, you can add explanation here
> to mention the design decision.

Will do.

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>-----Original Message-----
>From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
>owner@vger.kernel.org] On Behalf Of Bryan O'Donoghue
>Sent: Monday, December 29, 2014 9:23 AM
>To: tglx@linutronix.de; mingo@redhat.com; hpa@zytor.com; x86@kernel.org;
>dvhart@infradead.org; platform-driver-x86@vger.kernel.org; linux-
>kernel@vger.kernel.org
>Cc: Bryan O'Donoghue
>Subject: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000
>
Suggest to add a statement on 3 different types of IMR: General IMR, 
Host Memory I/O Boundary IMR & System Management Mode IMR. Then, call out
that this patch is meant to support general IMR type only.

>Intel's Quark X1000 SoC contains a set of registers called Isolated Memory
>Regions. IMRs are accessed over the IOSF mailbox interface. IMRs are areas
>carved out of memory that define read/write access rights to the various
>system agents within the Quark system. For a given agent in the system it is
>possible to specify if that agent may read or write an area of memory defined
>by an IMR with a granularity of 1 kilobyte.
>
>Quark_SecureBootPRM_330234_001.pdf section 4.5 details the concept of
>IMRs
Would it be better if we provide a URL to the pdf? 

>
>eSRAM flush, CPU Snoop, CPU SMM Mode, CPU non-SMM mode, PMU and
PMU? You meant RMU - Remote Management Unit

<snippet removed>

>
>diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ba397bd..8303ca2
>100644
>--- a/arch/x86/Kconfig
>+++ b/arch/x86/Kconfig
>@@ -526,6 +526,29 @@ config IOSF_MBI_DEBUG
>
> 	  If you don't require the option or are in doubt, say N.
>
>+config IMR
>+	tristate "Isolated Memory Region support"
>+	default m
>+	depends on IOSF_MBI
>+	---help---
>+	  This option enables support for Isolated Memory Regions.
>+	  IMRs are a set of registers that define read and write access masks
>+	  to prohibit certain system agents from accessing memory with 1k
>+	  granularity.
>+	  IMRs make it possible to control read/write access to an address
>+	  by hardware agents inside the SoC. Read and write masks can be
>+	  defined for
>+		- SMM mode
>+		- Non SMM mode
>+		- PCI VC0/VC1
>+		- CPU snoop
Add "(write mask only)" at the end. 

>+		- eSRAM flush
>+		- PMU access
Do you mean RMU (Remote Management Unit) as documented in data-sheet?

>+	  Quark contains a set of IMR registers and makes use of those
>+	  registers during it's bootup process.
>+
>+	  If you are running on a Galileo/Quark say Y here
>+
> config X86_RDC321X
> 	bool "RDC R-321x SoC"
> 	depends on X86_32
>diff --git a/arch/x86/include/asm/imr.h b/arch/x86/include/asm/imr.h new
>file mode 100644 index 0000000..fe8f3b8
>--- /dev/null
>+++ b/arch/x86/include/asm/imr.h
>@@ -0,0 +1,79 @@
>+/*
>+ * imr.h: Isolated Memory Region API
>+ *
>+ * Copyright(c) 2013 Intel Corporation.
>+ * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
>+ *
>+ * This program is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU General Public License
>+ * as published by the Free Software Foundation; version 2
>+ * of the License.
>+ */
>+#ifndef _IMR_H
>+#define _IMR_H
>+
>+#include <asm/intel-quark.h>
>+#include <linux/types.h>
>+
>+/*
>+ * Right now IMRs are not reported via CPUID though it'd be really
>+great if
>+ * future silicon did report via CPUID for this feature bringing it
>+in-line with
>+ * other similar features - like MTRRs, MSRs etc.
>+ *
>+ * A macro is defined here which is an analog to the other cpu_has_x
>+type
>+ * features
>+ */
>+#define cpu_has_imr cpu_is_quark
We don't really need this #define method since we are using x86_match_cpu().
So, please remove them. 

>+
>+/* IMR agent access mask bits */
>+#define IMR_ESRAM_FLUSH		0x80000000
>+#define IMR_CPU_SNOOP		0x40000000
Suggest to add a comment to mark CPU_SNOOP as applicable for write-mask only.

>+#define IMR_HB_ACCESS		0x20000000
>+#define IMR_VC1_ID3		0x00008000
>+#define IMR_VC1_ID2		0x00004000
>+#define IMR_VC1_ID1		0x00002000
>+#define IMR_VC1_ID0		0x00001000
>+#define IMR_VC0_ID3		0x00000800
>+#define IMR_VC0_ID2		0x00000400
>+#define IMR_VC0_ID1		0x00000200
>+#define IMR_VC0_ID0		0x00000100
>+#define IMR_SMM			0x00000002
>+#define IMR_NON_SMM		0x00000001
Per data-sheet, this is called CPU_0 and CPU0. Suggest to stick with the name used in datasheet...

>+#define IMR_ACCESS_NONE		0x00000000
>+
>+/* Definition of read/write masks from published BSP code */
>+#define IMR_READ_ACCESS_ALL	0xBFFFFFFF
>+#define IMR_WRITE_ACCESS_ALL	0xFFFFFFFF
>+
>+/* Number of IMRs provided by Quark X1000 SoC */
>+#define QUARK_X1000_IMR_NUM	0x07
>+#define QUARK_X1000_IMR_REGBASE 0x40
>+
>+/* IMR alignment bits - only bits 31:10 are checked for IMR validity */
>+#define IMR_ALIGN		0x400
>+#define IMR_MASK		(IMR_ALIGN - 1)
>+
>+/**
>+ * imr_add_range - Add an Isolated Memory Region
>+ * @base: Physical base address of region aligned to 4k
>+ * @size: Physical size of region in bytes
Please add side-note that 'size' should be 1-KiB aligned. 
Or should we consider auto-alignment feature...

>+ * @read_mask: Read access mask
>+ * @write_mask: Write access mask
>+ * @lock: Indicates whether or not to permenantly lock this region
Typo: permanently 

>+ * @return: Index of the IMR allocated or negative value indicating error
>+ */ 
> + int imr_add(unsigned long base, unsigned long size,
>+	    unsigned int rmask, unsigned int wmask, bool lock);
>+
>+/**
>+ * imr_del_range - Delete an Isolated Memory Region
>+ * @reg: IMR index to remove
>+ * @base: Physical base address of region aligned to 4k
>+ * @size: Physical size of region in bytes
>+ * @return:	-EINVAL on invalid range or out or range id
>+ *		-ENODEV if reg is valid but no IMR exists or is locked
>+ *		0 on success
>+ */
>+int imr_del(int reg, unsigned long base, unsigned long size);

How about just offer imr delete based index-only as returned by imr_add()?
We just need to check if that IMR is locked. If locked, then bail out. 
Else, we will zero-out IMR register for that index to remove it.  

>+
>+#endif /* _IMR_H */

<snippet>

>diff --git a/arch/x86/kernel/imr.c b/arch/x86/kernel/imr.c new file mode
>100644 index 0000000..4115138
>--- /dev/null
>+++ b/arch/x86/kernel/imr.c
>@@ -0,0 +1,529 @@
>+/**
>+ * intel_imr.c
>+ *
>+ * Copyright(c) 2013 Intel Corporation.
>+ * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
>+ *
>+ * IMR registers define an isolated region of memory that can
>+ * be masked to prohibit certain system agents from accessing memory.
>+ * When a device behind a masked port performs an access - snooped or
>+not, an
>+ * IMR may optionally prevent that transaction from changing the state
>+of memory
>+ * or from getting correct data in response to the operation.
>+ * Write data will be dropped and reads will return 0xFFFFFFFF, the
>+system will
>+ * reset and system BIOS will print out an error message to inform the
>+user that
>+ * an IMR has been violated.
>+ * This code is based on the Linux MTRR code and refernece code from Intel's
Typo: reference

>+ * Quark BSP EFI, Linux and grub code.
>+ */
>+#include <asm/intel-quark.h>
>+#include <asm/imr.h>
>+#include <asm/iosf_mbi.h>
>+#include <linux/debugfs.h>
>+#include <linux/init.h>
>+#include <linux/module.h>
>+#include <linux/platform_device.h>
>+#include <linux/types.h>
>+
>+struct imr_device {
>+	struct dentry	*debugfs_dir;
>+	struct mutex	lock;
>+	int		num;
>+	int		used;
This 'used' variable is not used elsewhere, please removed.  
Instead, suggest to rename 'init' field which is set during probe() function if it is Quark.
In all exported functions imr_add() & imr_delete(), we have test logic against init to check if
we should bail-out earlier (being defensive towards erroneous used of imr_xxx exported functions.)

>+	int		reg_base;
>+};
>+
>+static struct imr_device imr_dev;
>+
>+/**
>+ * Values derived from published code in Quark BSP
>+ *
>+ * addr_lo
>+ * 31		Lock bit
>+ * 30		Enable bit - not implemented on Quark X1000
>+ * 29:25	Reserved
>+ * 24:2		1 kilobyte aligned lo address
>+ * 1:0		Reserved
>+ *
>+ * addr_hi
>+ * 31:25	Reserved
>+ * 24:2		1 kilobyte aligned hi address
>+ * 1:0		Reserved
>+ */
>+#define IMR_LOCK	0x80000000
>+#define IMR_ENABLE	0x04000000
Enable bit is not present per data-sheet. So, we can remove this #define.

>+
>+struct imr {
>+	u32 addr_lo;
>+	u32 addr_hi;
>+	u32 rmask;
>+	u32 wmask;
>+};
>+
>+#define IMR_NUM_REGS	(sizeof(struct imr)/sizeof(u32))
>+#define IMR_SHIFT	8
>+#define imr_to_phys(x)	(x << IMR_SHIFT)
>+#define phys_to_imr(x)	(x >> IMR_SHIFT)
What about address masking (0xFFFFFC)? Don't we need that?

>+
>+#ifdef CONFIG_DEBUG_FS
>+
>+/**
>+ * imr_dbgfs_state_show
>+ * Print state of IMR registers
>+ *
>+ * @s:		pointer to seq_file for output
>+ * @unused:	unused parameter
>+ * @return	0 on success or error code passed from mbi_iosf on failure
>+ */
>+static int imr_dbgfs_state_show(struct seq_file *s, void *unused) {
>+	int i, ret = -ENODEV;
>+	struct imr imr;
>+	u32 size;
>+
>+	mutex_lock(&imr_dev.lock);
>+
>+	for (i = 0; i <= imr_dev.num; i++) {
>+
>+		ret = imr_read(i, &imr);
>+		if (ret)
>+			break;
>+
>+		/*
>+		 * Remember to add IMR_ALIGN bytes to size to indicate the
>+		 * inherent IMR_ALIGN size bytes contained in the masked away
>+		 * lower ten bits
>+		 */
>+		size = 0;
>+		if (imr_enabled(&imr)) {
>+			size = imr_to_phys(imr.addr_hi) -
>+			       imr_to_phys(imr.addr_lo);
>+			size += IMR_ALIGN;
>+		}

As explained in my separate email, even under lo=0 & hi=0, the size computed is still valid.
So, I believe that the test here is redundant.

>+		seq_printf(s, "imr%02i: base=0x%08x, end=0x%08x, size=0x%08x "o=
>+			   "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i,
>+			   imr_to_phys(imr.addr_lo),
>+			   imr_to_phys(imr.addr_hi) + IMR_MASK, size,
>+			   imr.rmask, imr.wmask,
>+			   imr_enabled(&imr) ? "enabled " : "disabled",
IMR enable-bit is not present and  imr_enabled() test is not robust.
Suggest to remove this indication which is not reliable. 

>+			   imr.addr_lo & IMR_LOCK ? "locked" : "unlocked");
>+	}
>+
>+	mutex_unlock(&imr_dev.lock);
>+
>+	return ret;
>+}
>+
<snippet removed>

>+
>+/**
>+ * imr_add_range
>+ * Add an Isolated Memory Region
>+ *
>+ * @base: Physical base address of region aligned to 4k
>+ * @size: Physical size of region in bytes
Please add side-note that 'size' should be 1-KiB aligned. 

>+ * @read_mask: Read access mask
>+ * @write_mask: Write access mask
>+ * @lock: Indicates whether or not to permenantly lock this region
Typo: permanently

>+ * @return: Index of the IMR allocated or negative value indicating
>+error  */ int imr_add(unsigned long base, unsigned long size,
>+	    unsigned int rmask, unsigned int wmask, bool lock) {
>+	unsigned long end = base + size;
>+	struct imr imr;
>+	int reg, i, overlap, ret;
>+
As explained above in imr_dev struct, we can add test against imr_dev.init
here and bail-out if this function is incorrectly used.

<snippet removed>
>+
>+	/* Allocate IMR */
>+	imr.addr_lo = IMR_ENABLE | phys_to_imr(base);
Please drop "IMR_ENABLE" here since not there is no such register bit-30.

>+
>+/**
>+ * imr_del_range
>+ * Delete an Isolated Memory Region
>+ *
>+ * @reg: IMR index to remove
>+ * @base: Physical base address of region aligned to 4k
>+ * @size: Physical size of region in bytes
>+ * @return:	-EINVAL on invalid range or out or range id
>+ *		-ENODEV if reg is valid but no IMR exists or is locked
>+ *		0 on success
>+ */
>+int imr_del(int reg, unsigned long base, unsigned long size) {
>+	struct imr imr;
>+	int found = 0, i, ret = 0;
>+	unsigned long  max = base + size;
>+
>+	if (imr_check_range(base, size))
>+		return -EINVAL;
>+
>+	if (reg > imr_dev.num)
>+		return -EINVAL;
>+
>+	mutex_lock(&imr_dev.lock);
>+
>+	/* if a specific IMR is given try to use it */
>+	if (reg >= 0) {
>+		ret = imr_read(reg, &imr);
>+		if (ret)
>+			goto done;
>+
>+		if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
>+			ret = -ENODEV;
>+			goto done;
>+		}
>+		found = 1;
>+	}
>+
>+	/* search for match based on address range */
>+	for (i = 0; i <= imr_dev.num && found == 0; i++) {
>+		ret = imr_read(reg, &imr);
>+		if (ret)
>+			goto done;
>+
>+		if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK)
>+			continue;
>+
>+		if ((imr_to_phys(imr.addr_lo) == base) &&
>+		    (imr_to_phys(imr.addr_hi) == max)) {
>+			found = 1;
>+			reg = i;
>+		}
>+	}
>+
>+	if (found == 0) {
>+		ret = -ENODEV;
>+		goto done;
>+	}
>+
>+	/* Tear down the IMR */
>+	imr.addr_lo = 0;
>+	imr.addr_hi = 0;
>+	imr.rmask = IMR_READ_ACCESS_ALL;
>+	imr.wmask = IMR_WRITE_ACCESS_ALL;
>+
>+	ret = imr_write(reg, &imr, false);
>+
>+done:
>+	mutex_unlock(&imr_dev.lock);
>+	return ret;
>+}
>+EXPORT_SYMBOL(imr_del);
As suggested earlier, we can just offer imr delete based index-only as returned by imr_add()?
We just need to check if that IMR is locked. If locked, then bail out. 
Else, we will zero-out IMR register for that index to remove it.  This should simplify the for-loop above.
Please consider...



>+
>+/**
>+ * intel_imr_probe
>+ * entry point for IMR driver
>+ *
>+ * return: -ENODEV for no IMR support 0 if good to go  */ static int
>+__init intel_imr_init(void) {
>+	struct cpuinfo_x86 *c = &cpu_data(cpu);
>+
>+	if (!cpu_has_imr(c))
>+		return -ENODEV;
>+
>+	if (iosf_mbi_available() == false)
>+		return -ENODEV;
>+
>+	if (cpu_is_quark(c)) {
>+		imr_dev.num = QUARK_X1000_IMR_NUM;
>+		imr_dev.reg_base = QUARK_X1000_IMR_REGBASE;
>+	} else {
>+		pr_err("Unknown IMR implementation\n");
>+		return -ENODEV;
>+	}
We can just have:  

if (!x86_match_cpu(soc_imr_ids) || !iosf_mbi_available()) { 
	pr_info("IMR init failed due to IOSF_MBI not available or SoC is not Quark.\n"); 
	return -ENODEV; 
} else {
	imr_dev.num = QUARK_X1000_IMR_NUM;
	imr_dev.reg_base = QUARK_X1000_IMR_REGBASE;   
}

Where the below is added before intel_imr_init() function
static const struct x86_cpu_id soc_imr_ids[] = {  
        { X86_VENDOR_INTEL, 5, 9}, /* Intel Quark SoC X1000 */ 
        {}   
}; 
MODULE_DEVICE_TABLE(x86cpu, soc_imr_ids);

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>-----Original Message-----
>From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
>owner@vger.kernel.org] On Behalf Of Bryan O'Donoghue
>Sent: Monday, December 29, 2014 9:23 AM
>To: tglx@linutronix.de; mingo@redhat.com; hpa@zytor.com; x86@kernel.org;
>dvhart@infradead.org; platform-driver-x86@vger.kernel.org; linux-
>kernel@vger.kernel.org
>Cc: Bryan O'Donoghue
>Subject: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000
>
Suggest to add a statement on 3 different types of IMR: General IMR, 
Host Memory I/O Boundary IMR & System Management Mode IMR. Then, call out
that this patch is meant to support general IMR type only.

>Intel's Quark X1000 SoC contains a set of registers called Isolated Memory
>Regions. IMRs are accessed over the IOSF mailbox interface. IMRs are areas
>carved out of memory that define read/write access rights to the various
>system agents within the Quark system. For a given agent in the system it is
>possible to specify if that agent may read or write an area of memory defined
>by an IMR with a granularity of 1 kilobyte.
>
>Quark_SecureBootPRM_330234_001.pdf section 4.5 details the concept of
>IMRs
Would it be better if we provide a URL to the pdf? 

>
>eSRAM flush, CPU Snoop, CPU SMM Mode, CPU non-SMM mode, PMU and
PMU? You meant RMU - Remote Management Unit

<snippet removed>

>
>diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ba397bd..8303ca2
>100644
>--- a/arch/x86/Kconfig
>+++ b/arch/x86/Kconfig
>@@ -526,6 +526,29 @@ config IOSF_MBI_DEBUG
>
> 	  If you don't require the option or are in doubt, say N.
>
>+config IMR
>+	tristate "Isolated Memory Region support"
>+	default m
>+	depends on IOSF_MBI
>+	---help---
>+	  This option enables support for Isolated Memory Regions.
>+	  IMRs are a set of registers that define read and write access masks
>+	  to prohibit certain system agents from accessing memory with 1k
>+	  granularity.
>+	  IMRs make it possible to control read/write access to an address
>+	  by hardware agents inside the SoC. Read and write masks can be
>+	  defined for
>+		- SMM mode
>+		- Non SMM mode
>+		- PCI VC0/VC1
>+		- CPU snoop
Add "(write mask only)" at the end. 

>+		- eSRAM flush
>+		- PMU access
Do you mean RMU (Remote Management Unit) as documented in data-sheet?

>+	  Quark contains a set of IMR registers and makes use of those
>+	  registers during it's bootup process.
>+
>+	  If you are running on a Galileo/Quark say Y here
>+
> config X86_RDC321X
> 	bool "RDC R-321x SoC"
> 	depends on X86_32
>diff --git a/arch/x86/include/asm/imr.h b/arch/x86/include/asm/imr.h new
>file mode 100644 index 0000000..fe8f3b8
>--- /dev/null
>+++ b/arch/x86/include/asm/imr.h
>@@ -0,0 +1,79 @@
>+/*
>+ * imr.h: Isolated Memory Region API
>+ *
>+ * Copyright(c) 2013 Intel Corporation.
>+ * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
>+ *
>+ * This program is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU General Public License
>+ * as published by the Free Software Foundation; version 2
>+ * of the License.
>+ */
>+#ifndef _IMR_H
>+#define _IMR_H
>+
>+#include <asm/intel-quark.h>
>+#include <linux/types.h>
>+
>+/*
>+ * Right now IMRs are not reported via CPUID though it'd be really
>+great if
>+ * future silicon did report via CPUID for this feature bringing it
>+in-line with
>+ * other similar features - like MTRRs, MSRs etc.
>+ *
>+ * A macro is defined here which is an analog to the other cpu_has_x
>+type
>+ * features
>+ */
>+#define cpu_has_imr cpu_is_quark
We don't really need this #define method since we are using x86_match_cpu().
So, please remove them. 

>+
>+/* IMR agent access mask bits */
>+#define IMR_ESRAM_FLUSH		0x80000000
>+#define IMR_CPU_SNOOP		0x40000000
Suggest to add a comment to mark CPU_SNOOP as applicable for write-mask only.

>+#define IMR_HB_ACCESS		0x20000000
>+#define IMR_VC1_ID3		0x00008000
>+#define IMR_VC1_ID2		0x00004000
>+#define IMR_VC1_ID1		0x00002000
>+#define IMR_VC1_ID0		0x00001000
>+#define IMR_VC0_ID3		0x00000800
>+#define IMR_VC0_ID2		0x00000400
>+#define IMR_VC0_ID1		0x00000200
>+#define IMR_VC0_ID0		0x00000100
>+#define IMR_SMM			0x00000002
>+#define IMR_NON_SMM		0x00000001
Per data-sheet, this is called CPU_0 and CPU0. Suggest to stick with the name used in datasheet...

>+#define IMR_ACCESS_NONE		0x00000000
>+
>+/* Definition of read/write masks from published BSP code */
>+#define IMR_READ_ACCESS_ALL	0xBFFFFFFF
>+#define IMR_WRITE_ACCESS_ALL	0xFFFFFFFF
>+
>+/* Number of IMRs provided by Quark X1000 SoC */
>+#define QUARK_X1000_IMR_NUM	0x07
>+#define QUARK_X1000_IMR_REGBASE 0x40
>+
>+/* IMR alignment bits - only bits 31:10 are checked for IMR validity */
>+#define IMR_ALIGN		0x400
>+#define IMR_MASK		(IMR_ALIGN - 1)
>+
>+/**
>+ * imr_add_range - Add an Isolated Memory Region
>+ * @base: Physical base address of region aligned to 4k
>+ * @size: Physical size of region in bytes
Please add side-note that 'size' should be 1-KiB aligned. 
Or should we consider auto-alignment feature...

>+ * @read_mask: Read access mask
>+ * @write_mask: Write access mask
>+ * @lock: Indicates whether or not to permenantly lock this region
Typo: permanently 

>+ * @return: Index of the IMR allocated or negative value indicating error
>+ */ 
> + int imr_add(unsigned long base, unsigned long size,
>+	    unsigned int rmask, unsigned int wmask, bool lock);
>+
>+/**
>+ * imr_del_range - Delete an Isolated Memory Region
>+ * @reg: IMR index to remove
>+ * @base: Physical base address of region aligned to 4k
>+ * @size: Physical size of region in bytes
>+ * @return:	-EINVAL on invalid range or out or range id
>+ *		-ENODEV if reg is valid but no IMR exists or is locked
>+ *		0 on success
>+ */
>+int imr_del(int reg, unsigned long base, unsigned long size);

How about just offer imr delete based index-only as returned by imr_add()?
We just need to check if that IMR is locked. If locked, then bail out. 
Else, we will zero-out IMR register for that index to remove it.  

>+
>+#endif /* _IMR_H */

<snippet>

>diff --git a/arch/x86/kernel/imr.c b/arch/x86/kernel/imr.c new file mode
>100644 index 0000000..4115138
>--- /dev/null
>+++ b/arch/x86/kernel/imr.c
>@@ -0,0 +1,529 @@
>+/**
>+ * intel_imr.c
>+ *
>+ * Copyright(c) 2013 Intel Corporation.
>+ * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
>+ *
>+ * IMR registers define an isolated region of memory that can
>+ * be masked to prohibit certain system agents from accessing memory.
>+ * When a device behind a masked port performs an access - snooped or
>+not, an
>+ * IMR may optionally prevent that transaction from changing the state
>+of memory
>+ * or from getting correct data in response to the operation.
>+ * Write data will be dropped and reads will return 0xFFFFFFFF, the
>+system will
>+ * reset and system BIOS will print out an error message to inform the
>+user that
>+ * an IMR has been violated.
>+ * This code is based on the Linux MTRR code and refernece code from Intel's
Typo: reference

>+ * Quark BSP EFI, Linux and grub code.
>+ */
>+#include <asm/intel-quark.h>
>+#include <asm/imr.h>
>+#include <asm/iosf_mbi.h>
>+#include <linux/debugfs.h>
>+#include <linux/init.h>
>+#include <linux/module.h>
>+#include <linux/platform_device.h>
>+#include <linux/types.h>
>+
>+struct imr_device {
>+	struct dentry	*debugfs_dir;
>+	struct mutex	lock;
>+	int		num;
>+	int		used;
This 'used' variable is not used elsewhere, please removed.  
Instead, suggest to rename 'init' field which is set during probe() function if it is Quark.
In all exported functions imr_add() & imr_delete(), we have test logic against init to check if
we should bail-out earlier (being defensive towards erroneous used of imr_xxx exported functions.)

>+	int		reg_base;
>+};
>+
>+static struct imr_device imr_dev;
>+
>+/**
>+ * Values derived from published code in Quark BSP
>+ *
>+ * addr_lo
>+ * 31		Lock bit
>+ * 30		Enable bit - not implemented on Quark X1000
>+ * 29:25	Reserved
>+ * 24:2		1 kilobyte aligned lo address
>+ * 1:0		Reserved
>+ *
>+ * addr_hi
>+ * 31:25	Reserved
>+ * 24:2		1 kilobyte aligned hi address
>+ * 1:0		Reserved
>+ */
>+#define IMR_LOCK	0x80000000
>+#define IMR_ENABLE	0x04000000
Enable bit is not present per data-sheet. So, we can remove this #define.

>+
>+struct imr {
>+	u32 addr_lo;
>+	u32 addr_hi;
>+	u32 rmask;
>+	u32 wmask;
>+};
>+
>+#define IMR_NUM_REGS	(sizeof(struct imr)/sizeof(u32))
>+#define IMR_SHIFT	8
>+#define imr_to_phys(x)	(x << IMR_SHIFT)
>+#define phys_to_imr(x)	(x >> IMR_SHIFT)
What about address masking (0xFFFFFC)? Don't we need that?

>+
>+#ifdef CONFIG_DEBUG_FS
>+
>+/**
>+ * imr_dbgfs_state_show
>+ * Print state of IMR registers
>+ *
>+ * @s:		pointer to seq_file for output
>+ * @unused:	unused parameter
>+ * @return	0 on success or error code passed from mbi_iosf on failure
>+ */
>+static int imr_dbgfs_state_show(struct seq_file *s, void *unused) {
>+	int i, ret = -ENODEV;
>+	struct imr imr;
>+	u32 size;
>+
>+	mutex_lock(&imr_dev.lock);
>+
>+	for (i = 0; i <= imr_dev.num; i++) {
>+
>+		ret = imr_read(i, &imr);
>+		if (ret)
>+			break;
>+
>+		/*
>+		 * Remember to add IMR_ALIGN bytes to size to indicate the
>+		 * inherent IMR_ALIGN size bytes contained in the masked away
>+		 * lower ten bits
>+		 */
>+		size = 0;
>+		if (imr_enabled(&imr)) {
>+			size = imr_to_phys(imr.addr_hi) -
>+			       imr_to_phys(imr.addr_lo);
>+			size += IMR_ALIGN;
>+		}

As explained in my separate email, even under lo=0 & hi=0, the size computed is still valid.
So, I believe that the test here is redundant.

>+		seq_printf(s, "imr%02i: base=0x%08x, end=0x%08x, size=0x%08x "o=
>+			   "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i,
>+			   imr_to_phys(imr.addr_lo),
>+			   imr_to_phys(imr.addr_hi) + IMR_MASK, size,
>+			   imr.rmask, imr.wmask,
>+			   imr_enabled(&imr) ? "enabled " : "disabled",
IMR enable-bit is not present and  imr_enabled() test is not robust.
Suggest to remove this indication which is not reliable. 

>+			   imr.addr_lo & IMR_LOCK ? "locked" : "unlocked");
>+	}
>+
>+	mutex_unlock(&imr_dev.lock);
>+
>+	return ret;
>+}
>+
<snippet removed>

>+
>+/**
>+ * imr_add_range
>+ * Add an Isolated Memory Region
>+ *
>+ * @base: Physical base address of region aligned to 4k
>+ * @size: Physical size of region in bytes
Please add side-note that 'size' should be 1-KiB aligned. 

>+ * @read_mask: Read access mask
>+ * @write_mask: Write access mask
>+ * @lock: Indicates whether or not to permenantly lock this region
Typo: permanently

>+ * @return: Index of the IMR allocated or negative value indicating
>+error  */ int imr_add(unsigned long base, unsigned long size,
>+	    unsigned int rmask, unsigned int wmask, bool lock) {
>+	unsigned long end = base + size;
>+	struct imr imr;
>+	int reg, i, overlap, ret;
>+
As explained above in imr_dev struct, we can add test against imr_dev.init
here and bail-out if this function is incorrectly used.

<snippet removed>
>+
>+	/* Allocate IMR */
>+	imr.addr_lo = IMR_ENABLE | phys_to_imr(base);
Please drop "IMR_ENABLE" here since not there is no such register bit-30.

>+
>+/**
>+ * imr_del_range
>+ * Delete an Isolated Memory Region
>+ *
>+ * @reg: IMR index to remove
>+ * @base: Physical base address of region aligned to 4k
>+ * @size: Physical size of region in bytes
>+ * @return:	-EINVAL on invalid range or out or range id
>+ *		-ENODEV if reg is valid but no IMR exists or is locked
>+ *		0 on success
>+ */
>+int imr_del(int reg, unsigned long base, unsigned long size) {
>+	struct imr imr;
>+	int found = 0, i, ret = 0;
>+	unsigned long  max = base + size;
>+
>+	if (imr_check_range(base, size))
>+		return -EINVAL;
>+
>+	if (reg > imr_dev.num)
>+		return -EINVAL;
>+
>+	mutex_lock(&imr_dev.lock);
>+
>+	/* if a specific IMR is given try to use it */
>+	if (reg >= 0) {
>+		ret = imr_read(reg, &imr);
>+		if (ret)
>+			goto done;
>+
>+		if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
>+			ret = -ENODEV;
>+			goto done;
>+		}
>+		found = 1;
>+	}
>+
>+	/* search for match based on address range */
>+	for (i = 0; i <= imr_dev.num && found == 0; i++) {
>+		ret = imr_read(reg, &imr);
>+		if (ret)
>+			goto done;
>+
>+		if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK)
>+			continue;
>+
>+		if ((imr_to_phys(imr.addr_lo) == base) &&
>+		    (imr_to_phys(imr.addr_hi) == max)) {
>+			found = 1;
>+			reg = i;
>+		}
>+	}
>+
>+	if (found == 0) {
>+		ret = -ENODEV;
>+		goto done;
>+	}
>+
>+	/* Tear down the IMR */
>+	imr.addr_lo = 0;
>+	imr.addr_hi = 0;
>+	imr.rmask = IMR_READ_ACCESS_ALL;
>+	imr.wmask = IMR_WRITE_ACCESS_ALL;
>+
>+	ret = imr_write(reg, &imr, false);
>+
>+done:
>+	mutex_unlock(&imr_dev.lock);
>+	return ret;
>+}
>+EXPORT_SYMBOL(imr_del);
As suggested earlier, we can just offer imr delete based index-only as returned by imr_add()?
We just need to check if that IMR is locked. If locked, then bail out. 
Else, we will zero-out IMR register for that index to remove it.  This should simplify the for-loop above.
Please consider...



>+
>+/**
>+ * intel_imr_probe
>+ * entry point for IMR driver
>+ *
>+ * return: -ENODEV for no IMR support 0 if good to go  */ static int
>+__init intel_imr_init(void) {
>+	struct cpuinfo_x86 *c = &cpu_data(cpu);
>+
>+	if (!cpu_has_imr(c))
>+		return -ENODEV;
>+
>+	if (iosf_mbi_available() == false)
>+		return -ENODEV;
>+
>+	if (cpu_is_quark(c)) {
>+		imr_dev.num = QUARK_X1000_IMR_NUM;
>+		imr_dev.reg_base = QUARK_X1000_IMR_REGBASE;
>+	} else {
>+		pr_err("Unknown IMR implementation\n");
>+		return -ENODEV;
>+	}
We can just have:  

if (!x86_match_cpu(soc_imr_ids) || !iosf_mbi_available()) { 
	pr_info("IMR init failed due to IOSF_MBI not available or SoC is not Quark.\n"); 
	return -ENODEV; 
} else {
	imr_dev.num = QUARK_X1000_IMR_NUM;
	imr_dev.reg_base = QUARK_X1000_IMR_REGBASE;   
}

Where the below is added before intel_imr_init() function
static const struct x86_cpu_id soc_imr_ids[] = {  
        { X86_VENDOR_INTEL, 5, 9}, /* Intel Quark SoC X1000 */ 
        {}   
}; 
MODULE_DEVICE_TABLE(x86cpu, soc_imr_ids);

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>>> +/**
>>> + * imr_enabled
>>> + * Determines if an IMR is enabled based on address range
>>> + *
>>> + * @imr:	Pointer to IMR descriptor
>>> + * @return	true if IMR enabled false if disabled
>>> + */
>>> +static int imr_enabled(struct imr *imr) {
>>> +	return (imr_to_phys(imr->addr_lo) && imr_to_phys(imr->addr_hi));
>>
>> What are testing here? You have bit 30 marked as "Enabled" above (but
>> it isn't in the datasheet). With Reserved bits in each register, this
>> test for non-zero doesn't seem robust.
>
>Good question.
>
>Bit 30 is not present in X1000 silicon, though is present in the BSP code. Lets
>forget about all non-X1000 cases for now since X1000 is the only processor
>currently available.
>
>On X1000 the only means of determining if an IMR is enabled is if it's address
>bits are set to some address everybody agrees means 'off', since the enable
>bit doesn't exist. Everybody in this case is ROM, BIOS, 2nd stage bootloader
>and kernel.
>
>In the BSP code, that address is zero. So in lieu of bit 30 'enable' we have
>address 0x00000000.
>
>The kernel could define an alternative address to 0x00000000 but, then this
>would break with the convention in BIOS etc.
>
>Since BIOS and grub code both use 0x00000000 as the 'off' address I think it
>makes sense for the kernel to continue to use that address.

Just add on top of what Daren mentioned in another mail, based on the Quark document,
the base address can start from zero. Say lo=0, hi=0, and WM & RM may be changed from default value, 
1st 1KiB will be marked as IMR. It seems to me that there is no good way to test if an IMR is 'occupied' and/or 'enabled'
since enable-bit is not available. But, what is benefit of testing against lo=0 & hi=0? The logic to calculate size will work under
lo=0 & hi=0 anway.

>
>>> +	/* Error out if we have an overlap or no free IMR entries */
>>
>> According to the datasheet, overlapping ranges are valid, and access
>> must be granted by all IMRs associated with a given address. Why
>> declare an overlap as invalid here?
>
>Simplicity.
>
>It's more straight forward to define your IMR memory map if you don't allow
>the address ranges to stomp all over each other.
>
>None of the BSP reference code does overlap.
>
>If there's an argument for an overlap use-case it can be supported pretty
>simply by simply removing the overlap checks.
>
>My own view is that it's not really desirable and easier to debug IMRs
>generally on a platform if overlaps aren't allowed.
I do agree on the benefit listed above. Perhaps, you can add explanation here
to mention the design decision.

RE: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Ong, Boon Leong]

>>> +/**
>>> + * imr_enabled
>>> + * Determines if an IMR is enabled based on address range
>>> + *
>>> + * @imr:	Pointer to IMR descriptor
>>> + * @return	true if IMR enabled false if disabled
>>> + */
>>> +static int imr_enabled(struct imr *imr) {
>>> +	return (imr_to_phys(imr->addr_lo) && imr_to_phys(imr->addr_hi));
>>
>> What are testing here? You have bit 30 marked as "Enabled" above (but
>> it isn't in the datasheet). With Reserved bits in each register, this
>> test for non-zero doesn't seem robust.
>
>Good question.
>
>Bit 30 is not present in X1000 silicon, though is present in the BSP code. Lets
>forget about all non-X1000 cases for now since X1000 is the only processor
>currently available.
>
>On X1000 the only means of determining if an IMR is enabled is if it's address
>bits are set to some address everybody agrees means 'off', since the enable
>bit doesn't exist. Everybody in this case is ROM, BIOS, 2nd stage bootloader
>and kernel.
>
>In the BSP code, that address is zero. So in lieu of bit 30 'enable' we have
>address 0x00000000.
>
>The kernel could define an alternative address to 0x00000000 but, then this
>would break with the convention in BIOS etc.
>
>Since BIOS and grub code both use 0x00000000 as the 'off' address I think it
>makes sense for the kernel to continue to use that address.

Just add on top of what Daren mentioned in another mail, based on the Quark document,
the base address can start from zero. Say lo=0, hi=0, and WM & RM may be changed from default value, 
1st 1KiB will be marked as IMR. It seems to me that there is no good way to test if an IMR is 'occupied' and/or 'enabled'
since enable-bit is not available. But, what is benefit of testing against lo=0 & hi=0? The logic to calculate size will work under
lo=0 & hi=0 anway.

>
>>> +	/* Error out if we have an overlap or no free IMR entries */
>>
>> According to the datasheet, overlapping ranges are valid, and access
>> must be granted by all IMRs associated with a given address. Why
>> declare an overlap as invalid here?
>
>Simplicity.
>
>It's more straight forward to define your IMR memory map if you don't allow
>the address ranges to stomp all over each other.
>
>None of the BSP reference code does overlap.
>
>If there's an argument for an overlap use-case it can be supported pretty
>simply by simply removing the overlap checks.
>
>My own view is that it's not really desirable and easier to debug IMRs
>generally on a platform if overlaps aren't allowed.
I do agree on the benefit listed above. Perhaps, you can add explanation here
to mention the design decision.

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Darren Hart]

On Tue, Jan 06, 2015 at 01:43:23PM +0000, Bryan O'Donoghue wrote:
> On 06/01/15 07:36, Darren Hart wrote:
> 
> >>Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
> >
> >Since you have Intel (C) below and then your own, are you the sole author?
> 
> Yes, for the platform code.
> 
> Platform code tears-down IMRs and sets-up up a new one around the kernel.
> Quark BSP does a similar thing in a different place.
> 
> To be safe I'm happy to add a Intel (C) to this file anyway.

I was just checking if we needed to credit another individual with code
authorship.

...

> >>+#define IMR_SHIFT	8
> >>+#define imr_to_phys(x)	(x << IMR_SHIFT)
> >>+#define phys_to_imr(x)	(x >> IMR_SHIFT)
> >>+
> >>+/**
> >>+ * imr_enabled
> >>+ * Determines if an IMR is enabled based on address range
> >>+ *
> >>+ * @imr:	Pointer to IMR descriptor
> >>+ * @return	true if IMR enabled false if disabled
> >>+ */
> >>+static int imr_enabled(struct imr *imr)
> >>+{
> >>+	return (imr_to_phys(imr->addr_lo) && imr_to_phys(imr->addr_hi));
> >
> >What are testing here? You have bit 30 marked as "Enabled" above (but it isn't
> >in the datasheet). With Reserved bits in each register, this test for non-zero
> >doesn't seem robust.
> 
> Good question.
> 
> Bit 30 is not present in X1000 silicon, though is present in the BSP code.
> Lets forget about all non-X1000 cases for now since X1000 is the only
> processor currently available.
> 
> On X1000 the only means of determining if an IMR is enabled is if it's
> address bits are set to some address everybody agrees means 'off', since the
> enable bit doesn't exist. Everybody in this case is ROM, BIOS, 2nd stage
> bootloader and kernel.
> 

OK, that's non-obvious, so let's add a comment.

> In the BSP code, that address is zero. So in lieu of bit 30 'enable' we have
> address 0x00000000.
> 
> The kernel could define an alternative address to 0x00000000 but, then this
> would break with the convention in BIOS etc.
> 
> Since BIOS and grub code both use 0x00000000 as the 'off' address I think it
> makes sense for the kernel to continue to use that address.

So, both lo and hi don't need to be non-zero then, either one being non-zero
would constitute "enabled"? Should the above test be an || then?

> 
> >>+	/* Error out if we have an overlap or no free IMR entries */
> >
> >According to the datasheet, overlapping ranges are valid, and access must be
> >granted by all IMRs associated with a given address. Why declare an overlap as
> >invalid here?
> 
> Simplicity.
> 
> It's more straight forward to define your IMR memory map if you don't allow
> the address ranges to stomp all over each other.
> 
> None of the BSP reference code does overlap.
> 
> If there's an argument for an overlap use-case it can be supported pretty
> simply by simply removing the overlap checks.
> 
> My own view is that it's not really desirable and easier to debug IMRs
> generally on a platform if overlaps aren't allowed.
> 

OK, let's add a comment to that effect.

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 06/01/15 07:36, Darren Hart wrote:

>> Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
>
> Since you have Intel (C) below and then your own, are you the sole author?

Yes, for the platform code.

Platform code tears-down IMRs and sets-up up a new one around the 
kernel. Quark BSP does a similar thing in a different place.

To be safe I'm happy to add a Intel (C) to this file anyway.

>> +config IMR
>> +	tristate "Isolated Memory Region support"
>> +	default m
>> +	depends on IOSF_MBI
>> +	---help---
>> +	  This option enables support for Isolated Memory Regions.
>
> It supports manipulating them specifically, correct? No support is needed to
> trigger an IMR violation and reboot the system, that happens in
> hardware/firmware without any OS involvement.

Exactly.

> So we're specifically providing the means to manipulate the IMRs.

True - I'll add that statement to the description.

>> +/*
>> + * Right now IMRs are not reported via CPUID though it'd be really great if
>> + * future silicon did report via CPUID for this feature bringing it in-line with
>> + * other similar features - like MTRRs, MSRs etc.
>
> I think we can drop the editorializing :-)

:)

>
> /*
>   * Unfortunately, IMRs are not reported via CPUID, unlike MTRRs, MSRs, etc.
>   * Define a macro analogous to cpu_has_x type features.
>   */

Done.

>> +/* Definition of read/write masks from published BSP code */
>> +#define IMR_READ_ACCESS_ALL	0xBFFFFFFF
>> +#define IMR_WRITE_ACCESS_ALL	0xFFFFFFFF
>> +
>> +/* Number of IMRs provided by Quark X1000 SoC */
>> +#define QUARK_X1000_IMR_NUM	0x07
>
> Hrm, I thought there were 8?

There are. All of the loops look like this

for (i = 0; i <= imr_dev.num; i++)

aka

for (i = 0; i <= QUARK_X1000_IMR_NUM; i++)

Worth changing IMR_NUM to 8 and changing the loops to < IMR_NUM to 
remove confusion.

> Also in the datasheet here:
>
> https://communities.intel.com/servlet/JiveServlet/previewBody/21828-102-2-25120/329676_QuarkDatasheet.pdf
>
>> + *
>> + * addr_lo
>> + * 31		Lock bit
>> + * 30		Enable bit - not implemented on Quark X1000
>
> With the exception of bit 30, also marked as reserved per the above datasheet.

Fair point. I'll refer to the spec directly for all of the bits.

>> +struct imr {
>> +	u32 addr_lo;
>> +	u32 addr_hi;
>> +	u32 rmask;
>> +	u32 wmask;
>> +};
>> +
>> +#define IMR_NUM_REGS	(sizeof(struct imr)/sizeof(u32))
>
> Perhaps call the imr imr_regs so nobody breaks this in the future by adding
> something other than a u32 to it? Alternatively, use a datatype that enforces
> this... like the union Andy suggested...

I'll take a look and see which suggestion fits better

>> +#define IMR_SHIFT	8
>> +#define imr_to_phys(x)	(x << IMR_SHIFT)
>> +#define phys_to_imr(x)	(x >> IMR_SHIFT)
>> +
>> +/**
>> + * imr_enabled
>> + * Determines if an IMR is enabled based on address range
>> + *
>> + * @imr:	Pointer to IMR descriptor
>> + * @return	true if IMR enabled false if disabled
>> + */
>> +static int imr_enabled(struct imr *imr)
>> +{
>> +	return (imr_to_phys(imr->addr_lo) && imr_to_phys(imr->addr_hi));
>
> What are testing here? You have bit 30 marked as "Enabled" above (but it isn't
> in the datasheet). With Reserved bits in each register, this test for non-zero
> doesn't seem robust.

Good question.

Bit 30 is not present in X1000 silicon, though is present in the BSP 
code. Lets forget about all non-X1000 cases for now since X1000 is the 
only processor currently available.

On X1000 the only means of determining if an IMR is enabled is if it's 
address bits are set to some address everybody agrees means 'off', since 
the enable bit doesn't exist. Everybody in this case is ROM, BIOS, 2nd 
stage bootloader and kernel.

In the BSP code, that address is zero. So in lieu of bit 30 'enable' we 
have address 0x00000000.

The kernel could define an alternative address to 0x00000000 but, then 
this would break with the convention in BIOS etc.

Since BIOS and grub code both use 0x00000000 as the 'off' address I 
think it makes sense for the kernel to continue to use that address.

>> +	/* Error out if we have an overlap or no free IMR entries */
>
> According to the datasheet, overlapping ranges are valid, and access must be
> granted by all IMRs associated with a given address. Why declare an overlap as
> invalid here?

Simplicity.

It's more straight forward to define your IMR memory map if you don't 
allow the address ranges to stomp all over each other.

None of the BSP reference code does overlap.

If there's an argument for an overlap use-case it can be supported 
pretty simply by simply removing the overlap checks.

My own view is that it's not really desirable and easier to debug IMRs 
generally on a platform if overlaps aren't allowed.


Best,
BOD

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Darren Hart]

On Mon, Dec 29, 2014 at 05:23:02PM +0000, Bryan O'Donoghue wrote:
> Intel's Quark X1000 SoC contains a set of registers called Isolated Memory
> Regions. IMRs are accessed over the IOSF mailbox interface. IMRs are areas
> carved out of memory that define read/write access rights to the various
> system agents within the Quark system. For a given agent in the system it is
> possible to specify if that agent may read or write an area of memory
> defined by an IMR with a granularity of 1 kilobyte.
> 
> Quark_SecureBootPRM_330234_001.pdf section 4.5 details the concept of IMRs

I won't repeat Andy's review, so please incorporate his suggestions unless I
specifically contradict him below... (which I don't intend to do...)

> 
> eSRAM flush, CPU Snoop, CPU SMM Mode, CPU non-SMM mode, PMU and VC0/VC1 can
> have individual read/write access masks applied to them for a given memory
> region in Quark X1000. Quark supports eightIMR sets.
> 
> Since all of the DMA capable SoC components in the X1000 are mapped to VC0

Please define less common acronymns the first time they are used:
Virtual Channel 0 (VC0)

> it is possible to define sections of memory as invalid for DMA write
> operations originating from Ethernet, USB, SD and any other DMA capable
> south-cluster component on VC0. Similarly it is possible to mark kernel
> memory as non-SMM mode read/write only or to mark BIOS runtime memory as SMM
> mode accessible only depending on the particular memory footprint on a given
> system.
> 
> On an IMR violation Quark SoC X1000 systems are configured to reset the
> system, so ensuring that the IMR memory map agrees with the EFI provided
> memory map is critical to ensure no IMR violations reset the system.
> 
> The API for accessing IMRs is based on MTRR code but doesn't provide a /proc
> or /sys interface to manipulate IMRs. Defining the size and extent of IMRs
> is exclusively the domain of in-kernel code.
> 

This provides a good description of what IMRs are and how they are used on X1000
SoCs, but it doesn't tell me what to expect in the following patch.

> Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>

Since you have Intel (C) below and then your own, are you the sole author?

> ---
>  arch/x86/Kconfig                   |  23 ++
>  arch/x86/include/asm/imr.h         |  79 ++++++
>  arch/x86/include/asm/intel-quark.h |  31 +++
>  arch/x86/kernel/Makefile           |   1 +
>  arch/x86/kernel/imr.c              | 529 +++++++++++++++++++++++++++++++++++++
>  5 files changed, 663 insertions(+)
>  create mode 100644 arch/x86/include/asm/imr.h
>  create mode 100644 arch/x86/include/asm/intel-quark.h
>  create mode 100644 arch/x86/kernel/imr.c
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index ba397bd..8303ca2 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -526,6 +526,29 @@ config IOSF_MBI_DEBUG
>  
>  	  If you don't require the option or are in doubt, say N.
>  
> +config IMR
> +	tristate "Isolated Memory Region support"
> +	default m
> +	depends on IOSF_MBI
> +	---help---
> +	  This option enables support for Isolated Memory Regions.

It supports manipulating them specifically, correct? No support is needed to
trigger an IMR violation and reboot the system, that happens in
hardware/firmware without any OS involvement. So we're specifically providing
the means to manipulate the IMRs.

> +	  IMRs are a set of registers that define read and write access masks
> +	  to prohibit certain system agents from accessing memory with 1k
> +	  granularity.

New line

> +	  IMRs make it possible to control read/write access to an address
> +	  by hardware agents inside the SoC. Read and write masks can be
> +	  defined for

colon

> +		- SMM mode
> +		- Non SMM mode
> +		- PCI VC0/VC1
> +		- CPU snoop
> +		- eSRAM flush
> +		- PMU access

New line

> +	  Quark contains a set of IMR registers and makes use of those

set of eight?

> +	  registers during it's bootup process.

its

> +
> +	  If you are running on a Galileo/Quark say Y here

period

> +
>  config X86_RDC321X
>  	bool "RDC R-321x SoC"
>  	depends on X86_32
> diff --git a/arch/x86/include/asm/imr.h b/arch/x86/include/asm/imr.h
> new file mode 100644
> index 0000000..fe8f3b8
> --- /dev/null
> +++ b/arch/x86/include/asm/imr.h
> @@ -0,0 +1,79 @@
> +/*
> + * imr.h: Isolated Memory Region API
> + *
> + * Copyright(c) 2013 Intel Corporation.
> + * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; version 2
> + * of the License.
> + */
> +#ifndef _IMR_H
> +#define _IMR_H
> +
> +#include <asm/intel-quark.h>
> +#include <linux/types.h>
> +
> +/*
> + * Right now IMRs are not reported via CPUID though it'd be really great if
> + * future silicon did report via CPUID for this feature bringing it in-line with
> + * other similar features - like MTRRs, MSRs etc.

I think we can drop the editorializing :-)

/*
 * Unfortunately, IMRs are not reported via CPUID, unlike MTRRs, MSRs, etc.
 * Define a macro analogous to cpu_has_x type features.
 */

> + *
> + * A macro is defined here which is an analog to the other cpu_has_x type
> + * features
> + */
> +#define cpu_has_imr cpu_is_quark
> +
> +/* IMR agent access mask bits */
> +#define IMR_ESRAM_FLUSH		0x80000000
> +#define IMR_CPU_SNOOP		0x40000000
> +#define IMR_HB_ACCESS		0x20000000
> +#define IMR_VC1_ID3		0x00008000
> +#define IMR_VC1_ID2		0x00004000
> +#define IMR_VC1_ID1		0x00002000
> +#define IMR_VC1_ID0		0x00001000
> +#define IMR_VC0_ID3		0x00000800
> +#define IMR_VC0_ID2		0x00000400
> +#define IMR_VC0_ID1		0x00000200
> +#define IMR_VC0_ID0		0x00000100
> +#define IMR_SMM			0x00000002
> +#define IMR_NON_SMM		0x00000001
> +#define IMR_ACCESS_NONE		0x00000000
> +
> +/* Definition of read/write masks from published BSP code */
> +#define IMR_READ_ACCESS_ALL	0xBFFFFFFF
> +#define IMR_WRITE_ACCESS_ALL	0xFFFFFFFF
> +
> +/* Number of IMRs provided by Quark X1000 SoC */
> +#define QUARK_X1000_IMR_NUM	0x07

Hrm, I thought there were 8?

...

> diff --git a/arch/x86/kernel/imr.c b/arch/x86/kernel/imr.c
> new file mode 100644
> index 0000000..4115138
> --- /dev/null
> +++ b/arch/x86/kernel/imr.c
> @@ -0,0 +1,529 @@
> +/**
> + * intel_imr.c
> + *
> + * Copyright(c) 2013 Intel Corporation.
> + * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
> + *
> + * IMR registers define an isolated region of memory that can
> + * be masked to prohibit certain system agents from accessing memory.
> + * When a device behind a masked port performs an access - snooped or not, an
> + * IMR may optionally prevent that transaction from changing the state of memory
> + * or from getting correct data in response to the operation.
> + * Write data will be dropped and reads will return 0xFFFFFFFF, the system will
> + * reset and system BIOS will print out an error message to inform the user that
> + * an IMR has been violated.
> + * This code is based on the Linux MTRR code and refernece code from Intel's
> + * Quark BSP EFI, Linux and grub code.

The above text block is oddly formatted. Please wrap to a uniform width (72 or
so) and use a blank line between paragraphs.

> + */
> +#include <asm/intel-quark.h>
> +#include <asm/imr.h>
> +#include <asm/iosf_mbi.h>
> +#include <linux/debugfs.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/types.h>
> +
> +struct imr_device {
> +	struct dentry	*debugfs_dir;
> +	struct mutex	lock;
> +	int		num;
> +	int		used;
> +	int		reg_base;
> +};
> +
> +static struct imr_device imr_dev;
> +
> +/**
> + * Values derived from published code in Quark BSP

Also in the datasheet here:

https://communities.intel.com/servlet/JiveServlet/previewBody/21828-102-2-25120/329676_QuarkDatasheet.pdf

> + *
> + * addr_lo
> + * 31		Lock bit
> + * 30		Enable bit - not implemented on Quark X1000

With the exception of bit 30, also marked as reserved per the above datasheet.
I'd prefer to reference the datasheet where possible rather than soon to be
obsolete code (assuming this is meant to replace it?)

> + * 29:25	Reserved
> + * 24:2		1 kilobyte aligned lo address

The above spec uses 23:2. Is it incorrect?
Section 12.7.4.5

> + * 1:0		Reserved
> + *
> + * addr_hi
> + * 31:25	Reserved
> + * 24:2		1 kilobyte aligned hi address
> + * 1:0		Reserved
> + */
> +#define IMR_LOCK	0x80000000
> +#define IMR_ENABLE	0x04000000
> +
> +struct imr {
> +	u32 addr_lo;
> +	u32 addr_hi;
> +	u32 rmask;
> +	u32 wmask;
> +};
> +
> +#define IMR_NUM_REGS	(sizeof(struct imr)/sizeof(u32))

Perhaps call the imr imr_regs so nobody breaks this in the future by adding
something other than a u32 to it? Alternatively, use a datatype that enforces
this... like the union Andy suggested...

> +#define IMR_SHIFT	8
> +#define imr_to_phys(x)	(x << IMR_SHIFT)
> +#define phys_to_imr(x)	(x >> IMR_SHIFT)
> +
> +/**
> + * imr_enabled
> + * Determines if an IMR is enabled based on address range
> + *
> + * @imr:	Pointer to IMR descriptor
> + * @return	true if IMR enabled false if disabled
> + */
> +static int imr_enabled(struct imr *imr)
> +{
> +	return (imr_to_phys(imr->addr_lo) && imr_to_phys(imr->addr_hi));

What are testing here? You have bit 30 marked as "Enabled" above (but it isn't
in the datasheet). With Reserved bits in each register, this test for non-zero
doesn't seem robust.

> +}

...

> +/**
> + * imr_write
> + * Write an IMR at a given imr index. Requires caller to hold imr mutex
> + * Note lock bits need to be written independently of address bits
> + *
> + * @imr_id:	IMR entry to write
> + * @imr:	IMR structure representing address and access masks
> + * @lock:	Indicates if the IMR lock bit should be applied
> + * @return	0 on success or error code passed from mbi_iosf on failure
> + */
> +static int imr_write(u32 imr_id, struct imr *imr, bool lock)
> +{
> +	unsigned long flags;
> +	u32 reg = imr_dev.reg_base + (imr_id * IMR_NUM_REGS);
> +	u32 reg_lock = reg;
> +	int ret;
> +
> +	local_irq_save(flags);
> +
> +	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE, reg,
> +				imr->addr_lo);
> +	if (ret)
> +		goto done;
> +
> +	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
> +				++reg, imr->addr_hi);
> +	if (ret)
> +		goto done;
> +
> +	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
> +				++reg, imr->rmask);
> +	if (ret)
> +		goto done;
> +
> +	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
> +				++reg, imr->wmask);
> +	if (ret)
> +		goto done;
> +
> +	/* Lock bit must be set separately to addr_lo address bits */
> +	if (lock) {
> +		imr->addr_lo |= IMR_LOCK;
> +		ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
> +					reg_lock, imr->addr_lo);
> +	}
> +
> +done:
> +	local_irq_restore(flags);
> +
> +	/*
> +	 * If writing to the IOSF failed then we're in an unknown state

comma at end

> +	 * likely a very bad state. An IMR in an invalid state will almost
> +	 * certainly lead to a memory access violation.
> +	 */
> +	if (ret)
> +		WARN(1, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n",

No need for the redundant if test.

WARN(ret, "IOSF...

> +			imr_to_phys(imr->addr_lo),
> +			imr_to_phys(imr->addr_hi) + IMR_MASK);
> +
> +	return ret;
> +}
> +
> +#ifdef CONFIG_DEBUG_FS
> +
> +/**
> + * imr_dbgfs_state_show
> + * Print state of IMR registers
> + *
> + * @s:		pointer to seq_file for output
> + * @unused:	unused parameter
> + * @return	0 on success or error code passed from mbi_iosf on failure
> + */
> +static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
> +{
> +	int i, ret = -ENODEV;

One line per variable please (per CodingStyle).
...

> +/**
> + * imr_debugfs_register
> + * Register debugfs hooks
> + *
> + * @imr:	IMR structure representing address and access masks
> + * @return	0 on success - errno on failure
> + */
> +static int imr_debugfs_register(struct imr_device *imr_dev)
> +{
> +	struct dentry *dir, *f;
> +
> +	dir = debugfs_create_dir("imr", NULL);
> +	if (!dir)
> +		return -ENOMEM;
> +
> +	f = debugfs_create_file("state", S_IFREG | S_IRUGO,
> +				dir, imr_dev, &imr_state_ops);
> +	if (!f)
> +		goto err;

		return -ENODEV;

And drop the err: label below.

> +
> +	imr_dev->debugfs_dir = dir;
> +
> +	return 0;
> +err:
> +	return -ENODEV;
> +}

...

> +/**
> + * imr_debugfs_unregister
> + * Dummy hook for !CONFIG_DEBUG_FS
> + *
> + * @imr:	IMR structure representing address and access masks
> + * @return	none
> + */
> +static void imr_debugfs_unregister(struct imr_device *imr_dev)
> +{
> +}
> +
> +#endif /* CONFIG_DEBUG_FS */
> +
> +/**
> + * imr_check_range
> + * Check the passed address range for an IMR is aligned
> + *
> + * @base: base address of intended IMR
> + * @size: size of intended IMR
> + * @return zero on valid range -EINVAL on unaligned base/size
> + */
> +static int imr_check_range(unsigned long base, unsigned long size)
> +{
> +	if ((base & (IMR_MASK)) || (size & (IMR_MASK))) {
> +		pr_warn("imr: base 0x%08lx size 0x%08lx must align to 1k\n",
> +			base, size);
> +		dump_stack();
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
> +/**
> + * imr_add_range
> + * Add an Isolated Memory Region
> + *
> + * @base: Physical base address of region aligned to 4k
> + * @size: Physical size of region in bytes
> + * @read_mask: Read access mask
> + * @write_mask: Write access mask
> + * @lock: Indicates whether or not to permenantly lock this region
> + * @return: Index of the IMR allocated or negative value indicating error
> + */
> +int imr_add(unsigned long base, unsigned long size,
> +	    unsigned int rmask, unsigned int wmask, bool lock)
> +{
> +	unsigned long end = base + size;
> +	struct imr imr;
> +	int reg, i, overlap, ret;
> +
> +	if (imr_check_range(base, size))
> +		return -EINVAL;
> +
> +	if (!size) {
> +		pr_warn("imr: invalid size zero!\n");
> +		return -EINVAL;
> +	}
> +
> +	mutex_lock(&imr_dev.lock);
> +
> +	/* Find an free IMR while checking for an existing overlapping range */
> +	overlap = 0;
> +	reg = -1;
> +	for (i = 0; i <= imr_dev.num; i++) {
> +		ret = imr_read(i, &imr);
> +		if (ret)
> +			goto done;
> +
> +		/* Find overlap */
> +		if (imr_enabled(&imr)) {
> +			if (base >= imr_to_phys(imr.addr_lo) &&
> +				base <= imr_to_phys(imr.addr_hi)) {
> +				overlap = 1;
> +				break;
> +			}
> +			if (end >= imr_to_phys(imr.addr_lo) &&
> +				end <= imr_to_phys(imr.addr_hi)) {
> +				overlap = 1;
> +				break;
> +			}
> +		} else {
> +			reg = i;
> +		}
> +	}
> +
> +	/* Error out if we have an overlap or no free IMR entries */

According to the datasheet, overlapping ranges are valid, and access must be
granted by all IMRs associated with a given address. Why declare an overlap as
invalid here?

> +	if (overlap) {
> +		ret = -EINVAL;
> +		goto done;
> +	}
> +	if (reg == -1) {
> +		ret = -ENODEV;
> +		goto done;
> +	}

...

Thanks,

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

On 31/12/14 15:05, Andy Shevchenko wrote:

<snip>
>> +int imr_del(int reg, unsigned long base, unsigned long size);
>
> Same comments as for add_range.
> Could it be imr_remove_range() ?

Can be. You've actually caught me out there, function name is "imr_del"
function description says imr_del_range(). Amazing to think I proof read
this file a number of times for exactly thing type of thing

I'm happy with

imr_add_range();
imr_remove_range();

>> +
>> +#endif /* _IMR_H */
>> diff --git a/arch/x86/include/asm/intel-quark.h
b/arch/x86/include/asm/intel-quark.h
>> new file mode 100644
>> index 0000000..f51ac8c
>> --- /dev/null
>> +++ b/arch/x86/include/asm/intel-quark.h

<snip>

>> +#ifdef CONFIG_X86_32
>> +static inline int cpu_is_quark(const struct cpuinfo_x86 *c)
>> +{
>> +       return (c->x86_vendor == X86_VENDOR_INTEL &&
>> +               c->x86 == 5 && c->x86_model == 9);
>> +}
>> +#else
>> +static inline int cpu_is_quark(const struct cpuinfo_x86 *c)
>> +{
>> +       return 0;
>> +}
>> +#endif
>> +
>> +#endif /* _ASM_X86_INTEL_QUARK_H */
>
> Could we use x86_match_cpu() instead?

I don't see why not. I'll kill this header and call out to
x86_match_cpu() in the Galileo and IMR code.

>> +       ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
>> +                               reg, &imr->addr_lo);
>> +       if (ret)
>> +               return ret;
>> +
>> +       ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
>> +                               ++reg, &imr->addr_hi);
>
> Could you use reg++ in previous line and so on?

Yes I could. Originally wrote the code with a pre-increment and then
changed the flow later on. Post-increment will work just as good now and
is more readable.

> One more idea, if you make a union inside the structure you may do
> this in a loop.
> struct imr {
>  union {
>   struct imr {
>  ...
>   };
>   u32 regs[IMR_NUM_REGS];
>  };
> }
> Mostly same for _write().

Since reg is incrementing on each iosf_mbi_dothing() that can work.

>> +       u32 reg = imr_dev.reg_base + (imr_id * IMR_NUM_REGS);
>> +       u32 reg_lock = reg;
>
> Do we need a separate variable? Would (reg - IMR_NUM_REGS) work for you?

Sure. A separate integer isn't required, I can make that change.

>> +done:
>> +       local_irq_restore(flags);
>
> Could you do like
>
>       local_irq_restore(flags);
>       return 0;
> done:
>       local_irq_restore(flags);
>       WARN(...)
>      return ret;
> ?

Doesn't change the logic so yeah, works for me.

>> +static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
>> +{
>> +       int i, ret = -ENODEV;
>> +       struct imr imr;
>> +       u32 size;
>> +
>> +       mutex_lock(&imr_dev.lock);
>
> It seems you may get the imr_dev via parameters. I suggest to avoid
> using global variables as much as possible.

Appreciated, you're right globals are bad.

I think in this case the mutex at that scope is necessary though. Same
with the debugfs handle.

>> +
>> +       for (i = 0; i <= imr_dev.num; i++) {
>
> num is not num, but last one? Sounds confusing for me.

Will change.

>> +
>> +       f = debugfs_create_file("state", S_IFREG | S_IRUGO,
>> +                               dir, imr_dev, &imr_state_ops);
>> +       if (!f)
>> +               goto err;
>
> Are you planing to extend the debugfs contents? Would it be okay to
> use only one file for now?

No not planning to extend.
OK with the one file.

>> +}
>
> No need to put this function under ifdef  - debugfs has the stubs.

Ah - wasn't aware of that.
Great stuff - I'll kill the ifdefs - thanks !

> Can you define pr_fmt() ?
>
> 1 KiB.

Yep will do
:g/pr_info/s//pr_fmt/g

>
>> +                       base, size);
>> +               dump_stack();
>
> dump_stack is really needed here? In that case why not to use WARN()?

Hmm - I nope - dump_stack() isn't relevant since it's an in-kernel API.
Did an unthinking copy/past from the mtrr code

I'll zap that.

>> +       if (imr_check_range(base, size))
>> +               return -EINVAL;
>
> ret = imr_();
> if (ret)
>  return ret;

Good catch.

>> +       for (i = 0; i <= imr_dev.num; i++) {
>> +               ret = imr_read(i, &imr);
>> +               if (ret)
>> +                       goto done;
>> +
>> +               /* Find overlap */
>> +               if (imr_enabled(&imr)) {
>> +                       if (base >= imr_to_phys(imr.addr_lo) &&
>> +                               base <= imr_to_phys(imr.addr_hi)) {
>
>> +                               overlap = 1;
>> +                               break;
>
> Maybe
> ret = -EINVAL;
> goto done;

Agree - I like that change.
Waste of time to complete the loop if an overlap is detected.


>> +       if (reg >= 0) {
>> +               ret = imr_read(reg, &imr);
>> +               if (ret)
>> +                       goto done;
>> +
>> +               if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
>> +                       ret = -ENODEV;
>> +                       goto done;
>> +               }
>> +               found = 1;
>
> You may put a loop to the else branch instead of checking found at
> each iteration.

Sure.

> Happy New Year!

Thanks for the feedback Andy !
Best wishes in the New Year.

BOD

Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Andy Shevchenko]

On Mon, Dec 29, 2014 at 7:23 PM, Bryan O'Donoghue
<pure.logic@nexus-software.ie> wrote:
> Intel's Quark X1000 SoC contains a set of registers called Isolated Memory
> Regions. IMRs are accessed over the IOSF mailbox interface. IMRs are areas
> carved out of memory that define read/write access rights to the various
> system agents within the Quark system. For a given agent in the system it is
> possible to specify if that agent may read or write an area of memory
> defined by an IMR with a granularity of 1 kilobyte.

1 KiB? (Check entire patchset).

>
> Quark_SecureBootPRM_330234_001.pdf section 4.5 details the concept of IMRs

Missed dot at the end of sentence.

> eSRAM flush, CPU Snoop, CPU SMM Mode, CPU non-SMM mode, PMU and VC0/VC1 can
> have individual read/write access masks applied to them for a given memory
> region in Quark X1000. Quark supports eightIMR sets.

Missed space.

> Since all of the DMA capable SoC components in the X1000 are mapped to VC0
> it is possible to define sections of memory as invalid for DMA write
> operations originating from Ethernet, USB, SD and any other DMA capable
> south-cluster component on VC0. Similarly it is possible to mark kernel
> memory as non-SMM mode read/write only or to mark BIOS runtime memory as SMM
> mode accessible only depending on the particular memory footprint on a given
> system.
>
> On an IMR violation Quark SoC X1000 systems are configured to reset the
> system, so ensuring that the IMR memory map agrees with the EFI provided
> memory map is critical to ensure no IMR violations reset the system.
>
> The API for accessing IMRs is based on MTRR code but doesn't provide a /proc
> or /sys interface to manipulate IMRs. Defining the size and extent of IMRs
> is exclusively the domain of in-kernel code.
>
> Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
> ---
>  arch/x86/Kconfig                   |  23 ++
>  arch/x86/include/asm/imr.h         |  79 ++++++
>  arch/x86/include/asm/intel-quark.h |  31 +++
>  arch/x86/kernel/Makefile           |   1 +
>  arch/x86/kernel/imr.c              | 529 +++++++++++++++++++++++++++++++++++++
>  5 files changed, 663 insertions(+)
>  create mode 100644 arch/x86/include/asm/imr.h
>  create mode 100644 arch/x86/include/asm/intel-quark.h
>  create mode 100644 arch/x86/kernel/imr.c
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index ba397bd..8303ca2 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -526,6 +526,29 @@ config IOSF_MBI_DEBUG
>
>           If you don't require the option or are in doubt, say N.
>
> +config IMR
> +       tristate "Isolated Memory Region support"
> +       default m
> +       depends on IOSF_MBI
> +       ---help---
> +         This option enables support for Isolated Memory Regions.
> +         IMRs are a set of registers that define read and write access masks
> +         to prohibit certain system agents from accessing memory with 1k

1 KiB

> +         granularity.
> +         IMRs make it possible to control read/write access to an address
> +         by hardware agents inside the SoC. Read and write masks can be
> +         defined for
> +               - SMM mode
> +               - Non SMM mode
> +               - PCI VC0/VC1
> +               - CPU snoop
> +               - eSRAM flush
> +               - PMU access
> +         Quark contains a set of IMR registers and makes use of those
> +         registers during it's bootup process.
> +
> +         If you are running on a Galileo/Quark say Y here
> +
>  config X86_RDC321X
>         bool "RDC R-321x SoC"
>         depends on X86_32
> diff --git a/arch/x86/include/asm/imr.h b/arch/x86/include/asm/imr.h
> new file mode 100644
> index 0000000..fe8f3b8
> --- /dev/null
> +++ b/arch/x86/include/asm/imr.h
> @@ -0,0 +1,79 @@
> +/*
> + * imr.h: Isolated Memory Region API
> + *
> + * Copyright(c) 2013 Intel Corporation.
> + * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>

2015 everywhere I guess.

> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; version 2
> + * of the License.
> + */
> +#ifndef _IMR_H
> +#define _IMR_H
> +
> +#include <asm/intel-quark.h>
> +#include <linux/types.h>
> +
> +/*
> + * Right now IMRs are not reported via CPUID though it'd be really great if
> + * future silicon did report via CPUID for this feature bringing it in-line with
> + * other similar features - like MTRRs, MSRs etc.
> + *
> + * A macro is defined here which is an analog to the other cpu_has_x type
> + * features
> + */
> +#define cpu_has_imr cpu_is_quark
> +
> +/* IMR agent access mask bits */
> +#define IMR_ESRAM_FLUSH                0x80000000
> +#define IMR_CPU_SNOOP          0x40000000
> +#define IMR_HB_ACCESS          0x20000000
> +#define IMR_VC1_ID3            0x00008000
> +#define IMR_VC1_ID2            0x00004000
> +#define IMR_VC1_ID1            0x00002000
> +#define IMR_VC1_ID0            0x00001000
> +#define IMR_VC0_ID3            0x00000800
> +#define IMR_VC0_ID2            0x00000400
> +#define IMR_VC0_ID1            0x00000200
> +#define IMR_VC0_ID0            0x00000100
> +#define IMR_SMM                        0x00000002
> +#define IMR_NON_SMM            0x00000001
> +#define IMR_ACCESS_NONE                0x00000000

Can it be defined via BIT(x)?

> +
> +/* Definition of read/write masks from published BSP code */
> +#define IMR_READ_ACCESS_ALL    0xBFFFFFFF
> +#define IMR_WRITE_ACCESS_ALL   0xFFFFFFFF
> +
> +/* Number of IMRs provided by Quark X1000 SoC */
> +#define QUARK_X1000_IMR_NUM    0x07
> +#define QUARK_X1000_IMR_REGBASE 0x40
> +
> +/* IMR alignment bits - only bits 31:10 are checked for IMR validity */
> +#define IMR_ALIGN              0x400
> +#define IMR_MASK               (IMR_ALIGN - 1)
> +
> +/**
> + * imr_add_range - Add an Isolated Memory Region
> + * @base: Physical base address of region aligned to 4k
> + * @size: Physical size of region in bytes
> + * @read_mask: Read access mask
> + * @write_mask: Write access mask
> + * @lock: Indicates whether or not to permenantly lock this region

It would be nice to indent descriptions after colon and use small
letter at the beginning. (Check entire patchset)

> + * @return: Index of the IMR allocated or negative value indicating error

Usually it goes as a separate section called Return like:

* Return:
* foo if A, otherwise bar.

> + */

Entire comment block should be in *.c file only.

> +int imr_add(unsigned long base, unsigned long size,

Leave _range suffix here and in the other one. It would be better I think.

> +           unsigned int rmask, unsigned int wmask, bool lock);
> +
> +/**
> + * imr_del_range - Delete an Isolated Memory Region
> + * @reg: IMR index to remove
> + * @base: Physical base address of region aligned to 4k
> + * @size: Physical size of region in bytes
> + * @return:    -EINVAL on invalid range or out or range id
> + *             -ENODEV if reg is valid but no IMR exists or is locked
> + *             0 on success
> + */
> +int imr_del(int reg, unsigned long base, unsigned long size);

Same comments as for add_range.
Could it be imr_remove_range() ?

> +
> +#endif /* _IMR_H */
> diff --git a/arch/x86/include/asm/intel-quark.h b/arch/x86/include/asm/intel-quark.h
> new file mode 100644
> index 0000000..f51ac8c
> --- /dev/null
> +++ b/arch/x86/include/asm/intel-quark.h
> @@ -0,0 +1,31 @@
> +/*
> + * intel-quark.h: Quark shared defines and helper functions
> + *
> + * Copyright 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; version 2
> + * of the License.
> + */
> +
> +#ifndef _ASM_X86_INTEL_QUARK_H
> +#define _ASM_X86_INTEL_QUARK_H
> +
> +#include <asm/processor.h>
> +
> +#ifdef CONFIG_X86_32
> +static inline int cpu_is_quark(const struct cpuinfo_x86 *c)
> +{
> +       return (c->x86_vendor == X86_VENDOR_INTEL &&
> +               c->x86 == 5 && c->x86_model == 9);
> +}
> +#else
> +static inline int cpu_is_quark(const struct cpuinfo_x86 *c)
> +{
> +       return 0;
> +}
> +#endif
> +
> +#endif /* _ASM_X86_INTEL_QUARK_H */

Could we use x86_match_cpu() instead?

> +
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 5d4502c..0252de5 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -104,6 +104,7 @@ obj-$(CONFIG_EFI)                   += sysfb_efi.o
>  obj-$(CONFIG_PERF_EVENTS)              += perf_regs.o
>  obj-$(CONFIG_TRACING)                  += tracepoint.o
>  obj-$(CONFIG_IOSF_MBI)                 += iosf_mbi.o
> +obj-$(CONFIG_IMR)                      += imr.o
>  obj-$(CONFIG_PMC_ATOM)                 += pmc_atom.o
>
>  ###
> diff --git a/arch/x86/kernel/imr.c b/arch/x86/kernel/imr.c
> new file mode 100644
> index 0000000..4115138
> --- /dev/null
> +++ b/arch/x86/kernel/imr.c
> @@ -0,0 +1,529 @@
> +/**
> + * intel_imr.c
> + *
> + * Copyright(c) 2013 Intel Corporation.
> + * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
> + *
> + * IMR registers define an isolated region of memory that can
> + * be masked to prohibit certain system agents from accessing memory.
> + * When a device behind a masked port performs an access - snooped or not, an
> + * IMR may optionally prevent that transaction from changing the state of memory
> + * or from getting correct data in response to the operation.
> + * Write data will be dropped and reads will return 0xFFFFFFFF, the system will
> + * reset and system BIOS will print out an error message to inform the user that
> + * an IMR has been violated.
> + * This code is based on the Linux MTRR code and refernece code from Intel's
> + * Quark BSP EFI, Linux and grub code.
> + */
> +#include <asm/intel-quark.h>
> +#include <asm/imr.h>
> +#include <asm/iosf_mbi.h>
> +#include <linux/debugfs.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/types.h>
> +
> +struct imr_device {
> +       struct dentry   *debugfs_dir;
> +       struct mutex    lock;
> +       int             num;
> +       int             used;
> +       int             reg_base;
> +};
> +
> +static struct imr_device imr_dev;
> +
> +/**

Just /*.

> + * Values derived from published code in Quark BSP
> + *
> + * addr_lo
> + * 31          Lock bit
> + * 30          Enable bit - not implemented on Quark X1000
> + * 29:25       Reserved
> + * 24:2                1 kilobyte aligned lo address
> + * 1:0         Reserved
> + *
> + * addr_hi
> + * 31:25       Reserved
> + * 24:2                1 kilobyte aligned hi address
> + * 1:0         Reserved
> + */
> +#define IMR_LOCK       0x80000000
> +#define IMR_ENABLE     0x04000000

Use BIT(x).

> +
> +struct imr {
> +       u32 addr_lo;
> +       u32 addr_hi;
> +       u32 rmask;
> +       u32 wmask;
> +};
> +
> +#define IMR_NUM_REGS   (sizeof(struct imr)/sizeof(u32))
> +#define IMR_SHIFT      8


> +#define imr_to_phys(x) (x << IMR_SHIFT)
> +#define phys_to_imr(x) (x >> IMR_SHIFT)

x -> (x)

> +
> +/**
> + * imr_enabled
> + * Determines if an IMR is enabled based on address range
> + *
> + * @imr:       Pointer to IMR descriptor
> + * @return     true if IMR enabled false if disabled
> + */
> +static int imr_enabled(struct imr *imr)
> +{
> +       return (imr_to_phys(imr->addr_lo) && imr_to_phys(imr->addr_hi));

No need to surround the return value by parentheses.

> +}
> +
> +/**
> + * imr_read
> + * Read an IMR at a given imr index. Requires caller to hold imr mutex

Summary.
* imr_read - read an IMR at a given index

This one goes to the Description I guess.
* Description:
* Requires caller to hold IMR device mutex.

Same for imr_write().

> + *
> + * @imr_id:    IMR entry to read
> + * @imr:       IMR structure representing address and access masks
> + * @return     0 on success or error code passed from mbi_iosf on failure
> + */
> +static int imr_read(u32 imr_id, struct imr *imr)
> +{
> +       u32 reg = imr_dev.reg_base + (imr_id * IMR_NUM_REGS);

No need to have parentheses.
Same for _write().

> +       int ret;
> +
> +       ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
> +                               reg, &imr->addr_lo);
> +       if (ret)
> +               return ret;
> +
> +       ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
> +                               ++reg, &imr->addr_hi);

Could you use reg++ in previous line and so on?

One more idea, if you make a union inside the structure you may do
this in a loop.
struct imr {
 union {
  struct imr {
 ...
  };
  u32 regs[IMR_NUM_REGS];
 };
}

Mostly same for _write().

> +       if (ret)
> +               return ret;
> +
> +       ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
> +                               ++reg, &imr->rmask);
> +       if (ret)
> +               return ret;
> +
> +       return iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
> +                               ++reg, &imr->wmask);
> +}
> +
> +/**
> + * imr_write
> + * Write an IMR at a given imr index. Requires caller to hold imr mutex
> + * Note lock bits need to be written independently of address bits
> + *
> + * @imr_id:    IMR entry to write
> + * @imr:       IMR structure representing address and access masks
> + * @lock:      Indicates if the IMR lock bit should be applied
> + * @return     0 on success or error code passed from mbi_iosf on failure
> + */
> +static int imr_write(u32 imr_id, struct imr *imr, bool lock)
> +{
> +       unsigned long flags;
> +       u32 reg = imr_dev.reg_base + (imr_id * IMR_NUM_REGS);
> +       u32 reg_lock = reg;

Do we need a separate variable? Would (reg - IMR_NUM_REGS) work for you?

> +       int ret;
> +
> +       local_irq_save(flags);
> +
> +       ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE, reg,
> +                               imr->addr_lo);
> +       if (ret)
> +               goto done;
> +
> +       ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
> +                               ++reg, imr->addr_hi);
> +       if (ret)
> +               goto done;
> +
> +       ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
> +                               ++reg, imr->rmask);
> +       if (ret)
> +               goto done;
> +
> +       ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
> +                               ++reg, imr->wmask);
> +       if (ret)
> +               goto done;
> +
> +       /* Lock bit must be set separately to addr_lo address bits */
> +       if (lock) {
> +               imr->addr_lo |= IMR_LOCK;
> +               ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
> +                                       reg_lock, imr->addr_lo);
> +       }
> +
> +done:
> +       local_irq_restore(flags);

Could you do like

      local_irq_restore(flags);
      return 0;
done:
      local_irq_restore(flags);
      WARN(...)
     return ret;
?

> +
> +       /*
> +        * If writing to the IOSF failed then we're in an unknown state
> +        * likely a very bad state. An IMR in an invalid state will almost
> +        * certainly lead to a memory access violation.
> +        */
> +       if (ret)
> +               WARN(1, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n",
> +                       imr_to_phys(imr->addr_lo),
> +                       imr_to_phys(imr->addr_hi) + IMR_MASK);
> +
> +       return ret;
> +}
> +
> +#ifdef CONFIG_DEBUG_FS
> +
> +/**
> + * imr_dbgfs_state_show
> + * Print state of IMR registers
> + *
> + * @s:         pointer to seq_file for output
> + * @unused:    unused parameter
> + * @return     0 on success or error code passed from mbi_iosf on failure
> + */
> +static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
> +{
> +       int i, ret = -ENODEV;
> +       struct imr imr;
> +       u32 size;
> +
> +       mutex_lock(&imr_dev.lock);

It seems you may get the imr_dev via parameters. I suggest to avoid
using global variables as much as possible.

> +
> +       for (i = 0; i <= imr_dev.num; i++) {

num is not num, but last one? Sounds confusing for me.

> +
> +               ret = imr_read(i, &imr);
> +               if (ret)
> +                       break;
> +
> +               /*
> +                * Remember to add IMR_ALIGN bytes to size to indicate the
> +                * inherent IMR_ALIGN size bytes contained in the masked away
> +                * lower ten bits
> +                */
> +               size = 0;

It might be an else branch.

> +               if (imr_enabled(&imr)) {
> +                       size = imr_to_phys(imr.addr_hi) -
> +                              imr_to_phys(imr.addr_lo);

Could it be one line?

> +                       size += IMR_ALIGN;

Could it fit this one too?

> +               }
> +               seq_printf(s, "imr%02i: base=0x%08x, end=0x%08x, size=0x%08x "
> +                          "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i,
> +                          imr_to_phys(imr.addr_lo),
> +                          imr_to_phys(imr.addr_hi) + IMR_MASK, size,
> +                          imr.rmask, imr.wmask,
> +                          imr_enabled(&imr) ? "enabled " : "disabled",
> +                          imr.addr_lo & IMR_LOCK ? "locked" : "unlocked");
> +       }
> +
> +       mutex_unlock(&imr_dev.lock);
> +
> +       return ret;
> +}
> +
> +/**
> + * imr_state_open
> + * Debugfs open callback
> + *
> + * @inode:     pointer to struct inode
> + * @file:      pointer to struct file
> + * @return     result of single open
> + */
> +static int imr_state_open(struct inode *inode, struct file *file)
> +{
> +       return single_open(file, imr_dbgfs_state_show, inode->i_private);
> +}
> +
> +static const struct file_operations imr_state_ops = {
> +       .open           = imr_state_open,
> +       .read           = seq_read,
> +       .llseek         = seq_lseek,
> +       .release        = single_release,
> +};
> +
> +/**
> + * imr_debugfs_register
> + * Register debugfs hooks
> + *
> + * @imr:       IMR structure representing address and access masks
> + * @return     0 on success - errno on failure
> + */
> +static int imr_debugfs_register(struct imr_device *imr_dev)
> +{
> +       struct dentry *dir, *f;
> +
> +       dir = debugfs_create_dir("imr", NULL);
> +       if (!dir)
> +               return -ENOMEM;

if (IS_ERR(dir))
 return PTR_ERR();

Though it seems not a case when you have this under ifdef.

> +
> +       f = debugfs_create_file("state", S_IFREG | S_IRUGO,
> +                               dir, imr_dev, &imr_state_ops);
> +       if (!f)
> +               goto err;

Are you planing to extend the debugfs contents? Would it be okay to
use only one file for now?

> +
> +       imr_dev->debugfs_dir = dir;
> +
> +       return 0;
> +err:
> +       return -ENODEV;

No need to have separate label for plain return.

> +}
> +
> +/**
> + * imr_debugfs_unregister
> + * Unregister debugfs hooks
> + *
> + * @imr:       IMR structure representing address and access masks
> + * @return     none
> + */
> +static void imr_debugfs_unregister(struct imr_device *imr_dev)
> +{

> +       if (!imr_dev->debugfs_dir)
> +               return;

Redundant check.

> +
> +       debugfs_remove_recursive(imr_dev->debugfs_dir);
> +       imr_dev->debugfs_dir = NULL;

No need to assign NULL.

> +}

No need to put this function under ifdef  - debugfs has the stubs.
Or add ifdefs around places where they are called and remove those
dummy functions below.

> +
> +#else
> +
> +/**
> + * imr_debugfs_register
> + * Register debugfs hooks
> + *
> + * @imr:       IMR structure representing address and access masks
> + * @return     0 on success - errno on failure
> + */
> +static int imr_debugfs_register(struct imr_device *imr_dev)
> +{
> +       return 0;
> +}
> +
> +/**
> + * imr_debugfs_unregister
> + * Dummy hook for !CONFIG_DEBUG_FS
> + *
> + * @imr:       IMR structure representing address and access masks
> + * @return     none
> + */
> +static void imr_debugfs_unregister(struct imr_device *imr_dev)
> +{
> +}
> +
> +#endif /* CONFIG_DEBUG_FS */
> +
> +/**
> + * imr_check_range
> + * Check the passed address range for an IMR is aligned
> + *
> + * @base: base address of intended IMR
> + * @size: size of intended IMR
> + * @return zero on valid range -EINVAL on unaligned base/size
> + */
> +static int imr_check_range(unsigned long base, unsigned long size)
> +{
> +       if ((base & (IMR_MASK)) || (size & (IMR_MASK))) {

Too many parentheses. Looks like you may do it less.

> +               pr_warn("imr: base 0x%08lx size 0x%08lx must align to 1k\n",

Can you define pr_fmt() ?

1 KiB.

> +                       base, size);
> +               dump_stack();

dump_stack is really needed here? In that case why not to use WARN()?

> +               return -EINVAL;
> +       }
> +       return 0;
> +}
> +
> +/**
> + * imr_add_range
> + * Add an Isolated Memory Region
> + *
> + * @base: Physical base address of region aligned to 4k
> + * @size: Physical size of region in bytes
> + * @read_mask: Read access mask
> + * @write_mask: Write access mask
> + * @lock: Indicates whether or not to permenantly lock this region
> + * @return: Index of the IMR allocated or negative value indicating error
> + */
> +int imr_add(unsigned long base, unsigned long size,
> +           unsigned int rmask, unsigned int wmask, bool lock)
> +{
> +       unsigned long end = base + size;
> +       struct imr imr;
> +       int reg, i, overlap, ret;
> +
> +       if (imr_check_range(base, size))
> +               return -EINVAL;

ret = imr_();
if (ret)
 return ret;

> +
> +       if (!size) {
> +               pr_warn("imr: invalid size zero!\n");
> +               return -EINVAL;
> +       }
> +
> +       mutex_lock(&imr_dev.lock);
> +
> +       /* Find an free IMR while checking for an existing overlapping range */
> +       overlap = 0;
> +       reg = -1;
> +       for (i = 0; i <= imr_dev.num; i++) {
> +               ret = imr_read(i, &imr);
> +               if (ret)
> +                       goto done;
> +
> +               /* Find overlap */
> +               if (imr_enabled(&imr)) {
> +                       if (base >= imr_to_phys(imr.addr_lo) &&
> +                               base <= imr_to_phys(imr.addr_hi)) {

> +                               overlap = 1;
> +                               break;

Maybe
ret = -EINVAL;
goto done;

> +                       }
> +                       if (end >= imr_to_phys(imr.addr_lo) &&
> +                               end <= imr_to_phys(imr.addr_hi)) {
> +                               overlap = 1;
> +                               break;

Ditto.

> +                       }

You may use one condition. If you still want to have them split you
may create a helper to check for overlap.

> +               } else {
> +                       reg = i;
> +               }
> +       }
> +
> +       /* Error out if we have an overlap or no free IMR entries */
> +       if (overlap) {
> +               ret = -EINVAL;
> +               goto done;
> +       }

...and remove overlap variable and this condition.

> +       if (reg == -1) {
> +               ret = -ENODEV;
> +               goto done;
> +       }
> +
> +       pr_debug("IMR %d phys 0x%08lx-0x%08lx rmask 0x%08x wmask 0x%08x\n",
> +               reg, base, end, rmask, wmask);
> +
> +       /* Allocate IMR */
> +       imr.addr_lo = IMR_ENABLE | phys_to_imr(base);
> +       imr.addr_hi = phys_to_imr(end);
> +       imr.rmask = rmask;
> +       imr.wmask = wmask;
> +
> +       ret = imr_write(reg, &imr, lock);
> +
> +done:
> +       mutex_unlock(&imr_dev.lock);
> +       return ret;
> +}
> +EXPORT_SYMBOL(imr_add);
> +
> +/**
> + * imr_del_range
> + * Delete an Isolated Memory Region
> + *
> + * @reg: IMR index to remove
> + * @base: Physical base address of region aligned to 4k
> + * @size: Physical size of region in bytes
> + * @return:    -EINVAL on invalid range or out or range id
> + *             -ENODEV if reg is valid but no IMR exists or is locked
> + *             0 on success
> + */
> +int imr_del(int reg, unsigned long base, unsigned long size)
> +{
> +       struct imr imr;
> +       int found = 0, i, ret = 0;
> +       unsigned long  max = base + size;
> +
> +       if (imr_check_range(base, size))
> +               return -EINVAL;
> +
> +       if (reg > imr_dev.num)
> +               return -EINVAL;
> +
> +       mutex_lock(&imr_dev.lock);
> +
> +       /* if a specific IMR is given try to use it */

Use capital letter to start a comment. Check a whole code.

> +       if (reg >= 0) {
> +               ret = imr_read(reg, &imr);
> +               if (ret)
> +                       goto done;
> +
> +               if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
> +                       ret = -ENODEV;
> +                       goto done;
> +               }
> +               found = 1;

You may put a loop to the else branch instead of checking found at
each iteration.

> +       }
> +
> +       /* search for match based on address range */
> +       for (i = 0; i <= imr_dev.num && found == 0; i++) {
> +               ret = imr_read(reg, &imr);
> +               if (ret)
> +                       goto done;
> +
> +               if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK)
> +                       continue;
> +
> +               if ((imr_to_phys(imr.addr_lo) == base) &&
> +                   (imr_to_phys(imr.addr_hi) == max)) {
> +                       reg = i;

> +                       found = 1;
break;

> +               }
> +       }
> +
> +       if (found == 0) {
> +               ret = -ENODEV;
> +               goto done;
> +       }
> +
> +       /* Tear down the IMR */
> +       imr.addr_lo = 0;
> +       imr.addr_hi = 0;
> +       imr.rmask = IMR_READ_ACCESS_ALL;
> +       imr.wmask = IMR_WRITE_ACCESS_ALL;
> +
> +       ret = imr_write(reg, &imr, false);
> +
> +done:
> +       mutex_unlock(&imr_dev.lock);
> +       return ret;
> +}
> +EXPORT_SYMBOL(imr_del);
> +
> +/**
> + * intel_imr_probe
> + * entry point for IMR driver
> + *
> + * return: -ENODEV for no IMR support 0 if good to go
> + */
> +static int __init intel_imr_init(void)
> +{
> +       struct cpuinfo_x86 *c = &cpu_data(cpu);
> +
> +       if (!cpu_has_imr(c))
> +               return -ENODEV;
> +
> +       if (iosf_mbi_available() == false)
> +               return -ENODEV;
> +
> +       if (cpu_is_quark(c)) {
> +               imr_dev.num = QUARK_X1000_IMR_NUM;
> +               imr_dev.reg_base = QUARK_X1000_IMR_REGBASE;
> +       } else {
> +               pr_err("Unknown IMR implementation\n");
> +               return -ENODEV;
> +       }
> +
> +       mutex_init(&imr_dev.lock);
> +
> +       return imr_debugfs_register(&imr_dev);
> +}
> +
> +/**
> + * intel_imr_exit
> + * exit point for IMR code. Deregisters debugfs, leave IMR state as-is.
> + *
> + * return: none
> + */
> +static void __exit intel_imr_exit(void)
> +{
> +       imr_debugfs_unregister(&imr_dev);
> +}
> +
> +module_init(intel_imr_init);
> +module_exit(intel_imr_exit);
> +
> +MODULE_AUTHOR("Bryan O'Donoghue <pure.logic@nexus-software.ie>");
> +MODULE_DESCRIPTION("Intel Isolated Memory Region driver");
> +MODULE_LICENSE("GPL");
> --
> 1.9.1
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

Happy New Year!

-- 
With Best Regards,
Andy Shevchenko

[PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

[Bryan O'Donoghue]

Intel's Quark X1000 SoC contains a set of registers called Isolated Memory
Regions. IMRs are accessed over the IOSF mailbox interface. IMRs are areas
carved out of memory that define read/write access rights to the various
system agents within the Quark system. For a given agent in the system it is
possible to specify if that agent may read or write an area of memory
defined by an IMR with a granularity of 1 kilobyte.

Quark_SecureBootPRM_330234_001.pdf section 4.5 details the concept of IMRs

eSRAM flush, CPU Snoop, CPU SMM Mode, CPU non-SMM mode, PMU and VC0/VC1 can
have individual read/write access masks applied to them for a given memory
region in Quark X1000. Quark supports eightIMR sets.

Since all of the DMA capable SoC components in the X1000 are mapped to VC0
it is possible to define sections of memory as invalid for DMA write
operations originating from Ethernet, USB, SD and any other DMA capable
south-cluster component on VC0. Similarly it is possible to mark kernel
memory as non-SMM mode read/write only or to mark BIOS runtime memory as SMM
mode accessible only depending on the particular memory footprint on a given
system.

On an IMR violation Quark SoC X1000 systems are configured to reset the
system, so ensuring that the IMR memory map agrees with the EFI provided
memory map is critical to ensure no IMR violations reset the system.

The API for accessing IMRs is based on MTRR code but doesn't provide a /proc
or /sys interface to manipulate IMRs. Defining the size and extent of IMRs
is exclusively the domain of in-kernel code.

Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
---
 arch/x86/Kconfig                   |  23 ++
 arch/x86/include/asm/imr.h         |  79 ++++++
 arch/x86/include/asm/intel-quark.h |  31 +++
 arch/x86/kernel/Makefile           |   1 +
 arch/x86/kernel/imr.c              | 529 +++++++++++++++++++++++++++++++++++++
 5 files changed, 663 insertions(+)
 create mode 100644 arch/x86/include/asm/imr.h
 create mode 100644 arch/x86/include/asm/intel-quark.h
 create mode 100644 arch/x86/kernel/imr.c

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ba397bd..8303ca2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -526,6 +526,29 @@ config IOSF_MBI_DEBUG
 
 	  If you don't require the option or are in doubt, say N.
 
+config IMR
+	tristate "Isolated Memory Region support"
+	default m
+	depends on IOSF_MBI
+	---help---
+	  This option enables support for Isolated Memory Regions.
+	  IMRs are a set of registers that define read and write access masks
+	  to prohibit certain system agents from accessing memory with 1k
+	  granularity.
+	  IMRs make it possible to control read/write access to an address
+	  by hardware agents inside the SoC. Read and write masks can be
+	  defined for
+		- SMM mode
+		- Non SMM mode
+		- PCI VC0/VC1
+		- CPU snoop
+		- eSRAM flush
+		- PMU access
+	  Quark contains a set of IMR registers and makes use of those
+	  registers during it's bootup process.
+
+	  If you are running on a Galileo/Quark say Y here
+
 config X86_RDC321X
 	bool "RDC R-321x SoC"
 	depends on X86_32
diff --git a/arch/x86/include/asm/imr.h b/arch/x86/include/asm/imr.h
new file mode 100644
index 0000000..fe8f3b8
--- /dev/null
+++ b/arch/x86/include/asm/imr.h
@@ -0,0 +1,79 @@
+/*
+ * imr.h: Isolated Memory Region API
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+#ifndef _IMR_H
+#define _IMR_H
+
+#include <asm/intel-quark.h>
+#include <linux/types.h>
+
+/*
+ * Right now IMRs are not reported via CPUID though it'd be really great if
+ * future silicon did report via CPUID for this feature bringing it in-line with
+ * other similar features - like MTRRs, MSRs etc.
+ *
+ * A macro is defined here which is an analog to the other cpu_has_x type
+ * features
+ */
+#define cpu_has_imr cpu_is_quark
+
+/* IMR agent access mask bits */
+#define IMR_ESRAM_FLUSH		0x80000000
+#define IMR_CPU_SNOOP		0x40000000
+#define IMR_HB_ACCESS		0x20000000
+#define IMR_VC1_ID3		0x00008000
+#define IMR_VC1_ID2		0x00004000
+#define IMR_VC1_ID1		0x00002000
+#define IMR_VC1_ID0		0x00001000
+#define IMR_VC0_ID3		0x00000800
+#define IMR_VC0_ID2		0x00000400
+#define IMR_VC0_ID1		0x00000200
+#define IMR_VC0_ID0		0x00000100
+#define IMR_SMM			0x00000002
+#define IMR_NON_SMM		0x00000001
+#define IMR_ACCESS_NONE		0x00000000
+
+/* Definition of read/write masks from published BSP code */
+#define IMR_READ_ACCESS_ALL	0xBFFFFFFF
+#define IMR_WRITE_ACCESS_ALL	0xFFFFFFFF
+
+/* Number of IMRs provided by Quark X1000 SoC */
+#define QUARK_X1000_IMR_NUM	0x07
+#define QUARK_X1000_IMR_REGBASE 0x40
+
+/* IMR alignment bits - only bits 31:10 are checked for IMR validity */
+#define IMR_ALIGN		0x400
+#define IMR_MASK		(IMR_ALIGN - 1)
+
+/**
+ * imr_add_range - Add an Isolated Memory Region
+ * @base: Physical base address of region aligned to 4k
+ * @size: Physical size of region in bytes
+ * @read_mask: Read access mask
+ * @write_mask: Write access mask
+ * @lock: Indicates whether or not to permenantly lock this region
+ * @return: Index of the IMR allocated or negative value indicating error
+ */
+int imr_add(unsigned long base, unsigned long size,
+	    unsigned int rmask, unsigned int wmask, bool lock);
+
+/**
+ * imr_del_range - Delete an Isolated Memory Region
+ * @reg: IMR index to remove
+ * @base: Physical base address of region aligned to 4k
+ * @size: Physical size of region in bytes
+ * @return:	-EINVAL on invalid range or out or range id
+ *		-ENODEV if reg is valid but no IMR exists or is locked
+ *		0 on success
+ */
+int imr_del(int reg, unsigned long base, unsigned long size);
+
+#endif /* _IMR_H */
diff --git a/arch/x86/include/asm/intel-quark.h b/arch/x86/include/asm/intel-quark.h
new file mode 100644
index 0000000..f51ac8c
--- /dev/null
+++ b/arch/x86/include/asm/intel-quark.h
@@ -0,0 +1,31 @@
+/*
+ * intel-quark.h: Quark shared defines and helper functions
+ *
+ * Copyright 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#ifndef _ASM_X86_INTEL_QUARK_H
+#define _ASM_X86_INTEL_QUARK_H
+
+#include <asm/processor.h>
+
+#ifdef CONFIG_X86_32
+static inline int cpu_is_quark(const struct cpuinfo_x86 *c)
+{
+	return (c->x86_vendor == X86_VENDOR_INTEL &&
+		c->x86 == 5 && c->x86_model == 9);
+}
+#else
+static inline int cpu_is_quark(const struct cpuinfo_x86 *c)
+{
+	return 0;
+}
+#endif
+
+#endif /* _ASM_X86_INTEL_QUARK_H */
+
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 5d4502c..0252de5 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -104,6 +104,7 @@ obj-$(CONFIG_EFI)			+= sysfb_efi.o
 obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o
 obj-$(CONFIG_TRACING)			+= tracepoint.o
 obj-$(CONFIG_IOSF_MBI)			+= iosf_mbi.o
+obj-$(CONFIG_IMR)			+= imr.o
 obj-$(CONFIG_PMC_ATOM)			+= pmc_atom.o
 
 ###
diff --git a/arch/x86/kernel/imr.c b/arch/x86/kernel/imr.c
new file mode 100644
index 0000000..4115138
--- /dev/null
+++ b/arch/x86/kernel/imr.c
@@ -0,0 +1,529 @@
+/**
+ * intel_imr.c
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@nexus-software.ie>
+ *
+ * IMR registers define an isolated region of memory that can
+ * be masked to prohibit certain system agents from accessing memory.
+ * When a device behind a masked port performs an access - snooped or not, an
+ * IMR may optionally prevent that transaction from changing the state of memory
+ * or from getting correct data in response to the operation.
+ * Write data will be dropped and reads will return 0xFFFFFFFF, the system will
+ * reset and system BIOS will print out an error message to inform the user that
+ * an IMR has been violated.
+ * This code is based on the Linux MTRR code and refernece code from Intel's
+ * Quark BSP EFI, Linux and grub code.
+ */
+#include <asm/intel-quark.h>
+#include <asm/imr.h>
+#include <asm/iosf_mbi.h>
+#include <linux/debugfs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+struct imr_device {
+	struct dentry	*debugfs_dir;
+	struct mutex	lock;
+	int		num;
+	int		used;
+	int		reg_base;
+};
+
+static struct imr_device imr_dev;
+
+/**
+ * Values derived from published code in Quark BSP
+ *
+ * addr_lo
+ * 31		Lock bit
+ * 30		Enable bit - not implemented on Quark X1000
+ * 29:25	Reserved
+ * 24:2		1 kilobyte aligned lo address
+ * 1:0		Reserved
+ *
+ * addr_hi
+ * 31:25	Reserved
+ * 24:2		1 kilobyte aligned hi address
+ * 1:0		Reserved
+ */
+#define IMR_LOCK	0x80000000
+#define IMR_ENABLE	0x04000000
+
+struct imr {
+	u32 addr_lo;
+	u32 addr_hi;
+	u32 rmask;
+	u32 wmask;
+};
+
+#define IMR_NUM_REGS	(sizeof(struct imr)/sizeof(u32))
+#define IMR_SHIFT	8
+#define imr_to_phys(x)	(x << IMR_SHIFT)
+#define phys_to_imr(x)	(x >> IMR_SHIFT)
+
+/**
+ * imr_enabled
+ * Determines if an IMR is enabled based on address range
+ *
+ * @imr:	Pointer to IMR descriptor
+ * @return	true if IMR enabled false if disabled
+ */
+static int imr_enabled(struct imr *imr)
+{
+	return (imr_to_phys(imr->addr_lo) && imr_to_phys(imr->addr_hi));
+}
+
+/**
+ * imr_read
+ * Read an IMR at a given imr index. Requires caller to hold imr mutex
+ *
+ * @imr_id:	IMR entry to read
+ * @imr:	IMR structure representing address and access masks
+ * @return	0 on success or error code passed from mbi_iosf on failure
+ */
+static int imr_read(u32 imr_id, struct imr *imr)
+{
+	u32 reg = imr_dev.reg_base + (imr_id * IMR_NUM_REGS);
+	int ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				reg, &imr->addr_lo);
+	if (ret)
+		return ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				++reg, &imr->addr_hi);
+	if (ret)
+		return ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				++reg, &imr->rmask);
+	if (ret)
+		return ret;
+
+	return iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				++reg, &imr->wmask);
+}
+
+/**
+ * imr_write
+ * Write an IMR at a given imr index. Requires caller to hold imr mutex
+ * Note lock bits need to be written independently of address bits
+ *
+ * @imr_id:	IMR entry to write
+ * @imr:	IMR structure representing address and access masks
+ * @lock:	Indicates if the IMR lock bit should be applied
+ * @return	0 on success or error code passed from mbi_iosf on failure
+ */
+static int imr_write(u32 imr_id, struct imr *imr, bool lock)
+{
+	unsigned long flags;
+	u32 reg = imr_dev.reg_base + (imr_id * IMR_NUM_REGS);
+	u32 reg_lock = reg;
+	int ret;
+
+	local_irq_save(flags);
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE, reg,
+				imr->addr_lo);
+	if (ret)
+		goto done;
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+				++reg, imr->addr_hi);
+	if (ret)
+		goto done;
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+				++reg, imr->rmask);
+	if (ret)
+		goto done;
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+				++reg, imr->wmask);
+	if (ret)
+		goto done;
+
+	/* Lock bit must be set separately to addr_lo address bits */
+	if (lock) {
+		imr->addr_lo |= IMR_LOCK;
+		ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+					reg_lock, imr->addr_lo);
+	}
+
+done:
+	local_irq_restore(flags);
+
+	/*
+	 * If writing to the IOSF failed then we're in an unknown state
+	 * likely a very bad state. An IMR in an invalid state will almost
+	 * certainly lead to a memory access violation.
+	 */
+	if (ret)
+		WARN(1, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n",
+			imr_to_phys(imr->addr_lo),
+			imr_to_phys(imr->addr_hi) + IMR_MASK);
+
+	return ret;
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+/**
+ * imr_dbgfs_state_show
+ * Print state of IMR registers
+ *
+ * @s:		pointer to seq_file for output
+ * @unused:	unused parameter
+ * @return	0 on success or error code passed from mbi_iosf on failure
+ */
+static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
+{
+	int i, ret = -ENODEV;
+	struct imr imr;
+	u32 size;
+
+	mutex_lock(&imr_dev.lock);
+
+	for (i = 0; i <= imr_dev.num; i++) {
+
+		ret = imr_read(i, &imr);
+		if (ret)
+			break;
+
+		/*
+		 * Remember to add IMR_ALIGN bytes to size to indicate the
+		 * inherent IMR_ALIGN size bytes contained in the masked away
+		 * lower ten bits
+		 */
+		size = 0;
+		if (imr_enabled(&imr)) {
+			size = imr_to_phys(imr.addr_hi) -
+			       imr_to_phys(imr.addr_lo);
+			size += IMR_ALIGN;
+		}
+		seq_printf(s, "imr%02i: base=0x%08x, end=0x%08x, size=0x%08x "
+			   "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i,
+			   imr_to_phys(imr.addr_lo),
+			   imr_to_phys(imr.addr_hi) + IMR_MASK, size,
+			   imr.rmask, imr.wmask,
+			   imr_enabled(&imr) ? "enabled " : "disabled",
+			   imr.addr_lo & IMR_LOCK ? "locked" : "unlocked");
+	}
+
+	mutex_unlock(&imr_dev.lock);
+
+	return ret;
+}
+
+/**
+ * imr_state_open
+ * Debugfs open callback
+ *
+ * @inode:	pointer to struct inode
+ * @file:	pointer to struct file
+ * @return	result of single open
+ */
+static int imr_state_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, imr_dbgfs_state_show, inode->i_private);
+}
+
+static const struct file_operations imr_state_ops = {
+	.open		= imr_state_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+/**
+ * imr_debugfs_register
+ * Register debugfs hooks
+ *
+ * @imr:	IMR structure representing address and access masks
+ * @return	0 on success - errno on failure
+ */
+static int imr_debugfs_register(struct imr_device *imr_dev)
+{
+	struct dentry *dir, *f;
+
+	dir = debugfs_create_dir("imr", NULL);
+	if (!dir)
+		return -ENOMEM;
+
+	f = debugfs_create_file("state", S_IFREG | S_IRUGO,
+				dir, imr_dev, &imr_state_ops);
+	if (!f)
+		goto err;
+
+	imr_dev->debugfs_dir = dir;
+
+	return 0;
+err:
+	return -ENODEV;
+}
+
+/**
+ * imr_debugfs_unregister
+ * Unregister debugfs hooks
+ *
+ * @imr:	IMR structure representing address and access masks
+ * @return	none
+ */
+static void imr_debugfs_unregister(struct imr_device *imr_dev)
+{
+	if (!imr_dev->debugfs_dir)
+		return;
+
+	debugfs_remove_recursive(imr_dev->debugfs_dir);
+	imr_dev->debugfs_dir = NULL;
+}
+
+#else
+
+/**
+ * imr_debugfs_register
+ * Register debugfs hooks
+ *
+ * @imr:	IMR structure representing address and access masks
+ * @return	0 on success - errno on failure
+ */
+static int imr_debugfs_register(struct imr_device *imr_dev)
+{
+	return 0;
+}
+
+/**
+ * imr_debugfs_unregister
+ * Dummy hook for !CONFIG_DEBUG_FS
+ *
+ * @imr:	IMR structure representing address and access masks
+ * @return	none
+ */
+static void imr_debugfs_unregister(struct imr_device *imr_dev)
+{
+}
+
+#endif /* CONFIG_DEBUG_FS */
+
+/**
+ * imr_check_range
+ * Check the passed address range for an IMR is aligned
+ *
+ * @base: base address of intended IMR
+ * @size: size of intended IMR
+ * @return zero on valid range -EINVAL on unaligned base/size
+ */
+static int imr_check_range(unsigned long base, unsigned long size)
+{
+	if ((base & (IMR_MASK)) || (size & (IMR_MASK))) {
+		pr_warn("imr: base 0x%08lx size 0x%08lx must align to 1k\n",
+			base, size);
+		dump_stack();
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/**
+ * imr_add_range
+ * Add an Isolated Memory Region
+ *
+ * @base: Physical base address of region aligned to 4k
+ * @size: Physical size of region in bytes
+ * @read_mask: Read access mask
+ * @write_mask: Write access mask
+ * @lock: Indicates whether or not to permenantly lock this region
+ * @return: Index of the IMR allocated or negative value indicating error
+ */
+int imr_add(unsigned long base, unsigned long size,
+	    unsigned int rmask, unsigned int wmask, bool lock)
+{
+	unsigned long end = base + size;
+	struct imr imr;
+	int reg, i, overlap, ret;
+
+	if (imr_check_range(base, size))
+		return -EINVAL;
+
+	if (!size) {
+		pr_warn("imr: invalid size zero!\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&imr_dev.lock);
+
+	/* Find an free IMR while checking for an existing overlapping range */
+	overlap = 0;
+	reg = -1;
+	for (i = 0; i <= imr_dev.num; i++) {
+		ret = imr_read(i, &imr);
+		if (ret)
+			goto done;
+
+		/* Find overlap */
+		if (imr_enabled(&imr)) {
+			if (base >= imr_to_phys(imr.addr_lo) &&
+				base <= imr_to_phys(imr.addr_hi)) {
+				overlap = 1;
+				break;
+			}
+			if (end >= imr_to_phys(imr.addr_lo) &&
+				end <= imr_to_phys(imr.addr_hi)) {
+				overlap = 1;
+				break;
+			}
+		} else {
+			reg = i;
+		}
+	}
+
+	/* Error out if we have an overlap or no free IMR entries */
+	if (overlap) {
+		ret = -EINVAL;
+		goto done;
+	}
+	if (reg == -1) {
+		ret = -ENODEV;
+		goto done;
+	}
+
+	pr_debug("IMR %d phys 0x%08lx-0x%08lx rmask 0x%08x wmask 0x%08x\n",
+		reg, base, end, rmask, wmask);
+
+	/* Allocate IMR */
+	imr.addr_lo = IMR_ENABLE | phys_to_imr(base);
+	imr.addr_hi = phys_to_imr(end);
+	imr.rmask = rmask;
+	imr.wmask = wmask;
+
+	ret = imr_write(reg, &imr, lock);
+
+done:
+	mutex_unlock(&imr_dev.lock);
+	return ret;
+}
+EXPORT_SYMBOL(imr_add);
+
+/**
+ * imr_del_range
+ * Delete an Isolated Memory Region
+ *
+ * @reg: IMR index to remove
+ * @base: Physical base address of region aligned to 4k
+ * @size: Physical size of region in bytes
+ * @return:	-EINVAL on invalid range or out or range id
+ *		-ENODEV if reg is valid but no IMR exists or is locked
+ *		0 on success
+ */
+int imr_del(int reg, unsigned long base, unsigned long size)
+{
+	struct imr imr;
+	int found = 0, i, ret = 0;
+	unsigned long  max = base + size;
+
+	if (imr_check_range(base, size))
+		return -EINVAL;
+
+	if (reg > imr_dev.num)
+		return -EINVAL;
+
+	mutex_lock(&imr_dev.lock);
+
+	/* if a specific IMR is given try to use it */
+	if (reg >= 0) {
+		ret = imr_read(reg, &imr);
+		if (ret)
+			goto done;
+
+		if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
+			ret = -ENODEV;
+			goto done;
+		}
+		found = 1;
+	}
+
+	/* search for match based on address range */
+	for (i = 0; i <= imr_dev.num && found == 0; i++) {
+		ret = imr_read(reg, &imr);
+		if (ret)
+			goto done;
+
+		if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK)
+			continue;
+
+		if ((imr_to_phys(imr.addr_lo) == base) &&
+		    (imr_to_phys(imr.addr_hi) == max)) {
+			found = 1;
+			reg = i;
+		}
+	}
+
+	if (found == 0) {
+		ret = -ENODEV;
+		goto done;
+	}
+
+	/* Tear down the IMR */
+	imr.addr_lo = 0;
+	imr.addr_hi = 0;
+	imr.rmask = IMR_READ_ACCESS_ALL;
+	imr.wmask = IMR_WRITE_ACCESS_ALL;
+
+	ret = imr_write(reg, &imr, false);
+
+done:
+	mutex_unlock(&imr_dev.lock);
+	return ret;
+}
+EXPORT_SYMBOL(imr_del);
+
+/**
+ * intel_imr_probe
+ * entry point for IMR driver
+ *
+ * return: -ENODEV for no IMR support 0 if good to go
+ */
+static int __init intel_imr_init(void)
+{
+	struct cpuinfo_x86 *c = &cpu_data(cpu);
+
+	if (!cpu_has_imr(c))
+		return -ENODEV;
+
+	if (iosf_mbi_available() == false)
+		return -ENODEV;
+
+	if (cpu_is_quark(c)) {
+		imr_dev.num = QUARK_X1000_IMR_NUM;
+		imr_dev.reg_base = QUARK_X1000_IMR_REGBASE;
+	} else {
+		pr_err("Unknown IMR implementation\n");
+		return -ENODEV;
+	}
+
+	mutex_init(&imr_dev.lock);
+
+	return imr_debugfs_register(&imr_dev);
+}
+
+/**
+ * intel_imr_exit
+ * exit point for IMR code. Deregisters debugfs, leave IMR state as-is.
+ *
+ * return: none
+ */
+static void __exit intel_imr_exit(void)
+{
+	imr_debugfs_unregister(&imr_dev);
+}
+
+module_init(intel_imr_init);
+module_exit(intel_imr_exit);
+
+MODULE_AUTHOR("Bryan O'Donoghue <pure.logic@nexus-software.ie>");
+MODULE_DESCRIPTION("Intel Isolated Memory Region driver");
+MODULE_LICENSE("GPL");
-- 
1.9.1