From 28a375df16c2b6d01227541f3956568995aa5fda Mon Sep 17 00:00:00 2001 From: Bryan O'Donoghue Date: Fri, 30 Jan 2015 16:29:38 +0000 Subject: x86/intel/quark: Add Isolated Memory Regions for Quark X1000 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. Tested-by: Ong, Boon Leong Signed-off-by: Bryan O'Donoghue Reviewed-by: Andy Shevchenko Reviewed-by: Darren Hart Reviewed-by: Ong, Boon Leong Cc: andy.shevchenko@gmail.com Cc: dvhart@infradead.org Link: http://lkml.kernel.org/r/1422635379-12476-2-git-send-email-pure.logic@nexus-software.ie Signed-off-by: Ingo Molnar --- drivers/platform/x86/Kconfig | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'drivers/platform') diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig index 638e797037da..97527614141b 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 -- cgit v1.2.2