From 40e0e7843e23d164625b9031514f5672f8758bf4 Mon Sep 17 00:00:00 2001 From: Tony Luck Date: Tue, 26 Oct 2021 15:00:45 -0700 Subject: [PATCH] x86/sgx: Add infrastructure to identify SGX EPC pages X86 machine check architecture reports a physical address when there is a memory error. Handling that error requires a method to determine whether the physical address reported is in any of the areas reserved for EPC pages by BIOS. SGX EPC pages do not have Linux "struct page" associated with them. Keep track of the mapping from ranges of EPC pages to the sections that contain them using an xarray. N.B. adds CONFIG_XARRAY_MULTI to the SGX dependecies. So "select" that in arch/x86/Kconfig for X86/SGX. Create a function arch_is_platform_page() that simply reports whether an address is an EPC page for use elsewhere in the kernel. The ACPI error injection code needs this function and is typically built as a module, so export it. Note that arch_is_platform_page() will be slower than other similar "what type is this page" functions that can simply check bits in the "struct page". If there is some future performance critical user of this function it may need to be implemented in a more efficient way. Note also that the current implementation of xarray allocates a few hundred kilobytes for this usage on a system with 4GB of SGX EPC memory configured. This isn't ideal, but worth it for the code simplicity. Signed-off-by: Tony Luck Signed-off-by: Dave Hansen Reviewed-by: Jarkko Sakkinen Tested-by: Reinette Chatre Link: https://lkml.kernel.org/r/20211026220050.697075-3-tony.luck@intel.com --- arch/x86/Kconfig | 1 + arch/x86/kernel/cpu/sgx/main.c | 9 +++++++++ 2 files changed, 10 insertions(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 95dd1ee01546..b9281fab4e3e 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1917,6 +1917,7 @@ config X86_SGX select SRCU select MMU_NOTIFIER select NUMA_KEEP_MEMINFO if NUMA + select XARRAY_MULTI help Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions that can be used by applications to set aside private regions of code diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 825aa91516c8..5c02cffdabc8 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -20,6 +20,7 @@ struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS]; static int sgx_nr_epc_sections; static struct task_struct *ksgxd_tsk; static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq); +static DEFINE_XARRAY(sgx_epc_address_space); /* * These variables are part of the state of the reclaimer, and must be accessed @@ -650,6 +651,8 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, } section->phys_addr = phys_addr; + xa_store_range(&sgx_epc_address_space, section->phys_addr, + phys_addr + size - 1, section, GFP_KERNEL); for (i = 0; i < nr_pages; i++) { section->pages[i].section = index; @@ -661,6 +664,12 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, return true; } +bool arch_is_platform_page(u64 paddr) +{ + return !!xa_load(&sgx_epc_address_space, paddr); +} +EXPORT_SYMBOL_GPL(arch_is_platform_page); + /** * A section metric is concatenated in a way that @low bits 12-31 define the * bits 12-31 of the metric and @high bits 0-19 define the bits 32-51 of the -- 2.34.1