[RFC PATCH 2/7] x86/entry: Add IST main stack

[Lai Jiangshan <jiangshanlai@gmail.com>]

From: Lai Jiangshan <jiangshan.ljs@antgroup.com>

Add IST main stack for atomic-IST-entry.

The size is THREAD_SIZE since there might be multiple super
exceptions being handled on the stack.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
 Documentation/x86/kernel-stacks.rst   | 2 ++
 arch/x86/include/asm/cpu_entry_area.h | 5 +++++
 arch/x86/kernel/dumpstack_64.c        | 6 ++++--
 arch/x86/mm/cpu_entry_area.c          | 1 +
 4 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/Documentation/x86/kernel-stacks.rst b/Documentation/x86/kernel-stacks.rst
index 6b0bcf027ff1..be89acf302da 100644
--- a/Documentation/x86/kernel-stacks.rst
+++ b/Documentation/x86/kernel-stacks.rst
@@ -105,6 +105,8 @@ The currently assigned IST stacks are:
   middle of switching stacks.  Using IST for MCE events avoids making
   assumptions about the previous state of the kernel stack.
 
+* ESTACK_IST. bla bla
+
 For more details see the Intel IA32 or AMD AMD64 architecture manuals.
 
 
diff --git a/arch/x86/include/asm/cpu_entry_area.h b/arch/x86/include/asm/cpu_entry_area.h
index 462fc34f1317..a373e8c37e25 100644
--- a/arch/x86/include/asm/cpu_entry_area.h
+++ b/arch/x86/include/asm/cpu_entry_area.h
@@ -10,6 +10,8 @@
 
 #ifdef CONFIG_X86_64
 
+#define IST_MAIN_STKSZ	THREAD_SIZE
+
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 #define VC_EXCEPTION_STKSZ	EXCEPTION_STKSZ
 #else
@@ -30,6 +32,8 @@
 	char	VC_stack[optional_stack_size];			\
 	char	VC2_stack_guard[guardsize];			\
 	char	VC2_stack[optional_stack_size];			\
+	char	IST_stack_guard[guardsize];			\
+	char	IST_stack[IST_MAIN_STKSZ];			\
 	char	IST_top_guard[guardsize];			\
 
 /* The exception stacks' physical storage. No guard pages required */
@@ -52,6 +56,7 @@ enum exception_stack_ordering {
 	ESTACK_MCE,
 	ESTACK_VC,
 	ESTACK_VC2,
+	ESTACK_IST,
 	N_EXCEPTION_STACKS
 };
 
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index f05339fee778..3413b23fa9f1 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -26,11 +26,12 @@ static const char * const exception_stack_names[] = {
 		[ ESTACK_MCE	]	= "#MC",
 		[ ESTACK_VC	]	= "#VC",
 		[ ESTACK_VC2	]	= "#VC2",
+		[ ESTACK_IST	]	= "#IST",
 };
 
 const char *stack_type_name(enum stack_type type)
 {
-	BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
+	BUILD_BUG_ON(N_EXCEPTION_STACKS != ARRAY_SIZE(exception_stack_names));
 
 	if (type == STACK_TYPE_TASK)
 		return "TASK";
@@ -89,6 +90,7 @@ struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = {
 	EPAGERANGE(MCE),
 	EPAGERANGE(VC),
 	EPAGERANGE(VC2),
+	EPAGERANGE(IST),
 };
 
 static __always_inline bool in_exception_stack(unsigned long *stack, struct stack_info *info)
@@ -98,7 +100,7 @@ static __always_inline bool in_exception_stack(unsigned long *stack, struct stac
 	struct pt_regs *regs;
 	unsigned int k;
 
-	BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
+	BUILD_BUG_ON(N_EXCEPTION_STACKS != 7);
 
 	begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
 	/*
diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c
index 7316a8224259..62341cb819ab 100644
--- a/arch/x86/mm/cpu_entry_area.c
+++ b/arch/x86/mm/cpu_entry_area.c
@@ -148,6 +148,7 @@ static void __init percpu_setup_exception_stacks(unsigned int cpu)
 	cea_map_stack(NMI);
 	cea_map_stack(DB);
 	cea_map_stack(MCE);
+	cea_map_stack(IST);
 
 	if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
 		if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) {
-- 
2.19.1.6.gb485710b