[PATCH v7 67/72] x86/smpboot: Load TSS and getcpu GDT entry before loading IDT

Joerg Roedel
2020-09-07T13:16:08Z

The IDT on 64bit contains vectors which use paranoid_entry() and/or IST
stacks. To make these vectors work the TSS and the getcpu GDT entry need
to be set up before the IDT is loaded.

Signed-off-by: Joerg Roedel <jroedel at suse.de>
---
 arch/x86/include/asm/processor.h |  1 +
 arch/x86/kernel/cpu/common.c     | 23 +++++++++++++++++++++++
 arch/x86/kernel/smpboot.c        |  2 +-
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index d8a82e650810..5ac507586769 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -696,6 +696,7 @@ extern void load_direct_gdt(int);
 extern void load_fixmap_gdt(int);
 extern void load_percpu_segment(int);
 extern void cpu_init(void);
+extern void cpu_init_exception_handling(void);
 extern void cr4_init(void);

 static inline unsigned long get_debugctlmsr(void)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 1d65365363a1..a9527c0c38fb 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1854,6 +1854,29 @@ static inline void tss_setup_io_bitmap(struct tss_struct
*tss)
 #endif
 }

+/*
+ * Setup everything needed to handle exceptions from the IDT, including the IST
+ * exceptions which use paranoid_entry()
+ */
+void cpu_init_exception_handling(void)
+{
+	struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw);
+	int cpu = raw_smp_processor_id();
+
+	/* paranoid_entry() gets the CPU number from the GDT */
+	setup_getcpu(cpu);
+
+	/* IST vectors need TSS to be set up. */
+	tss_setup_ist(tss);
+	tss_setup_io_bitmap(tss);
+	set_tss_desc(cpu, &get_cpu_entry_area(cpu)->tss.x86_tss);
+
+	load_TR_desc();
+
+	/* Finally load the IDT */
+	load_current_idt();
+}
+
 /*
  * cpu_init() initializes state that is per-CPU. Some data is already
  * initialized (naturally) in the bootstrap process, such as the GDT
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index f5ef689dd62a..de776b2e6046 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -227,7 +227,7 @@ static void notrace start_secondary(void *unused)
 	load_cr3(swapper_pg_dir);
 	__flush_tlb_all();
 #endif
-	load_current_idt();
+	cpu_init_exception_handling();
 	cpu_init();
 	x86_cpuinit.early_percpu_clock_init();
 	preempt_disable();
--
2.28.0