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Subject[tip: x86/seves] x86/smpboot: Load TSS and getcpu GDT entry before loading IDT
The following commit has been merged into the x86/seves branch of tip:

Commit-ID: 520d030852b4c9babfce9a79d8b5320b6b5545e6
Gitweb: https://git.kernel.org/tip/520d030852b4c9babfce9a79d8b5320b6b5545e6
Author: Joerg Roedel <jroedel@suse.de>
AuthorDate: Mon, 07 Sep 2020 15:16:08 +02:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Wed, 09 Sep 2020 11:33:20 +02:00

x86/smpboot: Load TSS and getcpu GDT entry before loading IDT

The IDT on 64-bit 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@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-68-joro@8bytes.org
---
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 97143d8..615dd44 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 81fba4d..beffea2 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1863,6 +1863,29 @@ static inline void tss_setup_io_bitmap(struct tss_struct *tss)
}

/*
+ * 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
* and IDT. We reload them nevertheless, this function acts as a
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index f5ef689..de776b2 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();
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