linux-kernel - [tip: x86/seves] x86/smpboot: Load TSS and getcpu GDT entry before loading IDT

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Date:   Thu, 10 Sep 2020 09:22:04 -0000
From:   "tip-bot2 for Joerg Roedel" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Joerg Roedel <jroedel@...e.de>, Borislav Petkov <bp@...e.de>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
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@...e.de>
AuthorDate:    Mon, 07 Sep 2020 15:16:08 +02:00
Committer:     Borislav Petkov <bp@...e.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@...e.de>
Signed-off-by: Borislav Petkov <bp@...e.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();