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Subject[PATCH 29/62] x86/head/64: Load IDT earlier
Date
From: Joerg Roedel <jroedel@suse.de>

Load the IDT right after switching to virtual addresses in head_64.S
so that the kernel can handle #VC exceptions.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/include/asm/desc.h | 1 +
arch/x86/kernel/head64.c | 7 +++++++
arch/x86/kernel/head_64.S | 17 +++++++++++++++++
arch/x86/kernel/idt.c | 22 ++++++++++++++++++++++
4 files changed, 47 insertions(+)

diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index 68a99d2a5f33..8a4c642ee2b3 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -440,6 +440,7 @@ extern void idt_setup_apic_and_irq_gates(void);
extern void idt_setup_early_pf(void);
extern void idt_setup_ist_traps(void);
extern void idt_setup_debugidt_traps(void);
+extern void setup_early_handlers(gate_desc *idt);
#else
static inline void idt_setup_early_pf(void) { }
static inline void idt_setup_ist_traps(void) { }
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 206a4b6144c2..7cdfb7113811 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -489,3 +489,10 @@ void __init x86_64_start_reservations(char *real_mode_data)

start_kernel();
}
+
+void __head early_idt_setup_early_handler(unsigned long physaddr)
+{
+ gate_desc *idt = fixup_pointer(idt_table, physaddr);
+
+ setup_early_handlers(idt);
+}
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index eefd6838b895..0af79f783659 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -98,6 +98,20 @@ SYM_CODE_START_NOALIGN(startup_64)
leaq _text(%rip), %rdi
pushq %rsi
call __startup_64
+ /* Save return value */
+ pushq %rax
+
+ /*
+ * Load IDT with early handlers - needed for SEV-ES
+ * Do this here because this must only happen on the boot CPU
+ * and the code below is shared with secondary CPU bringup.
+ */
+ leaq _text(%rip), %rdi
+ call early_idt_setup_early_handler
+
+ /* Restore __startup_64 return value*/
+ popq %rax
+ /* Restore pointer to real_mode_data */
popq %rsi

/* Form the CR3 value being sure to include the CR3 modifier */
@@ -194,6 +208,9 @@ SYM_CODE_START(secondary_startup_64)
*/
movq initial_stack(%rip), %rsp

+ /* Load IDT */
+ lidt idt_descr(%rip)
+
/* Check if nx is implemented */
movl $0x80000001, %eax
cpuid
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index 7d8fa631dca9..84250c090596 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -347,6 +347,28 @@ void __init idt_setup_early_handler(void)
load_idt(&idt_descr);
}

+#ifdef CONFIG_X86_64
+/*
+ * This function does the same as idt_setup_early_handler(), but is
+ * called directly from head_64.S before the kernel switches to virtual
+ * addresses. PV-ops don't work at that point, so set_intr_gate() can't
+ * be used here.
+ */
+void __init setup_early_handlers(gate_desc *idt)
+{
+ int i;
+
+ for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
+ struct idt_data data;
+ gate_desc desc;
+
+ init_idt_data(&data, i, early_idt_handler_array[i]);
+ idt_init_desc(&desc, &data);
+ native_write_idt_entry(idt, i, &desc);
+ }
+}
+#endif
+
/**
* idt_invalidate - Invalidate interrupt descriptor table
* @addr: The virtual address of the 'invalid' IDT
--
2.17.1
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