[PATCH 34/70] x86/head/64: Load IDT earlier

Joerg Roedel
2020-03-19T09:14:52Z

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/kernel/head64.c | 15 +++++++++++++++
arch/x86/kernel/head_64.S | 17 +++++++++++++++++
2 files changed, 32 insertions(+)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 206a4b6144c2..0ecdf28291fc 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -489,3 +489,18 @@ 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);
+ 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);
+ }
+}
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index b8ba72f31be9..8465290a1eb3 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -104,6 +104,20 @@ 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 */
@@ -200,6 +214,9 @@ 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
--
2.17.1