[kvm-unit-tests,7/9] x86: Move load_gdt_tss() to desc.c

Commit Message

Varad Gautam April 8, 2022, 10:31 a.m. UTC

Split load_gdt_tss() functionality into:
1. Load gdt/tss.
2. Setup segments in 64-bit mode.
3. Update cs segment via far-return.

and move load_gdt_tss() to desc.c to share this code between
EFI and non-EFI tests.

Signed-off-by: Varad Gautam <[e-mail]>
---
 lib/x86/desc.c       |  6 ++++++
 lib/x86/desc.h       |  1 +
 lib/x86/setup.c      |  9 ++++++++-
 x86/efi/efistart64.S | 22 +++++++++++++---------
 4 files changed, 28 insertions(+), 10 deletions(-)

Patch

diff --git a/lib/x86/desc.c b/lib/x86/desc.c
index 713ad0b..d627a22 100644
--- a/lib/x86/desc.c
+++ b/lib/x86/desc.c
@@ -370,6 +370,12 @@  void set_gdt_entry(int sel, unsigned long base,  u32 limit, u8 type, u8 flags)
 #endif
 }
 
+void load_gdt_tss(size_t tss_offset)
+{
+	lgdt(&gdt_descr);
+	ltr(tss_offset);
+}
+
 #ifndef __x86_64__
 void set_gdt_task_gate(u16 sel, u16 tss_sel)
 {
diff --git a/lib/x86/desc.h b/lib/x86/desc.h
index 5eb21e4..30a0c90 100644
--- a/lib/x86/desc.h
+++ b/lib/x86/desc.h
@@ -222,6 +222,7 @@  void set_idt_entry(int vec, void *addr, int dpl);
 void set_idt_sel(int vec, u16 sel);
 void set_idt_dpl(int vec, u16 dpl);
 void set_gdt_entry(int sel, unsigned long base, u32 limit, u8 access, u8 gran);
+void load_gdt_tss(size_t tss_offset);
 void set_intr_alt_stack(int e, void *fn);
 void print_current_tss_info(void);
 handler handle_exception(u8 v, handler fn);
diff --git a/lib/x86/setup.c b/lib/x86/setup.c
index 3f3b1e2..e5a690a 100644
--- a/lib/x86/setup.c
+++ b/lib/x86/setup.c
@@ -170,7 +170,9 @@  void setup_multiboot(struct mbi_bootinfo *bi)
 #ifdef CONFIG_EFI
 
 /* From x86/efi/efistart64.S */
-extern void load_gdt_tss(size_t tss_offset);
+extern void update_cs(void);
+extern void setup_segments64(u64 gs_base);
+extern u8 stacktop;
 
 static efi_status_t setup_memory_allocator(efi_bootinfo_t *efi_bootinfo)
 {
@@ -271,10 +273,15 @@  static void setup_page_table(void)
 static void setup_gdt_tss(void)
 {
 	size_t tss_offset;
+	u64 gs_base;
 
 	/* 64-bit setup_tss does not use the stacktop argument.  */
 	tss_offset = setup_tss(NULL);
 	load_gdt_tss(tss_offset);
+
+	update_cs();
+	gs_base = (u64)(&stacktop) - (PAGE_SIZE * (apic_id() + 1));
+	setup_segments64(gs_base);
 }
 
 efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
diff --git a/x86/efi/efistart64.S b/x86/efi/efistart64.S
index 7e924dc..c8fd3a2 100644
--- a/x86/efi/efistart64.S
+++ b/x86/efi/efistart64.S
@@ -37,15 +37,8 @@  ptl4:
 .code64
 .text
 
-.globl load_gdt_tss
-load_gdt_tss:
-	/* Load GDT */
-	lgdt gdt_descr(%rip)
-
-	/* Load TSS */
-	mov %rdi, %rax
-	ltr %ax
-
+.globl setup_segments64
+setup_segments64:
 	/* Update data segments */
 	mov $0x10, %ax /* 3rd entry in gdt64: 32/64-bit data segment */
 	mov %ax, %ds
@@ -54,6 +47,17 @@  load_gdt_tss:
 	mov %ax, %gs
 	mov %ax, %ss
 
+	/* Setup percpu base */
+	MSR_GS_BASE = 0xc0000101
+	mov %rdi, %rax
+	mov $0, %edx
+	mov $MSR_GS_BASE, %ecx
+	wrmsr
+
+	ret
+
+.globl update_cs
+update_cs:
 	/*
 	 * Update the code segment by putting it on the stack before the return
 	 * address, then doing a far return: this will use the new code segment