[kvm-unit-tests,1/9] x86: Move ap_init() to smp.c

Commit Message

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

ap_init() copies the SIPI vector to lowmem, sends INIT/SIPI to APs
and waits on the APs to come up.

Port this routine to C from asm and move it to smp.c to allow sharing
this functionality between the EFI (-fPIC) and non-EFI builds.

Call ap_init() from the EFI setup path to reset the APs to a known
location.

Signed-off-by: Varad Gautam <[e-mail]>
---
 lib/x86/setup.c      |  1 +
 lib/x86/smp.c        | 28 ++++++++++++++++++++++++++--
 lib/x86/smp.h        |  1 +
 x86/cstart64.S       | 20 ++------------------
 x86/efi/efistart64.S |  9 +++++++++
 5 files changed, 39 insertions(+), 20 deletions(-)

Patch

diff --git a/lib/x86/setup.c b/lib/x86/setup.c
index 0044b64..8be39cb 100644
--- a/lib/x86/setup.c
+++ b/lib/x86/setup.c
@@ -323,6 +323,7 @@  efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
 	load_idt();
 	mask_pic_interrupts();
 	enable_apic();
+	ap_init();
 	enable_x2apic();
 	smp_init();
 	setup_page_table();
diff --git a/lib/x86/smp.c b/lib/x86/smp.c
index 2ac0ef7..1a68557 100644
--- a/lib/x86/smp.c
+++ b/lib/x86/smp.c
@@ -18,6 +18,9 @@  static volatile int ipi_done;
 static volatile bool ipi_wait;
 static int _cpu_count;
 static atomic_t active_cpus;
+extern u8 sipi_entry;
+extern u8 sipi_end;
+volatile unsigned cpu_online_count = 1;
 
 static __attribute__((used)) void ipi(void)
 {
@@ -118,8 +121,6 @@  void smp_init(void)
     int i;
     void ipi_entry(void);
 
-    _cpu_count = fwcfg_get_nb_cpus();
-
     setup_idt();
     init_apic_map();
     set_idt_entry(IPI_VECTOR, ipi_entry, 0);
@@ -146,3 +147,26 @@  void smp_reset_apic(void)
 
     atomic_inc(&active_cpus);
 }
+
+void ap_init(void)
+{
+    u8 *dst_addr = 0;
+    size_t sipi_sz = (&sipi_end - &sipi_entry) + 1;
+
+    asm volatile("cld");
+
+    /* Relocate SIPI vector to dst_addr so it can run in 16-bit mode. */
+    memcpy(dst_addr, &sipi_entry, sipi_sz);
+
+    /* INIT */
+    apic_icr_write(APIC_DEST_ALLBUT | APIC_DEST_PHYSICAL | APIC_DM_INIT | APIC_INT_ASSERT, 0);
+
+    /* SIPI */
+    apic_icr_write(APIC_DEST_ALLBUT | APIC_DEST_PHYSICAL | APIC_DM_STARTUP, 0);
+
+    _cpu_count = fwcfg_get_nb_cpus();
+
+    while (_cpu_count != cpu_online_count) {
+        ;
+    }
+}
diff --git a/lib/x86/smp.h b/lib/x86/smp.h
index f74845e..40255c3 100644
--- a/lib/x86/smp.h
+++ b/lib/x86/smp.h
@@ -11,5 +11,6 @@  void on_cpu(int cpu, void (*function)(void *data), void *data);
 void on_cpu_async(int cpu, void (*function)(void *data), void *data);
 void on_cpus(void (*function)(void *data), void *data);
 void smp_reset_apic(void);
+void ap_init(void);
 
 #endif
diff --git a/x86/cstart64.S b/x86/cstart64.S
index 238cebf..06daa7c 100644
--- a/x86/cstart64.S
+++ b/x86/cstart64.S
@@ -160,6 +160,7 @@  gdt32:
 gdt32_end:
 
 .code16
+.globl sipi_entry
 sipi_entry:
 	mov %cr0, %eax
 	or $1, %eax
@@ -171,6 +172,7 @@  gdt32_descr:
 	.word gdt32_end - gdt32 - 1
 	.long gdt32
 
+.globl sipi_end
 sipi_end:
 
 .code32
@@ -249,21 +251,3 @@  lvl5:
 
 online_cpus:
 	.fill (max_cpus + 7) / 8, 1, 0
-
-ap_init:
-	cld
-	lea sipi_entry, %rsi
-	xor %rdi, %rdi
-	mov $(sipi_end - sipi_entry), %rcx
-	rep movsb
-	mov $APIC_DEFAULT_PHYS_BASE, %eax
-	movl $(APIC_DEST_ALLBUT | APIC_DEST_PHYSICAL | APIC_DM_INIT | APIC_INT_ASSERT), APIC_ICR(%rax)
-	movl $(APIC_DEST_ALLBUT | APIC_DEST_PHYSICAL | APIC_DM_STARTUP), APIC_ICR(%rax)
-	call fwcfg_get_nb_cpus
-1:	pause
-	cmpw %ax, cpu_online_count
-	jne 1b
-	ret
-
-.align 2
-cpu_online_count:	.word 1
diff --git a/x86/efi/efistart64.S b/x86/efi/efistart64.S
index 017abba..0425153 100644
--- a/x86/efi/efistart64.S
+++ b/x86/efi/efistart64.S
@@ -57,3 +57,12 @@  load_gdt_tss:
 	pushq $0x08 /* 2nd entry in gdt64: 64-bit code segment */
 	pushq %rdi
 	lretq
+
+.code16
+
+.globl sipi_entry
+sipi_entry:
+	jmp sipi_entry
+
+.globl sipi_end
+sipi_end: