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// QEMU multi-CPU initialization code
//
// Copyright (C) 2008 Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2006 Fabrice Bellard
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
#include "config.h" // CONFIG_*
#include "hw/rtc.h" // CMOS_BIOS_SMP_COUNT
#include "output.h" // dprintf
#include "romfile.h" // romfile_loadint
#include "stacks.h" // yield
#include "util.h" // smp_setup, msr_feature_control_setup
#include "x86.h" // wrmsr
#include "paravirt.h" // qemu_*_present_cpus_count
#define APIC_ICR_LOW ((u8*)BUILD_APIC_ADDR + 0x300)
#define APIC_SVR ((u8*)BUILD_APIC_ADDR + 0x0F0)
#define APIC_LINT0 ((u8*)BUILD_APIC_ADDR + 0x350)
#define APIC_LINT1 ((u8*)BUILD_APIC_ADDR + 0x360)
#define APIC_ENABLED 0x0100
#define MSR_IA32_APIC_BASE 0x01B
#define MSR_LOCAL_APIC_ID 0x802
#define MSR_IA32_APICBASE_EXTD (1ULL << 10) /* Enable x2APIC mode */
static struct { u32 index; u64 val; } smp_msr[32];
static u32 smp_msr_count;
void
wrmsr_smp(u32 index, u64 val)
{
wrmsr(index, val);
if (smp_msr_count >= ARRAY_SIZE(smp_msr)) {
warn_noalloc();
return;
}
smp_msr[smp_msr_count].index = index;
smp_msr[smp_msr_count].val = val;
smp_msr_count++;
}
static void
smp_write_msrs(void)
{
// MTRR and MSR_IA32_FEATURE_CONTROL setup
int i;
for (i=0; i<smp_msr_count; i++)
wrmsr(smp_msr[i].index, smp_msr[i].val);
}
u32 MaxCountCPUs;
static u32 CountCPUs;
// 256 bits for the found APIC IDs
static u32 FoundAPICIDs[256/32];
int apic_id_is_present(u8 apic_id)
{
return !!(FoundAPICIDs[apic_id/32] & (1ul << (apic_id % 32)));
}
static int
apic_id_init(void)
{
u32 eax, ebx, ecx, cpuid_features;
cpuid(1, &eax, &ebx, &ecx, &cpuid_features);
u32 apic_id = ebx>>24;
if (MaxCountCPUs < 256) { // xAPIC mode
// Track found apic id for use in legacy internal bios tables
FoundAPICIDs[apic_id/32] |= 1 << (apic_id % 32);
} else if (ecx & CPUID_X2APIC) {
// switch to x2APIC mode
u64 apic_base = rdmsr(MSR_IA32_APIC_BASE);
wrmsr(MSR_IA32_APIC_BASE, apic_base | MSR_IA32_APICBASE_EXTD);
apic_id = rdmsr(MSR_LOCAL_APIC_ID);
} else {
// x2APIC is masked by CPUID
apic_id = -1;
}
return apic_id;
}
void VISIBLE32FLAT
handle_smp(void)
{
if (!CONFIG_QEMU)
return;
// Track this CPU and detect the apic_id
int apic_id = apic_id_init();
dprintf(DEBUG_HDL_smp, "handle_smp: apic_id=0x%x\n", apic_id);
smp_write_msrs();
CountCPUs++;
}
// Atomic lock for shared stack across processors.
u32 SMPLock __VISIBLE;
u32 SMPStack __VISIBLE;
// find and initialize the CPUs by launching a SIPI to them
static void
smp_scan(void)
{
ASSERT32FLAT();
u32 eax, ebx, ecx, cpuid_features;
cpuid(1, &eax, &ebx, &ecx, &cpuid_features);
if (eax < 1 || !(cpuid_features & CPUID_APIC)) {
// No apic - only the main cpu is present.
dprintf(1, "No apic - only the main cpu is present.\n");
CountCPUs= 1;
return;
}
// mark the BSP initial APIC ID as found, too:
CountCPUs = 1;
// Setup jump trampoline to counter code.
u64 old = *(u64*)BUILD_AP_BOOT_ADDR;
// ljmpw $SEG_BIOS, $(entry_smp - BUILD_BIOS_ADDR)
extern void entry_smp(void);
u64 new = (0xea | ((u64)SEG_BIOS<<24)
| (((u32)entry_smp - BUILD_BIOS_ADDR) << 8));
*(u64*)BUILD_AP_BOOT_ADDR = new;
// enable local APIC
u32 val = readl(APIC_SVR);
writel(APIC_SVR, val | APIC_ENABLED);
/* Set LINT0 as Ext_INT, level triggered */
writel(APIC_LINT0, 0x8700);
/* Set LINT1 as NMI, level triggered */
writel(APIC_LINT1, 0x8400);
// Init the lock.
writel(&SMPLock, 1);
// broadcast SIPI
barrier();
writel(APIC_ICR_LOW, 0x000C4500);
u32 sipi_vector = BUILD_AP_BOOT_ADDR >> 12;
writel(APIC_ICR_LOW, 0x000C4600 | sipi_vector);
// switch to x2APIC mode after sending SIPI so that
// x2APIC and xAPIC mode could share AP wake up code
apic_id_init();
// Wait for other CPUs to process the SIPI.
u16 expected_cpus_count = qemu_get_present_cpus_count();
while (expected_cpus_count != CountCPUs)
asm volatile(
// Release lock and allow other processors to use the stack.
" movl %%esp, %1\n"
" movl $0, %0\n"
// Reacquire lock and take back ownership of stack.
"1:rep ; nop\n"
" lock btsl $0, %0\n"
" jc 1b\n"
: "+m" (SMPLock), "+m" (SMPStack)
: : "cc", "memory");
yield();
// Restore memory.
*(u64*)BUILD_AP_BOOT_ADDR = old;
dprintf(1, "Found %d cpu(s) max supported %d cpu(s)\n", CountCPUs,
MaxCountCPUs);
}
void
smp_setup(void)
{
if (!CONFIG_QEMU)
return;
MaxCountCPUs = romfile_loadint("etc/max-cpus", 0);
u16 smp_count = qemu_get_present_cpus_count();
if (MaxCountCPUs < smp_count)
MaxCountCPUs = smp_count;
smp_scan();
}
void
smp_resume(void)
{
if (!CONFIG_QEMU)
return;
smp_write_msrs();
smp_scan();
}
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