diff options
Diffstat (limited to 'sys/arch/amd64')
| -rw-r--r-- | sys/arch/amd64/cpu/cpu.c | 2 | ||||
| -rw-r--r-- | sys/arch/amd64/cpu/lapic.c | 187 |
2 files changed, 189 insertions, 0 deletions
diff --git a/sys/arch/amd64/cpu/cpu.c b/sys/arch/amd64/cpu/cpu.c index 942f5b3..9047064 100644 --- a/sys/arch/amd64/cpu/cpu.c +++ b/sys/arch/amd64/cpu/cpu.c @@ -32,6 +32,7 @@ #include <os/trace.h> #include <mu/cpu.h> #include <md/msr.h> +#include <md/lapic.h> struct cpu_info * cpu_self(void) @@ -49,4 +50,5 @@ void cpu_conf(struct cpu_info *ci) { wrmsr(IA32_GS_BASE, (uintptr_t)ci); + lapic_init(); } diff --git a/sys/arch/amd64/cpu/lapic.c b/sys/arch/amd64/cpu/lapic.c new file mode 100644 index 0000000..22d07a9 --- /dev/null +++ b/sys/arch/amd64/cpu/lapic.c @@ -0,0 +1,187 @@ +/* + * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of Hyra nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include <sys/cdefs.h> +#include <sys/param.h> +#include <sys/types.h> +#include <acpi/acpi.h> +#include <acpi/tables.h> +#include <kern/panic.h> +#include <os/mmio.h> +#include <os/trace.h> +#include <vm/vm.h> +#include <lib/stdbool.h> +#include <mu/cpu.h> +#include <md/lapic.h> +#include <md/cpuid.h> +#include <md/msr.h> + +#define dtrace(fmt, ...) trace("lapic: " fmt, ##__VA_ARGS__) + +/* IA32_APIC_BASE MSR bits */ +#define LAPIC_GLOBAL_EN BIT(11) +#define LAPIC_X2APIC_EN BIT(10) + +/* + * Register offsets + * + * See section 2.3.2 of the x2APIC specification + */ +#define LAPIC_REG_ID 0x0020 /* ID register */ +#define LAPIC_REG_SVR 0x00F0 /* Spurious vector register */ + +/* LAPIC SVR bits */ +#define LAPIC_SVR_EBS BIT(12) /* EOI-broadcast supression */ +#define LAPIC_SVR_FPC BIT(9) /* Focus processor checking */ +#define LAPIC_SVR_APIC_EN BIT(8) /* Software-enable Local APIC */ + +/* Accessed via RDMSR/WRMSR */ +#define X2APIC_MSR_BASE 0x00000800 + +static struct acpi_madt *madt; + +/* + * Read from a local APIC register + */ +static uint64_t +lapic_read(struct mcb *mcb, uint32_t reg) +{ + uint32_t *xapic_base; + + if (mcb->has_x2apic) { + return rdmsr(X2APIC_MSR_BASE + (reg >> 4)); + } + + xapic_base = PTR_OFFSET(mcb->xapic_io, reg); + return mmio_read32(xapic_base); +} + +/* + * Write to a Local APIC register + */ +static void +lapic_write(struct mcb *mcb, uint16_t reg, uint64_t val) +{ + uint32_t *xapic_base; + + if (mcb->has_x2apic) { + wrmsr(X2APIC_MSR_BASE + (reg >> 4), val); + return; + } + + xapic_base = PTR_OFFSET(mcb->xapic_io, reg); + return mmio_write32(xapic_base, val); +} + +/* + * Returns true if the processor has a Local APIC + * unit + */ +static inline bool +lapic_is_present(void) +{ + uint32_t edx, unused; + + CPUID(0x01, unused, unused, unused, edx); + return ISSET(edx, BIT(9)) != 0; +} + +/* + * Returns true if the Local APIC supports x2APIC + * mode + */ +static inline bool +lapic_has_x2apic(void) +{ + uint32_t ecx, unused; + + CPUID(0x01, unused, unused, ecx, unused); + return ISSET(ecx, BIT(21)) != 0; +} + +/* + * Enable the Local APIC unit + */ +static void +lapic_enable(struct mcb *mcb) +{ + uint64_t apic_base; + uint64_t svr; + bool has_x2apic = false; + + if (mcb == NULL) { + return; + } + + /* Hardware enable the Local APIC unit */ + has_x2apic = lapic_has_x2apic(); + apic_base = rdmsr(IA32_APIC_BASE); + apic_base |= LAPIC_GLOBAL_EN; + apic_base |= (has_x2apic << 10); + wrmsr(IA32_APIC_BASE, apic_base); + + mcb->has_x2apic = has_x2apic; + dtrace( + "lapic enabled in %s mode\n", + has_x2apic ? + "x2apic" : + "xapic" + ); + + /* Software enable the Local APIC unit */ + svr = lapic_read(mcb, LAPIC_REG_SVR); + svr |= LAPIC_SVR_APIC_EN; + lapic_write(mcb, LAPIC_REG_SVR, svr); +} + +void +lapic_init(void) +{ + struct cpu_info *ci; + struct mcb *mcb; + + if (!lapic_is_present()) { + panic("lapic: cpu lacks on-board local apic\n"); + } + + /* We need the MADT table */ + madt = acpi_query("APIC"); + if (__unlikely(madt == NULL)) { + panic("lapic: acpi madt table not present\n"); + } + + ci = cpu_self(); + if (ci == NULL) { + panic("lapic: could not get current processor\n"); + } + + mcb = &ci->mcb; + mcb->xapic_io = PHYS_TO_VIRT((uintptr_t)madt->lapic_addr); + lapic_enable(mcb); +} |