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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2023, Microsoft Corporation.
*
* Author:
* Saurabh Sengar <ssengar@microsoft.com>
*/
#include <asm/apic.h>
#include <asm/boot.h>
#include <asm/desc.h>
#include <asm/i8259.h>
#include <asm/mshyperv.h>
#include <asm/realmode.h>
extern struct boot_params boot_params;
static struct real_mode_header hv_vtl_real_mode_header;
void __init hv_vtl_init_platform(void)
{
pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
x86_platform.realmode_reserve = x86_init_noop;
x86_platform.realmode_init = x86_init_noop;
x86_init.irqs.pre_vector_init = x86_init_noop;
x86_init.timers.timer_init = x86_init_noop;
/* Avoid searching for BIOS MP tables */
x86_init.mpparse.find_smp_config = x86_init_noop;
x86_init.mpparse.get_smp_config = x86_init_uint_noop;
x86_platform.get_wallclock = get_rtc_noop;
x86_platform.set_wallclock = set_rtc_noop;
x86_platform.get_nmi_reason = hv_get_nmi_reason;
x86_platform.legacy.i8042 = X86_LEGACY_I8042_PLATFORM_ABSENT;
x86_platform.legacy.rtc = 0;
x86_platform.legacy.warm_reset = 0;
x86_platform.legacy.reserve_bios_regions = 0;
x86_platform.legacy.devices.pnpbios = 0;
}
static inline u64 hv_vtl_system_desc_base(struct ldttss_desc *desc)
{
return ((u64)desc->base3 << 32) | ((u64)desc->base2 << 24) |
(desc->base1 << 16) | desc->base0;
}
static inline u32 hv_vtl_system_desc_limit(struct ldttss_desc *desc)
{
return ((u32)desc->limit1 << 16) | (u32)desc->limit0;
}
typedef void (*secondary_startup_64_fn)(void*, void*);
static void hv_vtl_ap_entry(void)
{
((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params);
}
static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored)
{
u64 status;
int ret = 0;
struct hv_enable_vp_vtl *input;
unsigned long irq_flags;
struct desc_ptr gdt_ptr;
struct desc_ptr idt_ptr;
struct ldttss_desc *tss;
struct ldttss_desc *ldt;
struct desc_struct *gdt;
u64 rsp = current->thread.sp;
u64 rip = (u64)&hv_vtl_ap_entry;
native_store_gdt(&gdt_ptr);
store_idt(&idt_ptr);
gdt = (struct desc_struct *)((void *)(gdt_ptr.address));
tss = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS);
ldt = (struct ldttss_desc *)(gdt + GDT_ENTRY_LDT);
local_irq_save(irq_flags);
input = *this_cpu_ptr(hyperv_pcpu_input_arg);
memset(input, 0, sizeof(*input));
input->partition_id = HV_PARTITION_ID_SELF;
input->vp_index = target_vp_index;
input->target_vtl.target_vtl = HV_VTL_MGMT;
/*
* The x86_64 Linux kernel follows the 16-bit -> 32-bit -> 64-bit
* mode transition sequence after waking up an AP with SIPI whose
* vector points to the 16-bit AP startup trampoline code. Here in
* VTL2, we can't perform that sequence as the AP has to start in
* the 64-bit mode.
*
* To make this happen, we tell the hypervisor to load a valid 64-bit
* context (most of which is just magic numbers from the CPU manual)
* so that AP jumps right to the 64-bit entry of the kernel, and the
* control registers are loaded with values that let the AP fetch the
* code and data and carry on with work it gets assigned.
*/
input->vp_context.rip = rip;
input->vp_context.rsp = rsp;
input->vp_context.rflags = 0x0000000000000002;
input->vp_context.efer = __rdmsr(MSR_EFER);
input->vp_context.cr0 = native_read_cr0();
input->vp_context.cr3 = __native_read_cr3();
input->vp_context.cr4 = native_read_cr4();
input->vp_context.msr_cr_pat = __rdmsr(MSR_IA32_CR_PAT);
input->vp_context.idtr.limit = idt_ptr.size;
input->vp_context.idtr.base = idt_ptr.address;
input->vp_context.gdtr.limit = gdt_ptr.size;
input->vp_context.gdtr.base = gdt_ptr.address;
/* Non-system desc (64bit), long, code, present */
input->vp_context.cs.selector = __KERNEL_CS;
input->vp_context.cs.base = 0;
input->vp_context.cs.limit = 0xffffffff;
input->vp_context.cs.attributes = 0xa09b;
/* Non-system desc (64bit), data, present, granularity, default */
input->vp_context.ss.selector = __KERNEL_DS;
input->vp_context.ss.base = 0;
input->vp_context.ss.limit = 0xffffffff;
input->vp_context.ss.attributes = 0xc093;
/* System desc (128bit), present, LDT */
input->vp_context.ldtr.selector = GDT_ENTRY_LDT * 8;
input->vp_context.ldtr.base = hv_vtl_system_desc_base(ldt);
input->vp_context.ldtr.limit = hv_vtl_system_desc_limit(ldt);
input->vp_context.ldtr.attributes = 0x82;
/* System desc (128bit), present, TSS, 0x8b - busy, 0x89 -- default */
input->vp_context.tr.selector = GDT_ENTRY_TSS * 8;
input->vp_context.tr.base = hv_vtl_system_desc_base(tss);
input->vp_context.tr.limit = hv_vtl_system_desc_limit(tss);
input->vp_context.tr.attributes = 0x8b;
status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL);
if (!hv_result_success(status) &&
hv_result(status) != HV_STATUS_VTL_ALREADY_ENABLED) {
pr_err("HVCALL_ENABLE_VP_VTL failed for VP : %d ! [Err: %#llx\n]",
target_vp_index, status);
ret = -EINVAL;
goto free_lock;
}
status = hv_do_hypercall(HVCALL_START_VP, input, NULL);
if (!hv_result_success(status)) {
pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n",
target_vp_index, status);
ret = -EINVAL;
}
free_lock:
local_irq_restore(irq_flags);
return ret;
}
static int hv_vtl_apicid_to_vp_id(u32 apic_id)
{
u64 control;
u64 status;
unsigned long irq_flags;
struct hv_get_vp_from_apic_id_in *input;
u32 *output, ret;
local_irq_save(irq_flags);
input = *this_cpu_ptr(hyperv_pcpu_input_arg);
memset(input, 0, sizeof(*input));
input->partition_id = HV_PARTITION_ID_SELF;
input->apic_ids[0] = apic_id;
output = (u32 *)input;
control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID;
status = hv_do_hypercall(control, input, output);
ret = output[0];
local_irq_restore(irq_flags);
if (!hv_result_success(status)) {
pr_err("failed to get vp id from apic id %d, status %#llx\n",
apic_id, status);
return -EINVAL;
}
return ret;
}
static int hv_vtl_wakeup_secondary_cpu(int apicid, unsigned long start_eip)
{
int vp_id;
pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid);
vp_id = hv_vtl_apicid_to_vp_id(apicid);
if (vp_id < 0) {
pr_err("Couldn't find CPU with APIC ID %d\n", apicid);
return -EINVAL;
}
if (vp_id > ms_hyperv.max_vp_index) {
pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid);
return -EINVAL;
}
return hv_vtl_bringup_vcpu(vp_id, start_eip);
}
static int __init hv_vtl_early_init(void)
{
/*
* `boot_cpu_has` returns the runtime feature support,
* and here is the earliest it can be used.
*/
if (cpu_feature_enabled(X86_FEATURE_XSAVE))
panic("XSAVE has to be disabled as it is not supported by this module.\n"
"Please add 'noxsave' to the kernel command line.\n");
real_mode_header = &hv_vtl_real_mode_header;
apic_update_callback(wakeup_secondary_cpu_64, hv_vtl_wakeup_secondary_cpu);
return 0;
}
early_initcall(hv_vtl_early_init);
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