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fix: let nested-KVM vmlaunch succeed with Virtual NMIs

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Self-test and Linux guest were failing VM-instruction error 7. Share a KVM-style control adjust, request PIN_VIRTUAL_NMIS, and stop intercepting guest #PF. Land isolated XNU/Python/KDE scaffolding off the boot path.

Co-authored-by: Cursor <cursoragent@cursor.com>
This commit is contained in:
Linehu
2026-09-06 10:48:07 +08:00
co-authored by Cursor
parent cc0fcf26e3
commit 737a2cb0db
17 changed files with 1615 additions and 163 deletions
Download Patch File Download Diff File Expand all files Collapse all files
CODE/UTSM/vmm/linux_boot.c
+148 -40
View File
@@ -17,6 +17,7 @@
#include <utsm/ept.h>
#include <utsm/vmm.h>
#include <utsm/virtio_mmio.h>
#include <utsm/ipc_shm.h>
#include <utsm/log.h>
#include <utsm/types.h>
#include "../arch/x86_64/limine.h"
@@ -50,14 +51,6 @@ static inline u64 read_cr4_local(void) {
return v;
}
static u64 vmx_adjust_control(u64 value, u32 msr) {
u32 allowed0 = (u32)vmx_read_msr(msr);
u32 allowed1 = (u32)(vmx_read_msr(msr) >> 32);
u32 adjusted = (u32)value | allowed0;
adjusted &= allowed1;
return adjusted;
}
/* MSR bitmap (4KB, all zeros = don't intercept any MSR) */
static u8 g_linux_msr_bitmap[4096] __attribute__((aligned(4096)));
@@ -125,11 +118,13 @@ static void linux_vmcs_setup_host_state(void) {
/* ===== VMCS guest state for Linux ===== */
static void linux_vmcs_setup_guest_state(const struct linux_guest_info *gi) {
/* CR0/CR3/CR4: long mode with paging */
/* CR0/CR3/CR4: long mode with paging.
* P8.5: CR4 必须含 VMXE（IA32_VMX_CR4_FIXED0=0x2000 强制，
* 旧代码漏掉会触发 VM-entry invalid guest state）。 */
vmx_vmcs_write(VMCS_GUEST_CR0, CR0_PE | CR0_NE | CR0_PG | CR0_WP);
/* CR3 points to guest PML4 (GPA) */
vmx_vmcs_write(VMCS_GUEST_CR3, gi->pgt_gpa);
vmx_vmcs_write(VMCS_GUEST_CR4, CR4_PAE | CR4_PGE | CR4_PSE);
vmx_vmcs_write(VMCS_GUEST_CR4, CR4_VMXE | CR4_PAE | CR4_PGE | CR4_PSE);
/* Segment selectors from guest GDT */
vmx_vmcs_write(VMCS_GUEST_CS_SELECTOR, 0x08);
@@ -165,14 +160,18 @@ static void linux_vmcs_setup_guest_state(const struct linux_guest_info *gi) {
vmx_vmcs_write(VMCS_GUEST_GDTR_LIMIT, 0x28);
vmx_vmcs_write(VMCS_GUEST_IDTR_LIMIT, 0xFFFF);
/* Access rights */
/* Access rights.
* P8.5: selector=0 的段必须标记 unusable（access rights bit 16），
* 否则 VM-entry guest-state 检查失败：
* FS/GS selector=0 → 0x1C093（unusable）
* LDTR selector=0 → 0x10082（unusable，旧值 0x82 缺 bit 16） */
vmx_vmcs_write(VMCS_GUEST_CS_ACCESS, 0xA09B); /* 64-bit code, L=1 */
vmx_vmcs_write(VMCS_GUEST_SS_ACCESS, 0xC093);
vmx_vmcs_write(VMCS_GUEST_DS_ACCESS, 0xC093);
vmx_vmcs_write(VMCS_GUEST_ES_ACCESS, 0xC093);
vmx_vmcs_write(VMCS_GUEST_FS_ACCESS, 0xC093);
vmx_vmcs_write(VMCS_GUEST_GS_ACCESS, 0xC093);
vmx_vmcs_write(VMCS_GUEST_LDTR_ACCESS, 0x82); /* unusable */
vmx_vmcs_write(VMCS_GUEST_FS_ACCESS, 0x1C093); /* unusable (selector=0) */
vmx_vmcs_write(VMCS_GUEST_GS_ACCESS, 0x1C093); /* unusable (selector=0) */
vmx_vmcs_write(VMCS_GUEST_LDTR_ACCESS, 0x10082); /* unusable (selector=0) */
vmx_vmcs_write(VMCS_GUEST_TR_ACCESS, 0x8B); /* busy 64-bit TSS */
/* Guest RIP = Linux 64-bit entry (startup_64) */
@@ -204,10 +203,22 @@ static void linux_vmcs_setup_guest_state(const struct linux_guest_info *gi) {
/* ===== VMCS controls for Linux ===== */
static void linux_vmcs_setup_controls(u64 eptp) {
log_hex64("[LINUX] TRUE_PINBASED_CTLS raw=",
vmx_read_msr(IA32_VMX_TRUE_PINBASED_CTLS));
log_hex64("[LINUX] TRUE_PROCBASED_CTLS raw=",
vmx_read_msr(IA32_VMX_TRUE_PROCBASED_CTLS));
log_hex64("[LINUX] PROCBASED_CTLS2 raw=",
vmx_read_msr(IA32_VMX_PROCBASED_CTLS2));
log_hex64("[LINUX] TRUE_EXIT_CTLS raw=",
vmx_read_msr(IA32_VMX_TRUE_EXIT_CTLS));
log_hex64("[LINUX] TRUE_ENTRY_CTLS raw=",
vmx_read_msr(IA32_VMX_TRUE_ENTRY_CTLS));
/* Pin-based：外部中断 exit + NMI exit + VMX preemption timer（若支持）。
* preemption timer 提供 1ms 周期 exit，用于轮询 host 串口 RX、
* 推进 guest PIT tick、注入 pending virtio/COM1 IRQ。 */
u64 pin_want = PIN_EXT_INTERRUPT_EXITING | PIN_NMI_EXITING;
u64 pin_want = PIN_EXT_INTERRUPT_EXITING | PIN_NMI_EXITING |
PIN_VIRTUAL_NMIS;
if (vmx_preemption_timer_supported()) {
pin_want |= PIN_VMX_PREEMPTION_TIMER;
}
@@ -222,13 +233,12 @@ static void linux_vmcs_setup_controls(u64 eptp) {
| CPU_BASED_INVLPG_EXITING;
cpu = vmx_adjust_control(cpu, IA32_VMX_TRUE_PROCBASED_CTLS);
/* Secondary: EPT + VPID */
/* Secondary: EPT + VPID（经 capability MSR 调整；
* EPT 不可用则打日志——Linux guest 的 GPA 布局依赖 EPT）。 */
u64 cpu2 = SEC_EXEC_ENABLE_EPT | SEC_EXEC_ENABLE_VPID;
{
u64 msr = vmx_read_msr(IA32_VMX_PROCBASED_CTLS2);
u32 allowed1 = (u32)(msr >> 32);
cpu2 &= allowed1;
cpu2 |= SEC_EXEC_ENABLE_EPT;
cpu2 = vmx_adjust_control(cpu2, IA32_VMX_PROCBASED_CTLS2);
if (!(cpu2 & SEC_EXEC_ENABLE_EPT)) {
log_warn("[LINUX] EPT not available (shadow paging) - guest GPA map disabled");
}
u64 exit_ctrl = VM_EXIT_SAVE_DEBUG_CONTROLS
@@ -249,20 +259,31 @@ static void linux_vmcs_setup_controls(u64 eptp) {
/* MSR bitmap */
{
u64 hhdm = g_hhdm_request.response ? g_hhdm_request.response->offset : 0;
u64 msr_bitmap_phys = (u64)g_linux_msr_bitmap - hhdm;
u64 msr_bitmap_phys = vmx_kernel_virt_to_phys(g_linux_msr_bitmap);
log_hex64("[LINUX] MSR bitmap phys=", msr_bitmap_phys);
vmx_vmcs_write(VMCS_MSR_BITMAP, msr_bitmap_phys);
}
vmx_vmcs_write(VMCS_EPT_POINTER, eptp);
vmx_vmcs_write(VMCS_VPID, 2); /* VPID 1 = self-test, VPID 2 = Linux */
if (cpu2 & SEC_EXEC_ENABLE_EPT) {
vmx_vmcs_write(VMCS_EPT_POINTER, eptp);
} else {
vmx_vmcs_write(VMCS_EPT_POINTER, 0);
}
if (cpu2 & SEC_EXEC_ENABLE_VPID) {
vmx_vmcs_write(VMCS_VPID, 2); /* VPID 1 = self-test, VPID 2 = Linux */
} else {
vmx_vmcs_write(VMCS_VPID, 0);
}
/* Exception bitmap: catch #GP, #PF, #UD, #DF (triple fault handled separately) */
vmx_vmcs_write(VMCS_EXCEPTION_BITMAP, (1ULL << 13) | (1ULL << 14) | (1ULL << 6) | (1ULL << 8));
/* Linux owns its IDT. Intercepting #PF here livelocks: the guest
* page-fault handler never runs, so early mm faults spin in VM-exit. */
vmx_vmcs_write(VMCS_EXCEPTION_BITMAP, 0);
}
/* ===== Global for passing RSI to launch asm ===== */
static volatile u64 g_linux_rsi;
static volatile int g_linux_launch_failed;
static volatile u64 g_linux_launch_flags;
/* ===== Linux launch =====
*
@@ -306,17 +327,44 @@ int linux_launch(void) {
linux_vmcs_setup_controls(vmm_get_eptp());
linux_vmcs_setup_host_state();
/* 初始 arm preemption timer（1ms 后首次周期 exit） */
vmx_vmcs_write(VMCS_GUEST_PREEMPTION_TIMER, vmx_preemption_quantum_1ms());
/* 仅在 pin-based control 真正启用 timer 时 arm。 */
if (vmx_vmcs_read(VMCS_PIN_BASED_VM_EXEC_CONTROL) &
PIN_VMX_PREEMPTION_TIMER) {
vmx_vmcs_write(VMCS_GUEST_PREEMPTION_TIMER,
vmx_preemption_quantum());
} else {
vmx_vmcs_write(VMCS_GUEST_PREEMPTION_TIMER, 0);
}
/* Set RSI for Linux boot_params (passed via global, loaded in asm) */
g_linux_rsi = gi->bootparams_gpa;
/* P8.5: VMCLEAR + VMPTRLD —— VMLAUNCH 要求 VMCS 处于 "clear" 态。
* 自检成功后 VMCS 状态为 "launched"，不 VMCLEAR 会报
* "VMLAUNCH with non-clear VMCS"（error 4）。
* 内容不受影响：VMCLEAR 只回写内存并改状态，VMPTRLD 再挂载。 */
if (vmx_vmcs_clear(vmm_get_vmcs_phys()) != 0) {
log_error("[LINUX] vmclear failed");
return -4;
}
if (vmx_vmcs_load(vmm_get_vmcs_phys()) != 0) {
log_error("[LINUX] vmptrld after vmclear failed");
return -5;
}
log_hex64("[LINUX] RIP=", gi->kernel_entry);
log_hex64("[LINUX] RSP=", LINUX_GUEST_STACK_GPA + 0x1000);
log_hex64("[LINUX] RSI=", gi->bootparams_gpa);
log_hex64("[LINUX] CR3=", gi->pgt_gpa);
log_hex64("[LINUX] GDTR=", gi->gdt_gpa);
log_hex64("[LINUX] pin=", vmx_vmcs_read(VMCS_PIN_BASED_VM_EXEC_CONTROL));
log_hex64("[LINUX] cpu=", vmx_vmcs_read(VMCS_CPU_BASED_VM_EXEC_CONTROL));
log_hex64("[LINUX] cpu2=", vmx_vmcs_read(VMCS_SECONDARY_VM_EXEC_CONTROL));
log_hex64("[LINUX] exit=", vmx_vmcs_read(VMCS_VM_EXIT_CONTROLS));
log_hex64("[LINUX] entry=", vmx_vmcs_read(VMCS_VM_ENTRY_CONTROLS));
log_hex64("[LINUX] eptp=", vmx_vmcs_read(VMCS_EPT_POINTER));
log_hex64("[LINUX] msr_bitmap=", vmx_vmcs_read(VMCS_MSR_BITMAP));
log_hex64("[LINUX] vpid=", vmx_vmcs_read(VMCS_VPID));
log_info("[LINUX] vmlaunch");
/* vmlaunch with RSI = boot_params.
@@ -324,38 +372,98 @@ int linux_launch(void) {
* - On failure: failed=1, falls through
* - On success: enters guest, VM-Exit → vmx_vm_exit_handler
* - On terminate: handler restores RSP, jmps to post_guest label */
int failed;
g_linux_launch_failed = 1;
g_linux_launch_flags = 0;
__asm__ volatile(
"movq %%rsp, g_saved_host_rsp(%%rip)\n\t"
"leaq 1f(%%rip), %%rax\n\t"
"movq %%rax, g_saved_return_rip(%%rip)\n\t"
/* Linux 64-bit boot protocol requires every GPR except RSI zero. */
"xorl %%eax, %%eax\n\t"
"xorl %%ebx, %%ebx\n\t"
"xorl %%ecx, %%ecx\n\t"
"xorl %%edx, %%edx\n\t"
"xorl %%edi, %%edi\n\t"
"xorl %%ebp, %%ebp\n\t"
"xorl %%r8d, %%r8d\n\t"
"xorl %%r9d, %%r9d\n\t"
"xorl %%r10d, %%r10d\n\t"
"xorl %%r11d, %%r11d\n\t"
"xorl %%r12d, %%r12d\n\t"
"xorl %%r13d, %%r13d\n\t"
"xorl %%r14d, %%r14d\n\t"
"xorl %%r15d, %%r15d\n\t"
"movq g_linux_rsi(%%rip), %%rsi\n\t" /* RSI = boot_params GPA */
"vmlaunch\n\t"
/* ---- failure path ---- */
"movl $1, %0\n\t"
"movl $1, g_linux_launch_failed(%%rip)\n\t"
"pushfq\n\t"
"popq g_linux_launch_flags(%%rip)\n\t"
"jmp 2f\n\t"
/* ---- post_guest: terminate path jmps here ---- */
"1:\n\t"
"movl $0, %0\n\t"
"movl $0, g_linux_launch_failed(%%rip)\n\t"
"2:\n\t"
: "=r"(failed)
:: "rax", "rcx", "rdx", "rsi", "rdi",
"r8", "r9", "r10", "r11", "memory"
:
:
: "rax", "rbx", "rcx", "rdx", "rsi", "rdi", "rbp",
"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
"cc", "memory"
);
int failed = g_linux_launch_failed;
u64 vm_flags = g_linux_launch_flags;
if (failed) {
u64 error = vmx_vmcs_read(VMCS_VMX_INSTRUCTION_ERROR);
/* CF=1 → VMfailInvalid；ZF=1 → VMfailValid（error field 有效）。 */
if (vm_flags & 0x1) {
log_error("[LINUX] vmlaunch VMfailInvalid (invalid current-VMCS)");
} else if (vm_flags & 0x40) {
log_error("[LINUX] vmlaunch VMfailValid");
}
u64 error = 0;
if (vm_flags & 0x40) {
vmx_vmcs_read_checked(VMCS_VMX_INSTRUCTION_ERROR, &error);
}
log_hex64("[LINUX] vmlaunch failed, error=", error);
g_linux_guest_active = 0;
return -3;
}
/* Guest parked (HLT) — Linux daemon 已驻留，等待 linux_resume() 唤醒 */
g_linux_guest_active = 0; /* 回到 host 上下文，清除 active 标志 */
g_guest_parked = 1; /* 标记 guest 已 park，linux_resume() 可唤醒 */
log_info("[LINUX] guest parked (daemon ready)");
/* Only handle_hlt() may mark the Linux guest parked. A fatal exception,
* triple fault, or EPT failure also returns through post_guest, but must
* not make the compatibility layer report a ready daemon. */
g_linux_guest_active = 0;
log_hex64("[LINUX] last exit reason=", g_last_exit_reason);
log_hex64("[LINUX] vmexit count=", vmexit_get_count());
if (!g_guest_parked) {
log_error("[LINUX] guest terminated before daemon park");
return -6;
}
/* A kernel idle/fatal HLT is indistinguishable from the daemon's PARK at
* the VM-exit reason level. The daemon must first publish EXEC_READY
* through /dev/utsm; this proves the driver PING, SHM mapping, userspace
* daemon, and Linux→UTSM ring are all alive. */
{
struct utsm_ipc_msg ready;
int got_ready = 0;
for (int i = 0; i < 8; i++) {
if (ipc_shm_recv(&ready) != 0) break;
if (ready.type == UTSM_MSG_EXEC_READY) {
got_ready = 1;
break;
}
log_hex64("[LINUX] pre-ready message type=", ready.type);
}
if (!got_ready) {
g_guest_parked = 0;
log_error("[LINUX] HLT without EXEC_READY handshake");
return -7;
}
}
log_info("[LINUX] EXEC_READY received from /dev/utsm");
log_info("[LINUX] guest parked (daemon ready)");
return 0;
}