ohhhhhhhhhhh (exclude linux-extra-rootfs.img build artifact)

2026-10-01 23:13:42 +08:00
parent 737a2cb0db
commit 1074962546
533 changed files with 133239 additions and 5460 deletions
@@ -0,0 +1,205 @@
+/* linux_xsave.c — L2 guest XSAVE save/restore.
+ *
+ * Host UTSM is compiled -mno-sse. A naive XRSTOR of guest AVX/SSE
+ * state #GPs. Advertise XSAVE to the Linux guest only after we can
+ * XSAVE the guest area before returning to DSK, and XRSTOR it again
+ * on the next vmresume.
+ *
+ * RFBM/XCR0 = 7 (x87+SSE+AVX/YMM). persist glibc is x86-64-v3. */
+
+#include <utsm/linux_xsave.h>
+#include <utsm/vmx.h>
+#include <utsm/log.h>
+#include <utsm/types.h>
+
+#define LINUX_XSAVE_XCR0   0x7ULL
+#define LINUX_XSAVE_BYTES  832u
+#define LINUX_XSAVE_YMM_SIZE    256u
+#define LINUX_XSAVE_YMM_OFF     576u
+
+static int g_xsave_ok;
+static u64 g_guest_xcr0 = LINUX_XSAVE_XCR0;
+static u64 g_host_xcr0 = LINUX_XSAVE_XCR0;
+static u8 g_guest_xsave[4096] __attribute__((aligned(64)));
+static u8 g_host_xsave[4096] __attribute__((aligned(64)));
+
+static void xsave_zero(u8 *p, usize n) {
+    for (usize i = 0; i < n; i++)
+        p[i] = 0;
+}
+
+static void xsave_enable_osxsave(void) {
+    u64 cr4;
+    __asm__ volatile("mov %%cr4, %0" : "=r"(cr4));
+    if (!(cr4 & CR4_OSXSAVE)) {
+        cr4 |= CR4_OSXSAVE;
+        __asm__ volatile("mov %0, %%cr4" : : "r"(cr4) : "memory");
+    }
+    /* VM-exit reloads HOST_CR4. Keep OSXSAVE so later XSAVE is legal. */
+    vmx_vmcs_write(VMCS_HOST_CR4, cr4 | CR4_VMXE);
+}
+
+static void xsave_xsetbv(u64 xcr0) {
+    u32 lo = (u32)xcr0;
+    u32 hi = (u32)(xcr0 >> 32);
+    __asm__ volatile(".byte 0x0f, 0x01, 0xd1"
+                     :
+                     : "a"(lo), "c"(0), "d"(hi)
+                     : "memory");
+}
+
+static void xsave_mem(void *ptr, u64 rfbm) {
+    u32 lo = (u32)rfbm;
+    u32 hi = (u32)(rfbm >> 32);
+    __asm__ volatile(".byte 0x0f, 0xae, 0x27" /* xsave (%rdi) */
+                     :
+                     : "D"(ptr), "a"(lo), "d"(hi)
+                     : "memory");
+}
+
+static void xrstor_mem(void *ptr, u64 rfbm) {
+    u32 lo = (u32)rfbm;
+    u32 hi = (u32)(rfbm >> 32);
+    __asm__ volatile(".byte 0x0f, 0xae, 0x2f" /* xrstor (%rdi) */
+                     :
+                     : "D"(ptr), "a"(lo), "d"(hi)
+                     : "memory");
+}
+
+int linux_xsave_available(void) {
+    return g_xsave_ok;
+}
+
+void linux_xsave_init(void) {
+    u32 a, b, c, d;
+
+    if (g_xsave_ok)
+        return;
+
+    __asm__ volatile("cpuid"
+                     : "=a"(a), "=b"(b), "=c"(c), "=d"(d)
+                     : "a"(1), "c"(0));
+    if (!(c & (1u << 26))) {
+        log_warn("[LINUX] XSAVE not in host CPUID; persist glibc stays hidden");
+        return;
+    }
+
+    xsave_zero(g_guest_xsave, sizeof(g_guest_xsave));
+    xsave_zero(g_host_xsave, sizeof(g_host_xsave));
+    g_guest_xcr0 = LINUX_XSAVE_XCR0;
+    g_host_xcr0 = LINUX_XSAVE_XCR0;
+
+    xsave_enable_osxsave();
+    xsave_xsetbv(LINUX_XSAVE_XCR0);
+    /* Init-state XRSTOR so the first vmlaunch does not inherit host junk. */
+    xrstor_mem(g_guest_xsave, LINUX_XSAVE_XCR0);
+
+    g_xsave_ok = 1;
+    log_info("[LINUX] XSAVE ready for L2 (x87+SSE+AVX, XCR0=7)");
+    log_hex64("[LINUX] XSAVE area bytes=", LINUX_XSAVE_BYTES);
+}
+
+void linux_xsave_save_guest(void) {
+    if (!g_xsave_ok)
+        return;
+    xsave_enable_osxsave();
+    xsave_xsetbv(g_guest_xcr0);
+    xsave_mem(g_guest_xsave, g_guest_xcr0);
+}
+
+void linux_xsave_load_guest(void) {
+    if (!g_xsave_ok)
+        return;
+    xsave_enable_osxsave();
+    xsave_xsetbv(g_guest_xcr0);
+    xrstor_mem(g_guest_xsave, g_guest_xcr0);
+}
+
+void linux_xsave_save_host(void) {
+    if (!g_xsave_ok)
+        return;
+    xsave_enable_osxsave();
+    xsave_xsetbv(g_host_xcr0);
+    xsave_mem(g_host_xsave, g_host_xcr0);
+}
+
+void linux_xsave_load_host(void) {
+    if (!g_xsave_ok)
+        return;
+    xsave_enable_osxsave();
+    xsave_xsetbv(g_host_xcr0);
+    xrstor_mem(g_host_xsave, g_host_xcr0);
+}
+
+void linux_xsave_set_guest_xcr0(u64 xcr0) {
+    u64 allowed = LINUX_XSAVE_XCR0;
+    u64 v = xcr0 & allowed;
+    static int logged;
+
+    if (!g_xsave_ok)
+        return;
+    /* Intel requires x87. Keep SSE if this build advertises it. */
+    if (!(v & 1ULL))
+        v |= 1ULL;
+    if ((allowed & 2ULL) && !(v & 2ULL))
+        v |= 2ULL;
+    if (!logged && v != xcr0) {
+        logged = 1;
+        log_hex64("[LINUX] XSETBV clamped from=", xcr0);
+        log_hex64("[LINUX] XSETBV clamped to=", v);
+    }
+    g_guest_xcr0 = v;
+    xsave_enable_osxsave();
+    xsave_xsetbv(v);
+}
+
+void linux_xsave_adjust_cpuid(u32 leaf, u32 subleaf,
+                              u32 *eax, u32 *ebx, u32 *ecx, u32 *edx,
+                              u64 guest_cr4) {
+    if (!eax || !ebx || !ecx || !edx)
+        return;
+
+    if (!g_xsave_ok) {
+        if (leaf == 1) {
+            *ecx &= ~((1u << 26) | (1u << 27) | (1u << 28));
+        }
+        if (leaf == 0xD) {
+            *eax = 0;
+            *ebx = 0;
+            *ecx = 0;
+            *edx = 0;
+        }
+        return;
+    }
+
+    if (leaf == 1) {
+        *ecx |= (1u << 26); /* XSAVE */
+        if (guest_cr4 & CR4_OSXSAVE)
+            *ecx |= (1u << 27);
+        else
+            *ecx &= ~(1u << 27);
+        *ecx |= (1u << 28); /* AVX / XCR0 bit 2 */
+        return;
+    }
+
+    if (leaf != 0xD)
+        return;
+
+    /* Hide XSAVEOPT/XSAVEC/XSAVES. Standard XSAVE only. */
+    if (subleaf == 0) {
+        *eax = (u32)LINUX_XSAVE_XCR0;
+        *ebx = LINUX_XSAVE_BYTES;
+        *ecx = LINUX_XSAVE_BYTES;
+        *edx = 0;
+    } else if (subleaf == 2) {
+        *eax = LINUX_XSAVE_YMM_SIZE;
+        *ebx = LINUX_XSAVE_YMM_OFF;
+        *ecx = 0;
+        *edx = 0;
+    } else {
+        *eax = 0;
+        *ebx = 0;
+        *ecx = 0;
+        *edx = 0;
+    }
+}