kernel: enable SMEP and UMIP

kernel/cpu.c

@@ -268,23 +268,23 @@ static void init_cpu(struct cpu* cpu) {
         cr0 |= X86_CR0_MP;
         write_cr0(cr0);
 
-        uint32_t cr4 = read_cr4();
-        cr4 |= X86_CR4_OSFXSR | X86_CR4_OSXMMEXCPT;
-        write_cr4(cr4);
+        write_cr4(read_cr4() | X86_CR4_OSFXSR | X86_CR4_OSXMMEXCPT);
     }
 
-    if (cpu_has_feature(cpu, X86_FEATURE_PGE)) {
-        uint32_t cr4 = read_cr4();
-        cr4 |= X86_CR4_PGE;
-        write_cr4(cr4);
-    }
+    if (cpu_has_feature(cpu, X86_FEATURE_PGE))
+        write_cr4(read_cr4() | X86_CR4_PGE);
 
     if (cpu_has_feature(cpu, X86_FEATURE_PAT)) {
         uint64_t pat = rdmsr(0x277);
         pat &= ~((uint64_t)0x7 << 32); // Clear PAT4
         pat |= (uint64_t)1 << 32;      // Set write-combining
         wrmsr(0x277, pat);
     }
+
+    if (cpu_has_feature(cpu, X86_FEATURE_SMEP))
+        write_cr4(read_cr4() | X86_CR4_SMEP);
+    if (cpu_has_feature(cpu, X86_FEATURE_UMIP))
+        write_cr4(read_cr4() | X86_CR4_UMIP);
 }
 
 static struct cpu bsp;

run.sh

@@ -52,6 +52,7 @@ QEMU_BIN="${QEMU_BINARY_PREFIX}qemu-system-i386${QEMU_BINARY_SUFFIX}"
     -chardev stdio,mux=on,id=char0 \
     -serial chardev:char0 \
     -mon char0,mode=readline \
+    -cpu max \
     -m 512M \
     -smp "sockets=1,cores=${NUM_CPUS},threads=1" \
     "${QEMU_VIRT_TECH_ARGS[@]}"

run_tests.sh

@@ -8,6 +8,7 @@ set -e
     -append 'panic=poweroff init=/bin/init-test console=ttyS0' \
     -d guest_errors \
     -no-reboot \
+    -cpu max \
     -serial stdio \
     -vga none -display none \
     -m 512M \