Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:
 "Yet another pile of melted spectrum related changes:

   - sanitize the array_index_nospec protection mechanism: Remove the
     overengineered array_index_nospec_mask_check() magic and allow
     const-qualified types as index to avoid temporary storage in a
     non-const local variable.

   - make the microcode loader more robust by properly propagating error
     codes. Provide information about new feature bits after micro code
     was updated so administrators can act upon.

   - optimizations of the entry ASM code which reduce code footprint and
     make the code simpler and faster.

   - fix the {pmd,pud}_{set,clear}_flags() implementations to work
     properly on paravirt kernels by removing the address translation
     operations.

   - revert the harmful vmexit_fill_RSB() optimization

   - use IBRS around firmware calls

   - teach objtool about retpolines and add annotations for indirect
     jumps and calls.

   - explicitly disable jumplabel patching in __init code and handle
     patching failures properly instead of silently ignoring them.

   - remove indirect paravirt calls for writing the speculation control
     MSR as these calls are obviously proving the same attack vector
     which is tried to be mitigated.

   - a few small fixes which address build issues with recent compiler
     and assembler versions"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
  KVM/VMX: Optimize vmx_vcpu_run() and svm_vcpu_run() by marking the RDMSR path as unlikely()
  KVM/x86: Remove indirect MSR op calls from SPEC_CTRL
  objtool, retpolines: Integrate objtool with retpoline support more closely
  x86/entry/64: Simplify ENCODE_FRAME_POINTER
  extable: Make init_kernel_text() global
  jump_label: Warn on failed jump_label patching attempt
  jump_label: Explicitly disable jump labels in __init code
  x86/entry/64: Open-code switch_to_thread_stack()
  x86/entry/64: Move ASM_CLAC to interrupt_entry()
  x86/entry/64: Remove 'interrupt' macro
  x86/entry/64: Move the switch_to_thread_stack() call to interrupt_entry()
  x86/entry/64: Move ENTER_IRQ_STACK from interrupt macro to interrupt_entry
  x86/entry/64: Move PUSH_AND_CLEAR_REGS from interrupt macro to helper function
  x86/speculation: Move firmware_restrict_branch_speculation_*() from C to CPP
  objtool: Add module specific retpoline rules
  objtool: Add retpoline validation
  objtool: Use existing global variables for options
  x86/mm/sme, objtool: Annotate indirect call in sme_encrypt_execute()
  x86/boot, objtool: Annotate indirect jump in secondary_startup_64()
  x86/paravirt, objtool: Annotate indirect calls
  ...

arch/x86/kernel/cpu/bugs.c

@@ -300,6 +300,15 @@ retpoline_auto:
 		setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
 		pr_info("Spectre v2 mitigation: Enabling Indirect Branch Prediction Barrier\n");
 	}
+
+	/*
+	 * Retpoline means the kernel is safe because it has no indirect
+	 * branches. But firmware isn't, so use IBRS to protect that.
+	 */
+	if (boot_cpu_has(X86_FEATURE_IBRS)) {
+		setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW);
+		pr_info("Enabling Restricted Speculation for firmware calls\n");
+	}
 }
 
 #undef pr_fmt
@@ -326,8 +335,9 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c
 	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
 		return sprintf(buf, "Not affected\n");
 
-	return sprintf(buf, "%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
+	return sprintf(buf, "%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
 		       boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "",
+		       boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
 		       spectre_v2_module_string());
 }
 #endif

arch/x86/kernel/cpu/common.c

@@ -1749,3 +1749,33 @@ static int __init init_cpu_syscore(void)
 	return 0;
 }
 core_initcall(init_cpu_syscore);
+
+/*
+ * The microcode loader calls this upon late microcode load to recheck features,
+ * only when microcode has been updated. Caller holds microcode_mutex and CPU
+ * hotplug lock.
+ */
+void microcode_check(void)
+{
+	struct cpuinfo_x86 info;
+
+	perf_check_microcode();
+
+	/* Reload CPUID max function as it might've changed. */
+	info.cpuid_level = cpuid_eax(0);
+
+	/*
+	 * Copy all capability leafs to pick up the synthetic ones so that
+	 * memcmp() below doesn't fail on that. The ones coming from CPUID will
+	 * get overwritten in get_cpu_cap().
+	 */
+	memcpy(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability));
+
+	get_cpu_cap(&info);
+
+	if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability)))
+		return;
+
+	pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n");
+	pr_warn("x86/CPU: Please consider either early loading through initrd/built-in or a potential BIOS update.\n");
+}

arch/x86/kernel/cpu/microcode/amd.c

@@ -498,7 +498,7 @@ static unsigned int verify_patch_size(u8 family, u32 patch_size,
 	return patch_size;
 }
 
-static int apply_microcode_amd(int cpu)
+static enum ucode_state apply_microcode_amd(int cpu)
 {
 	struct cpuinfo_x86 *c = &cpu_data(cpu);
 	struct microcode_amd *mc_amd;
@@ -512,7 +512,7 @@ static int apply_microcode_amd(int cpu)
 
 	p = find_patch(cpu);
 	if (!p)
-		return 0;
+		return UCODE_NFOUND;
 
 	mc_amd  = p->data;
 	uci->mc = p->data;
@@ -523,13 +523,13 @@ static int apply_microcode_amd(int cpu)
 	if (rev >= mc_amd->hdr.patch_id) {
 		c->microcode = rev;
 		uci->cpu_sig.rev = rev;
-		return 0;
+		return UCODE_OK;
 	}
 
 	if (__apply_microcode_amd(mc_amd)) {
 		pr_err("CPU%d: update failed for patch_level=0x%08x\n",
 			cpu, mc_amd->hdr.patch_id);
-		return -1;
+		return UCODE_ERROR;
 	}
 	pr_info("CPU%d: new patch_level=0x%08x\n", cpu,
 		mc_amd->hdr.patch_id);
@@ -537,7 +537,7 @@ static int apply_microcode_amd(int cpu)
 	uci->cpu_sig.rev = mc_amd->hdr.patch_id;
 	c->microcode = mc_amd->hdr.patch_id;
 
-	return 0;
+	return UCODE_UPDATED;
 }
 
 static int install_equiv_cpu_table(const u8 *buf)

arch/x86/kernel/cpu/microcode/core.c

@@ -374,7 +374,7 @@ static int collect_cpu_info(int cpu)
 }
 
 struct apply_microcode_ctx {
-	int err;
+	enum ucode_state err;
 };
 
 static void apply_microcode_local(void *arg)
@@ -489,31 +489,30 @@ static void __exit microcode_dev_exit(void)
 /* fake device for request_firmware */
 static struct platform_device	*microcode_pdev;
 
-static int reload_for_cpu(int cpu)
+static enum ucode_state reload_for_cpu(int cpu)
 {
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 	enum ucode_state ustate;
-	int err = 0;
 
 	if (!uci->valid)
-		return err;
+		return UCODE_OK;
 
 	ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev, true);
-	if (ustate == UCODE_OK)
-		apply_microcode_on_target(cpu);
-	else
-		if (ustate == UCODE_ERROR)
-			err = -EINVAL;
-	return err;
+	if (ustate != UCODE_OK)
+		return ustate;
+
+	return apply_microcode_on_target(cpu);
 }
 
 static ssize_t reload_store(struct device *dev,
 			    struct device_attribute *attr,
 			    const char *buf, size_t size)
 {
+	enum ucode_state tmp_ret = UCODE_OK;
+	bool do_callback = false;
 	unsigned long val;
+	ssize_t ret = 0;
 	int cpu;
-	ssize_t ret = 0, tmp_ret;
 
 	ret = kstrtoul(buf, 0, &val);
 	if (ret)
@@ -526,15 +525,21 @@ static ssize_t reload_store(struct device *dev,
 	mutex_lock(&microcode_mutex);
 	for_each_online_cpu(cpu) {
 		tmp_ret = reload_for_cpu(cpu);
-		if (tmp_ret != 0)
+		if (tmp_ret > UCODE_NFOUND) {
 			pr_warn("Error reloading microcode on CPU %d\n", cpu);
 
-		/* save retval of the first encountered reload error */
-		if (!ret)
-			ret = tmp_ret;
+			/* set retval for the first encountered reload error */
+			if (!ret)
+				ret = -EINVAL;
+		}
+
+		if (tmp_ret == UCODE_UPDATED)
+			do_callback = true;
 	}
-	if (!ret)
-		perf_check_microcode();
+
+	if (!ret && do_callback)
+		microcode_check();
+
 	mutex_unlock(&microcode_mutex);
 	put_online_cpus();
 

arch/x86/kernel/cpu/microcode/intel.c

@@ -772,7 +772,7 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 	return 0;
 }
 
-static int apply_microcode_intel(int cpu)
+static enum ucode_state apply_microcode_intel(int cpu)
 {
 	struct microcode_intel *mc;
 	struct ucode_cpu_info *uci;
@@ -782,7 +782,7 @@ static int apply_microcode_intel(int cpu)
 
 	/* We should bind the task to the CPU */
 	if (WARN_ON(raw_smp_processor_id() != cpu))
-		return -1;
+		return UCODE_ERROR;
 
 	uci = ucode_cpu_info + cpu;
 	mc = uci->mc;
@@ -790,7 +790,7 @@ static int apply_microcode_intel(int cpu)
 		/* Look for a newer patch in our cache: */
 		mc = find_patch(uci);
 		if (!mc)
-			return 0;
+			return UCODE_NFOUND;
 	}
 
 	/* write microcode via MSR 0x79 */
@@ -801,7 +801,7 @@ static int apply_microcode_intel(int cpu)
 	if (rev != mc->hdr.rev) {
 		pr_err("CPU%d update to revision 0x%x failed\n",
 		       cpu, mc->hdr.rev);
-		return -1;
+		return UCODE_ERROR;
 	}
 
 	if (rev != prev_rev) {
@@ -818,7 +818,7 @@ static int apply_microcode_intel(int cpu)
 	uci->cpu_sig.rev = rev;
 	c->microcode = rev;
 
-	return 0;
+	return UCODE_UPDATED;
 }
 
 static enum ucode_state generic_load_microcode(int cpu, void *data, size_t size,