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

Pull x86 fixes from Thomas Gleixner:
 "A small set of x86 fixes:

   - Prevent a NULL pointer dereference in the X2APIC code in case of a
     CPU hotplug failure.

   - Prevent boot failures on HP superdome machines by invalidating the
     level2 kernel pagetable entries outside of the kernel area as
     invalid so BIOS reserved space won't be touched unintentionally.

     Also ensure that memory holes are rounded up to the next PMD
     boundary correctly.

   - Enable X2APIC support on Hyper-V to prevent boot failures.

   - Set the paravirt name when running on Hyper-V for consistency

   - Move a function under the appropriate ifdef guard to prevent build
     warnings"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot/acpi: Move get_cmdline_acpi_rsdp() under #ifdef guard
  x86/hyperv: Set pv_info.name to "Hyper-V"
  x86/apic/x2apic: Fix a NULL pointer deref when handling a dying cpu
  x86/hyperv: Make vapic support x2apic mode
  x86/boot/64: Round memory hole size up to next PMD page
  x86/boot/64: Make level2_kernel_pgt pages invalid outside kernel area

3 files changed, 26 insertions, 3 deletions

diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index 45e92cba92f5..b0889c48a2ac 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -156,7 +156,8 @@ static int x2apic_dead_cpu(unsigned int dead_cpu)
 {
 	struct cluster_mask *cmsk = per_cpu(cluster_masks, dead_cpu);
 
-	cpumask_clear_cpu(dead_cpu, &cmsk->mask);
+	if (cmsk)
+		cpumask_clear_cpu(dead_cpu, &cmsk->mask);
 	free_cpumask_var(per_cpu(ipi_mask, dead_cpu));
 	return 0;
 }
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 267daad8c036..c656d92cd708 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -216,6 +216,10 @@ static void __init ms_hyperv_init_platform(void)
 	int hv_host_info_ecx;
 	int hv_host_info_edx;
 
+#ifdef CONFIG_PARAVIRT
+	pv_info.name = "Hyper-V";
+#endif
+
 	/*
 	 * Extract the features and hints
 	 */
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 29ffa495bd1c..206a4b6144c2 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -222,13 +222,31 @@ unsigned long __head __startup_64(unsigned long physaddr,
 	 * we might write invalid pmds, when the kernel is relocated
 	 * cleanup_highmap() fixes this up along with the mappings
 	 * beyond _end.
+	 *
+	 * Only the region occupied by the kernel image has so far
+	 * been checked against the table of usable memory regions
+	 * provided by the firmware, so invalidate pages outside that
+	 * region. A page table entry that maps to a reserved area of
+	 * memory would allow processor speculation into that area,
+	 * and on some hardware (particularly the UV platform) even
+	 * speculative access to some reserved areas is caught as an
+	 * error, causing the BIOS to halt the system.
 	 */
 
 	pmd = fixup_pointer(level2_kernel_pgt, physaddr);
-	for (i = 0; i < PTRS_PER_PMD; i++) {
+
+	/* invalidate pages before the kernel image */
+	for (i = 0; i < pmd_index((unsigned long)_text); i++)
+		pmd[i] &= ~_PAGE_PRESENT;
+
+	/* fixup pages that are part of the kernel image */
+	for (; i <= pmd_index((unsigned long)_end); i++)
 		if (pmd[i] & _PAGE_PRESENT)
 			pmd[i] += load_delta;
-	}
+
+	/* invalidate pages after the kernel image */
+	for (; i < PTRS_PER_PMD; i++)
+		pmd[i] &= ~_PAGE_PRESENT;
 
 	/*
 	 * Fixup phys_base - remove the memory encryption mask to obtain