arm64 fixes:

- Limit the linear region to 51-bit when KVM is running in nVHE mode
   otherwise, depending on the placement of the ID map, kernel-VA to
   hyp-VA translations may produce addresses that either conflict with
   other HYP mappings or generate addresses outside of the 52-bit
   addressable range.
 
 - Instruct kmemleak not to scan the memory reserved for kdump as this
   range is removed from the kernel linear map and therefore not
   accessible.
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Catalin Marinas:

 - Limit the linear region to 51-bit when KVM is running in nVHE mode.

   Otherwise, depending on the placement of the ID map, kernel-VA to
   hyp-VA translations may produce addresses that either conflict with
   other HYP mappings or generate addresses outside of the 52-bit
   addressable range.

 - Instruct kmemleak not to scan the memory reserved for kdump as this
   range is removed from the kernel linear map and therefore not
   accessible.

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: kdump: Skip kmemleak scan reserved memory for kdump
  arm64: mm: limit linear region to 51 bits for KVM in nVHE mode

arch/arm64/mm/init.c

@@ -30,6 +30,7 @@
 #include <linux/crash_dump.h>
 #include <linux/hugetlb.h>
 #include <linux/acpi_iort.h>
+#include <linux/kmemleak.h>
 
 #include <asm/boot.h>
 #include <asm/fixmap.h>
@@ -101,6 +102,11 @@ static void __init reserve_crashkernel(void)
 	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
 		crash_base, crash_base + crash_size, crash_size >> 20);
 
+	/*
+	 * The crashkernel memory will be removed from the kernel linear
+	 * map. Inform kmemleak so that it won't try to access it.
+	 */
+	kmemleak_ignore_phys(crash_base);
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 }
@@ -222,7 +228,21 @@ early_param("mem", early_mem);
 
 void __init arm64_memblock_init(void)
 {
-	const s64 linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual);
+	s64 linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual);
+
+	/*
+	 * Corner case: 52-bit VA capable systems running KVM in nVHE mode may
+	 * be limited in their ability to support a linear map that exceeds 51
+	 * bits of VA space, depending on the placement of the ID map. Given
+	 * that the placement of the ID map may be randomized, let's simply
+	 * limit the kernel's linear map to 51 bits as well if we detect this
+	 * configuration.
+	 */
+	if (IS_ENABLED(CONFIG_KVM) && vabits_actual == 52 &&
+	    is_hyp_mode_available() && !is_kernel_in_hyp_mode()) {
+		pr_info("Capping linear region to 51 bits for KVM in nVHE mode on LVA capable hardware.\n");
+		linear_region_size = min_t(u64, linear_region_size, BIT(51));
+	}
 
 	/* Remove memory above our supported physical address size */
 	memblock_remove(1ULL << PHYS_MASK_SHIFT, ULLONG_MAX);