1 files changed, 37 insertions, 8 deletions

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 29258c75a2f3..a5d550f2fa6e 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -505,11 +505,14 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 /*
  * Keep the crash kernel below this limit.  On 32 bits earlier kernels
  * would limit the kernel to the low 512 MiB due to mapping restrictions.
+ * On 64bit, old kexec-tools need to under 896MiB.
  */
 #ifdef CONFIG_X86_32
-# define CRASH_KERNEL_ADDR_MAX  (512 << 20)
+# define CRASH_KERNEL_ADDR_LOW_MAX      (512 << 20)
+# define CRASH_KERNEL_ADDR_HIGH_MAX     (512 << 20)
 #else
-# define CRASH_KERNEL_ADDR_MAX  MAXMEM
+# define CRASH_KERNEL_ADDR_LOW_MAX      (896UL<<20)
+# define CRASH_KERNEL_ADDR_HIGH_MAX     MAXMEM
 #endif
 
 static void __init reserve_crashkernel_low(void)
@@ -519,19 +522,35 @@ static void __init reserve_crashkernel_low(void)
         unsigned long long low_base = 0, low_size = 0;
         unsigned long total_low_mem;
         unsigned long long base;
+        bool auto_set = false;
         int ret;
 
         total_low_mem = memblock_mem_size(1UL<<(32-PAGE_SHIFT));
+        /* crashkernel=Y,low */
         ret = parse_crashkernel_low(boot_command_line, total_low_mem,
                                                 &low_size, &base);
-        if (ret != 0 || low_size <= 0)
-                return;
+        if (ret != 0) {
+                /*
+                 * two parts from lib/swiotlb.c:
+                 *      swiotlb size: user specified with swiotlb= or default.
+                 *      swiotlb overflow buffer: now is hardcoded to 32k.
+                 *              We round it to 8M for other buffers that
+                 *              may need to stay low too.
+                 */
+                low_size = swiotlb_size_or_default() + (8UL<<20);
+                auto_set = true;
+        } else {
+                /* passed with crashkernel=0,low ? */
+                if (!low_size)
+                        return;
+        }
 
         low_base = memblock_find_in_range(low_size, (1ULL<<32),
                                         low_size, alignment);
 
         if (!low_base) {
-                pr_info("crashkernel low reservation failed - No suitable area found.\n");
+                if (!auto_set)
+                        pr_info("crashkernel low reservation failed - No suitable area found.\n");
 
                 return;
         }
@@ -552,14 +571,22 @@ static void __init reserve_crashkernel(void)
         const unsigned long long alignment = 16<<20;    /* 16M */
         unsigned long long total_mem;
         unsigned long long crash_size, crash_base;
+        bool high = false;
         int ret;
 
         total_mem = memblock_phys_mem_size();
 
+        /* crashkernel=XM */
         ret = parse_crashkernel(boot_command_line, total_mem,
                         &crash_size, &crash_base);
-        if (ret != 0 || crash_size <= 0)
-                return;
+        if (ret != 0 || crash_size <= 0) {
+                /* crashkernel=X,high */
+                ret = parse_crashkernel_high(boot_command_line, total_mem,
+                                &crash_size, &crash_base);
+                if (ret != 0 || crash_size <= 0)
+                        return;
+                high = true;
+        }
 
         /* 0 means: find the address automatically */
         if (crash_base <= 0) {
@@ -567,7 +594,9 @@ static void __init reserve_crashkernel(void)
                  *  kexec want bzImage is below CRASH_KERNEL_ADDR_MAX
                  */
                 crash_base = memblock_find_in_range(alignment,
-                               CRASH_KERNEL_ADDR_MAX, crash_size, alignment);
+                                        high ? CRASH_KERNEL_ADDR_HIGH_MAX :
+                                               CRASH_KERNEL_ADDR_LOW_MAX,
+                                        crash_size, alignment);
 
                 if (!crash_base) {
                         pr_info("crashkernel reservation failed - No suitable area found.\n");