[PATCH] x86/kexec: Add ACPI NVS region to the ident map

[Kairui Song]

With the recent addition of RSDP parsing in decompression stage, kexec
kernel now needs ACPI tables to be covered by the identity mapping.
And in commit 6bbeb276b71f ("x86/kexec: Add the EFI system tables and
ACPI tables to the ident map"), ACPI tables memory region was added to
the ident map.

But on some machines, there is only ACPI NVS memory region, and the ACPI
tables is located in the NVS region instead. In such case second kernel
will still fail when trying to access ACPI tables.

So, to fix the problem, add NVS memory region in the ident map as well.

Fixes: 6bbeb276b71f ("x86/kexec: Add the EFI system tables and ACPI tables to the ident map")
Suggested-by: Junichi Nomura <j-nomura@xxxxxxxxxxxxx>
Signed-off-by: Kairui Song <kasong@xxxxxxxxxx>
---

Tested with my laptop and VM, on top of current tip:x86/boot.

 arch/x86/kernel/machine_kexec_64.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 3c77bdf7b32a..a406602fdb3c 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -54,14 +54,26 @@ static int mem_region_callback(struct resource *res, void *arg)
 static int
 map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p)
 {
-	unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+	int ret;
+	unsigned long flags;
 	struct init_pgtable_data data;
 
 	data.info = info;
 	data.level4p = level4p;
 	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
-	return walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
-				   &data, mem_region_callback);
+
+	ret = walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
+				  &data, mem_region_callback);
+	if (ret && ret != -EINVAL)
+		return ret;
+
+	/* ACPI tables could be located in ACPI Non-volatile Storage region */
+	ret = walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1,
+				  &data, mem_region_callback);
+	if (ret && ret != -EINVAL)
+		return ret;
+
+	return 0;
 }
 #else
 static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; }
-- 
2.21.0