[PATCH v6 1/2] x86/kexec: Build identity mapping for EFI systab and ACPI tables

Junichi Nomura j-nomura at ce.jp.nec.com
Tue May 14 22:17:19 PDT 2019

Hi Kairui,

On 5/13/19 5:02 PM, Baoquan He wrote:
> On 05/13/19 at 09:50am, Borislav Petkov wrote:
>> On Mon, May 13, 2019 at 03:32:54PM +0800, Baoquan He wrote:
>> So we're going to try it again this cycle and if there's no fallout, it
>> will go upstream. If not, it will have to be fixed. The usual thing.
>> And I don't care if Kairui's patch fixes this one problem - judging by
>> the fragility of this whole thing, it should be hammered on one more
>> cycle on as many boxes as possible to make sure there's no other SNAFUs.
>> So go test it on more machines instead. I've pushed it here:
>> https://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git/log/?h=next-merge-window
> Pingfan has got a machine to reproduce the kexec breakage issue, and
> applying these two patches fix it. He planned to paste the test result.
> I will ask him to try this branch if he has time, or I can get his
> machine to test.
> Junichi, also have a try on Boris's branch in NEC's test environment?

while the patch set works on most of the machines I'm testing around,
I found kexec(1) fails to load kernel on a few machines if this patch
is applied.  Those machines don't have IORES_DESC_ACPI_TABLES region
and have ACPI tables in IORES_DESC_ACPI_NV_STORAGE region instead.

So I think map_acpi_tables() should try to map both regions.  I tried
following change in addition and it worked.

Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd.

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 3c77bdf..3837c4a 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -56,12 +56,22 @@ static int mem_region_callback(struct resource *res, void *arg)
 	unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 	struct init_pgtable_data data;
+	int ret;
 	data.info = info;
 	data.level4p = level4p;
-	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;
+	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;
 static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; }

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